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sys_bkgd_io_low_percentage

Last Updated：2023-08-18 09:26:34 Updated

sys_bkgd_io_low_percentage specifies the lowest percentage of traffic for background I/O tasks.

Property	Description
Parameter type	Integer
Default value	0
Value range	[0, 100]
Effective upon OBServer restart	No

If the value of this parameter is set to 0, the system will automatically adjust the I/O distribution.

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SQL - V2.2.77Enterprise Edition

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  - Function expressions
  - Interval expressions
  - Scalar subquery expressions
  - Expression lists
- Conditions
  - Overview of SQL conditions
  - Comparison conditions
  - Logical conditions
  - Pattern-matching conditions
  - NULL conditions
  - Compound conditions
  - BETWEEN conditions
  - EXISTS conditions
  - IN conditions
- Queries and subqueries
  - Overview of queries and subqueries
  - Simple queries
  - Hierarchical queries
  - Sets
  - Joins
  - Subqueries
- SQL statements
  - DDL
    - ALTER KEYSTORE
    - ALTER OUTLINE
    - ALTER SEQUENCE
    - ALTER SESSION
    - ALTER TABLE
    - ALTER TABLEGROUP
    - ALTER USER
    - CREATE INDEX
    - CREATE KEYSTORE
    - CREATE OUTLINE
    - CREATE RESTORE POINT
    - CREATE SEQUENCE
    - CREATE SYNONYM
    - CREATE TABLE
    - CREATE TABLEGROUP
    - CREATE TABLESPACE
    - CREATE USER
    - CREATE VIEW
    - DROP INDEX
    - DROP OUTLINE
    - DROP RESTORE POINT
    - DROP SEQUENCE
    - DROP SYNONYM
    - DROP TABLE
    - DROP TABLEGROUP
    - DROP TABLESPACE
    - DROP USER
    - DROP VIEW
    - RENAME
    - TRUNCATE TABLE
  - DML
    - DELETE
    - INSERT
    - MERGE
    - PURGE INDEX
    - PURGE RECYCLEBIN
    - PURGE TABLE
    - SELECT
    - UPDATE
  - DCL
    - AUDIT
    - EXPLAIN
    - FLASHBACK TABLE BEFORE DROP
    - GRANT
    - KILL
    - REVOKE
    - SAVEPOINT
    - SET NAMES
    - SET PASSWORD
    - SET VARIABLE
    - SHOW
    - SHOW RECYCLEBIN
    - SHRINK
    - TRANSACTION
SQL Tuning Guide
- Execution process of SQL queries
- SQL execution plan
  - Introduction to SQL execution plan
  - Execution plan operators
    - TABLE SCAN
    - TABLE LOOKUP
    - JOIN
    - COUNT
    - GROUP BY
    - WINDOW FUNCTION
    - SUBPLAN FILTER
    - DISTINCT
    - SEQUENCE
    - MATERIAL
    - SORT
    - LIMIT
    - FOR UPDATE
    - SELECT INTO
    - SUBPLAN SCAN
    - UNION
    - INTERSECT
    - EXCEPT/MINUS
    - INSERT
    - DELETE
    - UPDATE
    - MERGE
    - EXCHANGE
    - GI
  - Plan cache
  - Fast parameterization
  - Execution plan display (EXPLAIN)
  - Real-time execution plan display
- Distributed execution plan
  - Distributed execution and parallel query
  - Generate a distributed plan
  - Schedule distributed execution plans
  - Manage distributed execution plans
  - Execution of parallel queries
  - Parameter tuning for a parallel query
- SQL tuning
  - Overview of SQL tuning
  - General procedure of SQL tuning
  - Monitor the SQL execution performance
    - (g)v$sql_audit introduction
    - SQL Trace
    - Plan cache view
    - Examples of SQL performance analysis
      - Use SQL Audit to analyze wait events in a query
      - Analyze SQL queries that cause an abrupt RT jitter
      - View the shape of an execution plan and analyze the plan
      - Analyze slow SQL queries
      - Query SQL traffic distribution and QPS
      - Check whether SQL queries are balanced across servers in a cluster
      - Find the TOP N SQL queries
      - Analyze whether an unusually large number of remote execution requests exist in the system or the execution of an SQL statement
      - Find full table scan SQL statements in a tenant
      - Find the TOP N queries with the longest execution time within a specified period
      - Analyze queries related to distributed plans
      - Check whether the RPC execution count of a distributed subplan is balanced across servers in a cluster
  - Query rewrite
    - Overview
    - Rule-based query rewrite
    - Cost-based query rewrite
  - Query optimization
    - Access path
      - Overview
      - Rule-based path selection
      - Cost-based path selection
    - Join algorithms
      - Overview
      - Join algorithms
      - Join order
