tidb tidb_vars 源码
tidb tidb_vars 代码
文件路径：/sessionctx/variable/tidb_vars.go
// Copyright 2017 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package variable
import (
"math"
"github.com/pingcap/tidb/config"
"github.com/pingcap/tidb/parser/mysql"
"github.com/pingcap/tidb/sessionctx/variable/featuretag/concurrencyddl"
"github.com/pingcap/tidb/util/paging"
"go.uber.org/atomic"
)
/*
Steps to add a new TiDB specific system variable:
1. Add a new variable name with comment in this file.
2. Add the default value of the new variable in this file.
3. Add SysVar instance in 'defaultSysVars' slice.
*/
// TiDB system variable names that only in session scope.
const (
TiDBDDLSlowOprThreshold = "ddl_slow_threshold"
// TiDBSnapshot is used for reading history data, the default value is empty string.
// The value can be a datetime string like '2017-11-11 20:20:20' or a tso string. When this variable is set, the session reads history data of that time.
TiDBSnapshot = "tidb_snapshot"
// TiDBOptAggPushDown is used to enable/disable the optimizer rule of aggregation push down.
TiDBOptAggPushDown = "tidb_opt_agg_push_down"
// TiDBOptCartesianBCJ is used to disable/enable broadcast cartesian join in MPP mode
TiDBOptCartesianBCJ = "tidb_opt_broadcast_cartesian_join"
TiDBOptMPPOuterJoinFixedBuildSide = "tidb_opt_mpp_outer_join_fixed_build_side"
// TiDBOptDistinctAggPushDown is used to decide whether agg with distinct should be pushed to tikv/tiflash.
TiDBOptDistinctAggPushDown = "tidb_opt_distinct_agg_push_down"
// TiDBOptSkewDistinctAgg is used to indicate the distinct agg has data skew
TiDBOptSkewDistinctAgg = "tidb_opt_skew_distinct_agg"
// TiDBOpt3StageDistinctAgg is used to indicate whether to plan and execute the distinct agg in 3 stages
TiDBOpt3StageDistinctAgg = "tidb_opt_three_stage_distinct_agg"
// TiDBBCJThresholdSize is used to limit the size of small table for mpp broadcast join.
// Its unit is bytes, if the size of small table is larger than it, we will not use bcj.
TiDBBCJThresholdSize = "tidb_broadcast_join_threshold_size"
// TiDBBCJThresholdCount is used to limit the count of small table for mpp broadcast join.
// If we can't estimate the size of one side of join child, we will check if its row number exceeds this limitation.
TiDBBCJThresholdCount = "tidb_broadcast_join_threshold_count"
// TiDBOptWriteRowID is used to enable/disable the operations of insert、replace and update to _tidb_rowid.
TiDBOptWriteRowID = "tidb_opt_write_row_id"
// TiDBAutoAnalyzeRatio will run if (table modify count)/(table row count) is greater than this value.
TiDBAutoAnalyzeRatio = "tidb_auto_analyze_ratio"
// TiDBAutoAnalyzeStartTime will run if current time is within start time and end time.
TiDBAutoAnalyzeStartTime = "tidb_auto_analyze_start_time"
TiDBAutoAnalyzeEndTime = "tidb_auto_analyze_end_time"
// TiDBChecksumTableConcurrency is used to speed up the ADMIN CHECKSUM TABLE
// statement, when a table has multiple indices, those indices can be
// scanned concurrently, with the cost of higher system performance impact.
TiDBChecksumTableConcurrency = "tidb_checksum_table_concurrency"
// TiDBCurrentTS is used to get the current transaction timestamp.
// It is read-only.
TiDBCurrentTS = "tidb_current_ts"
// TiDBLastTxnInfo is used to get the last transaction info within the current session.
TiDBLastTxnInfo = "tidb_last_txn_info"
// TiDBLastQueryInfo is used to get the last query info within the current session.
TiDBLastQueryInfo = "tidb_last_query_info"
// TiDBLastDDLInfo is used to get the last ddl info within the current session.
TiDBLastDDLInfo = "tidb_last_ddl_info"
// TiDBLastPlanReplayerToken is used to get the last plan replayer token within the current session
TiDBLastPlanReplayerToken = "tidb_last_plan_replayer_token"
// TiDBConfig is a read-only variable that shows the config of the current server.
TiDBConfig = "tidb_config"
// TiDBBatchInsert is used to enable/disable auto-split insert data. If set this option on, insert executor will automatically
// insert data into multiple batches and use a single txn for each batch. This will be helpful when inserting large data.
TiDBBatchInsert = "tidb_batch_insert"
// TiDBBatchDelete is used to enable/disable auto-split delete data. If set this option on, delete executor will automatically
// split data into multiple batches and use a single txn for each batch. This will be helpful when deleting large data.
TiDBBatchDelete = "tidb_batch_delete"
// TiDBBatchCommit is used to enable/disable auto-split the transaction.
// If set this option on, the transaction will be committed when it reaches stmt-count-limit and starts a new transaction.
TiDBBatchCommit = "tidb_batch_commit"
// TiDBDMLBatchSize is used to split the insert/delete data into small batches.
// It only takes effort when tidb_batch_insert/tidb_batch_delete is on.
// Its default value is 20000. When the row size is large, 20k rows could be larger than 100MB.
// User could change it to a smaller one to avoid breaking the transaction size limitation.
TiDBDMLBatchSize = "tidb_dml_batch_size"
// The following session variables controls the memory quota during query execution.
// TiDBMemQuotaQuery controls the memory quota of a query.
TiDBMemQuotaQuery = "tidb_mem_quota_query" // Bytes.
// TiDBMemQuotaApplyCache controls the memory quota of a query.
TiDBMemQuotaApplyCache = "tidb_mem_quota_apply_cache"
// TiDBGeneralLog is used to log every query in the server in info level.
TiDBGeneralLog = "tidb_general_log"
// TiDBLogFileMaxDays is used to log every query in the server in info level.
TiDBLogFileMaxDays = "tidb_log_file_max_days"
// TiDBPProfSQLCPU is used to add label sql label to pprof result.
