PolarDB-X uses a storage-computing decoupled architecture. The storage layer (data node) parameters follow MySQL naming conventions. The table below lists common storage layer parameters you can configure in the PolarDB-X console. For all other parameters, see MySQL server system variables.
Restart required indicates whether the instance must be restarted for a parameter change to take effect. Parameters marked No take effect immediately after you save the change. Parameters marked Yes take effect only after you manually restart the instance — plan restarts accordingly to avoid service interruptions.
| Parameter | Restart required | Default value | Valid value | Description |
|---|---|---|---|---|
| loose_enable_gts | Yes | 1 | [0|1] | Whether to enable the Global Timestamp Service (GTS). |
| loose_gts_lease | Yes | 5000 | [0-10000] | Lease period of GTS. Unit: milliseconds. |
| performance_schema | No | ON | [ON,OFF] | Whether to monitor the performance of the ApsaraDB RDS for MySQL server. |
| binlog_rows_query_key_content | No | ON | [ON,OFF] | Whether to include SQL statements in binary logs. |
| loose_polarx_max_allowed_packet | No | 16777216 | (0-2147483648) | Maximum size of packets received and sent by the server over proprietary protocols. Unit: bytes. |
| innodb_buffer_pool_load_at_startup | Yes | ON | [ON|OFF] | Whether to reload the buffer pool after the server starts. |
| bulk_insert_buffer_size | No | 4194304 | [0-4294967295] | Number of records written to the temporary cache when batch-inserted data is cached. |
| show_old_temporals | No | OFF | [ON|OFF] | - |
| ft_query_expansion_limit | Yes | 20 | [0-1000] | Maximum number of matches when performing full-text searches on MyISAM tables using WITH QUERY EXPANSION. |
| innodb_old_blocks_time | No | 1000 | [0-1024] | Time window after the midpoint of a page is read, during which the page can be accessed without being promoted to the most-recently-used end of the LRU list. Unit: milliseconds. |
| innodb_stats_sample_pages | No | 8 | [1-4294967296] | Number of index pages sampled when estimating index statistics. |
| thread_stack | Yes | 262144 | [131072-18446744073709551615] | Memory allocated per connection thread. Unit: bytes. |
| lc_time_names | No | en_US | [ja_JP|pt_BR|en_US] | Language used to display day and month names and abbreviations. |
| innodb_thread_concurrency | No | 0 | [0-1000] | Maximum number of concurrent InnoDB threads. |
| default_time_zone | Yes | SYSTEM | [SYSTEM|-12:00|-11:00|-10:00|-9:00|-8:00|-7:00|-6:00|-5:00|-4:00|-3:00|-2:00|-1:00|+0:00|+1:00|+2:00|+3:00|+4:00|+5:00|+5:30|+5:45|+6:00|+6:30|+7:00|+8:00|+9:00|+10:00|+11:00|+12:00|+13:00] | Server time zone. |
| old_passwords | No | 0 | [0|2] | - |
| optimizer_search_depth | No | 62 | [0-62] | Recursion depth of the query optimizer when multiple tables are correlated. |
| innodb_compression_level | No | 6 | [0-9] | - |
| loose_innodb_log_optimize_ddl | No | OFF | [ON|OFF] | - |
| max_sort_length | No | 1024 | [4-8388608] | - |
