This topic provides a detailed reference for the kernel parameters available in PolarDB for MySQL. You can find parameters organized by their corresponding features.
For compatibility with MySQL configuration files, some cluster parameters in the PolarDB console are prefixed with loose_.
General parameters
Parameter name | Scope | Description |
implicit_primary_key | Global | Controls whether to automatically generate an implicit primary key when a table is created without one. Valid values:
Note
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In-Memory Column Index (IMCI) parameters
Parameter name | Scope | Description |
loose_allow_implicit_imci_alter_comment | Session | Specifies an IMCI can be created by modifying table-level comments. Valid values:
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loose_imci_enable_pack_order_key | Global/Session | Controls the data sorting feature when creating an IMCI. Valid values:
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loose_imci_enable_pack_order_key_changed_rebuild | Global | Specifies whether to rebuild the table when the sort order of the IMCI changes. Valid values:
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loose_imci_parallel_build_threads_per_table | Global | The number of threads for a single table when setting the sort key for an IMCI. Valid values: 1 to 128. Default value: 8. |
loose_imci_optimizer_switch | Global/Session | Specifies whether to Use hybrid plans to accelerate wide table queries that meet the conditions. Valid values:
Note If the tables involved in the query statement do not have statistics information, or if the IMCI's cardinality estimation and cost calculation features are not enabled, the JOIN REORDER feature will not be enabled even if this parameter is set to ON. |
loose_imci_auto_update_statistic | Global/Session | Specifies whether the join reorder for the IMCI optimizer recollects statistics information when the statistics information is outdated. Valid values:
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loose_imci_max_enum_join_pairs | Global | The number of equivalent execution plans that the IMCI optimizer is allowed to search when IMCI is used and join reordering is enabled. Valid values: 0 to 4294967295. Default value: 2000. |
loose_etl_from_imci | Global/Session | Specifies whether to enable the use of ETL to read data from column store. Valid values:
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loose_etl_from_imci_compress | Global/Session | Specifies whether to compress files when reading data from a read-only IMCI node. Valid values:
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loose_imci_enable_hybrid_plan | Global | Controls the Hybrid Plan acceleration for wide table queries feature. Valid values:
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loose_imci_enable_window_function | Global | Specifies whether SQL statements that contain window functions can use the In-Memory Column Index feature. Valid values:
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loose_imci_min_virtual_memory | Global | The minimum memory required for queries using the column store index. Valid values: 1 to 9223372036854775807. Default value: DBNodeClassMemory*3/20. Unit: Byte. |
loose_imci_max_virtual_memory | Global | The maximum memory allowed for queries using the column store index. Valid values: 1 to 9223372036854775807. Default value: 9223372036854775807. Unit: Byte. |
loose_imci_ap_threshold | Global/Session | The threshold that determines whether SQL statements are distributed to IMCI nodes. Valid values: 1 to 18446744073709551615. Default value: 50000. Note When automatic routing between column store and row store is enabled, if the estimated execution cost of an SQL statement exceeds 50000, the statement is routed to an IMCI node. |
loose_cost_threshold_for_imci | Session | The estimated execution cost threshold for the current SQL statement within the IMCI nodeIMCI-related parameters. Valid values: 1 to 18446744073709551615. Default value: 50000. Note When automatic routing between column store and row store is enabled, if the estimated execution cost of an SQL statement exceeds 50000, a column store execution plan is selected. Otherwise, a row store execution plan is used. |
loose_imci_enable_query_trace | Global | Controls whether to print kernel error logs during the query optimization process of column store index. Valid values:
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loose_polar_enable_implicit_imci_with_create_table | Global | Specifies whether to add full table coverage column indexes to all new tables. Valid values:
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loose_imci_columnar_advise_buffer_size | Global | Sets the available memory size for the Valid values: 0 to 18446744073709551615. Default value: 8388608. Unit: Byte. |
loose_imci_default_pack_shift | Global | Sets the row group size of the column store index. Valid values: 7 to 18. Default value: 14. Note For PolarDB for MySQL 8.0.1 with minor version 8.0.1.1.36 or earlier, the default value of this parameter is 16. |