  - Manage execution plans
    - Optimizer hints
    - Plan binding
    - SQL plan management
- Concepts
- FAQ about SQL tuning
Reference Guide (MySQL Mode)
- System views
  - Overview
  - Dictionary views
    - mysql.help_topic
    - mysql.help_category
    - mysql.help_keyword
    - mysql.help_relation
    - mysql.db
    - mysql.proc
    - mysql.time_zone
    - mysql.time_zone_name
    - mysql.time_zone_transition
    - mysql.time_zone_transition_type
    - mysql.user
    - information_schema.CHARACTER_SETS
    - information_schema.COLLATIONS
    - information_schema.COLLATION_CHARACTER_SET_APPLICABILITY
    - information_schema.COLUMNS
    - information_schema.DBA_OUTLINES
    - information_schema.ENGINES
    - information_schema.GLOBAL_STATUS
    - information_schema.GLOBAL_VARIABLES
    - information_schema.KEY_COLUMN_USAGE
    - information_schema.PARAMETERS
    - information_schema.PARTITIONS
    - information_schema.PROCESSLIST
    - information_schema.REFERENTIAL_CONSTRAINTS
    - information_schema.ROUTINES
    - information_schema.SCHEMATA
    - information_schema.SCHEMA_PRIVILEGES
    - information_schema.SESSION_STATUS
    - information_schema.SESSION_VARIABLES
    - information_schema.STATISTICS
    - information_schema.TABLES
    - information_schema.TABLE_CONSTRAINTS
    - information_schema.TABLE_PRIVILEGES
    - information_schema.USER_PRIVILEGES
    - information_schema.USER_RECYCLEBIN
    - information_schema.VIEWS
    - oceanbase.CDB_OB_BACKUP_ARCHIVELOG_SUMMARY
    - oceanbase.CDB_OB_BACKUP_JOB_DETAILS
    - oceanbase.CDB_OB_BACKUP_SET_DETAILS
    - oceanbase.CDB_OB_BACKUP_PROGRESS
    - oceanbase.CDB_OB_BACKUP_SET_EXPIRED
    - oceanbase.CDB_OB_BACKUP_ARCHIVELOG_PROGRESS
    - oceanbase.CDB_OB_BACKUP_CLEAN_HISTORY
    - oceanbase.CDB_OB_BACKUP_TASK_CLEAN_HISTORY
    - oceanbase.CDB_OB_RESTORE_PROGRESS
    - oceanbase.CDB_OB_RESTORE_HISTORY
    - oceanbase.CDB_CKPT_HISTORY
    - oceanbase.CDB_OB_BACKUP_VALIDATION_JOB
    - oceanbase.CDB_OB_BACKUP_VALIDATION_JOB_HISTORY
    - oceanbase.CDB_OB_TENANT_BACKUP_VALIDATION_TASK
    - oceanbase.CDB_OB_BACKUP_VALIDATION_TASK_HISTORY
    - oceanbase.CDB_OB_BACKUP_BACKUP_ARCHIVELOG_SUMMARY
    - oceanbase.CDB_OB_BACKUP_BACKUPSET_TASK_HISTORY
    - oceanbase.CDB_OB_BACKUP_BACKUPSET_TASK
    - oceanbase.CDB_OB_BACKUP_BACKUPSET_JOB_HISTORY
    - oceanbase.CDB_OB_BACKUP_BACKUPSET_JOB
    - oceanbase.CDB_OB_BACKUP_SET_OBSOLETE
    - oceanbase.CDB_OB_BACKUP_ARCHIVELOG
    - oceanbase.CDB_OB_BACKUP_BACKUP_ARCHIVELOG
    - oceanbase.CDB_OB_BACKUP_PIECE_FILES
    - oceanbase.CDB_OB_BACKUP_SET_FILES
  - Performance views
    - gv$plan_cache_stat
    - gv$plan_cache_plan_stat
    - gv$session_event
    - gv$session_wait
    - gv$session_wait_history
    - gv$system_event
    - gv$sesstat
    - gv$sysstat
    - gv$sql_audit
    - gv$latch
    - gv$memory
    - gv$memstore
    - gv$memstore_info
    - gv$plan_cache_plan_explain
    - gv$obrpc_outgoing
    - gv$obrpc_incoming
    - gv$sql
    - gv$sql_plan_monitor
    - gv$outline
    - gv$concurrent_limit_sql
    - gv$sql_plan_statistics
    - gv$server_memstore
    - gv$unit_load_balance_event_history
    - gv$tenant
    - gv$database
    - gv$table
    - gv$unit
    - gv$partition
    - gv$lock_wait_stat
    - gv$session_longops
    - gv$tenant_memstore_allocator_info
    - gv$minor_merge_info
    - gv$tenant_px_worker_stat
    - gv$partition_audit
    - gv$ps_stat
    - gv$ps_item_info
    - gv$sql_workarea
    - gv$sql_workarea_histogram
    - gv$ob_sql_workarea_memory_info
    - gv$server_schema_info
    - gv$merge_info
    - gv$lock
    - v$statname
    - v$event_name
    - v$session_event
    - v$session_wait
    - v$session_wait_history
    - v$sesstat
    - v$sysstat
    - v$system_event
    - v$memory
    - v$memstore
    - v$memstore_info
    - v$plan_cache_stat
    - v$plan_cache_plan_stat
    - v$plan_cache_plan_explain
    - v$sql_audit
    - v$obrpc_outgoing
    - v$obrpc_incoming
    - v$sql
    - v$sql_plan_monitor
    - v$sql_plan_statistics
    - v$unit
    - v$partition
    - v$lock_wait_stat
    - v$session_longops
    - v$latch
    - v$tenant_memstore_allocator_info
    - v$tenant_px_worker_stat
    - v$partition_audit
    - v$ob_cluster
    - v$ob_standby_status
    - v$ob_cluster_stats