| slave_pending_jobs_size_max | No | 1073741824 | [1024-18446744073709551615] | - |
| innodb_online_alter_log_max_size | No | 134217728 | [134217728-2147483647] | - |
| key_cache_block_size | No | 1024 | [512-16384] | - |
| mysql_native_password_proxy_users | No | OFF | [ON|OFF] | - |
| innodb_adaptive_max_sleep_delay | No | 150000 | [1-1000000] | - |
| innodb_purge_rseg_truncate_frequency | No | 128 | [1-128] | - |
| query_alloc_block_size | No | 8192 | [1024-16384] | - |
| innodb_lock_wait_timeout | No | 50 | [1-1073741824] | - |
| innodb_purge_threads | Yes | 1 | [1-32] | - |
| innodb_compression_failure_threshold_pct | No | 5 | [0-100] | - |
| innodb_compression_pad_pct_max | No | 50 | [0-70] | - |
| binlog_rows_query_log_events | No | ON | [ON|OFF] | - |
| innodb_stats_persistent_sample_pages | No | 20 | [0-4294967295] | - |
| innodb_ft_total_cache_size | Yes | 640000000 | [32000000-1600000000] | - |
| innodb_flush_method | Yes | O_DIRECT | [fsync|O_DSYNC|littlesync|nosync|O_DIRECT|O_DIRECT_NO_FSYNC] | - |
| eq_range_index_dive_limit | No | 10 | [0-4294967295] | - |
| loose_max_execution_time | No | 0 | [0-4294967295] | - |
| loose_optimizer_trace_features | No | greedy_search=on,range_optimizer=on,dynamic_range=on,repeated_subselect=on | .* | - |
| rds_reserved_connections | No | 512 | [0-512] | - |
| connect_timeout | No | 10 | [1-3600] | - |
| innodb_purge_batch_size | Yes | 300 | [1-5000] | - |
| div_precision_increment | No | 4 | [0-30] | - |
| avoid_temporal_upgrade | No | OFF | [ON|OFF] | - |
| innodb_sync_array_size | Yes | 1 | [1-64] | - |
| sync_binlog | No | 1 | [0-2147483647] | - |
| innodb_stats_method | No | nulls_equal | [nulls_equal|nulls_unequal|nulls_ignored] | - |
| lock_wait_timeout | No | 31536000 | [1-1073741824] | - |
| net_read_timeout | No | 30 | [1-18446744073709551615] | - |
| innodb_deadlock_detect | No | ON | [ON|OFF] | - |
| innodb_write_io_threads | Yes | 4 | [1-64] | - |
| end_markers_in_json | No | OFF | [ON|OFF] | - |
| ngram_token_size | Yes | 2 | [0-20] | - |
| loose_innodb_numa_interleave | Yes | ON | [ON|OFF] | - |
| max_binlog_stmt_cache_size | No | 18446744073709547520 | [4096-18446744073709547520] | - |
| innodb_checksum_algorithm | No | crc32 | [innodb|crc32|none|strict_innodb|strict_crc32|strict_none] | - |
| query_cache_type | Yes | 0 | [0|1|2] | - |
| innodb_ft_enable_diag_print | No | OFF | [ON|OFF] | - |
| innodb_ft_enable_stopword | No | ON | [ON|OFF] | - |
| innodb_io_capacity | No | 20000 | [0-18446744073709551615] | - |
| slow_launch_time | No | 2 | [1-1024] | - |
| innodb_table_locks | No | ON | [ON|OFF] | - |
| innodb_stats_persistent | No | ON | [ON|OFF] | - |
| tmp_table_size | No | 2097152 | [262144-134217728] | - |
| disconnect_on_expired_password | Yes | ON | [ON|OFF] | - |
| default_storage_engine | Yes | InnoDB | [InnoDB|innodb] | - |
| net_retry_count | No | 10 | [1-4294967295] | - |
| innodb_ft_cache_size | Yes | 8000000 | [1600000-80000000] | - |
