This topic describes the kernel parameters for PolarDB for MySQL 8.0.
2025
November 5, 2025
Type | Parameter | Level | Description |
New | loose_imci_vector_index_dump_rows_threshold | Global | Controls the incremental write size for a vector index. A background task periodically checks the increment between the current vector index snapshot offset and the IMCI snapshot offset. When the number of incremental rows exceeds this threshold, the background task commits the new data rows and appends them to the vector index.
Note This parameter is available only for PolarDB for MySQL 8.0.2 clusters of minor version 8.0.2.2.30 and later. |
loose_imci_vector_index_train_rows | Global | A pre-training step is required before you build a quantization-based vector index. This parameter specifies the size of the vector data for pre-training and applies only to the FAISS_HNSW_PQ algorithm.
Note This parameter is available only for PolarDB for MySQL 8.0.2 clusters of minor version 8.0.2.2.30 and later. | |
loose_imci_parallel_build_vector_threads_per_table | Global | Building a vector index is a time-consuming operation. This parameter specifies the number of concurrent threads for building a vector index in the background.
Note This parameter is available only for PolarDB for MySQL 8.0.2 clusters of minor version 8.0.2.2.30 and later. | |
loose_imci_enable_vector_search | Session | Controls the use of AISearch to accelerate Approximate Nearest Neighbor (ANN) search.
Note This parameter is available only for PolarDB for MySQL 8.0.2 clusters of minor version 8.0.2.2.30 and later. | |
loose_imci_vector_search_filter_pct | Session | When the estimated selectivity of predicate filtering is greater than or equal to this parameter value, vector index retrieval is prioritized.
The current default value indicates that when the estimated selectivity of a predicate is greater than or equal to 20%, the system prioritizes vector index retrieval and then performs predicate filtering to obtain the retrieval results. Note This parameter is available only for PolarDB for MySQL 8.0.2 clusters of minor version 8.0.2.2.30 and later. | |
loose_imci_enable_vector_search_inline_filter | Session | Specifies whether a vector query that contains a predicate uses an inline filter.
Note This parameter is available only for PolarDB for MySQL 8.0.2 clusters of minor version 8.0.2.2.30 and later. | |
loose_imci_hnswpq_k_factor | Session | When the vector index uses the
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loose_dashscope_sk | Session | This parameter is used to set the API key required to call the remote Embedding service when the Note This parameter is available only for PolarDB for MySQL 8.0.2 clusters of minor version 8.0.2.2.31 and later. | |
Modified | innodb_lru_scan_depth | Global | Adjusts the LRU dirty page flushing threshold. You can modify this parameter in the console. Valid values: 100 to 1099511627776. Note
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loose_max_execution_time | Global | Controls the running time of a query statement. The default value is changed to 86400000. Valid values: 0 to 4294967295. Default value: 86400000. Unit: milliseconds. Note This parameter takes effect immediately. You do not need to restart the cluster. | |
autocommit | Global | Specifies whether to execute each individual SQL statement, such as
Note This parameter takes effect immediately. You do not need to restart the cluster. |
October 29, 2025
Type | Parameter | Level | Description |
New | loose_timer_cache_size | Global | Specifies the maximum number of timers that can be cached. This parameter is used to optimize database performance when the Valid values: 0 to 1000000. Default value: 0. Note This parameter is available for the following database engine versions:
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Modified | default_time_zone | Global | Specifies a time zone name. The valid values for the time zone parameter are expanded. |
October 21, 2025
Type | Parameter | Level | Description |
New | loose_imci_nci_lsm_enable_recover | Global | Indicates whether LOADING_NCI for an In-Memory Column Index (IMCI) can be resumed using checkpoints after a restart.
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loose_imci_max_open_table_concurrency | Global | Controls the maximum number of concurrent queries that can simultaneously open tables for an In-Memory Column Index (IMCI). Valid values: 1 to 9223372036854775807. Default value: 9223372036854775807. Note This parameter is available for the following database engine versions:
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loose_imci_query_priority | Global/Session | Adjusts the query priority for the In-Memory Column Index (IMCI) at the current session level. Valid values: -9999 to 9999. Default value: 0. Note This parameter is available for the following database engine versions:
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loose_innodb_btr_cur_fine_history_length | Global | Specifies that when the length of the Valid values: 10000 to 4294967295. Default value: 100000. Note This parameter is available for the following database engine versions:
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Modified | loose_imci_scheduling_policy | Global | You can control the scheduling policy for In-Memory Column Index (IMCI), which now supports priority scheduling (PRIORITY_QUEUE). Valid values:
Note This parameter is available for the following database engine versions:
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loose_innodb_ro_read_no_sync_enable | Global | The default value of this parameter is changed to ON. Enabling this parameter can significantly improve the page I/O read performance of read-only (RO) nodes.
Note This parameter is available for the following database engine versions:
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October 14, 2025
Type | Parameter | Level | Description |
New | loose_innodb_blob_prepare_pages | Global | Specifies whether to enable pre-allocation and write optimization for large object (BLOB) pages.
Note This parameter is available for the following database engine versions:
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loose_innodb_blob_prepare_max_extern_size | Global | The maximum BLOB length for which large object write optimization is enabled. Valid values: 8192 to 536870912. Default value: 409600. Unit: bytes. Note This parameter is available for the following database engine versions:
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Modified | loose_slow_log_record_imci | Global | Specifies whether to record IMCI information in the slow query log. The default value is changed from OFF to ON.
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September 18, 2025
Type | Parameter | Level | Description |
New | loose_innodb_polar_replica_skip_supremum | Global | Specifies whether to perform a right shift after a read-only node locates a page supremum record.
Note This parameter is available for the following database engine versions:
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August 11, 2025
Type | Parameter | Level | Description |
New | loose_innodb_flush_pages_using_space_id | Global | Specifies whether to enable the Faster TRUNCATE/DROP TABLE feature to quickly truncate or drop tables. Valid values:
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loose_ps_str_using_collation_connection | Session | When you use a Valid values:
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loose_adaptive_imci_chosen_rows_threshold | Session | Sets the minimum number of rows to trigger the adaptive execution plan switching feature during automatic request distribution among row store and column store nodes when you use the IMCI feature. Valid values: 0 to 18446744073709551615. Default value: 10000. Note
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loose_sql_ap_selects_refine_reason | Global | Specifies whether the system returns a detailed error code when an analytical processing (AP) query fails. Valid values:
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loose_partition_cost_enhancement_enabled | Global/Session | Optimizes the cost calculation logic for partitioned tables. Valid values:
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loose_hybrid_opt_fetch_imci_stats_thread_enabled | Global | Specifies whether to enable a background thread on a row store node to scrape performance statistics from a column store node. Valid values:
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loose_hybrid_opt_dispatch_enabled | Session | Specifies whether to enable the hybrid optimizer's automatic request distribution among row store and column store nodes. Valid values:
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loose_partition_wise_join_enabled | Global/Session | Specifies whether to enable the Valid values:
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Modified | loose_innodb_enable_ttl_purge | Global |
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loose_innodb_ttl_min_interval | Global |
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loose_innodb_ttl_purge_thread | Global |
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loose_innodb_ttl_cluster_index_purge_batch_size | Global |
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loose_innodb_ttl_index_purge_batch_size | Global |
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loose_innodb_ttl_purge_start_hour | Global |
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loose_innodb_ttl_purge_end_hour | Global |
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July 28, 2025
Type | Parameter | Level | Description |
New | loose_innodb_blob_slave_read_consistent | Global | Specifies whether to use slave_slow_read when reading LOBs on a secondary node. Valid values:
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loose_innodb_slave_dummy_index_cached_share_strategy | Global | Optimizes the time consumed by Runtime Apply and reduces the occurrence of slow SQL statements caused by cold data access on read-only (RO) nodes. Valid values:
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Modified | long_query_time | Global | The comment for the parameter is modified to include the unit. The default unit is seconds. Valid values: 0.03 to 31536000. The default value is 1. The unit is seconds. |
July 3, 2025
Type | Parameter | Level | Description |
New | loose_sql_big_selects | Session | Specifies whether to allow large-scale SELECT queries. Valid values:
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Modified | loose_imci_serverless_enable_proactive | Global | Specifies whether a Serverless column store node automatically scales out when a query is running or a DDL statement is in a queue. Valid values:
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June 26, 2025
Type | Parameter | Level | Description |
New | loose_innodb_ttl_finished_job_expired_days | Global | The TTL feature adds support for cleaning up expired data in the Valid values: 1 to 365. Default value: 90. The default unit is days. Note
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June 19, 2025
Type | Parameter | Level | Description |
New | loose_polar_performance_schema_enable_row_locks | Global | Specifies whether you can view row lock monitoring information when the Polar Performance Schema feature is enabled.
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Modified | loose_polar_enable_imci_with_standby | Global | Modify whether Standby nodes can attach IMCI read-only (RO) nodes by default. Valid values:
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May 22, 2025
Type | Parameter | Level | Description |
New | loose_imci_include_function_index_field | Global/Session | Specifies whether to create a columnstore index (IMCI) for function-based index columns when you build a columnstore index.
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loose_imci_card_est_using_index | Global/Session | Specifies whether to use a row store index to improve the cardinality estimation for the In-Memory Column Index (IMCI).
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loose_imci_groupby_lazy_load | Global/Session | Specifies whether to materialize all involved column values before executing a GROUP BY operation.
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loose_imci_implicit_orderby | Global/Session | Specifies whether to add an implicit sorting operation to queries without an ORDER BY clause to ensure the stability of the result set.
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loose_imci_implicit_orderby_rollup | Global/Session | Does In-Memory Column Index (IMCI) automatically add an implicit sort to make the order of the result set identical to that of MySQL when executing a query that contains ROLL UP?
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loose_imci_use_adapt_aggr | Global/Session | Specifies whether to use the adaptive GROUP BY algorithm when you execute In-Memory Column Index (IMCI) queries.