    - v$ob_cluster_event_history
    - v$ps_stat
    - v$ps_item_info
    - v$sql_workarea
    - v$sql_workarea_active
    - v$sql_workarea_histogram
    - v$ob_sql_workarea_memory_info
    - v$ob_timestamp_service
    - v$server_schema_info
    - v$merge_info
    - v$lock
    - v$sql_monitor_statname
    - v$restore_point
    - v$ob_cluster_failover_info
    - v$encrypted_tables
    - v$encrypted_tablespaces
    - v$ob_all_clusters
- System variables
  - System variable overview
  - auto_increment_increment
  - auto_increment_offset
  - autocommit
  - character_set_client
  - character_set_connection
  - character_set_database
  - character_set_results
  - character_set_server
  - character_set_system
  - collation_connection
  - collation_database
  - collation_server
  - interactive_timeout
  - last_insert_id
  - max_allowed_packet
  - sql_mode
  - time_zone
  - tx_isolation
  - version_comment
  - wait_timeout
  - binlog_row_image
  - character_set_filesystem
  - connect_timeout
  - datadir
  - debug_sync
  - div_precision_increment
  - explicit_defaults_for_timestamp
  - group_concat_max_len
  - identity
  - lower_case_table_names
  - net_read_timeout
  - net_write_timeout
  - read_only
  - sql_auto_is_null
  - sql_select_limit
  - timestamp
  - tx_read_only
  - version
  - sql_warnings
  - max_user_connections
  - init_connect
  - license
  - net_buffer_length
  - system_time_zone
  - query_cache_size
  - query_cache_type
  - sql_quote_show_create
  - max_sp_recursion_depth
  - sql_safe_updates
  - ob_default_replica_num
  - ob_proxy_partition_hit
  - ob_log_level
  - ob_max_parallel_degree
  - ob_query_timeout
  - ob_read_consistency
  - ob_enable_transformation
  - ob_trx_timeout
  - ob_enable_plan_cache
  - ob_enable_index_direct_select
  - ob_proxy_set_trx_executed
  - ob_enable_aggregation_pushdown
  - ob_last_schema_version
  - ob_global_debug_sync
  - ob_proxy_global_variables_version
  - ob_enable_trace_log
  - ob_enable_hash_group_by
  - ob_enable_blk_nestedloop_join
  - ob_bnl_join_cache_size
  - ob_org_cluster_id
  - ob_plan_cache_percentage
  - ob_plan_cache_evict_high_percentage
  - ob_plan_cache_evict_low_percentage
  - recyclebin
  - ob_capability_flag
  - ob_stmt_parallel_degree
  - is_result_accurate
  - error_on_overlap_time
  - ob_compatibility_mode
  - ob_create_table_strict_mode
  - ob_sql_work_area_percentage
  - ob_route_policy
  - ob_enable_transmission_checksum
  - foreign_key_checks
  - ob_enable_truncate_flashback
  - ob_tcp_invited_nodes
  - sql_throttle_current_priority
  - sql_throttle_priority
  - sql_throttle_rt
  - sql_throttle_network
  - auto_increment_cache_size
  - ob_enable_jit
  - ob_temp_tablespace_size_percentage
  - ob_timestamp_service
  - plugin_dir
  - undo_retention
  - ob_sql_audit_percentage
  - ob_enable_sql_audit
  - optimizer_use_sql_plan_baselines
  - optimizer_capture_sql_plan_baselines
  - parallel_max_servers
  - parallel_servers_target
  - ob_early_lock_release
  - ob_trx_idle_timeout
  - block_encryption_mode
  - ob_reserved_meta_memory_percentage
  - ob_check_sys_variable
  - tracefile_identifier
  - transaction_isolation
  - ob_trx_lock_timeout
  - validate_password_check_user_name
  - validate_password_length
  - validate_password_mixed_case_count
  - validate_password_number_count
  - validate_password_policy
  - validate_password_special_char_count
  - default_password_lifetime
  - ob_trace_info
  - secure_file_priv
  - ob_pl_block_timeout
  - performance_schema
  - transaction_read_only
  - max_connections
- System configuration items
  - Overview of system configuration items
  - all_cluster_list
  - enable_unit_balance_resource_weight
  - plan_cache_high_watermark
  - plan_cache_low_watermark
  - sql_audit_queue_size
  - tenant_cpu_variation_per_server
  - max_stale_time_for_weak_consistency
  - sql_work_area
  - auto_leader_switch_interval
  - auto_delete_expired_backup
  - autoinc_cache_refresh_interval
  - audit_sys_operations
  - audit_trail
  - balancer_idle_time
  - balancer_log_interval
  - balancer_timeout_check_interval
  - balancer_task_timeout
  - balancer_tolerance_percentage
  - balancer_emergency_percentage
  - balance_blacklist_failure_threshold
  - balance_blacklist_retry_interval
  - backup_concurrency
  - backup_dest
  - backup_net_limit