TiDBPProfSQLCPU = "tidb_pprof_sql_cpu"
// TiDBRetryLimit is the maximum number of retries when committing a transaction.
TiDBRetryLimit = "tidb_retry_limit"
// TiDBDisableTxnAutoRetry disables transaction auto retry.
TiDBDisableTxnAutoRetry = "tidb_disable_txn_auto_retry"
// TiDBEnableChunkRPC enables TiDB to use Chunk format for coprocessor requests.
TiDBEnableChunkRPC = "tidb_enable_chunk_rpc"
// TiDBOptimizerSelectivityLevel is used to control the selectivity estimation level.
TiDBOptimizerSelectivityLevel = "tidb_optimizer_selectivity_level"
// TiDBOptimizerEnableNewOnlyFullGroupByCheck is used to open the newly only_full_group_by check by maintaining functional dependency.
TiDBOptimizerEnableNewOnlyFullGroupByCheck = "tidb_enable_new_only_full_group_by_check"
TiDBOptimizerEnableOuterJoinReorder = "tidb_enable_outer_join_reorder"
// TiDBTxnMode is used to control the transaction behavior.
TiDBTxnMode = "tidb_txn_mode"
// TiDBRowFormatVersion is used to control tidb row format version current.
TiDBRowFormatVersion = "tidb_row_format_version"
// TiDBEnableTablePartition is used to control table partition feature.
// The valid value include auto/on/off:
// on or auto: enable table partition if the partition type is implemented.
// off: always disable table partition.
TiDBEnableTablePartition = "tidb_enable_table_partition"
// TiDBEnableListTablePartition is used to control list table partition feature.
TiDBEnableListTablePartition = "tidb_enable_list_partition"
// TiDBSkipIsolationLevelCheck is used to control whether to return error when set unsupported transaction
// isolation level.
TiDBSkipIsolationLevelCheck = "tidb_skip_isolation_level_check"
// TiDBLowResolutionTSO is used for reading data with low resolution TSO which is updated once every two seconds
TiDBLowResolutionTSO = "tidb_low_resolution_tso"
// TiDBReplicaRead is used for reading data from replicas, followers for example.
TiDBReplicaRead = "tidb_replica_read"
// TiDBAdaptiveClosestReadThreshold is for reading data from closest replicas(with same 'zone' label).
// TiKV client should send read request to the closest replica(leader/follower) if the estimated response
// size exceeds this threshold; otherwise, this request should be sent to leader.
// This variable only take effect when `tidb_replica_read` is 'closest-adaptive'.
TiDBAdaptiveClosestReadThreshold = "tidb_adaptive_closest_read_threshold"
// TiDBAllowRemoveAutoInc indicates whether a user can drop the auto_increment column attribute or not.
TiDBAllowRemoveAutoInc = "tidb_allow_remove_auto_inc"
// TiDBMultiStatementMode enables multi statement at the risk of SQL injection
// provides backwards compatibility
TiDBMultiStatementMode = "tidb_multi_statement_mode"
// TiDBEvolvePlanTaskMaxTime controls the max time of a single evolution task.
TiDBEvolvePlanTaskMaxTime = "tidb_evolve_plan_task_max_time"
// TiDBEvolvePlanTaskStartTime is the start time of evolution task.
TiDBEvolvePlanTaskStartTime = "tidb_evolve_plan_task_start_time"
// TiDBEvolvePlanTaskEndTime is the end time of evolution task.
TiDBEvolvePlanTaskEndTime = "tidb_evolve_plan_task_end_time"
// TiDBSlowLogThreshold is used to set the slow log threshold in the server.
TiDBSlowLogThreshold = "tidb_slow_log_threshold"
// TiDBRecordPlanInSlowLog is used to log the plan of the slow query.
TiDBRecordPlanInSlowLog = "tidb_record_plan_in_slow_log"
// TiDBEnableSlowLog enables TiDB to log slow queries.
TiDBEnableSlowLog = "tidb_enable_slow_log"
// TiDBCheckMb4ValueInUTF8 is used to control whether to enable the check wrong utf8 value.
TiDBCheckMb4ValueInUTF8 = "tidb_check_mb4_value_in_utf8"
// TiDBFoundInPlanCache indicates whether the last statement was found in plan cache
TiDBFoundInPlanCache = "last_plan_from_cache"
// TiDBFoundInBinding indicates whether the last statement was matched with the hints in the binding.
TiDBFoundInBinding = "last_plan_from_binding"
// TiDBAllowAutoRandExplicitInsert indicates whether explicit insertion on auto_random column is allowed.
TiDBAllowAutoRandExplicitInsert = "allow_auto_random_explicit_insert"
// TiDBTxnScope indicates whether using global transactions or local transactions.
TiDBTxnScope = "txn_scope"
// TiDBTxnReadTS indicates the next transaction should be staleness transaction and provide the startTS
TiDBTxnReadTS = "tx_read_ts"
// TiDBReadStaleness indicates the staleness duration for following statement
TiDBReadStaleness = "tidb_read_staleness"
// TiDBEnablePaging indicates whether paging is enabled in coprocessor requests.
TiDBEnablePaging = "tidb_enable_paging"
// TiDBReadConsistency indicates whether the autocommit read statement goes through TiKV RC.
TiDBReadConsistency = "tidb_read_consistency"
// TiDBSysdateIsNow is the name of the `tidb_sysdate_is_now` system variable
TiDBSysdateIsNow = "tidb_sysdate_is_now"
// RequireSecureTransport indicates the secure mode for data transport
RequireSecureTransport = "require_secure_transport"
// TiFlashFastScan indicates whether use fast scan in tiflash.
TiFlashFastScan = "tiflash_fastscan"
// TiDBEnableUnsafeSubstitute indicates whether to enable generate column takes unsafe substitute.
TiDBEnableUnsafeSubstitute = "tidb_enable_unsafe_substitute"
// TiDBEnableTiFlashReadForWriteStmt indicates whether to enable TiFlash to read for write statements.