| binlog_cache_size | No | 2097152 | [4096-16777216] | - |
| innodb_max_dirty_pages_pct | No | 75 | [0-99] | - |
| query_cache_limit | No | 1048576 | [1-1048576] | - |
| innodb_disable_sort_file_cache | No | ON | [ON|OFF] | - |
| innodb_lru_scan_depth | No | 1024 | [100-18446744073709551615] | - |
| innodb_ft_result_cache_limit | No | 2000000000 | [1000000-4294967295] | - |
| long_query_time | No | 1 | [0.03-31536000] | - |
| interactive_timeout | No | 7200 | [10-86400] | - |
| innodb_read_io_threads | Yes | 4 | [1-64] | - |
| transaction_prealloc_size | No | 4096 | [1024-131072] | - |
| open_files_limit | Yes | 65535 | [1-18446744073709551615] | - |
| innodb_open_files | Yes | 3000 | [10-4294967295] | - |
| max_heap_table_size | No | 67108864 | [16384-1844674407370954752] | - |
| automatic_sp_privileges | No | ON | [ON|OFF] | - |
| explicit_defaults_for_timestamp | No | OFF | [ON|OFF] | - |
| ft_max_word_len | Yes | 84 | [10-4294967295] | - |
| innodb_autoextend_increment | No | 64 | [1-1000] | - |
| sql_mode | No | (\s*|REAL_AS_FLOAT|PIPES_AS_CONCAT|ANSI_QUOTES|IGNORE_SPACE|ONLY_FULL_GROUP_BY|NO_UNSIGNED_SUBTRACTION|NO_DIR_IN_CREATE|POSTGRESQL|ORACLE|MSSQL|DB2|MAXDB|NO_KEY_OPTIONS|NO_TABLE_OPTIONS|NO_FIELD_OPTIONS|MYSQL323|MYSQL40|ANSI|NO_AUTO_VALUE_ON_ZERO|NO_BACKSLASH_ESCAPES|STRICT_TRANS_TABLES|STRICT_ALL_TABLES|NO_ZERO_IN_DATE|NO_ZERO_DATE|ALLOW_INVALID_DATES|ERROR_FOR_DIVISION_BY_ZERO|TRADITIONAL|HIGH_NOT_PRECEDENCE|NO_ENGINE_SUBSTITUTION|PAD_CHAR_TO_FULL_LENGTH|NO_AUTO_CREATE_USER)(,NO_AUTO_CREATE_USER|,REAL_AS_FLOAT|,PIPES_AS_CONCAT|,ANSI_QUOTES|,IGNORE_SPACE|,ONLY_FULL_GROUP_BY|,NO_UNSIGNED_SUBTRACTION|,NO_DIR_IN_CREATE|,POSTGRESQL|,ORACLE|,MSSQL|,DB2|,MAXDB|,NO_KEY_OPTIONS|,NO_TABLE_OPTIONS|,NO_FIELD_OPTIONS|,MYSQL323|,MYSQL40|,ANSI|,NO_AUTO_VALUE_ON_ZERO|,NO_BACKSLASH_ESCAPES|,STRICT_TRANS_TABLES|,STRICT_ALL_TABLES|,NO_ZERO_IN_DATE|,NO_ZERO_DATE|,ALLOW_INVALID_DATES|,ERROR_FOR_DIVISION_BY_ZERO|,TRADITIONAL|,HIGH_NOT_PRECEDENCE|,NO_ENGINE_SUBSTITUTION|,PAD_CHAR_TO_FULL_LENGTH)* | - | |
| innodb_stats_transient_sample_pages | No | 8 | [1-4294967295] | - |
| innodb_random_read_ahead | No | OFF | [ON|OFF] | - |
| session_track_state_change | No | OFF | [ON|OFF] | - |
| table_open_cache | No | 2000 | [1-524288] | Size of the high-speed cache for table file handles. |
| range_optimizer_max_mem_size | No | 8388608 | [0-18446744073709551615] | - |
| innodb_status_output | No | OFF | [ON|OFF] | - |
| innodb_log_compressed_pages | No | OFF | [ON|OFF] | - |
| slave_net_timeout | No | 60 | [15-300] | - |
| delay_key_write | No | ON | [ON|OFF|ALL] | - |
| query_cache_wlock_invalidate | No | OFF | [ON|OFF] | - |
| max_points_in_geometry | No | 65536 | [3-1048576] | - |
| max_prepared_stmt_count | No | 16382 | [0-1048576] | - |
| wait_timeout | No | 86400 | [1-31536000] | - |
| query_cache_min_res_unit | No | 1024 | [512-18446744073709551608] | Minimum block size for storing query results in the query cache. Unit: bytes. |
| innodb_print_all_deadlocks | No | OFF | [OFF|ON] | - |
