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DBA_TAB_COMMENTS

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

Overview

DBA_TAB_COMMENTS describes comments on all tables and views in the database.

ALL_TAB_COMMENTS
USER_TAB_COMMENTS

Field description

Field name	Type	Nullable	Description
OWNER	VARCHAR2(128)	NO	The owner of the table or view.
TABLE_NAME	VARCHAR2(128)	NO	The name of the table or view.
TABLE_TYPE	VARCHAR2(11)	NO	The type of the object.
COMMENTS	VARCHAR2(4000)	NO	The comment on the object.

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OceanBase Database

SQL - V2.2.77Enterprise Edition

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  - Query table data
    - About query statements
    - Search for data that satisfies specified conditions in a table
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    - Query data from multiple tables
    - Use operators and functions in a query
      - Use arithmetic operators in queries
      - Use numeric functions in queries
      - Use string connectors in a query
      - Use string functions in queries
      - Use date and time functions in queries
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      - Use aggregate functions in queries
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  - About DML statements
    - Overview of DML statements
    - About the INSERT statement
    - About the UPDATE statement
    - About the MERGE statement
    - About the DELETE statement
  - About transaction control statements
  - Commit a transaction
  - Roll back a transaction
  - Transaction savepoints
  - About transaction timeout
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  - About the DDL statement
  - Create and manage tables
    - About SQL data types
    - Create a table
    - About auto-increment columns
    - About types of column constraints
    - About table indexes
    - Flash back a deleted table
  - Create and manage partitioned tables
    - Overview of partitioning
    - Partition routing
    - Partitioning strategies
    - Indexing on partitioned tables
    - Recommendations for using partitioned tables
  - Create and manage table groups
    - About table groups
    - Specify a table group when creating a table
    - View information about a table group
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SQL Reference (MySQL Mode)
- Elements
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  - CREATE DATABASE
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  - CREATE RESTORE POINT
  - CREATE SYNONYM
  - CREATE TABLE
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  - CREATE VIEW
  - DELETE
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  - SESSION
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  - TRANSACTION
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SQL Reference (Oracle Mode)
- SQL overview
- Pseudocolumns
- Elements
  - Built-in data types
    - Overview of built-in data types
    - Character data types
      - Overview of character data types
      - CHAR data type
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      - VARCHAR data type
    - Numeric data types
      - Overview of numeric data types
      - NUMBER data type
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      - Floating-point numbers
      - Numeric precedence
    - Date, time, and interval data types
      - Overview of datetime and interval data types
      - DATE data type
      - TIMESTAMP data type
      - TIMESTAMP WITH TIME ZONE data type
      - TIMESTAMP WITH LOCAL TIME ZONE data type
      - INTERVAL YEAR TO MONTH data type
      - INTERVAL DAY TO SECOND data type
      - Calculation of DATE and INTERVAL values
    - RAW data type
    - Large object data types
      - Overview of large object data types
      - BLOB data type
      - CLOB data type
  - Comparison rules of data types
    - Overview of data type comparison rules
    - Numeric values
    - Date values
    - Character values
    - Data type precedence
    - Data type conversion
    - Security notes for data conversions
  - Literals
    - Literal overview
    - Text literals
    - Numeric literals
    - Datetime literals
      - Date literals
      - Timestamp literals
    - Interval literals
  - Formatting
    - Formatting overview
    - Number formatting
    - Datetime formatting
    - RR datetime format element
    - String-to-date conversion rules
  - Null values
    - Null value overview
    - Null values in SQL functions
    - Null values in comparison conditions
    - Null values in conditional expressions
  - Comments
    - Overview
    - Comments in SQL statements
    - Comments on schema objects and non-schema objects
    - Hint
      - Hint overview
      - Lists of hints
        Hints related to access paths
        Hints related to join orders
        Hints related to join operations
        Hints related to parallel execution
        Hints related to query policies
        Hints related to query transformation