TiDBEnableTiFlashReadForWriteStmt = "tidb_enable_tiflash_read_for_write_stmt"
)
// TiDB system variable names that both in session and global scope.
const (
// TiDBBuildStatsConcurrency is used to speed up the ANALYZE statement, when a table has multiple indices,
// those indices can be scanned concurrently, with the cost of higher system performance impact.
TiDBBuildStatsConcurrency = "tidb_build_stats_concurrency"
// TiDBDistSQLScanConcurrency is used to set the concurrency of a distsql scan task.
// A distsql scan task can be a table scan or a index scan, which may be distributed to many TiKV nodes.
// Higher concurrency may reduce latency, but with the cost of higher memory usage and system performance impact.
// If the query has a LIMIT clause, high concurrency makes the system do much more work than needed.
TiDBDistSQLScanConcurrency = "tidb_distsql_scan_concurrency"
// TiDBOptInSubqToJoinAndAgg is used to enable/disable the optimizer rule of rewriting IN subquery.
TiDBOptInSubqToJoinAndAgg = "tidb_opt_insubq_to_join_and_agg"
// TiDBOptPreferRangeScan is used to enable/disable the optimizer to always prefer range scan over table scan, ignoring their costs.
TiDBOptPreferRangeScan = "tidb_opt_prefer_range_scan"
// TiDBOptEnableCorrelationAdjustment is used to indicates if enable correlation adjustment.
TiDBOptEnableCorrelationAdjustment = "tidb_opt_enable_correlation_adjustment"
// TiDBOptLimitPushDownThreshold determines if push Limit or TopN down to TiKV forcibly.
TiDBOptLimitPushDownThreshold = "tidb_opt_limit_push_down_threshold"
// TiDBOptCorrelationThreshold is a guard to enable row count estimation using column order correlation.
TiDBOptCorrelationThreshold = "tidb_opt_correlation_threshold"
// TiDBOptCorrelationExpFactor is an exponential factor to control heuristic approach when tidb_opt_correlation_threshold is not satisfied.
TiDBOptCorrelationExpFactor = "tidb_opt_correlation_exp_factor"
// TiDBOptCPUFactor is the CPU cost of processing one expression for one row.
TiDBOptCPUFactor = "tidb_opt_cpu_factor"
// TiDBOptCopCPUFactor is the CPU cost of processing one expression for one row in coprocessor.
TiDBOptCopCPUFactor = "tidb_opt_copcpu_factor"
// TiDBOptTiFlashConcurrencyFactor is concurrency number of tiflash computation.
TiDBOptTiFlashConcurrencyFactor = "tidb_opt_tiflash_concurrency_factor"
// TiDBOptNetworkFactor is the network cost of transferring 1 byte data.
TiDBOptNetworkFactor = "tidb_opt_network_factor"
// TiDBOptScanFactor is the IO cost of scanning 1 byte data on TiKV.
TiDBOptScanFactor = "tidb_opt_scan_factor"
// TiDBOptDescScanFactor is the IO cost of scanning 1 byte data on TiKV in desc order.
TiDBOptDescScanFactor = "tidb_opt_desc_factor"
// TiDBOptSeekFactor is the IO cost of seeking the start value in a range on TiKV or TiFlash.
TiDBOptSeekFactor = "tidb_opt_seek_factor"
// TiDBOptMemoryFactor is the memory cost of storing one tuple.
TiDBOptMemoryFactor = "tidb_opt_memory_factor"
// TiDBOptDiskFactor is the IO cost of reading/writing one byte to temporary disk.
TiDBOptDiskFactor = "tidb_opt_disk_factor"
// TiDBOptConcurrencyFactor is the CPU cost of additional one goroutine.
TiDBOptConcurrencyFactor = "tidb_opt_concurrency_factor"
// TiDBOptForceInlineCTE is used to enable/disable inline CTE
TiDBOptForceInlineCTE = "tidb_opt_force_inline_cte"
// Variables for the Cost Model Ver2
// TiDBOptCPUFactorV2 is the CPU factor for the Cost Model Ver2
TiDBOptCPUFactorV2 = "tidb_opt_cpu_factor_v2"
// TiDBOptCopCPUFactorV2 is the CopCPU factor for the Cost Model Ver2
TiDBOptCopCPUFactorV2 = "tidb_opt_copcpu_factor_v2"
// TiDBOptTiFlashCPUFactorV2 is the TiFlashCPU factor for the Cost Model Ver2
TiDBOptTiFlashCPUFactorV2 = "tidb_opt_tiflash_cpu_factor_v2"
// TiDBOptNetworkFactorV2 is the network factor for the Cost Model Ver2
TiDBOptNetworkFactorV2 = "tidb_opt_network_factor_v2"
// TiDBOptScanFactorV2 is the scan factor for the Cost Model Ver2
TiDBOptScanFactorV2 = "tidb_opt_scan_factor_v2"
// TiDBOptDescScanFactorV2 is the desc scan factor for the Cost Model Ver2
TiDBOptDescScanFactorV2 = "tidb_opt_desc_factor_v2"
// TiDBOptTiFlashScanFactorV2 is the TiFlashScan factor for the Cost Model Ver2
TiDBOptTiFlashScanFactorV2 = "tidb_opt_tiflash_scan_factor_v2"
// TiDBOptSeekFactorV2 is the seek factor for the Cost Model Ver2
TiDBOptSeekFactorV2 = "tidb_opt_seek_factor_v2"
// TiDBOptMemoryFactorV2 is the memory factor for the Cost Model Ver2
TiDBOptMemoryFactorV2 = "tidb_opt_memory_factor_v2"
// TiDBOptDiskFactorV2 is the disk factor for the Cost Model Ver2
TiDBOptDiskFactorV2 = "tidb_opt_disk_factor_v2"
// TiDBOptConcurrencyFactorV2 is the concurrency factor for the Cost Model Ver2
TiDBOptConcurrencyFactorV2 = "tidb_opt_concurrency_factor_v2"
// TiDBIndexJoinBatchSize is used to set the batch size of an index lookup join.
// The index lookup join fetches batches of data from outer executor and constructs ranges for inner executor.
// This value controls how much of data in a batch to do the index join.