loose_slow_log_record_imci | Global | Specifies whether to add information related to column store index to slow logs. Valid values:
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loose_imci_default_write_policy | Global | Sets the write policy for column store index data. Valid values:
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Elastic parallel queries (EPQ) parameters
Parameter name | Scope | Description |
loose_max_parallel_degree | Global/Session | The maximum degree of parallelism for a single query, which is the maximum number of Workers for parallel execution. Valid values: 0 to 1024. Default value: 0. This value specifies that the elastic parallel query feature is disabled. Note
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loose_max_parallel_workers | Global | The maximum number of parallel worker threads allowed to run simultaneously. When this value is exceeded, parallel queries need to enter the task queue and wait. Valid values: 1 to 10000. Default value: twice the number of CPU cores. Note
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loose_queuing_parallel_degree_limit | Global | The maximum sum of DOP values for parallel queries that can enter the queue at a time. If the specified value is exceeded, parallel queries are prohibited and sequential execution is used. Valid values: 0 to 10000. Default value: 64. |
loose_pq_max_queuing_time | Global/Session | The maximum waiting time for parallel queries in the queue. If the waiting time exceeds this value, the query falls back to sequential execution. Valid values: 0 to 18446744073709551615. Default value: 200. Unit: milliseconds. |
loose_parallel_degree_policy | Global | Sets the parallel degree configuration policy for a single query. Valid values:
Note For more information about parallel degree configuration policies, see Parallel resource control strategy configuration. |
loose_records_threshold_for_parallelism | Session | If the optimizer estimates that a table in the statement has a scan record count exceeding this threshold, the optimizer considers selecting a parallel execution plan. Valid values: 0 to 18446744073709551615. Default value: 10000. Note If your business volume is small or the concurrency of complex query business is low, choose to set this threshold to 2000 or above. |
loose_cost_threshold_for_parallelism | If the optimizer estimates that the sequential execution cost of a query exceeds this threshold, the optimizer considers selecting a parallel execution plan. Valid values: 0 to 18446744073709551615. Default value: 50000. | |
loose_records_threshold_for_mpp | If the number of scanned rows of a table involved in a query statement exceeds this threshold, the optimizer considers using multi-node parallel execution. Valid values: 0 to 18446744073709551615. Default: 0, which means Automatically Taking N Times The Value Of Loose_records_threshold_for_parallelism, Where N Is The Number Of Nodes In The EPQ Cluster. | |
loose_cost_threshold_for_mpp | If the sequential execution cost of a query statement exceeds this threshold, the optimizer considers using multi-node parallel execution. Valid values: 0 to 18446744073709551615. Default value: 0, which means Automatically Taking N Times The Value Of Loose_cost_threshold_for_parallelism, Where N Is The Number Of Nodes. | |
loose_auto_dop_cpu_pct_hwm | Global | The CPU usage threshold. If CPU usage exceeds this threshold, PolarDB prohibits parallel query plans. Valid values: 0 to 100. Default value: 70. |
loose_auto_dop_mem_pct_hwm | The memory usage threshold. If memory usage exceeds this threshold, PolarDB prohibits parallel query plans. Valid values: 0 to 100. Default value: 90. | |
loose_auto_dop_iops_pct_hwm | The IOPS usage threshold. If IOPS usage exceeds this threshold, PolarDB prohibits parallel query plans. Valid values: 0 to 100. Default value: 80. |
Query optimization parameters
Parameter name | Scope | Description |
loose_polar_optimizer_switch | Global/Session | Only enables or disables the subquery folding feature. By default, subqueries are not merged. Valid values:
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Global/Session | Query optimization control switch. Valid values:
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Global/Session | The join condition pushdown switch. Valid values:
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loose_in_predicate_conversion_threshold | Global | Controls the IN predicate to JOIN conversion feature. When the number of elements in the IN list of an SQL statement is greater than or equal to this parameter value, the SQL statement is converted, and the IN predicate is converted to JOIN. Valid values: 0 to 999999. Default value: 5000. Note If this parameter is set to 0, the feature is disabled. |
loose_join_elimination_mode | Global | Controls the left join elimination feature. Valid values:
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loose_join_predicate_pushdown_opt_mode | Global | Controls on which nodes to enable the join condition pushdown feature. Valid values:
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loose_having_cond_pushdown_mode | Global | Controls on which nodes to enable the condition pushdown (HAVING to WHERE) feature. Valid values:
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loose_derived_cond_pushdown_mode | Global | Controls the condition pushdown (WHERE condition to derived table) switch. Valid values:
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loose_subquery_cond_pushdown_mode | Global | Controls the condition pushdown (WHERE clause to IN subquery) feature. Valid values:
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loose_join_cond_push_into_derived_mode | Global | Controls the condition pushdown (join condition to materialized derived table) feature. Valid values:
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loose_predicate_deduce_mode | Global | Controls the transitive predicate generation (enhanced condition pushdown) feature. Valid values:
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loose_plan_cache_type | Session | The auto plan cache mode. Valid values:
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loose_plan_cache_expire_time | Session | If an execution plan in the auto plan cache is not hit for this period of time, the memory is reclaimed. Unit: seconds. Valid values: 0 to 4294967295. Default value: 1800. |
loose_auto_plan_cache_pct_threshold | Session | The specified ratio of the optimization time of a SQL statement to the overall execution time. Valid values: 0 to 100. Default value: 20. |
loose_auto_plan_cache_time_threshold | Session | The upper limit of the total execution time of an SQL statement. Unit: microseconds. Valid values: 0 to 18446744073709551615. Default value: 400. |
loose_auto_plan_cache_count_threshold | Session | When the Valid values: 0 to 18446744073709551615. Default value: 512. Note The execution plan in the cache 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 |
loose_adaptive_plans_switch | Global/Session | Controls the adaptive execution plan switching feature. Valid values:
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loose_adaptive_cost_threshold_for_imci | Global/Session | Sets the cost threshold for row and column adaptive execution plan switching distribution. Valid values: 1 to 18446744073709551615. Default value: 50000. Note This parameter is supported for the following database engine versions:
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loose_adaptive_plans_max_time | Global/Session | The maximum execution time allowed for an SQL statement to switch adaptive execution plans. If the execution time of an SQL statement exceeds the value, the execution plan is not switched even if the threshold for execution plan switching is reached. Valid values: 0 to 1800000. Default value: 500. Unit: milliseconds. |
loose_adaptive_ordering_rows_threshold | Global/Session | Sets the checkpoint for adaptive selection of ordered indexes. The smaller the valid index value, the earlier the adaptive check and adjustment will be performed. Valid values: 0 to 4294967295. Default value: 50000. |
loose_optimizer_switch | Global/Session | The main control switch for Limit Offset pushdown. Variables related to the LIMIT OFFSET pushdown feature:
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loose_bloom_filter_enabled | Global/Session | The Bloom Filter optimization switch. Valid values:
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DDL optimization parameters
Parameter name | Scope | Description |
loose_innodb_support_instant_add_column | Global | The switch for the instantly add column feature. Valid values:
Note This parameter is supported for the following database engine versions:
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loose_innodb_polar_instant_modify_column_enable | Global | Controls the instantly modify column feature. Valid values:
Note The PolarDB for MySQL instantly modify column feature is in the canary release. To use this feature, go to the Quota Center, find the quota name based on the quota ID |
loose_innodb_polar_instant_modify_column_max_times | Global | Sets the maximum number of instantly modify column operations allowed for a single table. Valid values: 1 to 64. Default value: 16. |
loose_innodb_support_instant_modify_charset | Global | Controls the instantly change a column character set feature. Valid values:
Note Depending on your database engine versions:
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loose_innodb_polar_parallel_ddl_threads | Session | Controls the number of parallel threads for each DDL operation. Valid values: 1 to 16. Default value: 1, which means executing single-threaded DDL. If the value of this parameter is not 1 when you create secondary indexes, the parallel DDL feature is automatically enabled. Note If the value of this parameter is 1, the system uses two concurrent threads by default. |
innodb_parallel_build_primary_index | Global | Controls whether to allow the use of the parallel DDL feature when creating primary key indexes. Valid values:
Note This parameter is in the canary release. To use it, go to the Quota Center, find Quota Name as PolarDB Parallel Primary Key Creation Trial Whitelist, and click Apply in the Operation column to apply for a trial. |