| loose_thread_pool_size | No | 32 | [1-1024] | Number of thread pool groups. Threads are evenly divided across groups and managed per group. |
| binlog_stmt_cache_size | No | 32768 | [4096-16777216] | - |
| transaction_isolation | No | READ-COMMITTED | [READ-UNCOMMITTED|READ-COMMITTED|REPEATABLE-READ|SERIALIZABLE] | Transaction isolation level. |
| innodb_buffer_pool_dump_at_shutdown | No | ON | [ON|OFF] | - |
| query_prealloc_size | No | 8192 | [8192-1048576] | - |
| key_cache_age_threshold | No | 300 | [100-4294967295] | - |
| loose_rds_kill_connections | No | 20 | [0, 18446744073709551615] | - |
| transaction_alloc_block_size | No | 8192 | [1024-131072] | - |
| optimizer_trace_limit | No | 1 | [0-4294967295] | - |
| metadata_locks_cache_size | Yes | 1024 | [1-1048576] | - |
| optimizer_prune_level | No | 1 | [0|1] | - |
| innodb_max_purge_lag | No | 0 | [0-4294967295] | - |
| innodb_buffer_pool_dump_pct | No | 25 | [1-100] | - |
| innodb_max_dirty_pages_pct_lwm | No | 0 | [0-99] | - |
| max_sp_recursion_depth | No | 0 | [0-255] | - |
| innodb_status_output_locks | No | OFF | [ON|OFF] | - |
| updatable_views_with_limit | No | YES | [YES|NO] | - |
| binlog_row_image | No | full | [full|minimal] | - |
| innodb_change_buffer_max_size | No | 25 | [0-50] | - |
| innodb_optimize_fulltext_only | No | OFF | [ON|OFF] | - |
| loose_opt_rds_last_error_gtid | No | ON | [ON|OFF] | - |
| innodb_ft_max_token_size | Yes | 84 | [10-84] | - |
| innodb_max_undo_log_size | No | 1073741824 | [10485760-18446744073709551615] | - |
| slave_parallel_type | No | LOGICAL_CLOCK | DATABASE,LOGICAL_CLOCK | - |
| loose_rds_check_core_file_enabled | No | ON | [ON|OFF] | - |
| innodb_adaptive_hash_index | No | ON | [ON|OFF] | - |
| innodb_sync_spin_loops | No | 30 | [0-4294967295] | - |
| net_write_timeout | No | 60 | [1-18446744073709551615] | - |
| flush_time | No | 0 | [0-31536000] | - |
| lower_case_table_names | Yes | 1 | [0|1] | - |
| sha256_password_proxy_users | No | OFF | [ON|OFF] | - |
| character_set_filesystem | No | binary | [utf8|latin1|gbk|binary] | - |
| innodb_flush_sync | No | ON | [ON|OFF] | - |
| tls_version | Yes | TLSv1,TLSv1.1,TLSv1.2 | [TLSv1,TLSv1.1,TLSv1.2|TLSv1,TLSv1.1] | - |
| key_cache_division_limit | No | 100 | [1-100] | - |
| delayed_insert_timeout | No | 300 | [1-3600] | - |
| preload_buffer_size | No | 32768 | [1024-1073741824] | - |
| innodb_read_ahead_threshold | No | 56 | [0-1024] | - |
| loose_optimizer_switch | No | index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on,index_condition_pushdown=on,mrr=on,mrr_cost_based=on,block_nested_loop=on,batched_key_access=off,materialization=on,semijoin=on,loosescan=on,firstmatch=on,subquery_materialization_cost_based=on,use_index_extensions=on | .* | - |
| concurrent_insert | No | 1 | [0|1|2] | Whether to enable concurrent inserts. |
| block_encryption_mode | No | "aes-128-ecb" | ["aes-128-ecb"|"aes-192-ecb"|"aes-256-ecb"|"aes-128-cbc"|"aes-192-cbc"|"aes-256-cbc"] | - |