  - backup_recovery_window
  - backup_region
  - builtin_db_data_verify_cycle
  - bf_cache_miss_count_threshold
  - bf_cache_priority
  - cache_wash_threshold
  - clog_cache_priority
  - clog_sync_time_warn_threshold
  - clog_disk_usage_limit_percentage
  - clog_transport_compress_all
  - clog_transport_compress_func
  - clog_persistence_compress_func
  - clog_max_unconfirmed_log_count
  - cluster
  - cluster_id
  - cpu_count
  - cpu_quota_concurrency
  - cpu_reserved
  - config_additional_dir
  - data_copy_concurrency
  - data_dir
  - datafile_disk_percentage
  - dtl_buffer_size
  - datafile_size
  - default_compress_func
  - default_compress
  - default_progressive_merge_num
  - default_row_format
  - devname
  - data_disk_usage_limit_percentage
  - disk_io_thread_count
  - dead_socket_detection_timeout
  - enable_clog_persistence_compress
  - election_cpu_quota
  - enable_one_phase_commit
  - enable_sys_unit_standalone
  - enable_pg
  - enable_smooth_leader_switch
  - election_blacklist_interval
  - enable_election_group
  - enable_auto_leader_switch
  - enable_global_freeze_trigger
  - enable_manual_merge
  - enable_merge_by_turn
  - enable_perf_event
  - enable_rebalance
  - enable_record_trace_log
  - enable_record_trace_id
  - enable_early_lock_release
  - enable_rereplication
  - enable_rich_error_msg
  - enable_rootservice_standalone
  - enable_sql_audit
  - enable_sql_operator_dump
  - enable_async_syslog
  - enable_syslog_recycle
  - enable_syslog_wf
  - enable_upgrade_mode
  - enable_separate_sys_clog
  - enable_ddl
  - enable_major_freeze
  - enable_rebuild_on_purpose
  - enable_log_archive
  - enable_monotonic_weak_read
  - external_kms_info
  - freeze_trigger_percentage
  - flush_log_at_trx_commit
  - fuse_row_cache_priority
  - force_refresh_location_cache_interval
  - force_refresh_location_cache_threshold
  - get_leader_candidate_rpc_timeout
  - global_major_freeze_residual_memory
  - global_write_halt_residual_memory
  - ignore_replay_checksum_error
  - global_index_build_single_replica_timeout
  - high_priority_net_thread_count
  - ignore_replica_checksum_error
  - ignore_replay_checksum_error
  - index_cache_priority
  - index_clog_cache_priority
  - index_info_block_cache_priority
  - internal_sql_execute_timeout
  - large_query_worker_percentage
  - large_query_threshold
  - leak_mod_to_check
  - lease_time
  - location_cache_cpu_quota
  - location_cache_expire_time
  - location_cache_priority
  - location_cache_refresh_min_interval
  - location_fetch_concurrency
  - location_refresh_thread_count
  - log_archive_checkpoint_interval
  - log_archive_concurrency
  - log_restore_concurrency
  - major_freeze_duty_time
  - max_kept_major_version_number
  - max_string_print_length
  - max_syslog_file_count
  - merge_stat_sampling_ratio
  - major_compact_trigger
  - memory_chunk_cache_size
  - memory_limit
  - memory_limit_percentage
  - memory_reserved
  - merge_thread_count
  - merger_check_interval
  - merger_completion_percentage
  - merger_switch_leader_duration_time
  - merger_warm_up_duration_time
  - max_px_worker_count
  - migration_disable_time
  - min_observer_version
  - minor_deferred_gc_time
  - minor_freeze_times
  - minor_warm_up_duration_time
  - mysql_port
  - minor_merge_concurrency
  - multiblock_read_gap_size
  - multiblock_read_size
  - micro_block_merge_verify_level
  - migrate_concurrency
  - minor_compact_trigger
  - memstore_limit_percentage
  - net_thread_count
  - obconfig_url
  - ob_enable_batched_multi_statement
  - partition_table_check_interval
  - partition_table_scan_batch_count
  - plan_cache_evict_interval
  - px_task_size
  - px_workers_per_cpu_quota
  - replica_safe_remove_time
  - resource_hard_limit
  - resource_soft_limit
  - rootservice_async_task_queue_size
  - rootservice_async_task_thread_count
  - rootservice_list
  - rootservice_ready_check_interval
  - row_compaction_update_limit
  - row_purge_thread_count
  - rpc_port
  - rpc_timeout
  - restore_concurrency
  - rootservice_memory_limit
  - rebuild_replica_data_lag_threshold
  - schema_history_expire_time
  - ssl_client_authentication
  - server_check_interval
  - server_data_copy_in_concurrency
  - server_data_copy_out_concurrency
  - server_permanent_offline_time
  - server_temporary_offline_time