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loose_imci_optimize_const_join_memory | Global/Session | Specifies whether IMCI performs memory allocation optimization when transforming an IN subquery into a semi-join.
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loose_imci_hybrid_index_join_fanout | Global/Session | If the In-Memory Column Index (IMCI) optimizer selects an algorithm and the fanout of an index exceeds the preset threshold, the system proactively excludes that index from being used for an Index Join during the execution plan generation phase. Valid values: 0 to 9223372036854775807. Default value: 4. Unit: number. Note
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loose_imci_hybrid_index_search_rows | Global/Session | In the IMCI Hybrid Plan policy, if the number of point lookups in a query exceeds the threshold, the system will not use the Hybrid Plan to accelerate the query. Valid values: 0 to 9223372036854775807. Default value: 1024. Unit: number. Note
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loose_imci_query_quota_ratio | Global/Session | The percentage of memory that is actually used by a query executed by an In-Memory Column Index (IMCI) after the reserved memory is deducted. Valid values: 0.01 to 1.00. Default value: 0.8. Unit: percentage. Note
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loose_imci_window_small_sort_size | Global/Session | When an In-Memory Column Index (IMCI) executes a window function, the system selects the optimal execution algorithm based on the partition size and a row count threshold. Valid values: 0 to 9223372036854775807. Default value: 16384. Unit: rows. Note
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loose_polar_enable_explain_ddl | Global | Specifies whether to enable the EXPLAIN DDL feature.
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loose_polar_enable_explain_ddl_on_primary | Global | Specifies whether EXPLAIN DDL operations can be executed on the read/write node.
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loose_polar_max_collect_thd_num_in_explain_ddl | Global | Controls the number of potential MDL-blocking threads collected by EXPLAIN DDL. Valid values: 1 to 512. Default value: 16. Unit: number. Note
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May 19, 2025
Type | Parameter | Level | Description |
New | loose_innodb_polar_sync_fil_op_with_replica_time | Global | The maximum time the primary node waits for the secondary node to apply physical logs during a DDL file operation. Valid values: 1 to 31536000. Default value: 2. Unit: seconds. Note This parameter takes effect immediately. You do not need to restart the cluster. |
Modified | loose_pq_cte_parallel_scan | Global/Session | Specifies whether to allow parallel scanning on a materialized table in a Common Table Expression (CTE).
Note This parameter is available only for PolarDB for MySQL 8.0.2 clusters of minor version 8.0.2.2.6 and later. |
open_files_limit | Global | The maximum number of file descriptors that InnoDB can use. The valid value range is adjusted. Valid values: 4000 to 1000000. Default value: 655350. Unit: bytes. |
May 7, 2025
Type | Parameter | Level | Description |
New | loose_pq_enabled | Global | Specifies whether to enable parallel query.
Note This parameter is available only for PolarDB for MySQL 8.0.1 clusters of minor version 8.0.1.1.45 and later. |
loose_innodb_polar_primary_sync_tablespace_op_with_replica | Global | Specifies whether a file operation on the primary node waits for the secondary node to apply changes to a specific Log Sequence Number (LSN) during a DDL operation.
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loose_imci_nci_lsm_bp_shard | Global | Specifies the number of NCI Buffer Pool shards for In-Memory Column Index (IMCI). In scenarios with many IMCIs (number of columnstore indexes × loose_imci_nci_lsm_bp_shard × 245 bytes), you can reduce the number of shards to lower memory usage and improve resource utilization. Valid values: 1 to 2048. Default value: 800. Unit: number. | |
Modified | loose_max_digest_length | Global | The parameter can be modified without restarting the cluster. Specifies the maximum length of the digest text in the performance schema table. Valid values: 0 to 1048576. Default value: 1024. Unit: bytes. Note This parameter is available only for PolarDB for MySQL 8.0.1 clusters of minor version 8.0.1.1.39 and later. |
loose_innodb_orca_processor_threads | Global | Orca (compatible with the Redis protocol) number of command processing threads. Valid values: 1 to 512. Default value: {LEAST(GREATEST({DBNodeClassCPU*6},16),512)}. Unit: number. Note
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loose_innodb_orca_network_threads | Global | Orca (compatible with the Redis protocol) number of network threads. Note
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April 10, 2025
Type | Parameter | Level | Description |
New | loose_index_merge_limitation | Global/Session | Specifies whether to use INDEX MERGE in DML statements. Valid values: '[^'\"]*'. Default value: 'INTERSECTION_DML'. Note
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loose_extend_stats_expired_time | Global | Specifies the expiration time for extended statistics information. Valid values: 0 to 31536000. Default value: 0. Unit: seconds. Note
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April 2, 2025
Type | Parameter | Level | Description |
New | loose_adaptive_cost_threshold_for_imci | Global/Session | Specifies the cost threshold for adaptive request distribution between row and column stores, decoupling it from the original cost threshold. Valid values: 1 to 18446744073709551615. Default value: 50000. Note
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loose_imci_rb_ctrl_threads_cnt | Global/Session | Specifies the number of threads in the background task thread pool for the IMCI RowBuf module. Valid values: 8 to 512. Default value: 16. Note
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loose_imci_rb_ctrl_max_threads_cnt | Global/Session | Specifies the maximum number of threads in the background task thread pool for the IMCI RowBuf module. Valid values: 8 to 1024. Default value: 512. Note
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March 27, 2025
Type | Parameter | Level | Description |
New | loose_innodb_lf_hash_shard_count | Global | Optimizes the maintenance of statistics in scenarios with a massive number of tables, such as in a Software as a Service (SaaS) environment. This significantly improves the performance of table schema queries (such as DESC TABLE) and read/write operations under high concurrency. Valid values: 1 to 128. Default value: 1. Note This parameter is available for the following database engine versions:
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March 20, 2025
Type | Parameter | Level | Description |
New | loose_imci_enable_multi_stmt_query | Global/Session | Added a setting to control whether multi-statement queries can be routed to read-only column store nodes.
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loose_innodb_slave_log_apply_worker | Global | Allows you to flexibly adjust the number of Apply threads in the console to improve the replication performance of secondary nodes. Valid values: 1 to 64. Default value: 8. |
March 13, 2025
Type | Parameter | Level | Description |
New | loose_stats_manager_enabled | Global | Specifies whether to enable the statistics management feature. Valid values:
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loose_polar_enable_sic | Global | Specifies whether to enable the SIC communication feature. Valid values:
Note This parameter is available only for PolarDB for MySQL 8.0.2 clusters of minor version 8.0.2.2.28 and later. | |
loose_stats_manager_auto_gathering_mode | Global | Specifies whether to enable the automatic statistics update feature. Valid values:
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loose_extend_stats_enabled | Global | Specifies whether to enable the extended statistics feature. Valid values:
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loose_stats_manager_auto_gathering_interval | Global | The working interval for the automatic statistics update feature. Valid values: 0 to 18446744073709551615. Default value: 60. Unit: seconds. Note
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loose_stats_manager_auto_gathering_dop | Global | The degree of parallelism for the automatic statistics sampling feature. Valid values: 0 to 128. Default value: 2. Unit: number. Note
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loose_stats_manager_offload_task_timeout | Global | The task timeout for the automatic statistics sampling feature. Valid values: 0 to 18446744073709551615. Default value: 3600. Unit: seconds. Note
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loose_stats_task_cpu_threshold | Global | The CPU threshold that allows automatic statistics updates. Valid values: 0 to 100. Default value: 40. Note
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loose_stats_manager_offload_sample_max_mem_size | Global | The memory size for cross-node statistics sampling. Valid values: 1000000 to 18446744073709551615. Default value: 20000000. Unit: bytes. Note
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loose_stats_manager_offload_sample_max_rows | Global | The number of rows for cross-node statistics sampling. Valid values: 1 to 18446744073709551615. Default value: 10000000. Unit: rows. Note
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loose_extend_stats_use_column_stats | Global/Session | Specifies whether to use the column statistics feature. Valid values:
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loose_extend_stats_sample_max_mem_size | Global/Session | The memory size for extended statistics sampling. Valid values: 1000000 to 18446744073709551615. Default value: 20000000. Unit: bytes. Note
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loose_extend_stats_sample_max_rows | Global/Session | The number of rows for extended statistics sampling. Valid values: 1 to 18446744073709551615. Default value: 10000000. Unit: rows. Note
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Modified | loose_innodb_ro_read_no_sync_enable | Global | The RO No Sync parameter is made visible. Enabling this parameter can significantly improve the page I/O read performance of read-only (RO) nodes. Valid values:
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February 20, 2025
Type | Parameter | Level | Description |
Modified | loose_imci_query_wait_timeout | Global | This parameter is made dynamically adjustable in the console. The timeout for a queued IMCI query. Valid values: 1 to 9223372036854775807. Default value: 600. Unit: seconds. Note
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internal_tmp_disk_storage_engine | Global | This parameter is no longer displayed for PolarDB for MySQL 8.0.2. By default, internal temporary tables use the default storage engine, InnoDB. |
February 12, 2025
Type | Parameter | Level | Description |
New | loose_polar_output_connection_tp_state | Global | When you execute the Valid values:
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loose_imci_stats_scan_max_ndv | Global/Session | When collecting statistics, if the cardinality of a column is below a preset threshold, the optimizer will scan all rows of that column to obtain the most accurate statistics. Valid values: 0 to 9223372036854775807. Default value: 0. Unit: number. Note
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loose_imci_stats_expired_time | Global/Session | An In-Memory Column Index (IMCI), when monitoring statistics information, triggers an update if the update ratio is not met but the elapsed time exceeds the threshold. Valid values: 0 to 9223372036854775807. Default value: 9223372036854775807. Unit: seconds. Note
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Modified | loose_max_digest_length | Global | This parameter is made dynamically adjustable in the console. Specifies the maximum length of the digest text in the performance schema table. Valid values: 0 to 1048576. Default value: 1024. Unit: bytes. Note
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loose_thread_pool_high_priority_users | Global | This parameter is made dynamically adjustable in the console. By optimizing the console configuration, the high-priority user list is now dynamically configurable, supporting real-time parameter modification. Note
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innodb_online_alter_log_max_size | Global | This parameter is made dynamically adjustable in the console. Modifies the maximum size of the log file during online index creation. Valid values: 65536 to 1099511627775. Default value: 107374182400. Unit: bytes. Note This parameter takes effect immediately. You do not need to restart the cluster. |
January 16, 2025
Type | Parameter | Level | Description |
New | loose_innodb_enable_ttl_purge | Global | Specifies whether to enable the data cleanup (TTL) switch. Valid values:
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loose_innodb_ttl_min_interval | Global | Specifies the minimum allowed time when setting the data expiration time. Valid values: 0 to 4294967295. Default value: 100. The default unit is seconds. Note
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loose_innodb_ttl_purge_thread | Global | The number of threads for cleaning up expired TTL data. After modification, you must reset the Valid values: 2 to 32. Default value: 4. Unit: number. Note
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loose_innodb_ttl_cluster_index_purge_batch_size | Global | The number of primary keys to scan during TTL data cleanup. Valid values: 10000 to 1000000. Default value: 10000. Unit: number. Note
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loose_innodb_ttl_index_purge_batch_size | Global | The data in the TTL column index to scan during TTL data cleanup. Valid values: 500 to 1000000. Default value: 500. Unit: number. Note
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loose_innodb_ttl_purge_start_hour | Global | The start time for TTL data cleanup. The value cannot be greater than Valid values: 0 to 23. Default value: 0. Unit: seconds. Note
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loose_innodb_ttl_purge_end_hour | Global | The end time for TTL data cleanup. The value cannot be less than Valid values: 0 to 23. Default value: 0. Unit: seconds. Note
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loose_innodb_buffer_pool_instances | Global | Specifies the number of buffer pool instances. Valid values: 1 to 64. Default value: 8. Unit: number. |
January 10, 2025
Type | Parameter | Level | Description |
New | loose_polar_enable_imci_with_standby | Global | Specifies whether to allow standby nodes to attach IMCI read-only (RO) nodes. Valid values:
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loose_max_digest_length | Global | Specifies the maximum length of the digest text in the performance schema table. Valid values: 0 to 1048576. Default value: 1024. Unit: bytes. Note This parameter is available only for PolarDB for MySQL 8.0.1.1.39 and later. |
January 9, 2025
Type | Parameter | Level | Description |
New | loose_rows_examined_agg_all_query_blocks | Session | Specifies whether to aggregate the number of rows for all query blocks. Valid values:
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loose_polar_enable_explain_ddl | Global | Specifies whether to enable the EXPLAIN DDL feature. Valid values:
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loose_polar_enable_explain_ddl_on_primary | Global | Specifies whether to allow EXPLAIN DDL operations on the read/write node. Valid values:
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loose_polar_max_collect_thd_num_in_explain_ddl | Global | Controls the number of potential MDL-blocking threads collected by EXPLAIN DDL. Valid values: 1 to 512. Default value: 16. Note
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loose_adaptive_ordering_rows_threshold | Session | The threshold for the number of rows to check during the ordered index selection process of the adaptive execution plan switching feature. Valid values: 0 to 4294967295. Default value: 50000. Unit: rows. Note
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loose_sql_trace_sample_query_max_len | Global | The maximum length of an SQL Trace query. Valid values: 0 to 4294967295. Default value: 8192. Unit: bytes. Note
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2024
November 25, 2024
Type | Parameter | Level | Description |
New | loose_sql_require_primary_key | Session | Specifies whether a table must have a primary key when it is created and whether the primary key can be removed using an ALTER TABLE statement. Valid values:
Note This parameter takes effect immediately. You do not need to restart the cluster. |
Modified | innodb_open_files | Global | The innodb_open_files parameter is changed to a dynamic parameter, and its configurable range is expanded. Valid values: 11 to 81920. Default value: 20000. Unit: number. Note This parameter takes effect immediately. You do not need to restart the cluster. |
December 26, 2024
Type | Parameter | Level | Description |
New | loose_imci_proxy_invisible_before_recover_finish | Global | Specifies whether to allow SQL routing to the In-Memory Column Index (IMCI) node after the node starts and before the column index is ready. Valid values:
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Modified | loose_imci_nci_lru_cache_capacity | Global | The parameter is made dynamically adjustable in the console. Controls the size of the IMCI Valid values: [1-{DBNodeClassMemory*80/100}]. Default value: {DBNodeClassMemory*8/100}. Note
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December 19, 2024
Type | Parameter | Level | Description |
New | loose_join_cond_push_into_derived_mode | Session | Specifies whether to enable the join condition pushdown (join condition pushdown to a materialized derived table) feature. Valid values:
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loose_imci_in_to_semijoin_threshold | Global/Session | When the length of the IN list reaches this threshold, the optimizer converts the IN operator to a SEMI JOIN. Valid values: 0 to 9223372036854775807. Default value: 64. Unit: number. Note
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loose_imci_union_pipeline_size | Global/Session | The maximum number of UNION operations allowed in a single pipeline. Valid values: 2 to 1024. Default value: 3. Unit: number. Note
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loose_imci_expr_batch_size | Global/Session | The vectorized batch processing size for IMCI query execution. Valid values: 64 to 32768. Default value: 4096. Unit: rows. Note
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Modified | loose_derived_cond_pushdown_mode | Global | The default value of the parameter is changed from OFF to REPLICA_ON. Specifies whether to enable condition pushdown (pushing down WHERE clause conditions to derived tables). Valid values:
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loose_imci_in_multi_stmt_transaction | Global | The default value of the switch that supports IMCI read forwarding for multi-statement transactions is changed from OFF to ON. Note This parameter takes effect immediately. You do not need to restart the cluster. |
November 25, 2024
Type | Parameter | Level | Description |
New | loose_sql_require_primary_key | Session | Specifies whether a table must have a primary key when it is created and whether the primary key can be removed using an ALTER TABLE statement. Valid values:
Note This parameter takes effect immediately. You do not need to restart the cluster. |
Modified | innodb_open_files | Global | The innodb_open_files parameter is changed to a dynamic parameter, and its configurable range is expanded. Valid values: 11 to 81920. Default value: 20000. Unit: number. Note This parameter takes effect immediately. You do not need to restart the cluster. |
November 20, 2024
Type | Parameter | Level | Description |
New | loose_imci_in_multi_stmt_transaction | Global | Specifies whether to support reading IMCI columnstore data in multi-statement transactions. Valid values:
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Modified | loose_imci_lru_cache_capacity | Global |
Note DBNodeClassMemory: The memory size of the purchased cluster specifications. |
loose_imci_nci_lsm_memtbl_check_all_size | Global |
Default value: [DBNodeClassMemory*10/100]. Note DBNodeClassMemory: The memory size of the purchased cluster specifications. |
November 13, 2024
Type | Parameter | Level | Description |
New | loose_partition_level_mdl_enabled | Global | Specifies whether to enable the partition MDL feature. When enabled, this feature allows concurrent DDL and DML operations on different partitions. Valid values:
Note This parameter is available only for PolarDB for MySQL 8.0.2.2.6.1 and later. |
November 11, 2024
Type | Parameter | Level | Description |
Modified | loose_imci_scc_wait_csn_timeout_sec | Global |
Note This parameter takes effect immediately. You do not need to restart the cluster. |
November 7, 2024
Type | Parameter | Level | Description |
New | loose_imci_enable_query_fts_like | Session | Specifies whether to enable the conversion of full-text indexes for columnstore indexes, which converts
Note This parameter is available for the following database engine versions:
|
loose_imci_plan_use_mpp | Global/Session | Specifies whether to generate a Massively Parallel Processing (MPP) plan. Valid values:
Note This parameter is available for the following database engine versions:
| |
loose_imci_scc_wait_csn_timeout_sec | Global | The timeout period for an IMCI node to wait for SCC replication. Valid values: 0 to 1000000000. Default value: 1. Unit: seconds. Note
| |
loose_imci_mpp_cost_threshold | Global/Session | The minimum cost threshold for generating an MPP plan is the product of Valid values: 1 to 10000. Default value: 300. Unit: milliseconds. Note
|
October 17, 2024
Type | Parameter | Level | Description |
New | loose_innodb_log_io_threads | Global | The number of I/O threads for log flushing. Valid values: 1 to 64. Default value: 4. |
Modified | loose_allocator_policy_disabled | Global | Specifies whether to enable the memory control policy. Valid values:
Note This parameter is available for the following database engine versions:
|
loose_innodb_use_shadow_flush | Global | Specifies whether to enable the lock-free dirty data flushing feature. Valid values:
Note
|
October 10, 2024
Type | Parameter | Level | Description |
New | loose_adaptive_plans_switch | Global/Session | Controls whether to enable the adaptive execution plan switching feature. Valid values:
Note
|
loose_etl_from_imci | Global/Session | Controls whether to use ETL to read data from the column store. Valid values:
Note
| |
loose_max_adaptive_digest_length | Session | The maximum length of an adaptive digest. Valid values: [0, 67108864]. Default value: 2097152. Unit: bytes. Note
| |
loose_adaptive_plans_max_time | Global/Session | The maximum running time of an SQL statement that is eligible for the adaptive execution plan switching feature. If the actual running time of a query statement exceeds this threshold, the execution plan is not switched, even if the conditions for switching are met. Valid values: [0, 1800000]. Default value: 500. Unit: milliseconds. Note
| |
Modified | loose_xengine_bulk_load_size | Global/Session | Controls the batch size for pre-committed transactions that are supported by X-Engine. The range of valid values is modified to [1, 1073741824]. The default value is 100000. Unit: rows. Note
|
September 26, 2024
Type | Parameter | Level | Description |
New | loose_pq_mpp_enabled | Global | Specifies whether to enable the global switch for ePQ multi-node parallel queries. Valid values:
Note
|
loose_pq_remain_subq_on_leader_with_offset | Session | Specifies whether to enable subquery pushdown for ePQ parallel queries when a large LIMIT OFFSET clause is used. Valid values:
Note
| |
Modified | loose_innodb_purge_batch_size | Global | The default value is adjusted based on instance specifications to improve CPU utilization. |
2024.09.19
Type | Parameter | Level | Description |
New | loose_polar_support_cluster_mdl_preemption | Global/Session | Specifies whether to enable the preemptive Data Definition Language (DDL) feature for the read-write (RW) node. Valid values:
Note
|
loose_polar_primary_mdl_preempt_after_wait_second | Global | Sets the timeout period, in seconds, to wait for a blocked metadata lock (MDL) synchronization on the RW node. If the lock is not acquired within this period, the system preempts the waiting thread. The value range for this new parameter is [1-31536000]. The default value is 10. Note
|
2024.09.05
Type | Parameter | Level | Description |
New | loose_winmagic_mode | Global/Session | Specifies whether to enable WinMagic. Valid values:
Note
|
loose_subquery_coalesce_mode | Global/Session | Specifies whether to enable subquery merging. Valid values:
Note
| |
loose_simplify_subq_mode | Global/Session | Specifies whether to enable subquery simplification. Valid values:
Note
|
2024.08.29
Type | Parameter | Level | Description |
Modification | loose_imci_build_bloomfilter_max_field_len | Global |
|
August 22, 2024
Type | Parameter | Level | Note |
Added | loose_innodb_polar_wait_slave_reply_max_time | Global | After the semi-synchronous replication feature is enabled, this parameter specifies the maximum time that a write transaction waits for a sync confirmation from the secondary zone before the transaction is committed. If a confirmation is not received from the secondary zone within this time, the transaction is still committed. Value range: [0-18446744073709550]. Default value: 500. Unit: milliseconds. Note
|
loose_enable_large_trx_optimization | Global | Specifies whether to enable the Binlog large transaction optimization feature. Default value: OFF. Valid values:
Note
| |
loose_binlog_large_trx_threshold_up | Global | The threshold for the large transaction optimization for binary logging feature. When this feature is enabled, if the binary log from a single transaction exceeds this threshold, the transaction is committed using an optimized method.