| slow_query_log | No | ON | [ON|OFF] | Whether to record slow query logs. |
| net_buffer_length | No | 16384 | [1024-1048576] | - |
| query_cache_size | No | 3145728 | [0-104857600] | - |
| delayed_insert_limit | No | 100 | [1-4294967295] | - |
| innodb_large_prefix | No | ON | [ON|OFF] | - |
| innodb_monitor_disable | No | all | - | |
| innodb_adaptive_flushing_lwm | No | 10 | [0-70] | - |
| innodb_log_checksums | No | ON | [ON|OFF] | - |
| delayed_queue_size | No | 1000 | [1-4294967295] | - |
| session_track_gtids | No | OFF | [OFF|OWN_GTID|ALL_GTIDS] | - |
| innodb_thread_sleep_delay | No | 10000 | [0-1000000] | - |
| loose_rds_set_connection_id_enabled | No | ON | [ON|OFF] | - |
| innodb_old_blocks_pct | No | 37 | [5-95] | - |
| innodb_ft_sort_pll_degree | Yes | 2 | [1-16] | - |
| log_slow_admin_statements | No | OFF | [ON|OFF] | - |
| innodb_stats_on_metadata | No | OFF | [ON|OFF] | - |
| stored_program_cache | No | 256 | [16-524288] | - |
| group_concat_max_len | No | 1024 | [4-1844674407370954752] | - |
| innodb_sort_buffer_size | Yes | 1048576 | [65536-67108864] | - |
| innodb_page_cleaners | Yes | 1 | [1-64] | - |
| innodb_spin_wait_delay | No | 6 | [0-4294967295] | - |
| myisam_sort_buffer_size | No | 262144 | [262144-16777216] | - |
| innodb_rollback_segments | No | 128 | [1-128] | - |
| innodb_commit_concurrency | Yes | 0 | [0-1000] | - |
| innodb_concurrency_tickets | No | 5000 | [1-4294967295] | - |
| table_definition_cache | No | 512 | [1-524288] | - |
| auto_increment_increment | No | 1 | [1-65535] | - |
| binlog_checksum | Yes | CRC32 | - | - |
| max_seeks_for_key | No | 18446744073709500000 | [1-18446744073709551615] | - |
| sync_relay_log | No | 1 | [0-2147483647] | - |
| max_length_for_sort_data | No | 1024 | [0-838860] | - |
| back_log | Yes | 3000 | [0-65535] | - |
| max_error_count | No | 64 | [0-65535] | - |
| innodb_io_capacity_max | No | 40000 | [0-18446744073709551615] | - |
| innodb_strict_mode | No | OFF | [ON|OFF] | - |
| binlog_order_commits | Yes | OFF | - | - |
| min_examined_row_limit | No | 0 | [0-4294967295] | - |
| innodb_ft_min_token_size | Yes | 3 | [0-16] | - |
| innodb_stats_auto_recalc | No | ON | [ON|OFF] | - |
| max_connect_errors | No | 100 | [0-4294967295] | - |
| session_track_schema | No | ON | [ON|OFF] | - |
| join_buffer_size | No | 262144 | [128-4294967295] | - |
| innodb_change_buffering | No | all | [none|inserts|deletes|changes|purges|all] | - |
| optimizer_trace_max_mem_size | No | 16384 | [0-4294967295] | - |
| innodb_autoinc_lock_mode | Yes | 2 | [0|1|2] | - |
| innodb_rollback_on_timeout | Yes | OFF | [OFF|ON] | - |
| loose_opt_rds_enable_show_slave_lag | No | ON | [ON|OFF] | - |
| max_write_lock_count | No | 102400 | [1-102400] | - |
| master_verify_checksum | Yes | OFF | - | - |
| innodb_ft_num_word_optimize | No | 2000 | [0-10000] | - |
| max_join_size | No | 18446744073709551615 | [1-18446744073709551615] | - |
| loose_validate_password_length | No | 8 | [1-12] | - |