  - stack_size
  - server_balance_critical_disk_waterlevel
  - server_balance_disk_tolerance_percent
  - system_memory
  - server_balance_cpu_mem_tolerance_percent
  - server_cpu_quota_max
  - server_cpu_quota_min
  - sql_audit_memory_limit
  - sys_bkgd_io_high_percentage
  - sys_bkgd_io_low_percentage
  - sys_bkgd_io_timeout
  - sys_bkgd_net_percentage
  - sys_bkgd_migration_change_member_list_timeout
  - sys_bkgd_migration_retry_num
  - syslog_level
  - switchover_process_thread_count
  - system_cpu_quota
  - sys_cpu_limit_trigger
  - system_trace_level
  - syslog_io_bandwidth_limit
  - tablet_size
  - tableapi_transport_compress_func
  - tenant_task_queue_size
  - tenant_groups
  - trace_log_slow_query_watermark
  - trace_log_sampling_interval
  - trx_2pc_retry_interval
  - trx_try_wait_lock_timeout
  - trx_force_kill_threshold
  - tde_method
  - token_reserved_percentage
  - unit_balance_resource_weight
  - user_block_cache_priority
  - user_row_cache_priority
  - user_tab_col_stat_cache_priority
  - user_iort_up_percentage
  - use_large_pages
  - virtual_table_location_cache_expire_time
  - workers_per_cpu_quota
  - wait_leader_batch_count
  - writing_throttling_maximum_duration
  - writing_throttling_trigger_percentage
  - weak_read_version_refresh_interval
  - workarea_size_policy
  - zone
  - zone_merge_concurrency
  - zone_merge_order
  - zone_merge_timeout
  - ob_ssl_invited_common_names
  - ssl_external_kms_info
  - ob_event_history_recycle_interval
  - backup_backup_dest
  - plsql_ccflags
  - plsql_code_type
  - plsql_debug
  - plsql_optimize_level
  - plsql_v2_compatibility
  - plsql_warnings
  - recyclebin_object_expire_time
  - log_archive_batch_buffer_limit
  - clog_disk_utilization_threshold
  - backup_backup_archive_log_batch_count
  - backup_backup_archivelog_retry_interval
  - backup_backupset_batch_count
  - backup_backupset_retry_interval
  - open_cursors
  - location_cache_refresh_rpc_timeout
  - location_cache_refresh_sql_timeout
  - backup_dest_option
  - backup_backup_dest_option
  - backup_zone
  - backup_log_archive_option
  - enable_tcp_keepalive
  - tcp_keepidle
  - tcp_keepintvl
  - tcp_keepcnt
- Reserved keywords
Reference Guide (Oracle Mode)
- System views
  - Dictionary views
    - ALL_ALL_TABLES
    - ALL_ARGUMENTS
    - ALL_COL_COMMENTS
    - ALL_COLL_TYPES
    - ALL_COL_PRIVS
    - ALL_CONSTRAINTS
    - ALL_CONS_COLUMNS
    - ALL_DEF_AUDIT_OPTS
    - ALL_ERRORS
    - ALL_INDEXES
    - ALL_IND_COLUMNS
    - ALL_IND_EXPRESSIONS
    - ALL_IND_PARTITIONS
    - ALL_IND_SUBPARTITIONS
    - ALL_METHOD_PARAMS
    - ALL_OBJECTS
    - ALL_PART_INDEXES
    - ALL_PART_KEY_COLUMNS
    - ALL_PART_TABLES
    - ALL_PROCEDURES
    - ALL_PROFILES
    - ALL_SCHEDULER_JOB_ARGS
    - ALL_SCHEDULER_PROGRAM_ARGS
    - ALL_SEQUENCES
    - ALL_SOURCE
    - ALL_SUBPARTITION_TEMPLATES
    - ALL_SUBPART_KEY_COLUMNS
    - ALL_SYNONYMS
    - ALL_TABLES
    - ALL_TAB_COLS
    - ALL_TAB_COLUMNS
    - ALL_TAB_COMMENTS
    - ALL_TAB_PARTITIONS
    - ALL_TAB_PRIVS
    - ALL_TAB_SUBPARTITIONS
    - ALL_TRIGGERS
    - ALL_TYPES
    - ALL_TYPE_ATTRS
    - ALL_TYPE_METHODS
    - ALL_USERS
    - ALL_VIEWS
    - AUDIT_ACTIONS
    - DBA_ALL_TABLES
    - DBA_ARGUMENTS
    - DBA_AUDIT_EXISTS
    - DBA_AUDIT_OBJECT
    - DBA_AUDIT_SESSION
    - DBA_AUDIT_STATEMENT
    - DBA_AUDIT_TRAIL
    - DBA_COLL_TYPES
    - DBA_COL_COMMENTS
    - DBA_COL_PRIVS
    - DBA_CONSTRAINTS
    - DBA_CONS_COLUMNS
    - DBA_ERRORS
    - DBA_INDEXES
    - DBA_IND_COLUMNS
    - DBA_IND_EXPRESSIONS
    - DBA_IND_PARTITIONS
    - DBA_IND_SUBPARTITIONS
    - DBA_METHOD_PARAMS
    - DBA_OBJECTS
    - DBA_OBJ_AUDIT_OPTS
    - DBA_PART_INDEXES
    - DBA_PART_KEY_COLUMNS
    - DBA_PART_TABLES
    - DBA_PROCEDURES
    - DBA_PROFILES
    - DBA_ROLES
    - DBA_ROLE_PRIVS
    - DBA_SCHEDULER_JOB_ARGS
    - DBA_SCHEDULER_PROGRAM_ARGS
    - DBA_SEGMENTS
    - DBA_SEQUENCES
    - DBA_SOURCE
    - DBA_STMT_AUDIT_OPTS
    - DBA_SUBPARTITION_TEMPLATES
    - DBA_SUBPART_KEY_COLUMNS
    - DBA_SYNONYMS
    - DBA_SYS_PRIVS
    - DBA_TABLES
    - DBA_TABLESPACES
    - DBA_TAB_COLS
    - DBA_TAB_COLUMNS
    - DBA_TAB_COMMENTS
    - DBA_TAB_PARTITIONS
    - DBA_TAB_PRIVS
    - DBA_TAB_SUBPARTITIONS
    - DBA_TRIGGERS
    - DBA_TYPES
    - DBA_TYPE_ATTRS
    - DBA_TYPE_METHODS