// Large value may reduce the latency but consumes more system resource.
TiDBIndexJoinBatchSize = "tidb_index_join_batch_size"
// TiDBIndexLookupSize is used for index lookup executor.
// The index lookup executor first scan a batch of handles from a index, then use those handles to lookup the table
// rows, this value controls how much of handles in a batch to do a lookup task.
// Small value sends more RPCs to TiKV, consume more system resource.
// Large value may do more work than needed if the query has a limit.
TiDBIndexLookupSize = "tidb_index_lookup_size"
// TiDBIndexLookupConcurrency is used for index lookup executor.
// A lookup task may have 'tidb_index_lookup_size' of handles at maximum, the handles may be distributed
// in many TiKV nodes, we execute multiple concurrent index lookup tasks concurrently to reduce the time
// waiting for a task to finish.
// Set this value higher may reduce the latency but consumes more system resource.
// tidb_index_lookup_concurrency is deprecated, use tidb_executor_concurrency instead.
TiDBIndexLookupConcurrency = "tidb_index_lookup_concurrency"
// TiDBIndexLookupJoinConcurrency is used for index lookup join executor.
// IndexLookUpJoin starts "tidb_index_lookup_join_concurrency" inner workers
// to fetch inner rows and join the matched (outer, inner) row pairs.
// tidb_index_lookup_join_concurrency is deprecated, use tidb_executor_concurrency instead.
TiDBIndexLookupJoinConcurrency = "tidb_index_lookup_join_concurrency"
// TiDBIndexSerialScanConcurrency is used for controlling the concurrency of index scan operation
// when we need to keep the data output order the same as the order of index data.
TiDBIndexSerialScanConcurrency = "tidb_index_serial_scan_concurrency"
// TiDBMaxChunkSize is used to control the max chunk size during query execution.
TiDBMaxChunkSize = "tidb_max_chunk_size"
// TiDBAllowBatchCop means if we should send batch coprocessor to TiFlash. It can be set to 0, 1 and 2.
// 0 means never use batch cop, 1 means use batch cop in case of aggregation and join, 2, means to force sending batch cop for any query.
// The default value is 0
TiDBAllowBatchCop = "tidb_allow_batch_cop"
// TiDBAllowMPPExecution means if we should use mpp way to execute query or not.
// Default value is `true`, means to be determined by the optimizer.
// Value set to `false` means never use mpp.
TiDBAllowMPPExecution = "tidb_allow_mpp"
// TiDBHashExchangeWithNewCollation means if hash exchange is supported when new collation is on.
// Default value is `true`, means support hash exchange when new collation is on.
// Value set to `false` means not support hash exchange when new collation is on.
TiDBHashExchangeWithNewCollation = "tidb_hash_exchange_with_new_collation"
// TiDBEnforceMPPExecution means if we should enforce mpp way to execute query or not.
// Default value is `false`, means to be determined by variable `tidb_allow_mpp`.
// Value set to `true` means enforce use mpp.
// Note if you want to set `tidb_enforce_mpp` to `true`, you must set `tidb_allow_mpp` to `true` first.
TiDBEnforceMPPExecution = "tidb_enforce_mpp"
// TiDBMaxTiFlashThreads is the maximum number of threads to execute the request which is pushed down to tiflash.
// Default value is -1, means it will not be pushed down to tiflash.
// If the value is bigger than -1, it will be pushed down to tiflash and used to create db context in tiflash.
TiDBMaxTiFlashThreads = "tidb_max_tiflash_threads"
// TiDBMPPStoreFailTTL is the unavailable time when a store is detected failed. During that time, tidb will not send any task to
// TiFlash even though the failed TiFlash node has been recovered.
TiDBMPPStoreFailTTL = "tidb_mpp_store_fail_ttl"
// TiDBInitChunkSize is used to control the init chunk size during query execution.
TiDBInitChunkSize = "tidb_init_chunk_size"
// TiDBMinPagingSize is used to control the min paging size in the coprocessor paging protocol.
TiDBMinPagingSize = "tidb_min_paging_size"
// TiDBMaxPagingSize is used to control the max paging size in the coprocessor paging protocol.
TiDBMaxPagingSize = "tidb_max_paging_size"
// TiDBEnableCascadesPlanner is used to control whether to enable the cascades planner.
TiDBEnableCascadesPlanner = "tidb_enable_cascades_planner"
// TiDBSkipUTF8Check skips the UTF8 validate process, validate UTF8 has performance cost, if we can make sure
// the input string values are valid, we can skip the check.
TiDBSkipUTF8Check = "tidb_skip_utf8_check"
// TiDBSkipASCIICheck skips the ASCII validate process
// old tidb may already have fields with invalid ASCII bytes
// disable ASCII validate can guarantee a safe replication
TiDBSkipASCIICheck = "tidb_skip_ascii_check"
// TiDBHashJoinConcurrency is used for hash join executor.
// The hash join outer executor starts multiple concurrent join workers to probe the hash table.
// tidb_hash_join_concurrency is deprecated, use tidb_executor_concurrency instead.
TiDBHashJoinConcurrency = "tidb_hash_join_concurrency"
// TiDBProjectionConcurrency is used for projection operator.
// This variable controls the worker number of projection operator.
// tidb_projection_concurrency is deprecated, use tidb_executor_concurrency instead.
TiDBProjectionConcurrency = "tidb_projection_concurrency"
// TiDBHashAggPartialConcurrency is used for hash agg executor.
// The hash agg executor starts multiple concurrent partial workers to do partial aggregate works.
// tidb_hashagg_partial_concurrency is deprecated, use tidb_executor_concurrency instead.
TiDBHashAggPartialConcurrency = "tidb_hashagg_partial_concurrency"
// TiDBHashAggFinalConcurrency is used for hash agg executor.
// The hash agg executor starts multiple concurrent final workers to do final aggregate works.
// tidb_hashagg_final_concurrency is deprecated, use tidb_executor_concurrency instead.
TiDBHashAggFinalConcurrency = "tidb_hashagg_final_concurrency"
// TiDBWindowConcurrency is used for window parallel executor.