Note
| |
Modify | loose_temptable_max_mmap | Global |
|
2024.08.15
Type | Parameter | Level | Description |
New | loose_innodb_polar_page_track | Global | Specifies whether to enable the SCC optimization feature MTT. Valid values:
Note This parameter applies to the following database engine versions:
|
Modified | default_time_zone | Global/Session | Expands the range of supported time zones for the
|
2024.08.01
Type | Parameter | Level | Description |
New | loose_predicate_deduce_mode | Global/Session | Specifies whether to enable transitive predicate generation. Valid values:
Note
|
2024.08.01
Type | Parameter | Level | Description |
Modified | loose_innodb_redo_log_buf_enable | Global | Configuration of this parameter in the console is no longer supported for MySQL 8.0.2 and later. |
loose_innodb_redo_log_buf_size | Global | Configuration of this parameter in the console is no longer supported for MySQL 8.0.2 and later. |
2024.07.25
Type | Parameter | Level | Description |
Modified | loose_temptable_max_mmap | Global |
|
2024.07.19
Type | Parameter | Level | Description |
New | loose_innodb_log_wait_for_flush_spin_delay | Global | The number of spin-waits for a transaction that is waiting for the redo log to be flushed to disk. Value range: [0, 18,446,744,073,709,551,615]. Default value: 25,000. |
loose_innodb_log_flusher_spin_delay | Global | The number of spin-waits required when the redo log is flushed to disk. Value range: [0, 18,446,744,073,709,551,615]. Default value: 25,000. | |
Modified | loose_innodb_log_writer_spin_delay | Global | Changes to the redo log write configuration now take effect without a cluster restart. |
2024.07.11
Type | Parameter | Level | Description |
New | loose_outer_join_transform_mode | Global/Session | Specifies whether to enable the transformation of outer joins to inner joins. Valid values:
Note This parameter applies to the database engine MySQL 8.0.2 with minor version 8.0.2.2.19 or later. |
July 4, 2024
Type | Parameter | Level | Description |
Add | loose_sync_gtids_to_replica | Global | Specifies whether to enable real-time synchronization of global transaction identifiers (GTIDs) to read-only nodes.
Note This parameter is available for the following database engine versions:
|
2024.06.26
Type | Parameter | Level | Description |
New | loose_distinct_elimination_mode | Global/Session | Specifies whether to enable the DISTINCT elimination feature. Valid values:
Note This parameter is available only for PolarDB for MySQL 8.0.2 and the minor version must be 8.0.2.2.23 or later. |
thread_pool_reset_waiting_state_before_queuing | Global | Specifies whether to reset the waiting state of a connection before it is queued in the thread pool. Valid values:
Note This parameter is available only for PolarDB for MySQL 8.0.1 and the minor version must be 8.0.1.1.43 or later. |
June 24, 2024
Type | Parameter | Level | Description |
Modified | loose_rds_audit_log_event_buffer_size | Global | Increases the maximum length of a single SQL statement in an audit log record to 1,048,576. |
June 21, 2024
Type | Parameter | Level | Description |
New | loose_enable_join_elimination_for_dml | Global/Session | Specifies whether to enable the JOIN elimination optimization feature for DML statements. Valid values:
Note This parameter applies only to PolarDB for MySQL version 8.0.1, and the minor version must be 8.0.1.1.43 or later. |
loose_hybrid_opt_compatible_transform_switch | Global/Session | Controls optimization options for the hybrid row-column execution optimizer for In-Memory Column Index (IMCI). The default value is an empty string. The options are as follows:
Example: Note This parameter applies only to PolarDB for MySQL 8.0.1 minor version 8.0.1.1.43 and later. |
June 20, 2024
Type | Parameter | Level | Description |
New | loose_deprecated_join_elim | Global/Session | Controls the LEFT JOIN elimination feature of the original
Note This parameter applies only to PolarDB for MySQL 8.0.2.2.24 and later. |
Modified | loose_join_elimination_mode | Global/Session | The JOIN elimination optimization is updated to support more scenarios. The default value of this parameter is changed to OFF. Note
|
2024.06.12
Type | Parameter | Level | Description |
New | mcv_improved_records_per_key | Global/Session | Specifies whether to use Most Common Values (MCV) to improve the estimation for Records per key. Valid values:
|
June 7, 2024
Type | Parameter | Level | Description |
New | loose_common_subcond_extract_mode | Global/Session | Specifies whether to enable the common sub-expression extraction feature. The valid values are:
Note This parameter is available only for PolarDB for MySQL 8.0.2.2.23.1 and later. |
loose_optimize_ref_access_cost | Global/Session | Specifies whether to optimize the cost estimation for the number of rows scanned in a JOIN ref index scan. The valid values are:
| |
limit_orderby_pushdown_mode | Global/Session | Specifies whether to enable the limit_orderby_pushdown feature. The valid values are:
|
June 5, 2024
Type | Parameter | Level | Description |
New | loose_thread_pool_idle_timeout | Global | The timeout period for idle threads in the thread pool. A worker thread is shut down if it remains idle for longer than this period. Valid values: 1 to 4294967295. The default value is 60. |
loose_innodb_log_wait_for_write_spin_delay | Global | Specifies the number of times a transaction spins while waiting for the redo log to be written to disk. Valid values: 0 to 18446744073709551615. The default value is 25000. | |
loose_imci_enable_hybrid_plan | Global | This parameter is introduced in version 8.0.2. Controls the Hybrid Plan feature that accelerates wide table queries. Valid values:
|
2024-05-29
Type | Parameter | Level | Description |
New | loose_gis_geometry_from_text_ignore_error | Global/Session | Controls whether the
|
loose_derived_cond_pushdown_mode | Global/Session | This parameter is new in version 8.0.1. Controls the condition pushdown feature from WHERE clauses to derived tables. Valid values:
| |
loose_having_cond_pushdown_mode | Global/Session | This parameter is new in version 8.0.1. Controls the HAVING condition pushdown optimization feature. Valid values:
| |
loose_subquery_cond_pushdown_mode | Global/Session | This parameter is new in version 8.0.1. Controls the predicate pushdown to subquery feature. Valid values:
| |
loose_enable_imci_mem_inhibit_pct_change | Global | This parameter is new in version 8.0.2.2.23. Specifies whether to allow online modification of the memory allocation ratio between In-Memory Column Index (IMCI) and InnoDB.
| |
Modified | imci_max_virtual_memory | Global | The default value is changed to DBNodeClassMemory × 3/5. This limits the maximum number of concurrent column store queries to 6 under the default setting. |
loose_xengine_use_memory_pct | Global | For versions 8.0.1.1.42 and later, and 8.0.2.2.23 and later, modifying this parameter does not require a restart. |
2024.05.16
Type | Parameter | Level | Description |
New | loose_csv_oss_query | Global | Specifies whether to push down query conditions for tables in OSS to OSS for execution. Valid values:
Note This parameter is available only for PolarDB for MySQL 8.0.2.2.23 and later versions. |
loose_csv_oss_file_filter | Global | Specifies whether to use the file filter optimization when querying tables in OSS. Valid values:
Note This parameter is available only for PolarDB for MySQL 8.0.2.2.23 and later versions. |
2024-05-10
Type | Parameter | Level | Description |
New | loose_enable_compatiable_optimize_for_imci | Global/Session | Controls whether certain optimization options for the row store also apply to the column store. Valid values:
Note This parameter is available only for PolarDB for MySQL 8.0.1.1.39 and later. |
loose_enable_join_elimination_for_dml | Global/Session | Specifies whether to enable the JOIN elimination feature for DML statements. Valid values:
|
May 9, 2024
Type | Parameter | Level | Description |
New | loose_enable_large_trx_optimization | Global | Controls the Binlog large transaction optimization mechanism. Valid values:
Note
|
loose_binlog_large_trx_threshold_up | Global | The threshold for the Binlog large transaction optimization feature. After you enable optimized binlog writing for large transactions, optimized binlog writing is triggered for a transaction when the size of binlogs generated by the transaction exceeds the threshold.