    - DBA_USERS
    - DBA_VIEWS
    - DBA_RECYCLEBIN
    - NLS_DATABASE_PARAMETERS
    - NLS_INSTANCE_PARAMETERS
    - NLS_SESSION_PARAMETERS
    - STMT_AUDIT_OPTION_MAP
    - USER_ALL_TABLES
    - USER_ARGUMENTS
    - USER_AUDIT_OBJECT
    - USER_AUDIT_SESSION
    - USER_AUDIT_STATEMENT
    - USER_AUDIT_TRAIL
    - USER_COLL_TYPES
    - USER_COL_COMMENTS
    - USER_COL_PRIVS
    - USER_CONSTRAINTS
    - USER_CONS_COLUMNS
    - USER_ERRORS
    - USER_INDEXES
    - USER_IND_COLUMNS
    - USER_IND_EXPRESSIONS
    - USER_IND_PARTITIONS
    - USER_IND_SUBPARTITIONS
    - USER_OBJECTS
    - USER_PART_INDEXES
    - USER_PART_KEY_COLUMNS
    - USER_PART_TABLES
    - USER_PROCEDURES
    - USER_PROFILES
    - USER_ROLE_PRIVS
    - USER_SEGMENTS
    - USER_SEQUENCES
    - USER_SOURCE
    - USER_SUBPARTITION_TEMPLATES
    - USER_SUBPART_KEY_COLUMNS
    - USER_SYNONYMS
    - USER_SYS_PRIVS
    - USER_TAB_SUBPARTITIONS
    - USER_TRIGGERS
    - USER_TABLES
    - USER_TABLESPACES
    - USER_TAB_COLS
    - USER_TAB_COLUMNS
    - USER_TAB_COMMENTS
    - USER_TAB_PARTITIONS
    - USER_TYPES
    - USER_TYPE_ATTRS
    - USER_TYPE_METHODS
    - USER_VIEWS
    - USER_RECYCLEBIN
    - ROLE_TAB_PRIVS
    - ROLE_SYS_PRIVS
    - ROLE_ROLE_PRIVS
    - DICTIONARY
    - DICT
  - Performance views
    - GV$LOCK
    - GV$CONCURRENT_LIMIT_SQL
    - GV$INSTANCE
    - GV$MEMORY
    - GV$MEMSTORE
    - GV$MEMSTORE_INFO
    - GV$OB_SQL_WORKAREA_MEMORY_INFO
    - GV$OUTLINE
    - GV$PLAN_CACHE_PLAN_EXPLAIN
    - GV$PLAN_CACHE_PLAN_STAT
    - GV$PLAN_CACHE_STAT
    - GV$PS_ITEM_INFO
    - GV$PS_STAT
    - GV$SERVER_MEMSTORE
    - GV$SESSION_WAIT
    - GV$SESSION_WAIT_HISTORY
    - GV$SESSTAT
    - GV$SQL_AUDIT
    - GV$SQL_WORKAREA
    - GV$SQL_WORKAREA_ACTIVE
    - GV$SQL_WORKAREA_HISTOGRAM
    - GV$SYSSTAT
    - GV$SYSTEM_EVENT
    - GV$GLOBAL_TRANSACTION
    - V$INSTANCE
    - V$MEMORY
    - V$MEMSTORE
    - V$MEMSTORE_INFO
    - V$NLS_PARAMETERS
    - V$OB_SQL_WORKAREA_MEMORY_INFO
    - V$PLAN_CACHE_PLAN_EXPLAIN
    - V$PLAN_CACHE_PLAN_STAT
    - V$PLAN_CACHE_STAT
    - V$PS_ITEM_INFO
    - V$PS_STAT
    - V$SESSION_WAIT
    - V$SESSION_WAIT_HISTORY
    - V$SESSTAT
    - V$SQL_AUDIT
    - V$SQL_WORKAREA
    - V$SQL_WORKAREA_ACTIVE
    - V$SQL_WORKAREA_HISTOGRAM
    - V$SYSSTAT
    - V$SYSTEM_EVENT
    - V$VERSION
    - V$SQL_MONITOR_STATNAME
    - V$RESTORE_POINT
    - V$GLOBAL_TRANSACTION
    - V$TIMEZONE_NAMES
    - V$LOCK
    - V$ENCRYPTED_TABLES
    - V$ENCRYPTED_TABLESPACES
- System variables
  - System variable overview
  - auto_increment_increment
  - auto_increment_offset
  - autocommit
  - character_set_client
  - character_set_connection
  - character_set_results
  - character_set_system
  - collation_connection
  - interactive_timeout
  - last_insert_id
  - max_allowed_packet
  - sql_mode
  - time_zone
  - tx_isolation
  - version_comment
  - wait_timeout
  - binlog_row_image
  - character_set_filesystem
  - connect_timeout
  - datadir
  - debug_sync
  - div_precision_increment
  - group_concat_max_len
  - identity
  - lower_case_table_names
  - net_read_timeout
  - net_write_timeout
  - read_only
  - sql_auto_is_null
  - sql_select_limit
  - timestamp
  - tx_read_only
  - version
  - sql_warnings
  - max_user_connections
  - init_connect
  - license
  - net_buffer_length
  - system_time_zone
  - query_cache_size
  - query_cache_type
  - sql_quote_show_create
  - max_sp_recursion_depth
  - ob_default_replica_num
  - ob_proxy_partition_hit
  - ob_log_level
  - ob_max_parallel_degree
  - ob_query_timeout
  - ob_read_consistency
  - ob_enable_transformation
  - ob_trx_timeout
  - ob_enable_plan_cache
  - ob_enable_index_direct_select
  - ob_proxy_set_trx_executed
  - ob_enable_aggregation_pushdown
  - ob_last_schema_version
  - ob_global_debug_sync
  - ob_proxy_global_variables_version
  - ob_enable_trace_log
  - ob_enable_hash_group_by
  - ob_enable_blk_nestedloop_join
  - ob_bnl_join_cache_size
  - ob_org_cluster_id
  - ob_plan_cache_percentage
  - ob_plan_cache_evict_high_percentage
  - ob_plan_cache_evict_low_percentage
  - recyclebin
  - ob_capability_flag
  - ob_stmt_parallel_degree
  - is_result_accurate
  - error_on_overlap_time
  - ob_compatibility_mode
  - ob_create_table_strict_mode
  - ob_sql_work_area_percentage