loose_innodb_polar_use_sample_sort | Session | The sample sort optimization feature switch. Valid values:
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loose_innodb_polar_use_parallel_bulk_load | Session | The parallel bulk load optimization feature switch. Valid values:
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loose_innodb_polar_ddl_build_index_readahead | Global | The DDL readahead feature switch. Valid values:
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loose_innodb_polar_ddl_build_index_readahead_page_num | Global | The number of pages for DDL readahead. The size of a page is 16 KB. Valid values: 32 to 256. Default value: 64. |
loose_innodb_polar_ddl_async_io | Global | The DDL asynchronous I/O feature switch. Valid values:
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loose_innodb_polar_parallel_merge_ways | Session | The number of ways for merge sort. Valid values: 2 to 16. Default value: 2. This value indicates that the database uses two-way merge sort by default. If you specify a value greater than 2, the multi-way merge sort feature is enabled. |
loose_innodb_flush_pages_using_space_id | Global | The Faster TRUNCATE/DROP TABLE feature switch. Valid values:
Note PolarDB for MySQL clusters must run version 5.7 with minor version 5.7.1.0.21 or later. |
loose_polar_nonblock_ddl_mode | Session | The Nonblock DDL feature switch. Valid values:
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loose_polar_nonblock_ddl_retry_times | Session | Sets the number of retry attempts when obtaining a MDL-X lock times out. Valid values: 0 to 31536000. Default value: 0 (the value calculated from the Note We recommend that you set the value of this parameter to 4194304. |
loose_polar_nonblock_ddl_retry_interval | Session | Sets the time interval for retrying to obtain a MDL-X lock after a timeout. Valid values: 0 to 31536000. Unit: seconds. Default value: 6. |
loose_polar_nonblock_ddl_lock_wait_timeout | Session | Sets the timeout period for obtaining a MDL-X lock. Valid values: 1 to 31536000. Unit: seconds. Default value: 1. |
loose_innodb_bulk_load_page_grained_redo_enable | Global | The DDL physical replication optimization feature switch. Valid values:
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loose_polar_support_mdl_sync_preemption | Session | The preemptive DDL feature switch. Valid values:
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loose_polar_mdl_sync_preempt_after_wait_second | Global | Sets the timeout period for synchronizing MDL locks when they are blocked. If the MDL lock is not synchronized when the specified timeout period ends, a preemption thread is initiated. Valid values: 1 to 31536000. Default value: 10. |
loose_polar_enable_explain_ddl | Global | The EXPLAIN DDL feature switch. Valid values:
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loose_polar_max_collect_thd_num_in_explain_ddl | Global | Controls the number of potential MDL blocking threads to collect. Valid values: 1 to 512. Default value: 16. |
loose_polar_performance_schema | Global | Controls whether to enable the Polar Performance Schema feature. Valid values:
Note You need to set the loose_polar_performance_schema parameter to |
performance_schema_max_thread_instances | Global | Configures the maximum number of threads that Polar Performance Schema can monitor. Valid values: -1 to 65536. A value of -1 indicates that the number of threads is automatically adjusted to adapt to business changes. Note This parameter is tuned. We recommend that you do not modify this parameter. |
performance_schema_max_metadata_locks | Global | Configures the maximum number of MDLs that Polar Performance Schema can monitor. Valid values: -1 to 1048576. A value of -1 indicates that the number of MDLs is automatically adjusted to adapt to business changes. Note This parameter is tuned. We recommend that you do not modify this parameter. |
loose_recycle_bin | Global/Session | The table recycle bin feature switch. Valid values:
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loose_recycle_scheduler | Global | The asynchronous cleanup task thread switch for the recycle bin. Valid values:
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loose_recycle_bin_retention | Global | The maximum retention period for data in the recycle bin. Valid values: 86400 to 1209600 (14 days). Unit: seconds. Default value: 604800 (7 days). Important The status of the recycle bin cleanup task thread is as follows:
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Binary log management parameters
Parameter name | Scope | Description |
loose_enable_large_trx_optimization | Global | Enables or disables the binary logging large transaction optimization mechanism. Valid values:
Note Changes to this parameter take effect immediately without the need to restart the cluster. |