Note
|
May 7, 2024
Type | Parameter | Level | Description |
New | loose_use_oss_meta | Session | Specifies whether to use OSS META to manage OSS data. Valid values:
|
April 11, 2024
Type | Parameter | Level | Description |
Modified | loose_polar_allow_create_hybrid_partition | Global/Session | The default value is now OFF. |
loose_polar_allow_unique_check_ignore | Global/Session | The default value is now OFF. |
April 3, 2024
Type | Parameter | Level | Description |
Modified | loose_subquery_cond_pushdown_mode | Global/Session | The default value of this parameter is set to OFF. Note This parameter applies only to version 8.0.2. |
loose_derived_cond_pushdown_mode | Global/Session | The default value of this parameter is set to OFF. Note This parameter applies only to version 8.0.2. | |
loose_having_cond_pushdown_mode | Global/Session | The default value of this parameter is set to OFF. Note This parameter applies only to version 8.0.2. | |
loose_primary_fast_lookup | Global/Session | The default value of this parameter is set to OFF. Note This change applies only to version 8.0.2. |
April 2, 2024
Type | Parameter | Level | Description |
New | loose_imci_explain_print_row_cost | Global/Session | Specifies whether to display the row count and cost information in the column-based execution plan when you execute EXPLAIN for a query that is dispatched to a column store node. Valid values:
|
March 29, 2024
Type | Parameter | Level | Description |
New | loose_innodb_buffer_pool_resize_cancel | Global | Specifies whether to automatically cancel a blocked Buffer Pool scale-in operation during Serverless auto-scaling. The valid values are:
|
init_connect | Global | The SQL statement that is automatically executed when a new connection is established. The valid values are:
|
March 25, 2024
Type | Parameter | Level | Description |
New | loose_temptable_use_mmap | Global | Specifies whether the TempTable engine uses memory mapping (mmap) files. Valid values:
|
Modified | loose_innodb_use_shadow_flush | Global/Session | The default value of this parameter is changed to ON. Note This parameter applies only to version 8.0.1. |
March 21, 2024
Type | Parameter | Level | Description |
New | loose_imci_build_max_pddl_threads | Global | The number of threads for executing a parallel DDL statement on an In-Memory Column Index (IMCI). Valid values: 0 to 512. The default value is 0. |
loose_imci_max_pddl_threads_cpu_ratio | Global | The ratio used to adjust the total number of DDL execution threads for an IMCI based on the number of CPUs. Valid values: 0.1 to 100.0. The default value is 1.5. | |
loose_imci_enable_pack_order_key_changed_rebuild | Global | Specifies whether to rebuild a table when the order key of an IMCI changes. The valid values are as follows:
| |
loose_imci_pack_order_key_sort_level | Global | The sort level for DDL sorting on an IMCI. Valid values: 0 to 2. The default value is 1. |
2024-03-04
Type | Parameter | Level | Description |
Modified | default_storage_engine | Global | The XENGINE and xengine options are added to the value range of this parameter. |
2024.02.29
Type | Parameter | Level | Description |
Modified | loose_imci_default_pack_shift | Global | The value range for the parameter changed from 6–18 to 7–18. |
February 21, 2024
Type | Parameter | Level | Description |
New | loose_temptable_max_mmap | Global | The maximum amount of memory that the TempTable storage engine can allocate from memory-mapped (MMAP) files before it writes data to disk. Value range: 0 to 1099511627776. Default value: 322122547200. Unit: bytes. |
2024.02.04
Type | Parameter | Level | Description |
New | loose_imci_build_bloomfilter_max_field_len | Global | The maximum length of a field for building a Bloom filter for an In-Memory Column Index (IMCI). Value range: 1 to 4096. Default value: 64. Unit: Characters. |
2024.01.25
Type | Parameter | Level | Description |
New | loose_polar_archive_thread_cnt | Global | The maximum number of threads for archiving cold data in parallel. Valid values: 1 to 1024. Default value: 1. Note This parameter applies only to version 8.0.2. |
Modified | loose_max_oss_connections | Global | The valid value range for the |
January 22, 2024
Type | Parameter | Level | Description |
New | loose_innodb_support_instant_modify_charset | Global | Controls the instant character set modification feature. Valid values:
Note This parameter applies only to version 8.0.1. |
January 18, 2024
Type | Parameter | Level | Description |
New | loose_imci_enable_dynamic_filter | Global/Session | Controls the dynamic filter. Valid values:
|
loose_imci_dynamic_filter_in_limits | Global/Session | Specifies the maximum number of rows in the dynamic filter inlist. If the number of rows exceeds this threshold, the dynamic filter inlist is automatically disabled. Valid values: 1 to 100000. Default value: 1000. Unit: rows. |
2024.01.15
Type | Parameter | Level | Description |
New | loose_adaptive_plans_switch | Global/Session | Controls the PolarDB adaptive execution plan switching feature. Valid values:
Note This parameter is available only for version 8.0.1. |
loose_adaptive_plans_max_time | Global/Session | Specifies the maximum running time for an SQL statement to be eligible for adaptive plan switching. If a query statement's running time under its original plan exceeds this value, the plan is not switched, even if the switching threshold is met. Valid values: 0 to 1800000. The default value is 500. Unit: milliseconds. Note This parameter is available only for version 8.0.1. | |
loose_xformer_mode | Global/Session | Controls the cost-based query transformation feature. Valid values:
Note This parameter is available only for version 8.0.2. | |
loose_xformer_max_nested_level | Global/Session | The maximum depth of query blocks in a query statement. If the depth of query blocks in a query statement exceeds this value, the cost-based query transformation feature is disabled. Valid values: 1 to 64. The default value is 5. Note This parameter is available only for version 8.0.2. | |
loose_xformer_iteration_limit | Global | The maximum number of iterations for the cost-based query transformation feature. Valid values: 1 to 10. The default value is 1. Note This parameter is available only for version 8.0.2. | |
loose_xformer_search_strategy | Global | The space search strategy for the cost-based query transformation feature. Valid values:
Note This parameter is available only for version 8.0.2. |
2024.01.09
Type | Parameter | Level | Description |
New | loose_polarfs_cache_enabled | Global | Specifies whether to use the PFS cache to optimize the performance of non-O_DIRECT I/O. Valid values:
|
2023
December 25, 2023
Type | Parameter | Level | Description |
New | loose_xengine_max_background_compactions | Global | The maximum number of background compression threads in the X-Engine engine. Valid values: 2 to 22. Default value: 2. |
loose_xengine_max_total_wal_size | Global | The total size of transaction logs in the X-Engine engine. Valid values: {DBNodeClassMemory × 1/100} to {DBNodeClassMemory × 1/4}. The default value is calculated based on the cluster specifications and the memory allocation ratio of different engines. Unit: bytes. | |
loose_xengine_db_total_write_buffer_size | Global | The size of the write buffer in the X-Engine engine. Valid values: {DBNodeClassMemory × 1/20} to {DBNodeClassMemory × 1/4}. The default value is calculated based on the cluster specifications and the memory allocation ratio of different engines. Unit: bytes. | |
loose_xengine_block_cache_size | Global | The size of the read buffer in the X-Engine engine. Valid values: {DBNodeClassMemory × 3/20} to {DBNodeClassMemory × 3/4}. The default value is calculated based on the cluster specifications and the memory allocation ratio of different engines. Unit: bytes. | |
loose_xengine_max_background_flushes | Global | The maximum number of background threads used for flush operations in the X-Engine engine. Valid values: 1 to 64. Default value: 2. | |
Modified | loose_innodb_primary_flush_max_lsn_lag | Global/Session | The default value of the |
December 18, 2023
Type | Parameter | Level | Description |
New | max_connections | Global/Session | The maximum number of connections to the database. Valid values: 1 to 200,000. Default value: 2,312. |
max_user_connections | Global/Session | The maximum number of connections for a single user. Valid values: 10 to 200,000. Default value: 1,800. | |
innodb_buffer_pool_size | Global/Session | The size of the memory buffer for the InnoDB engine. Valid values: {DBNodeClassMemory × 1/4} to {DBNodeClassMemory × 4/5}. Default value: 3,328 MB. Unit: bytes. | |
innodb_log_buffer_size | Global/Session | The size of the buffer that the InnoDB engine uses to write to log files on disk. Valid values: 1048576 to 4294967295. Default value: 32 MB. Unit: bytes. |
December 12, 2023
Type | Parameter | Level | Description |
New | loose_polar_enable_imci_with_mm | Global | Specifies whether to allow the creation of an In-Memory Column Index (IMCI) in a Multi-master Cluster. Valid values:
|
December 11, 2023
Type | Parameter | Level | Description |
New | loose_pq_mpp_shared_subquery | Global/Session | Specifies whether to enable cross-node parallel execution for shared access subqueries in elastic parallel query (ePQ). Valid values:
Note This parameter applies only to version 8.0.2. |
loose_pq_mpp_allow_imci_node | Global/Session | Specifies whether elastic parallel query (ePQ) is allowed to schedule parallel worker tasks to column store nodes. Valid values:
Note This parameter applies only to version 8.0.2. |
November 22, 2023
Type | Parameter | Level | Description |
New | loose_imci_dynamic_pack_shift_policy | Global | Controls the dynamic adjustment policy for pack_shift. Valid values:
|
November 21, 2023
Type | Parameter | Level | Description |
New | loose_opt_outline_enable | Global | Controls whether to enable the Statement Outline feature. Valid values:
|
November 9, 2023
Type | Parameter | Level | Description |
New | loose_imci_enable_max_pddl_threads_adjust | Global | Specifies whether the column store node dynamically adjusts the maximum number of DDL threads based on cluster specifications when the In-Memory Column Index (IMCI) feature is enabled. Valid values:
|
loose_innodb_persist_replica_enable | Global | Controls whether read-only nodes remain available when the read/write node is unavailable. Valid values:
|
November 7, 2023
Type | Parameter | Level | Description |
New | derived_table_pruning_mode | Global/Session | Specifies the scope for enabling the feature that prunes redundant columns in derived tables. Valid values:
Note This parameter applies only to version 8.0.2. |
November 3, 2023
Type | Parameter | Level | Description |
New | loose_imci_mpp_partition_cnt | Global/Session | The number of partitions for data distribution in the multi-node parallel processing feature of In-Memory Column Index (IMCI). Valid values: 1 to 2,017. Default value: 293. |
October 25, 2023
Type | Parameter | Level | Description |
New | default_tmp_storage_engine | Global/Session | Sets the storage engine for temporary tables. Valid values:
|
tls_version | Global | Sets the encryption protocol version for OpenSSL. Valid values:
| |
Modified | collation_server | Global/Session | The value `utf8mb4_unicode_ci` is added to the valid values. |
Deleted | loose_imci_default_pack_shift_part | Global | The |
October 17, 2023
Type | Parameter | Level | Description |
New | loose_xengine_parallel_scan_enabled | Global | Specifies whether to allow parallel queries on tables in X-Engine. Valid values:
Note This parameter applies only to version 8.0.1. |
October 12, 2023
Type | Parameter | Level | Description |
New | loose_imci_enable_hybrid_plan | Global | Controls the Hybrid Plan feature for accelerating wide table queries. Valid values:
Note This parameter applies only to version 8.0.1. |
loose_imci_pruner_lru_cache_capacity | Global | Sets the cache size for the IMCI pruner in the bloom filter. Valid values: 8388608 to {DBNodeClassMemory × 20/100}. Default value: {DBNodeClassMemory × 1/100}. Unit: bytes. | |
loose_imci_default_write_policy | Global | Specifies the write policy for In-Memory Column Index (IMCI) data. Valid values:
| |
Modified | loose_records_threshold_for_parallelism | Global/Session | The valid range for this parameter is changed. The new valid range is 1 to 18446744073709551615. |
September 25, 2023
Type | Parameter | Level | Description |
New | loose_imci_default_pack_shift_part | Global | Sets the pack_shift size for creating an In-Memory Column Index (IMCI) on a partitioned table. Valid values: 6 to 18. Default value: 13. |
Modified | loose_imci_default_pack_shift | Global | The default value of this parameter is changed. The new default value is 14. |
September 5, 2023
Type | Parameter | Level | Description |
New | loose_max_oss_connections | Global | The maximum number of connections to Object Storage Service (OSS). Valid values: 1 to 100. Default value: 10. |
loose_imci_enable_read_during_load_nci | Global | Specifies whether the column store node is allowed to provide snapshot read services during the reconstruction of the row-to-column mapping relationship (LOADING_NCI) after a restart. Valid values:
| |
Modified | loose_imci_thread_pool_size | Global | The restart policy for the |
August 31, 2023
Type | Parameter | Level | Description |
New | loose_imci_enable_pack_order_key | Global/Session | Specifies whether to sort by order_key when rebuilding an In-Memory Column Index (IMCI). Valid values:
|
Modified | loose_imci_nci_bp_threads_cnt | Global | The default value of this parameter is changed to LEAST(GREATEST({DBNodeClassCPU}, 16), 32). |
loose_imci_nci_memtbl_threads_cnt | Global | The default value of this parameter is changed to LEAST(GREATEST({DBNodeClassCPU × 1/2}, 8), 32). |
August 17, 2023
Type | Parameter | Level | Description |
New | loose_xengine_bulk_load_size | Global/Session | The number of rows in a small transaction when a large transaction is split. Valid values: 1 to 1,073,741,824. Default value: 10,000. |
August 9, 2023
Type | Parameter | Level | Description |
New | innodb_ft_server_stopword_table | Global/Session | Sets the stop words for a full-text index. |
loose_imci_nci_lsm_bp_flushing_dirty_max | Global | The maximum memory that can be used for dirty pages to be flushed by the row-to-column mapping component of the In-Memory Column Index (IMCI). Valid values: {DBNodeClassMemory × 1/20} to {DBNodeClassMemory × 1/2}. Default value: {DBNodeClassMemory × 1/20}. Unit: bytes. | |
Modified | loose_oss_outfile_buffer_size | Global | The default value of this parameter is changed to GREATEST(LEAST({DBInstanceClassCPU - 4},1),4) × 33554432. |
Deleted | loose_nci_lsm_bp_flushing_dirty_max | Global | This parameter is deleted. |
July 31, 2023
Type | Parameter | Level | Description |
Modified | loose_imci_nci_bp_threads_cnt | Global | The default value of this parameter is changed to DBNodeClassCPU. |
loose_imci_nci_memtbl_threads_cnt | Global | The default value of this parameter is changed to DBNodeClassCPU × 1/2. |
July 14, 2023
Type | Parameter | Level | Description |
Modified | loose_mm_parallel_upgrade_degree | Global | The default value of this parameter is changed to 32. Note This parameter applies only to version 8.0.1. |
innodb_purge_threads | Global | The default value of this parameter is changed to LEAST(GREATEST({DBNodeClassCPU}, 4), 32). | |
innodb_purge_batch_size | Global | The default value of this parameter is changed to 1,000. |
July 10, 2023
Type | Parameter | Level | Description |
Modified | loose_sql_trace_type | Global/Session | A new SQL Trace type is added: SLOW_QUERY. |
July 3, 2023
Type | Parameter | Level | Description |
New | loose_imci_max_dop | Global/Session | The maximum degree of parallelism (DOP) for a single query statement on an In-Memory Column Index (IMCI). Valid values: 1 to 1,024. Default value: DBNodeClassCPU. |
loose_imci_query_memory_limit | Global/Session | The memory limit for a single query statement on an In-Memory Column Index (IMCI). Valid values: {DBNodeClassMemory × 1/20} to {DBNodeClassMemory × 1/2}. Default value: {DBNodeClassMemory × 1/10}. | |
loose_imci_execution_memory_limit | Global | The maximum memory that can be used by queries on an In-Memory Column Index (IMCI). Valid values: {DBNodeClassMemory × 1/10} to {DBNodeClassMemory × 1/2}. Default value: {DBNodeClassMemory × 3/20}. | |
loose_imci_io_channel_count | Global | The number of I/O threads for an In-Memory Column Index (IMCI). Valid values: 1 to 64. Default value: DBNodeClassCPU × 1. | |
loose_imci_lru_cache_capacity | Global | The cache space for an In-Memory Column Index (IMCI). Valid values: {DBNodeClassMemory × 1/10} to {DBNodeClassMemory × 1/2}. Default value: {DBNodeClassMemory × 3/20}. | |
loose_imci_nci_lsm_memtbl_check_all_size | Global | The maximum memory usage for the row-to-column mapping component of an In-Memory Column Index (IMCI). Valid values: {DBNodeClassMemory × 1/20} to {DBNodeClassMemory × 1/2}. Default value: {DBNodeClassMemory × 3/10}. | |
loose_imci_nci_bp_threads_cnt | Global | The number of background dirty page flushing threads for the row-to-column mapping component of an In-Memory Column Index (IMCI). Valid values: 1 to 128. Default value: DBNodeClassCPU × 7/20. | |
loose_imci_nci_memtbl_threads_cnt | Global | The number of background reorganization threads for the row-to-column mapping component of an In-Memory Column Index (IMCI). Valid values: 1 to 128. Default value: DBNodeClassCPU × 4/20. | |
loose_imci_parallel_load_nci_threads | Global | The number of threads for parallel recovery of the row-to-column mapping component during the startup and recovery of an In-Memory Column Index (IMCI). Valid values: 2 to 128. Default value: DBNodeClassCPU × 1/2. | |
Modified | loose_imci_auto_update_statistic | Global/Session | The default value of this parameter is changed to ASYNC. |
loose_imci_force_hash_match | Global/Session | The default value of this parameter is changed to ON. |
June 30, 2023
Type | Parameter | Level | Description |
New | loose_innodb_purge_history | Global | The retention period for a read view. Valid values: 0 to 1,000,000. Default value: 10,000. Unit: ms. Note This parameter applies only to version 8.0.2. |
Modified | loose_partition_level_mdl_enabled | Global | The default value of this parameter is changed to ON. Note This parameter applies only to version 8.0.2. |
max_prepared_stmt_count | Global | The default value of this parameter is changed to 100,000. |
June 28, 2023
Type | Parameter | Level | Description |
New | sort_buffer_size | Global/Session | The size of the buffer allocated for sort operations in each session. Valid values: 32768 to 4294967295. Default value: 1,024 KB. Unit: bytes. |
imci_enable_add_column_instant_ddl | Global/Session | Specifies whether to enable Instant DDL when adding a column to a table that has an In-Memory Column Index (IMCI). Valid values:
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Modified | loose_innodb_replica_share_log | Global | The default value of the parameter is changed to OFF. |
June 26, 2023
Type | Parameter | Level | Description |
New | loose_hybrid_partition_query_mix_engine_enabled | Global/Session | Controls whether partitions on non-InnoDB engines in a hybrid partition can be accessed. Valid values:
Note This parameter applies only to version 8.0.1. |
loose_dynamic_partition_prune_enabled | Global/Session | Specifies whether to enable dynamic partition pruning when you query a partitioned table. Valid values:
Note This parameter applies only to version 8.0.2. | |
loose_imci_parallel_build_threads_per_table | Global | Sets the number of threads for building an In-Memory Column Index (IMCI) for a single table. Valid values: 1 to 128. Default value: 8. | |
loose_imci_background_build_threads | Global | Sets the number of background job threads for generating an In-Memory Column Index (IMCI). Valid values: 1 to 128. Default value: 4. |
June 13, 2023
Type | Parameter | Level | Description |
New | binlog_row_metadata | Global | Sets the scope of table metadata added to the binary log when row-based logging is used. Valid values:
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May 30, 2023
Type | Parameter | Level | Description |
New | loose_default_collation_for_utf8mb4 | Global/Session | Sets the default collation when the character set is utf8mb4. Valid values:
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May 22, 2023
Type | Parameter | Level | Description |
New | loose_index_worst_seeks_cost | Session | Controls an optimizer feature. When enabled, the estimated cost of a ref index does not exceed a maximum value that is dynamically calculated by an internal algorithm. Valid values:
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lower_case_table_names | Global/Session | Specifies whether table names are case-sensitive. Valid values:
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loose_index_worst_seeks_cost_factor | Session | A factor used by the optimizer to calculate the maximum cost of a ref index when estimating the ref index cost. Valid values: 0.01 to 18446744073709551615. Default value: 1. | |
loose_innodb_estimate_range_least_sample_rows_enabled | Global | Specifies whether to read at least a certain number of rows before ending the estimation of scanned rows for an index dive. Valid values:
Note This parameter applies only to version 8.0.2. |
May 11, 2023
Type | Parameter | Level | Description |
Modified | loose_imci_thread_pool_size | Global | Allows you to set the maximum capacity of the In-Memory Column Index (IMCI) thread pool in the console. The value must be an integer from 1 to 2048. The default value is DBNodeClassCPU × 3. |
loose_innodb_polar_log_rdma_transfer | Global | Controls whether to transfer redo logs over an RDMA network. Valid values:
Note This parameter applies only to version 8.0.1. |
May 4, 2023
Type | Parameter | Level | Description |
New | loose_query_cache_size | Global | The upper limit on memory usage for the Fast Query Cache. Valid values: 0 to 6442450944. Unit: bytes. Default value: 4,096 MB. |
April 28, 2023
Type | Parameter | Level | Description |
New | loose_thread_pool_waiting_thread_timeout_sec | Global | The timeout period for a thread to wait for a lock (row lock, MDL, or CCL). After this period, the thread pool creates a new thread to process requests. Valid values: 0 to 31,536,000. Unit: seconds. Default value: 1. |
loose_mm_parallel_upgrade_degree | Global | The degree of parallelism for a minor version upgrade of a Multi-master Cluster (Database/Table). Valid values: 1 to 32. Default value: 1. Note This parameter applies only to version 8.0.1. | |
Modified | loose_innodb_redo_log_buf_size | Global | The upper limit of the valid range for this parameter is modified. |
April 22, 2023
Type | Parameter | Level | Description |
New | loose_slow_log_record_imci | Global | Specifies whether to add information related to In-Memory Column Index (IMCI) to the slow query log. Valid values:
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April 19, 2023
Type | Parameter | Level | Description |
New | loose_max_string_alloc_size | Global | Sets the maximum length of the SQL string that can be expanded during the execute phase of a prepared statement. Valid values: 0 to 4294967295. The default value is 0, which indicates no limit on the string length. Unit: bytes. |
loose_imci_force_hash_match | Global/Session | Controls the late materialization feature for In-Memory Column Index (IMCI). Valid values:
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loose_polar_nonblock_ddl_mode | Session | Controls the Nonblock DDL feature. Valid values:
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loose_polar_nonblock_ddl_lock_wait_timeout | Session | Sets the timeout period for acquiring an MDL-X lock. Valid values: 1 to 31,536,000. Unit: seconds. Default value: 1. | |
loose_polar_nonblock_ddl_retry_interval | Session | Sets the retry interval after a timeout for acquiring an MDL-X lock. Valid values: 1 to 31,536,000. Unit: seconds. Default value: 6. | |
loose_polar_nonblock_ddl_retry_times | Session | Sets the number of retries after a timeout for acquiring an MDL-X lock. Valid values: 0 to 31,536,000. The default value is 0, which is calculated based on the Note We recommend that you set this parameter to 4194304. | |
loose_plan_cache_type | Session | The mode for Auto Plan Cache. Valid values:
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loose_plan_cache_expire_time | Session | The time after which an execution plan in the Plan Cache that has not been hit is reclaimed. Unit: seconds. Valid values: 0 to UINT_MAX. Default value: 1800. | |
loose_auto_plan_cache_pct_threshold | Session | The percentage threshold of the optimization time relative to the overall execution time of a statement. Valid values: 0 to 100. Default value: 20. | |
loose_auto_plan_cache_time_threshold | Session | The overall execution time threshold for an SQL statement. Unit: microseconds. Valid values: 0 to ULONG_MAX. Default value: 400. | |
loose_auto_plan_cache_count_threshold | Session | When the Valid values: 0 to ULONG_MAX. Default value: 512. Note The cached execution plan takes effect only when the number of times it is cached in the Plan Cache is greater than or equal to the value of the |
April 13, 2023
Type | Parameter | Level | Description |
New | innodb_undo_log_truncate | Global | Enables or disables the undo log reclaim feature. Valid values:
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March 23, 2023
Type | Parameter | Level | Description |
New | loose_foreign_key_checks | Global/Session | Specifies whether to check foreign key constraints. Valid values:
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Modified | max_execution_time | Global/Session |
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March 15, 2023
Type | Parameter | Level | Description |
New | loose_thread_pool_ehs_enabled | Global | Controls the Thread Pool EHS feature. Valid values:
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loose_thread_pool_ehs_server_stall_active_conns_per_core_limit | Global | The number of active connections per CPU core for EHS, used to evaluate whether the database is in a high concurrency state. Valid values: 1 to 100. Default value: 3. | |
loose_thread_pool_ehs_server_stall_qps_limit | Global | The QPS limit. This is used to evaluate whether the database is in a high concurrency state. Valid values: 1 to 10,000,000. Default value: 20. Unit: times/second. | |
loose_thread_pool_ehs_tpgs_long | Global | The historical time referenced for evaluating the database status. Valid values: 1 to 1,000. Default value: 60. Unit: seconds. | |
loose_thread_pool_ehs_trx_long_sec_limit | Global | The time at which EHS marks a transaction as a long-running transaction. Valid values: 1 to 31,536,000. Default value: 100. Unit: seconds. | |
loose_thread_pool_ehs_detail_log | Global | Controls whether to print detailed EHS logs to the error log. Valid values:
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loose_kill_idle_transaction_timeout | Global/Session | The waiting time before an idle connection with an open transaction is killed. Valid values: 0 to 31,536,000. Default value: 0. Unit: seconds. Note A value of 0 indicates that the connection is never killed. | |
Modified | loose_range_optimizer_max_mem_size | Global/Session | The restart policy for the |
March 6, 2023
Type | Parameter | Level | Description |
New | loose_group_by_compatible_sorting | Global/Session | Controls the Group By sorting compatibility mode. Valid values:
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March 2, 2023
Type | Parameter | Level | Description |
Add | loose_mini_master_bw_list | Global | Specifies the blacklists and whitelists for RW nodes (master_id) in a multi-master backup high availability (HA) configuration. Use the following format: Use a plus sign ( For example, `+2,3;-4,5,6` indicates that nodes 2 and 3 are on the whitelist, and nodes 4, 5, and 6 are on the blacklist. Note This parameter is available only for version 8.0.1. |
Modified | information_schema_stats_expiry | Global/Session | Lets you set the time for the server to retrieve data from the storage engine and replace the data in the cache. The value can range from 0 to 31536000. The default value is 86400. The unit is seconds. Note This parameter applies only to version 8.0.1. |
February 22, 2023
Type | Parameter | Level | Description |
New | loose_bypass_thread_pool_ips | Global | The IP addresses of clients that can bypass the thread pool to connect to the database. Only IPv4 addresses are supported. Separate multiple addresses with commas (,), for example, '192.XX.XX.1,192.XX.XX.2'. |
loose_bypass_thread_pool_check_ignore_proxy | Global | Specifies whether to ignore the IP addresses of clients that connect to the database through a database proxy when
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loose_innodb_backquery_capacity_limit | Global | The size of the undo log for flashback queries. If the undo log size is greater than or equal to this value, the system reduces the time for flashback queries. Valid values: 100 to 200,000,000. Unit: MB. Default value: 100,000,000. | |
loose_pq_fallback_local_if_remote_invalid | Session | Specifies whether an elastic parallel query (ePQ) falls back to local execution when cross-machine scheduling fails. If fallback is disabled, an error is returned. Valid values:
Note This parameter applies only to version 8.0.2. | |
loose_pq_sched_adaptive_resource_factor | Global | Specifies whether elastic parallel query (ePQ) automatically adjusts its use of available resources based on the real-time load. Valid values are:
Note This parameter applies only to version 8.0.2. | |
loose_pq_sched_multi_nodes_mode | Global | The multi-node scheduling mode for elastic parallel query (ePQ). Valid values:
Note This parameter is available only in version 8.0.2. | |
loose_pq_sched_adaptive_resource_frequency | Global | The frequency at which elastic parallel query (ePQ) automatically adjusts the resource availability ratio. The value can range from 0 to 18446744073709551615. The default value is 3. The unit is seconds. Note This parameter applies only to version 8.0.2. | |
loose_pq_sched_adaptive_resource_inc_step | Global | The percentage for a single upward adjustment when elastic parallel query (ePQ) automatically adjusts the resource usage ratio. Valid values: 0 to 100. Default: 50. Note This parameter applies only to version 8.0.2. | |
loose_pq_sched_adaptive_resource_dec_step | Global | The percentage for a single resource scale-down when elastic parallel query (ePQ) performs an automatic adjustment. The value range is 0 to 100. The default value is 50. Note This parameter applies only to version 8.0.2. |
February 16, 2023
Type | Parameter | Level | Note |
Modify | loose_imci_optimizer_switch | Global/Session | Specifies whether to use Hybrid Plan to accelerate wide table queries. The valid values are:
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February 3, 2023
Type | Parameter | Level | Note |
Add | loose_join_elimination_mode | Global/Session | Controls the join elimination optimization feature. The valid values are as follows:
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loose_join_predicate_pushdown_opt_mode | Global/Session | Controls join condition pushdown optimization. Valid values:
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loose_having_cond_pushdown_mode | Global/Session | Controls the HAVING condition pushdown optimization feature. Valid values:
Note This parameter applies only to version 8.0.2. |
January 18, 2023
Type | Parameter | Level | Note |
Added | loose_xengine_sort_buffer_size | Global | The size of the DDL sort buffer. Valid values: 65536 to {DBNodeClassMemory × 1/32}. Default value: 4194304. Unit: byte. Note This parameter applies only to version 8.0.1. |
loose_awr_sqldetail_enabled | Global | Specifies whether to enable the SQL Detail feature. Valid values:
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loose_awr_sqldetail_switch | Global | The operation type for SQL detail records. The sub-switches are as follows:
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loose_awr_sqldetail_retention | Global | The retention period for audit records. Records that exceed this period are automatically deleted. Valid values: 0 to 18446744073709551615. Default value: 2592000. Unit: seconds. Note This parameter applies only to version 8.0.1. | |
loose_imci_auto_update_statistic | Global | Specifies whether the In-Memory Column Index (IMCI) optimizer recollects statistics information when the information is outdated. The valid values are as follows:
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loose_imci_max_enum_join_pairs | Global | The number of equivalent execution plans that the IMCI query optimizer can search when using the IMCI feature and enabling join reranking. Value range: 0 to 4294967295. Default: 2000. | |
loose_partial_result_cache_enabled | Global | Specifies whether to enable the Partial Result Cache feature. The valid values are as follows:
Note This parameter is available only in version 8.0.2. | |
loose_partial_result_cache_cost_threshold | Global | The cost threshold for PTRC. PTRC is used for a query only if its total cost exceeds this threshold. Valid values: 0 to 18446744073709551615. Default value: 10000. Note This parameter applies only to version 8.0.2. | |
loose_partial_result_cache_check_frequency | Global | The number of cumulative cache misses that triggers a PTRC dynamic feedback detection. Valid values: 0 to 18446744073709551615. Default: 200. Note This parameter is available only in version 8.0.2. | |
loose_partial_result_cache_low_hit_rate | Global | The low-watermark threshold for the PTRC hit rate. The optimizer uses PTRC only if the estimated hit rate is above this value. If the actual hit rate drops below this value, the dynamic feedback mechanism stops the use of PTRC. Valid values: 0 to 100. Default value: 20. Note This parameter applies only to version 8.0.2. | |
loose_partial_result_cache_high_hit_rate | Global | The high-water mark threshold for the PTRC hit rate. When memory usage reaches its limit and the hit rate exceeds this value, the memory cache is converted to a file storage cache. The cached data is also transferred to files. Valid values: 0 to 100. The default value is 70. Note This parameter applies only to version 8.0.2. | |
loose_partial_result_cache_max_mem_size | Global | The cumulative memory usage of PTRCs in a single query. A query can contain multiple PTRCs. The total memory used by these PTRCs cannot exceed this value. Valid values: 0 to 18446744073709551615. Unit: Byte. The default value is 67108864. Note This parameter applies only to version 8.0.2. | |
Modify | loose_max_parallel_workers | Global | You can change the maximum number of concurrent parallel worker threads in the console. Valid values: 0 to 10000. The default value is 1. |
January 4, 2023
Type | Parameter | Level | Note |
Modify | loose_csv_oss_buff_size | Session | The value range of the
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2022
2022-12-16
Type | Parameter | Level | Description |
New | loose_max_oss_outfile_threads | Session | The number of concurrent oss outfile threads that PolarDB can start. Valid values: 1 to 100. The default value is 1. Run the |
loose_oss_outfile_buffer_size | Session | The amount of memory that each oss outfile thread can use. A larger memory size generally results in a faster export speed. Valid values: 102400 to 536870912. Unit: bytes. The default value is 134217728. |
2022-11-28
Type | Parameter | Level | Description |
New | loose_sql_trace_type | Global | The SQL Trace type. Valid values:
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loose_sql_sharing_size | Global | The maximum memory size for SQL Sharing, which is a basic component of SQL Trace. Valid values: 8388608 to 1073741824. Unit: bytes. The default value is 134217728. | |
loose_sql_trace_plan_expire_time | Global | The expiration time for execution plans traced by SQL Trace. If an execution plan is not hit within this time, it is marked as expired and can be evicted. Valid values: 0 to 18446744073709551615. Unit: seconds. The default value is 604800. |
2022-11-11
Type | Parameter | Level | Description |
New | loose_oss_outfile_buffer_size | Session | The amount of memory that each oss outfile thread can use. Valid values: 102400 to 536870912. Unit: bytes. The default value is 134217728. Note This parameter is available only for version 8.0.1. |
loose_max_oss_outfile_threads | Session | The number of concurrent oss outfile threads that the current cluster can start. Valid values: 1 to 100. The default value is 1. Note This parameter is available only for version 8.0.1. | |
loose_imci_default_pack_shift | Global | Adjusts the default pack size for an In-Memory Column Index (IMCI). Valid values: 6 to 18. The default value is 16. Pack size (number of rows) = 2loose_imci_default_pack_shift. |
2022-10-27
Type | Parameter | Level | Description |
New | loose_imci_columnar_advise_buffer_size | Global | The maximum memory size for caching the intermediate results of Valid values: 0 to 18446744073709551615. Unit: bytes. The default value is 8388608. Note This parameter is available only for version 8.0.1. |
2022-10-24
Type | Parameter | Level | Description |
Modified | loose_innodb_logical_read_ahead_threads | Global | Adjusts the default number of threads for logical read-ahead. Note Available only for version 8.0.1. |
2022-10-14
Type | Parameter | Level | Description |
New | loose_innodb_polar_ddl_async_io | Global | A switch that controls the asynchronous I/O feature for DDL statements. Valid values:
Note This parameter is available only for version 8.0.1. |
loose_pq_cte_parallel_scan | Global | Enables the parallel materialization scan feature for Common Table Expressions (CTEs). Valid values:
Note This parameter is available only for version 8.0.2. | |
loose_pq_derived_enforce_sort_order | Global | Specifies whether to ensure that the output order of a parallel scan is the same as that of a sequential scan after the parallel scan feature for derived tables is enabled. Valid values:
Note This parameter is available only for version 8.0.2. | |
loose_pq_derived_table_parallel_scan | Global | Specifies whether to support parallel scans for materialized queries that contain derived tables. Valid values:
Note This parameter is available only for version 8.0.2. | |
loose_pq_semi_join_materialization_parallel | Global | Specifies whether to allow the inner table of a subquery in a semi-join to be accelerated in parallel when the semi-join is executed using MaterializeLookup or MaterializeScan in a parallel query.
Note This parameter is available only for version 8.0.2. | |
Modified | loose_thread_pool_enabled | Global | The thread pool is enabled by default for new clusters. |
2022-09-16
Type | Parameter | Level | Description |
New | loose_ccl_mode | Global | The action to take after the number of requests reaches the concurrency control limit. Valid values:
Note This parameter is available only for version 8.0.1. |
loose_polar_nonblock_ddl_mode | Global | A switch that controls the nonblocking DDL statement feature. Valid values:
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loose_polar_nonblock_ddl_retry_times | Global | The number of retries to acquire an MDL-X lock after a timeout. Valid values: 0 to 31536000. Unit: seconds. The default value is 0, which is calculated based on the Note This parameter is available only for version 8.0.1. | |
loose_polar_nonblock_ddl_lock_wait_timeout | Global | The timeout period for acquiring an MDL-X lock. Valid values: 1 to 31536000. Unit: seconds. The default value is 1. Note This parameter is available only for version 8.0.1. | |
loose_polar_nonblock_ddl_retry_interval | Global | The retry interval for acquiring an MDL-X lock after a timeout. Valid values: 1 to 31536000. Unit: seconds. The default value is 6. Note This parameter is available only for version 8.0.1. | |
loose_cost_threshold_for_mpp | Global | If the optimizer estimates that the cost of sequential execution for a query exceeds this threshold, the optimizer prioritizes the multi-node elastic parallel query policy. Valid values: 0 to 18446744073709551615. The default value is 0. This parameter is calculated using the following formula:
In the formula, N is the number of database nodes in the multi-node elastic parallel query (ePQ) cluster group. Note This parameter is available only for version 8.0.2. | |
loose_records_threshold_for_mpp | Global | If the optimizer estimates that the number of scanned records in a query exceeds this threshold, the optimizer prioritizes the multi-node elastic parallel query policy. Valid values: 0 to 18446744073709551615. The default value is 0. This parameter is calculated using the following formula:
In the formula, N is the number of database nodes in the multi-node elastic parallel query (ePQ) cluster group. Note This parameter is available only for PolarDB for AI version 8.0.2. | |
loose_pq_max_queuing_time | Global | During a parallel query, if the number of parallel worker threads exceeds the value of Valid values: 0 to 18446744073709551615. Unit: milliseconds. The default value is 200. Note This parameter is available only for version 8.0.2. |