  - ob_route_policy
  - ob_enable_transmission_checksum
  - foreign_key_checks
  - ob_enable_truncate_flashback
  - ob_tcp_invited_nodes
  - sql_throttle_current_priority
  - sql_throttle_priority
  - sql_throttle_rt
  - sql_throttle_network
  - auto_increment_cache_size
  - ob_enable_jit
  - ob_temp_tablespace_size_percentage
  - ob_timestamp_service
  - plugin_dir
  - undo_retention
  - ob_sql_audit_percentage
  - ob_enable_sql_audit
  - optimizer_use_sql_plan_baselines
  - optimizer_capture_sql_plan_baselines
  - parallel_max_servers
  - parallel_servers_target
  - ob_early_lock_release
  - ob_trx_idle_timeout
  - ob_reserved_meta_memory_percentage
  - nls_date_format
  - nls_timestamp_format
  - nls_timestamp_tz_format
  - nls_language
  - nls_territory
  - nls_sort
  - nls_comp
  - nls_characterset
  - nls_nchar_characterset
  - nls_date_language
  - nls_length_semantics
  - nls_calendar
  - nls_nchar_conv_excp
  - nls_numeric_characters
  - tracefile_identifier
  - transaction_isolation
  - ob_trx_lock_timeout
  - ob_trace_info
  - secure_file_priv
  - ob_pl_block_timeout
  - performance_schema
  - transaction_read_only
- System configuration items
  - Overview of system configuration items
  - all_cluster_list
  - enable_unit_balance_resource_weight
  - plan_cache_high_watermark
  - plan_cache_low_watermark
  - sql_audit_queue_size
  - tenant_cpu_variation_per_server
  - max_stale_time_for_weak_consistency
  - sql_work_area
  - auto_leader_switch_interval
  - auto_delete_expired_backup
  - autoinc_cache_refresh_interval
  - audit_sys_operations
  - audit_trail
  - balancer_idle_time
  - balancer_log_interval
  - balancer_timeout_check_interval
  - balancer_task_timeout
  - balancer_tolerance_percentage
  - balancer_emergency_percentage
  - balance_blacklist_failure_threshold
  - balance_blacklist_retry_interval
  - backup_concurrency
  - backup_dest
  - backup_net_limit
  - backup_recovery_window
  - backup_region
  - builtin_db_data_verify_cycle
  - bf_cache_miss_count_threshold
  - bf_cache_priority
  - cache_wash_threshold
  - clog_cache_priority
  - clog_sync_time_warn_threshold
  - clog_disk_usage_limit_percentage
  - clog_transport_compress_all
  - clog_transport_compress_func
  - clog_persistence_compress_func
  - clog_max_unconfirmed_log_count
  - cluster
  - cluster_id
  - cpu_count
  - cpu_quota_concurrency
  - cpu_reserved
  - config_additional_dir
  - data_copy_concurrency
  - data_dir
  - datafile_disk_percentage
  - dtl_buffer_size
  - datafile_size
  - default_compress_func
  - default_compress
  - default_progressive_merge_num
  - default_row_format
  - devname
  - data_disk_usage_limit_percentage
  - disk_io_thread_count
  - dead_socket_detection_timeout
  - enable_clog_persistence_compress
  - election_cpu_quota
  - enable_one_phase_commit
  - enable_sys_unit_standalone
  - enable_pg
  - enable_smooth_leader_switch
  - election_blacklist_interval
  - enable_election_group
  - enable_auto_leader_switch
  - enable_global_freeze_trigger
  - enable_manual_merge
  - enable_merge_by_turn
  - enable_perf_event
  - enable_rebalance
  - enable_record_trace_log
  - enable_record_trace_id
  - enable_early_lock_release
  - enable_rereplication
  - enable_rich_error_msg
  - enable_rootservice_standalone
  - enable_sql_audit
  - enable_sql_operator_dump
  - enable_async_syslog
  - enable_syslog_recycle
  - enable_syslog_wf
  - enable_upgrade_mode
  - enable_separate_sys_clog
  - enable_ddl
  - enable_major_freeze
  - enable_rebuild_on_purpose
  - enable_log_archive
  - enable_monotonic_weak_read
  - external_kms_info
  - freeze_trigger_percentage
  - flush_log_at_trx_commit
  - fuse_row_cache_priority
  - force_refresh_location_cache_interval
  - force_refresh_location_cache_threshold
  - get_leader_candidate_rpc_timeout
  - global_major_freeze_residual_memory
  - global_write_halt_residual_memory
  - ignore_replay_checksum_error
  - global_index_build_single_replica_timeout
  - high_priority_net_thread_count
  - ignore_replica_checksum_error
  - ignore_replay_checksum_error
  - index_cache_priority
  - index_clog_cache_priority
  - index_info_block_cache_priority
  - internal_sql_execute_timeout
  - large_query_worker_percentage
  - large_query_threshold
  - leak_mod_to_check
  - lease_time