loose_binlog_large_trx_threshold_up | Global | The threshold for binary logging large transaction optimization. After optimized binary log writing for large transactions is enabled, optimized binary log writing is triggered when the size of binary logs generated by a transaction exceeds the threshold. Valid values: 10 MB to 300 GB. Default value: 1 GB. Note Changes to this parameter take effect immediately without the need to restart the cluster. |
High concurrency optimization
Parameter name | Scope | Description |
loose_ccl_mode | Global | The behavior of SQL statements when the concurrency limit is exceeded. Valid values:
Note Only PolarDB for MySQL 8.0 supports this parameter. For PolarDB for MySQL 5.6 and 5.7 clusters, the SQL statement waits when the maximum number of concurrent threads is reached. |
loose_ccl_max_waiting_count | Global | When the Valid values: 0 to 65536. Default value: 0. Note Only PolarDB for MySQL 5.7 and 8.0 support this parameter. |
loose_hotspot | Global | The main switch for the hot row optimization feature. Valid values:
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loose_thread_pool_enabled | Global | Specifies whether to enable the thread pool feature. Valid values:
Note
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loose_thread_pool_size | Global | The number of thread groups in the thread pool. The valid values vary based on the number of CPU cores in the primary node. Valid values: DBNodeClassCPU to DBNodeClassCPU*10. Default value: DBNodeClassCPU*2. Note
Examples:
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loose_thread_pool_high_prio_mode | Global | The high-priority queue mode for the thread pool. Valid values:
Note Only PolarDB for MySQL 5.6 and 5.7 support this parameter. |
loose_thread_pool_high_prio_tickets | Global | The maximum number of tickets for the queue with a high priority. Valid values: 0 to 4294967295. Default value: 4294967295. Note Only PolarDB for MySQL 5.6 and 5.7 support this parameter. |
loose_thread_pool_idle_timeout | Global | The time threshold for releasing idle threads in the thread pool. Idle threads that have not served any requests for longer than this threshold are released. Valid values: 0 to 31536000. Default value: 60. Unit: seconds. Note Only PolarDB for MySQL 5.6 and 5.7 support this parameter. |
loose_thread_pool_oversubscribe | Global | The maximum number of active threads allowed in each thread group. Valid values: 1 to 1000. Default value: 20. An active thread is a thread that is executing a SQL statement. A thread is not active if the statement that the thread is executing is in the following status:
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loose_thread_pool_stall_limit | Global | The time threshold for determining whether the thread pool enters the congested state. When the thread pool enters the congested state, the system creates new threads to execute SQL statements. Valid values: 1 to 18446744073709551615. Default value: 10. Unit: milliseconds. Note For database engine MySQL 5.6, the default value is 30 milliseconds. |
loose_bypass_thread_pool_ips | Global | Client IP addresses that are not blocked by the thread pool. Even if the thread pool is full, SQL statements from these IP addresses can be executed for management operations. Sample configurations: Note Only PolarDB for MySQL 8.0.1 with minor version 8.0.1.1.19 supports this parameter. |
loose_bypass_thread_pool_check_ignore_proxy | Global | Database accounts with a high priority. Requests from these accounts are placed in the high-priority queue of the thread pool for priority processing. Sample configurations: Note
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loose_thread_pool_high_priority_users | Global | The timeout threshold for DDL operations in the thread pool. When the threshold is reached, the DDL statements are marked as timeout, and the system automatically creates a new thread to execute the statements. Valid values: 0 to 864000. Default value: 600. Unit: seconds. Note Only PolarDB for MySQL 8.0.1 with minor version 8.0.1.1.19 supports this parameter. |
loose_thread_pool_mark_ddl_thread_timeout_sec | Global | The timeout threshold for DDL operations in the thread pool. When the threshold is reached, the DDL operation is labeled as timed out, and the system automatically creates a new thread to execute the operation. Valid values: 0 to 864000. Default value: 600. Unit: seconds. Note Only PolarDB for MySQL 8.0.1 with minor version 8.0.1.1.19 supports this parameter. |
loose_thread_pool_mark_ddl_thread_timeout_immediately | Global | Specifies whether to immediately mark DDL operations as timeout when the thread pool is under high load and the low-priority queue is stacked. In this case, the system creates a new thread to execute the request. This parameter is applicable to scenarios where many DDL statements are executed. Valid values:
Note Only PolarDB for MySQL 8.0.1 with minor version 8.0.1.1.19 supports this parameter. |
loose_innodb_polar_blink_tree | Global | Controls the B-tree concurrency control optimization mechanism. Valid values:
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Partitioned table parameters
Parameter | Scope | Description |
loose_partition_level_mdl_enabled | Global | The online partition maintenance feature switch. Valid values:
Note You must restart the cluster to validate the modification. |
loose_hybrid_partition_query_mix_engine_enabled | Global | Specifies whether to query partition data in non-InnoDB engines when querying hybrid partitioned tables. Valid values:
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Flashback query parameters
Parameter | Scope | Description |
loose_innodb_backquery_enable | Global | Enables or disables the flashback query feature. Valid values:
Note
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loose_innodb_backquery_window | Global | The time duration supported by flashback queries. Valid values: 1 to 604800. Default value: 86400. Unit: seconds. |
loose_innodb_backquery_capacity_limit | Global | The undo log capacity supported by flashback queries. When the undo log capacity is greater than or equal to this value, the time duration supported by flashback queries is shortened. Valid values: 100 to 200000000. Default value: 100000000. Unit: MB. |
Cold data archiving parameters
Parameter | Scope | Description |
loose_csv_oss_buff_size | Session | The memory size occupied by a single OSS thread. Default value: 134217728. Unit: Byte. Valid values: 4096 to 134217728. |
loose_csv_max_oss_threads | Global | The number of OSS threads allowed to run currently. Valid values: 1 to 100. Default value: 1. Unit: threads. |
loose_max_oss_outfile_threads | Session | The number of OSS OUTFILE threads that PolarDB can start simultaneously. Valid values: 1 to 100. Default value: 1. Unit: threads. Use the Note For clusters running PolarDB for MySQL 8.0.1.1.38 or later, this parameter is invalid. |
loose_oss_outfile_buffer_size | Global | The memory size that a single OSS OUTFILE thread can use. In most cases, the export speed increases if a thread can use more memory. Valid values: 102400 to 536870912. Default value: 134217728. Unit: Byte. |
Data cleanup parameters
Parameter name | Scope | Description |
loose_innodb_enable_ttl_purge | Global | Specifies whether to enable the time to live (TTL) feature. Valid values:
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loose_innodb_ttl_min_interval | Global | The minimum TTL value. Valid values: 0 to 4294967295. Default value: 100. Default unit: seconds. |
loose_innodb_ttl_purge_thread | Global | The number of threads for purging expired data in data cleanup (TTL). After modification, reset the Valid values: 2 to 32. Default value: 4. Unit: threads. |
loose_innodb_ttl_cluster_index_purge_batch_size | Global | The number of primary keys scanned during data cleanup (TTL). Valid values: 10000 to 1000000. Default value: 10000. Unit: keys. |
loose_innodb_ttl_index_purge_batch_size | Global | The data scanned from the TTL column index during data cleanup (TTL). Valid values: 500 to 1000000. Default value: 500. Unit: rows. |
loose_innodb_ttl_purge_start_hour | Global | The start time for data cleanup (TTL). This value must not exceed Valid values: 0 to 23. Default value: 0. Unit: seconds. |
loose_innodb_ttl_purge_end_hour | Global | The end time for data cleanup (TTL). This value must not be less than Valid values: 0 to 23. Default value: 0. Unit: seconds. |
Parameters in other features
Parameter name | Scope | Description |
loose_innodb_polar_log_rdma_transfer | Global | The RDMA log transfer feature switch. Valid values:
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loose_partial_result_cache_enabled | Global/Session | The Partial Result Cache (PTRC) feature switch. Valid values:
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loose_partial_result_cache_cost_threshold | Global/Session | The cost threshold for Partial Result Cache (PTRC). PTRC is triggered only if the cost of the entire query exceeds this threshold value. Valid values: 0 to 18446744073709551615. Default value: 10000. |
loose_partial_result_cache_check_frequency | Global/Session | The frequency of triggering dynamic feedback detection for Partial Result Cache (PTRC). A detection is triggered when the cumulative number of cache misses reaches this value. Valid values: 0 to 18446744073709551615. Default value: 200. |
loose_partial_result_cache_low_hit_rate | Global/Session | The low watermark threshold for the hit rate of Partial Result Cache (PTRC). The system uses PTRC only if the estimated hit rate is higher than this value, and stops using PTRC if the actual hit rate becomes lower than this value during execution of the query. Valid values: 0 to 100. Default value: 20. |
loose_partial_result_cache_high_hit_rate | Global/Session | The high watermark threshold for the hit rate of Partial Result Cache (PTRC). If the maximum amount of memory used by PTRC is reached, and the hit rate is higher than this value, the cached results are dumped from memory to disks, and new cache is stored in disks. Valid values: 0 to 100. Default value: 70. |
loose_partial_result_cache_max_mem_size | Global/Session | The cumulative memory usage of Partial Result Cache (PTRC) in a single query. A query may have multiple PTRCs. The total memory used by multiple PTRCs cannot exceed this value. Valid values: 0 to 18446744073709551615. Default value: 67108864. Unit: Byte. |