        Other hints
  - Database objects
    - Schema objects
  - Database naming conventions
    - Overview of the naming conventions of database objects
    - Naming rules of database objects
    - Examples of schema object names
    - Rules for naming schema objects
  - Methods of referencing database objects
    - Overview of database object references
    - Reference schema objects
    - Reference partitioned tables and indexes
    - Reference object type attributes and methods
- Operators
  - Operator overview
  - Arithmetic operators
  - Concatenation operators
  - Hierarchical query operators
  - Set operators
  - Collations
- Functions
  - Function overview
  - Single-row functions
    - Numeric functions
      - ABS
      - ACOS
      - BITAND
      - CEIL
      - EXP
      - FLOOR
      - LN
      - LOG
      - MOD
      - POWER
      - REMAINDER
      - ROUND
      - SIGN
      - SQRT
      - TRUNC
    - String functions that return strings
      - CHR
      - CONCAT
      - INITCAP
      - LOWER
      - LPAD
      - LTRIM
      - REGEXP_REPLACE
      - REPLACE
      - RPAD
      - RTRIM
      - SUBSTR
      - TRANSLATE
      - TRIM
      - UPPER
    - String functions that return numbers
      - ASCII
      - INSTR
      - LENGTH
    - Datetime functions
      - ADD_MONTHS
      - CURRENT_DATE
      - CURRENT_TIMESTAMP
      - DBTIMEZONE
      - EXTRACT(datetime)
      - FROM_TZ
      - LAST_DAY
      - LOCALTIMESTAMP
      - MONTHS_BETWEEN
      - NEXT_DAY
      - NUMTODSINTERVAL
      - NUMTOYMINTERVAL
      - ROUND (date)
      - SESSIONTIMEZONE
      - SYS_EXTRACT_UTC
      - SYSDATE
      - SYSTIMESTAMP
      - TO_CHAR (datetime)
      - TO_DSINTERVAL
      - TO_TIMESTAMP
      - TO_TIMESTAMP_TZ
      - TO_YMINTERVAL
      - TRUNC (date)
      - TZ_OFFSET
    - General comparison functions
      - GREATEST
      - LEAST
    - Conversion functions
      - CAST
      - HEXTORAW
      - RAWTOHEX
      - TO_BINARY_DOUBLE
      - TO_BINARY_FLOAT
      - TO_CHAR (character)
      - TO_CHAR (datetime)
      - TO_CHAR (number)
      - TO_DATE
      - TO_DSINTERVAL
      - TO_NUMBER
      - TO_TIMESTAMP
      - TO_TIMESTAMP_TZ
      - TO_YMINTERVAL
    - Encoding and decoding functions
      - DECODE
      - ORA_HASH
      - VSIZE
    - Null value-related functions
      - COALESCE
      - LNNVL
      - NVL
      - NVL2
  - Aggregate functions
    - APPROX_COUNT_DISTINCT
    - AVG
    - COUNT
    - KEEP
    - LISTAGG
    - MAX
    - MIN
    - ROLLUP
    - STDDEV
    - STDDEV_POP
    - STDDEV_SAMP
    - SUM
    - VARIANCE
    - WMSYS.WM_CONCAT/WM_CONCAT
  - Analytic functions
    - Description of window functions
    - AVG
    - COUNT
    - KEEP
    - SUM
    - MAX
    - MIN
    - LISTAGG
    - STDDEV
    - STDDEV_POP
    - STDDEV_SAMP
    - VARIANCE
    - RANK
    - LEAD
    - LAG
    - FIRST_VALUE
    - LAST_VALUE
    - NTH_VALUE
    - CUME_DIST
    - DENSE_RANK
    - NTILE
    - PERCENT_RANK
    - RATIO_TO_REPORT
    - ROW_NUMBER
    - WMSYS.WM_CONCAT/WM_CONCAT
- Expressions
  - Overview of SQL expressions
  - Simple expressions
  - Compound expressions
  - Case expressions
  - Column expressions
  - Datetime expressions
  - 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
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    - 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
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  - autocommit
  - character_set_client
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  - collation_connection
  - interactive_timeout
  - last_insert_id
  - max_allowed_packet
  - sql_mode
  - time_zone
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  - 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
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  - 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
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  - ob_read_consistency
  - ob_enable_transformation
  - ob_trx_timeout
  - ob_enable_plan_cache
  - ob_enable_index_direct_select
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  - ob_enable_aggregation_pushdown
  - ob_last_schema_version
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  - 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
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  - recyclebin
  - ob_capability_flag
  - ob_stmt_parallel_degree
  - is_result_accurate
  - error_on_overlap_time
  - ob_compatibility_mode
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  - ob_sql_work_area_percentage
  - ob_route_policy
  - ob_enable_transmission_checksum
  - foreign_key_checks
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  - ob_tcp_invited_nodes
  - sql_throttle_current_priority
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  - sql_throttle_rt
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  - 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
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Version release records
- V2.2
  - OceanBase Database V2.2.77