// tidb_window_concurrency is deprecated, use tidb_executor_concurrency instead.
TiDBWindowConcurrency = "tidb_window_concurrency"
// TiDBMergeJoinConcurrency is used for merge join parallel executor
TiDBMergeJoinConcurrency = "tidb_merge_join_concurrency"
// TiDBStreamAggConcurrency is used for stream aggregation parallel executor.
// tidb_stream_agg_concurrency is deprecated, use tidb_executor_concurrency instead.
TiDBStreamAggConcurrency = "tidb_streamagg_concurrency"
// TiDBEnableParallelApply is used for parallel apply.
TiDBEnableParallelApply = "tidb_enable_parallel_apply"
// TiDBBackoffLockFast is used for tikv backoff base time in milliseconds.
TiDBBackoffLockFast = "tidb_backoff_lock_fast"
// TiDBBackOffWeight is used to control the max back off time in TiDB.
// The default maximum back off time is a small value.
// BackOffWeight could multiply it to let the user adjust the maximum time for retrying.
// Only positive integers can be accepted, which means that the maximum back off time can only grow.
TiDBBackOffWeight = "tidb_backoff_weight"
// TiDBDDLReorgWorkerCount defines the count of ddl reorg workers.
TiDBDDLReorgWorkerCount = "tidb_ddl_reorg_worker_cnt"
// TiDBDDLFlashbackConcurrency defines the count of ddl flashback workers.
TiDBDDLFlashbackConcurrency = "tidb_ddl_flashback_concurrency"
// TiDBDDLReorgBatchSize defines the transaction batch size of ddl reorg workers.
TiDBDDLReorgBatchSize = "tidb_ddl_reorg_batch_size"
// TiDBDDLErrorCountLimit defines the count of ddl error limit.
TiDBDDLErrorCountLimit = "tidb_ddl_error_count_limit"
// TiDBDDLReorgPriority defines the operations' priority of adding indices.
// It can be: PRIORITY_LOW, PRIORITY_NORMAL, PRIORITY_HIGH
TiDBDDLReorgPriority = "tidb_ddl_reorg_priority"
// TiDBEnableAutoIncrementInGenerated disables the mysql compatibility check on using auto-incremented columns in
// expression indexes and generated columns described here https://dev.mysql.com/doc/refman/5.7/en/create-table-generated-columns.html for details.
TiDBEnableAutoIncrementInGenerated = "tidb_enable_auto_increment_in_generated"
// TiDBPlacementMode is used to control the mode for placement
TiDBPlacementMode = "tidb_placement_mode"
// TiDBMaxDeltaSchemaCount defines the max length of deltaSchemaInfos.
// deltaSchemaInfos is a queue that maintains the history of schema changes.
TiDBMaxDeltaSchemaCount = "tidb_max_delta_schema_count"
// TiDBScatterRegion will scatter the regions for DDLs when it is ON.
TiDBScatterRegion = "tidb_scatter_region"
// TiDBWaitSplitRegionFinish defines the split region behaviour is sync or async.
TiDBWaitSplitRegionFinish = "tidb_wait_split_region_finish"
// TiDBWaitSplitRegionTimeout uses to set the split and scatter region back off time.
TiDBWaitSplitRegionTimeout = "tidb_wait_split_region_timeout"
// TiDBForcePriority defines the operations' priority of all statements.
// It can be "NO_PRIORITY", "LOW_PRIORITY", "HIGH_PRIORITY", "DELAYED"
TiDBForcePriority = "tidb_force_priority"
// TiDBConstraintCheckInPlace indicates to check the constraint when the SQL executing.
// It could hurt the performance of bulking insert when it is ON.
TiDBConstraintCheckInPlace = "tidb_constraint_check_in_place"
// TiDBEnableWindowFunction is used to control whether to enable the window function.
TiDBEnableWindowFunction = "tidb_enable_window_function"
// TiDBEnablePipelinedWindowFunction is used to control whether to use pipelined window function, it only works when tidb_enable_window_function = true.
TiDBEnablePipelinedWindowFunction = "tidb_enable_pipelined_window_function"
// TiDBEnableStrictDoubleTypeCheck is used to control table field double type syntax check.
TiDBEnableStrictDoubleTypeCheck = "tidb_enable_strict_double_type_check"
// TiDBOptProjectionPushDown is used to control whether to pushdown projection to coprocessor.
TiDBOptProjectionPushDown = "tidb_opt_projection_push_down"
// TiDBEnableVectorizedExpression is used to control whether to enable the vectorized expression evaluation.
TiDBEnableVectorizedExpression = "tidb_enable_vectorized_expression"
// TiDBOptJoinReorderThreshold defines the threshold less than which
// we'll choose a rather time-consuming algorithm to calculate the join order.
TiDBOptJoinReorderThreshold = "tidb_opt_join_reorder_threshold"
// TiDBSlowQueryFile indicates which slow query log file for SLOW_QUERY table to parse.
TiDBSlowQueryFile = "tidb_slow_query_file"
// TiDBEnableFastAnalyze indicates to use fast analyze.
TiDBEnableFastAnalyze = "tidb_enable_fast_analyze"
// TiDBExpensiveQueryTimeThreshold indicates the time threshold of expensive query.
TiDBExpensiveQueryTimeThreshold = "tidb_expensive_query_time_threshold"
// TiDBEnableIndexMerge indicates to generate IndexMergePath.
TiDBEnableIndexMerge = "tidb_enable_index_merge"
// TiDBEnableNoopFuncs set true will enable using fake funcs(like get_lock release_lock)
TiDBEnableNoopFuncs = "tidb_enable_noop_functions"
// TiDBEnableStmtSummary indicates whether the statement summary is enabled.
TiDBEnableStmtSummary = "tidb_enable_stmt_summary"
// TiDBStmtSummaryInternalQuery indicates whether the statement summary contain internal query.
TiDBStmtSummaryInternalQuery = "tidb_stmt_summary_internal_query"
// TiDBStmtSummaryRefreshInterval indicates the refresh interval in seconds for each statement summary.