| log_throttle_queries_not_using_indexes | No | 0 | [0-4294967295] | - |
| innodb_max_purge_lag_delay | No | 0 | [0-10000000] | - |
| loose_optimizer_trace | No | enabled=off,one_line=off | .* | - |
| loose_thread_handling | Yes | one-thread-per-connection | [one-thread-per-connection|pool-of-threads] | - |
| default_week_format | No | 0 | [0-7] | - |
| innodb_cmp_per_index_enabled | No | OFF | [ON|OFF] | - |
| show_compatibility_56 | No | OFF | [ON|OFF] | - |
| host_cache_size | No | 644 | [0-65535] | Size of the host cache. |
| low_priority_updates | No | 0 | [0|1] | - |
| auto_increment_offset | No | 1 | [1-65535] | Auto-increment step size for the auto-increment column. |
| range_alloc_block_size | No | 4096 | [4096-18446744073709551615] | - |
| ft_min_word_len | Yes | 4 | [1-3600] | - |
| sort_buffer_size | No | 262144 | [32768-4294967295] | Size of the sort buffer used to sort data. Unit: bytes. |
| max_allowed_packet | No | 1073741824 | [16384-1073741824] | Maximum packet size the server can receive. Unit: bytes. |
| thread_cache_size | No | 256 | [0-16384] | Size of the thread cache. |
| optimizer_trace_offset | No | -1 | [0-4294967295] | - |
| character_set_server | Yes | utf8 | [utf8|latin1|gbk|gb18030|utf8mb4] | Default character set for databases. |
| innodb_adaptive_flushing | No | ON | [ON|OFF] | Whether to dynamically adjust the dirty page flush rate based on workload. |
| log_queries_not_using_indexes | No | OFF | [ON|OFF] | Whether to log queries that do not use indexes in the slow query log. |
| innodb_monitor_enable | No | all | - | |
| table_open_cache_instances | Yes | 16 | [1-64] | Number of table cache instances. |
| innodb_flush_neighbors | No | 1 | [0|1|2] | Whether to flush neighbor dirty pages when a dirty page is written from the buffer pool. Neighbor dirty pages share the same extent as the flushed page. |
| innodb_buffer_pool_instances | Yes | 8 | [1-64] | Number of buffer pool instances. |
| innodb_data_file_purge | No | OFF | [ON|OFF] | Whether to enable the Purge Large File Asynchronously feature. |
| innodb_data_file_purge_all_at_shutdown | No | OFF | [ON|OFF] | Whether to delete all files when the host running the PolarDB-X instance shuts down. |
| innodb_data_file_purge_immediate | No | OFF | [ON|OFF] | Whether to retain data files and revoke only their links. |
| innodb_data_file_purge_interval | No | 100 | [1-1073741824] | Interval at which InnoDB deletes files. Unit: milliseconds. |
| innodb_data_file_purge_max_size | No | 512 | [1-1073741824] | Maximum size of a single file that can be deleted. Unit: MB. |
| hotspot | No | OFF | [ON|OFF] | Whether to enable the hot spot update feature. |
| hotspot_lock_type | No | OFF | [ON|OFF] | Lock type used for hot spot updates. |
| loose_innodb_data_file_purge_interval | No | 100 | [0-10000] | Interval at which files are purged. Unit: milliseconds. |
| loose_innodb_data_file_purge_max_size | No | 128 | [16-1073741824] | Maximum size of a single file that can be purged. Unit: MB. |