  - location_cache_cpu_quota
  - location_cache_expire_time
  - location_cache_priority
  - location_cache_refresh_min_interval
  - location_fetch_concurrency
  - location_refresh_thread_count
  - log_archive_checkpoint_interval
  - log_archive_concurrency
  - log_restore_concurrency
  - major_freeze_duty_time
  - max_kept_major_version_number
  - max_string_print_length
  - max_syslog_file_count
  - merge_stat_sampling_ratio
  - major_compact_trigger
  - memory_chunk_cache_size
  - memory_limit
  - memory_limit_percentage
  - memory_reserved
  - merge_thread_count
  - merger_check_interval
  - merger_completion_percentage
  - merger_switch_leader_duration_time
  - merger_warm_up_duration_time
  - max_px_worker_count
  - migration_disable_time
  - min_observer_version
  - minor_deferred_gc_time
  - minor_freeze_times
  - minor_warm_up_duration_time
  - mysql_port
  - minor_merge_concurrency
  - multiblock_read_gap_size
  - multiblock_read_size
  - micro_block_merge_verify_level
  - migrate_concurrency
  - minor_compact_trigger
  - memstore_limit_percentage
  - net_thread_count
  - obconfig_url
  - ob_enable_batched_multi_statement
  - partition_table_check_interval
  - partition_table_scan_batch_count
  - plan_cache_evict_interval
  - px_task_size
  - px_workers_per_cpu_quota
  - replica_safe_remove_time
  - resource_hard_limit
  - resource_soft_limit
  - rootservice_async_task_queue_size
  - rootservice_async_task_thread_count
  - rootservice_list
  - rootservice_ready_check_interval
  - row_compaction_update_limit
  - row_purge_thread_count
  - rpc_port
  - rpc_timeout
  - restore_concurrency
  - rootservice_memory_limit
  - rebuild_replica_data_lag_threshold
  - schema_history_expire_time
  - ssl_client_authentication
  - server_check_interval
  - server_data_copy_in_concurrency
  - server_data_copy_out_concurrency
  - server_permanent_offline_time
  - server_temporary_offline_time
  - stack_size
  - server_balance_critical_disk_waterlevel
  - server_balance_disk_tolerance_percent
  - system_memory
  - server_balance_cpu_mem_tolerance_percent
  - server_cpu_quota_max
  - server_cpu_quota_min
  - sql_audit_memory_limit
  - sys_bkgd_io_high_percentage
  - sys_bkgd_io_low_percentage
  - sys_bkgd_io_timeout
  - sys_bkgd_net_percentage
  - sys_bkgd_migration_change_member_list_timeout
  - sys_bkgd_migration_retry_num
  - syslog_level
  - switchover_process_thread_count
  - system_cpu_quota
  - sys_cpu_limit_trigger
  - system_trace_level
  - syslog_io_bandwidth_limit
  - tablet_size
  - tableapi_transport_compress_func
  - tenant_task_queue_size
  - tenant_groups
  - trace_log_slow_query_watermark
  - trace_log_sampling_interval
  - trx_2pc_retry_interval
  - trx_try_wait_lock_timeout
  - trx_force_kill_threshold
  - tde_method
  - token_reserved_percentage
  - unit_balance_resource_weight
  - user_block_cache_priority
  - user_row_cache_priority
  - user_tab_col_stat_cache_priority
  - user_iort_up_percentage
  - use_large_pages
  - virtual_table_location_cache_expire_time
  - workers_per_cpu_quota
  - wait_leader_batch_count
  - writing_throttling_maximum_duration
  - writing_throttling_trigger_percentage
  - weak_read_version_refresh_interval
  - workarea_size_policy
  - zone
  - zone_merge_concurrency
  - zone_merge_order
  - zone_merge_timeout
  - ob_ssl_invited_common_names
  - ssl_external_kms_info
  - ob_event_history_recycle_interval
  - backup_backup_dest
  - plsql_ccflags
  - plsql_code_type
  - plsql_debug
  - plsql_optimize_level
  - plsql_v2_compatibility
  - plsql_warnings
  - recyclebin_object_expire_time
  - log_archive_batch_buffer_limit
  - clog_disk_utilization_threshold
  - backup_backup_archive_log_batch_count
  - backup_backup_archivelog_retry_interval
  - backup_backupset_batch_count
  - backup_backupset_retry_interval
  - open_cursors
  - location_cache_refresh_rpc_timeout
  - location_cache_refresh_sql_timeout
  - backup_dest_option
  - backup_backup_dest_option
  - backup_zone
  - backup_log_archive_option
  - enable_tcp_keepalive
  - tcp_keepidle
  - tcp_keepintvl
  - tcp_keepcnt
- Reserved keywords
FAQ
- Product FAQ
- Deployment FAQ
- SQL FAQ
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- FAQ about primary and secondary databases
Version release records
- V2.2
  - OceanBase Database V2.2.77