TiDBStmtSummaryRefreshInterval = "tidb_stmt_summary_refresh_interval"
// TiDBStmtSummaryHistorySize indicates the history size of each statement summary.
TiDBStmtSummaryHistorySize = "tidb_stmt_summary_history_size"
// TiDBStmtSummaryMaxStmtCount indicates the max number of statements kept in memory.
TiDBStmtSummaryMaxStmtCount = "tidb_stmt_summary_max_stmt_count"
// TiDBStmtSummaryMaxSQLLength indicates the max length of displayed normalized sql and sample sql.
TiDBStmtSummaryMaxSQLLength = "tidb_stmt_summary_max_sql_length"
// TiDBCapturePlanBaseline indicates whether the capture of plan baselines is enabled.
TiDBCapturePlanBaseline = "tidb_capture_plan_baselines"
// TiDBUsePlanBaselines indicates whether the use of plan baselines is enabled.
TiDBUsePlanBaselines = "tidb_use_plan_baselines"
// TiDBEvolvePlanBaselines indicates whether the evolution of plan baselines is enabled.
TiDBEvolvePlanBaselines = "tidb_evolve_plan_baselines"
// TiDBEnableExtendedStats indicates whether the extended statistics feature is enabled.
TiDBEnableExtendedStats = "tidb_enable_extended_stats"
// TiDBIsolationReadEngines indicates the tidb only read from the stores whose engine type is involved in IsolationReadEngines.
// Now, only support TiKV and TiFlash.
TiDBIsolationReadEngines = "tidb_isolation_read_engines"
// TiDBStoreLimit indicates the limit of sending request to a store, 0 means without limit.
TiDBStoreLimit = "tidb_store_limit"
// TiDBMetricSchemaStep indicates the step when query metric schema.
TiDBMetricSchemaStep = "tidb_metric_query_step"
// TiDBMetricSchemaRangeDuration indicates the range duration when query metric schema.
TiDBMetricSchemaRangeDuration = "tidb_metric_query_range_duration"
// TiDBEnableCollectExecutionInfo indicates that whether execution info is collected.
TiDBEnableCollectExecutionInfo = "tidb_enable_collect_execution_info"
// TiDBExecutorConcurrency is used for controlling the concurrency of all types of executors.
TiDBExecutorConcurrency = "tidb_executor_concurrency"
// TiDBEnableClusteredIndex indicates if clustered index feature is enabled.
TiDBEnableClusteredIndex = "tidb_enable_clustered_index"
// TiDBPartitionPruneMode indicates the partition prune mode used.
TiDBPartitionPruneMode = "tidb_partition_prune_mode"
// TiDBRedactLog indicates that whether redact log.
TiDBRedactLog = "tidb_redact_log"
// TiDBRestrictedReadOnly is meant for the cloud admin to toggle the cluster read only
TiDBRestrictedReadOnly = "tidb_restricted_read_only"
// TiDBSuperReadOnly is tidb's variant of mysql's super_read_only, which has some differences from mysql's super_read_only.
TiDBSuperReadOnly = "tidb_super_read_only"
// TiDBShardAllocateStep indicates the max size of continuous rowid shard in one transaction.
TiDBShardAllocateStep = "tidb_shard_allocate_step"
// TiDBEnableTelemetry indicates that whether usage data report to PingCAP is enabled.
TiDBEnableTelemetry = "tidb_enable_telemetry"
// TiDBEnableAmendPessimisticTxn indicates if amend pessimistic transactions is enabled.
TiDBEnableAmendPessimisticTxn = "tidb_enable_amend_pessimistic_txn"
// TiDBMemoryUsageAlarmRatio indicates the alarm threshold when memory usage of the tidb-server exceeds.
TiDBMemoryUsageAlarmRatio = "tidb_memory_usage_alarm_ratio"
// TiDBEnableRateLimitAction indicates whether enabled ratelimit action
TiDBEnableRateLimitAction = "tidb_enable_rate_limit_action"
// TiDBEnableAsyncCommit indicates whether to enable the async commit feature.
TiDBEnableAsyncCommit = "tidb_enable_async_commit"
// TiDBEnable1PC indicates whether to enable the one-phase commit feature.
TiDBEnable1PC = "tidb_enable_1pc"
// TiDBGuaranteeLinearizability indicates whether to guarantee linearizability.
TiDBGuaranteeLinearizability = "tidb_guarantee_linearizability"
// TiDBAnalyzeVersion indicates how tidb collects the analyzed statistics and how use to it.
TiDBAnalyzeVersion = "tidb_analyze_version"
// TiDBEnableIndexMergeJoin indicates whether to enable index merge join.
TiDBEnableIndexMergeJoin = "tidb_enable_index_merge_join"
// TiDBTrackAggregateMemoryUsage indicates whether track the memory usage of aggregate function.
TiDBTrackAggregateMemoryUsage = "tidb_track_aggregate_memory_usage"
// TiDBEnableExchangePartition indicates whether to enable exchange partition.
TiDBEnableExchangePartition = "tidb_enable_exchange_partition"
// TiDBAllowFallbackToTiKV indicates the engine types whose unavailability triggers fallback to TiKV.
// Now we only support TiFlash.
TiDBAllowFallbackToTiKV = "tidb_allow_fallback_to_tikv"
// TiDBEnableTopSQL indicates whether the top SQL is enabled.
TiDBEnableTopSQL = "tidb_enable_top_sql"
// TiDBTopSQLMaxTimeSeriesCount indicates the max number of statements been collected in each time series.
TiDBTopSQLMaxTimeSeriesCount = "tidb_top_sql_max_time_series_count"
// TiDBTopSQLMaxMetaCount indicates the max capacity of the collect meta per second.
TiDBTopSQLMaxMetaCount = "tidb_top_sql_max_meta_count"
// TiDBEnableLocalTxn indicates whether to enable Local Txn.
TiDBEnableLocalTxn = "tidb_enable_local_txn"
// TiDBEnableMDL indicates whether to enable MDL.
TiDBEnableMDL = "tidb_enable_metadata_lock"
// TiDBTSOClientBatchMaxWaitTime indicates the max value of the TSO Batch Wait interval time of PD client.
TiDBTSOClientBatchMaxWaitTime = "tidb_tso_client_batch_max_wait_time"
// TiDBTxnCommitBatchSize is used to control the batch size of transaction commit related requests sent by TiDB to TiKV.
// If a single transaction has a large amount of writes, you can increase the batch size to improve the batch effect,
// setting too large will exceed TiKV's raft-entry-max-size limit and cause commit failure.
TiDBTxnCommitBatchSize = "tidb_txn_commit_batch_size"
// TiDBEnableTSOFollowerProxy indicates whether to enable the TSO Follower Proxy feature of PD client.
TiDBEnableTSOFollowerProxy = "tidb_enable_tso_follower_proxy"
// TiDBEnableOrderedResultMode indicates if stabilize query results.
TiDBEnableOrderedResultMode = "tidb_enable_ordered_result_mode"
// TiDBRemoveOrderbyInSubquery indicates whether to remove ORDER BY in subquery.
TiDBRemoveOrderbyInSubquery = "tidb_remove_orderby_in_subquery"
// TiDBEnablePseudoForOutdatedStats indicates whether use pseudo for outdated stats
TiDBEnablePseudoForOutdatedStats = "tidb_enable_pseudo_for_outdated_stats"
// TiDBRegardNULLAsPoint indicates whether regard NULL as point when optimizing
TiDBRegardNULLAsPoint = "tidb_regard_null_as_point"
// TiDBTmpTableMaxSize indicates the max memory size of temporary tables.
TiDBTmpTableMaxSize = "tidb_tmp_table_max_size"
// TiDBEnableLegacyInstanceScope indicates if instance scope can be set with SET SESSION.
TiDBEnableLegacyInstanceScope = "tidb_enable_legacy_instance_scope"
// TiDBTableCacheLease indicates the read lock lease of a cached table.
TiDBTableCacheLease = "tidb_table_cache_lease"
// TiDBStatsLoadSyncWait indicates the time sql execution will sync-wait for stats load.
TiDBStatsLoadSyncWait = "tidb_stats_load_sync_wait"
// TiDBEnableMutationChecker indicates whether to check data consistency for mutations
TiDBEnableMutationChecker = "tidb_enable_mutation_checker"
// TiDBTxnAssertionLevel indicates how strict the assertion will be, which helps to detect and preventing data &
// index inconsistency problems.
TiDBTxnAssertionLevel = "tidb_txn_assertion_level"
// TiDBIgnorePreparedCacheCloseStmt indicates whether to ignore close-stmt commands for prepared statements.
TiDBIgnorePreparedCacheCloseStmt = "tidb_ignore_prepared_cache_close_stmt"
// TiDBEnableNewCostInterface is a internal switch to indicates whether to use the new cost calculation interface.
TiDBEnableNewCostInterface = "tidb_enable_new_cost_interface"
// TiDBCostModelVersion is a internal switch to indicates the cost model version.
TiDBCostModelVersion = "tidb_cost_model_version"
// TiDBBatchPendingTiFlashCount indicates the maximum count of non-available TiFlash tables.
TiDBBatchPendingTiFlashCount = "tidb_batch_pending_tiflash_count"
// TiDBQueryLogMaxLen is used to set the max length of the query in the log.
TiDBQueryLogMaxLen = "tidb_query_log_max_len"
// TiDBEnableNoopVariables is used to indicate if noops appear in SHOW [GLOBAL] VARIABLES
TiDBEnableNoopVariables = "tidb_enable_noop_variables"
// TiDBNonTransactionalIgnoreError is used to ignore error in non-transactional DMLs.
// When set to false, a non-transactional DML returns when it meets the first error.
// When set to true, a non-transactional DML finishes all batches even if errors are met in some batches.
TiDBNonTransactionalIgnoreError = "tidb_nontransactional_ignore_error"
// Fine grained shuffle is disabled when TiFlashFineGrainedShuffleStreamCount is zero.
TiFlashFineGrainedShuffleStreamCount = "tiflash_fine_grained_shuffle_stream_count"
TiFlashFineGrainedShuffleBatchSize = "tiflash_fine_grained_shuffle_batch_size"
// TiDBSimplifiedMetrics controls whether to unregister some unused metrics.
TiDBSimplifiedMetrics = "tidb_simplified_metrics"
// TiDBMemoryDebugModeMinHeapInUse is used to set tidb memory debug mode trigger threshold.
// When set to 0, the function is disabled.
// When set to a negative integer, use memory debug mode to detect the issue of frequent allocation and release of memory.
// We do not actively trigger gc, and check whether the `tracker memory * (1+bias ratio) > heap in use` each 5s.
// When set to a positive integer, use memory debug mode to detect the issue of memory tracking inaccurate.
// We trigger runtime.GC() each 5s, and check whether the `tracker memory * (1+bias ratio) > heap in use`.
TiDBMemoryDebugModeMinHeapInUse = "tidb_memory_debug_mode_min_heap_inuse"
// TiDBMemoryDebugModeAlarmRatio is used set tidb memory debug mode bias ratio. Treat memory bias less than this ratio as noise.
TiDBMemoryDebugModeAlarmRatio = "tidb_memory_debug_mode_alarm_ratio"
// TiDBEnableAnalyzeSnapshot indicates whether to read data on snapshot when collecting statistics.
// When set to false, ANALYZE reads the latest data.
// When set to true, ANALYZE reads data on the snapshot at the beginning of ANALYZE.
TiDBEnableAnalyzeSnapshot = "tidb_enable_analyze_snapshot"
// TiDBDefaultStrMatchSelectivity controls some special cardinality estimation strategy for string match functions (like and regexp).
// When set to 0, Selectivity() will try to evaluate those functions with TopN and NULL in the stats to estimate,
// and the default selectivity and the selectivity for the histogram part will be 0.1.
// When set to (0, 1], Selectivity() will use the value of this variable as the default selectivity of those
// functions instead of the selectionFactor (0.8).
TiDBDefaultStrMatchSelectivity = "tidb_default_string_match_selectivity"
// TiDBEnablePrepPlanCache indicates whether to enable prepared plan cache
TiDBEnablePrepPlanCache = "tidb_enable_prepared_plan_cache"
// TiDBPrepPlanCacheSize indicates the number of cached statements.
TiDBPrepPlanCacheSize = "tidb_prepared_plan_cache_size"
// TiDBEnableGeneralPlanCache indicates whether to enable general plan cache.
TiDBEnableGeneralPlanCache = "tidb_enable_general_plan_cache"
// TiDBGeneralPlanCacheSize controls the size of general plan cache.
TiDBGeneralPlanCacheSize = "tidb_general_plan_cache_size"
// TiDBConstraintCheckInPlacePessimistic controls whether to skip certain kinds of pessimistic locks.
TiDBConstraintCheckInPlacePessimistic = "tidb_constraint_check_in_place_pessimistic"
// TiDBEnableForeignKey indicates whether to enable foreign key feature.
// TODO(crazycs520): remove this after foreign key GA.
TiDBEnableForeignKey = "tidb_enable_foreign_key"
// TiDBOptRangeMaxSize is the max memory limit for ranges. When the optimizer estimates that the memory usage of complete
// ranges would exceed the limit, it chooses less accurate ranges such as full range. 0 indicates that there is no memory
// limit for ranges.
TiDBOptRangeMaxSize = "tidb_opt_range_max_size"
)
// TiDB vars that have only global scope
const (
// TiDBGCEnable turns garbage collection on or OFF
TiDBGCEnable = "tidb_gc_enable"
// TiDBGCRunInterval sets the interval that GC runs
TiDBGCRunInterval = "tidb_gc_run_interval"
// TiDBGCLifetime sets the retention window of older versions
TiDBGCLifetime = "tidb_gc_life_time"
// TiDBGCConcurrency sets the concurrency of garbage collection. -1 = AUTO value
TiDBGCConcurrency = "tidb_gc_concurrency"
// TiDBGCScanLockMode enables the green GC feature (default)
TiDBGCScanLockMode = "tidb_gc_scan_lock_mode"
// TiDBGCMaxWaitTime sets max time for gc advances the safepoint delayed by active transactions
TiDBGCMaxWaitTime = "tidb_gc_max_wait_time"
// TiDBEnableEnhancedSecurity restricts SUPER users from certain operations.
TiDBEnableEnhancedSecurity = "tidb_enable_enhanced_security"
// TiDBEnableHistoricalStats enables the historical statistics feature (default off)
TiDBEnableHistoricalStats = "tidb_enable_historical_stats"
// TiDBPersistAnalyzeOptions persists analyze options for later analyze and auto-analyze
TiDBPersistAnalyzeOptions = "tidb_persist_analyze_options"
// TiDBEnableColumnTracking enables collecting predicate columns.
TiDBEnableColumnTracking = "tidb_enable_column_tracking"
// TiDBDisableColumnTrackingTime records the last time TiDBEnableColumnTracking is set off.
// It is used to invalidate the collected predicate columns after turning off TiDBEnableColumnTracking, which avoids physical deletion.
// It doesn't have cache in memory, and we directly get/set the variable value from/to mysql.tidb.
TiDBDisableColumnTrackingTime = "tidb_disable_column_tracking_time"
// TiDBStatsLoadPseudoTimeout indicates whether to fallback to pseudo stats after load timeout.
TiDBStatsLoadPseudoTimeout = "tidb_stats_load_pseudo_timeout"
// TiDBMemQuotaBindingCache indicates the memory quota for the bind cache.
TiDBMemQuotaBindingCache = "tidb_mem_quota_binding_cache"
// TiDBRCReadCheckTS indicates the tso optimization for read-consistency read is enabled.
TiDBRCReadCheckTS = "tidb_rc_read_check_ts"
// TiDBRCWriteCheckTs indicates whether some special write statements don't get latest tso from PD at RC
TiDBRCWriteCheckTs = "tidb_rc_write_check_ts"
// TiDBCommitterConcurrency controls the number of running concurrent requests in the commit phase.
TiDBCommitterConcurrency = "tidb_committer_concurrency"
// TiDBEnableBatchDML enables batch dml.
TiDBEnableBatchDML = "tidb_enable_batch_dml"
// TiDBStatsCacheMemQuota records stats cache quota
TiDBStatsCacheMemQuota = "tidb_stats_cache_mem_quota"
// TiDBMemQuotaAnalyze indicates the memory quota for all analyze jobs.
TiDBMemQuotaAnalyze = "tidb_mem_quota_analyze"
// TiDBEnableAutoAnalyze determines whether TiDB executes automatic analysis.
TiDBEnableAutoAnalyze = "tidb_enable_auto_analyze"
// TiDBMemOOMAction indicates what operation TiDB perform when a single SQL statement exceeds
// the memory quota specified by tidb_mem_quota_query and cannot be spilled to disk.
TiDBMemOOMAction = "tidb_mem_oom_action"
// TiDBPrepPlanCacheMemoryGuardRatio is used to prevent [performance.max-memory] from being exceeded
TiDBPrepPlanCacheMemoryGuardRatio = "tidb_prepared_plan_cache_memory_guard_ratio"
// TiDBMaxAutoAnalyzeTime is the max time that auto analyze can run. If auto analyze runs longer than the value, it
// will be killed. 0 indicates that there is no time limit.
TiDBMaxAutoAnalyzeTime = "tidb_max_auto_analyze_time"
// TiDBEnableConcurrentDDL indicates whether to enable the new DDL framework.
TiDBEnableConcurrentDDL = "tidb_enable_concurrent_ddl"
// TiDBAuthSigningCert indicates the path of the signing certificate to do token-based authentication.
TiDBAuthSigningCert = "tidb_auth_signing_cert"
// TiDBAuthSigningKey indicates the path of the signing key to do token-based authentication.
TiDBAuthSigningKey = "tidb_auth_signing_key"
// TiDBGenerateBinaryPlan indicates whether binary plan should be generated in slow log and statements summary.
TiDBGenerateBinaryPlan = "tidb_generate_binary_plan"
// TiDBEnableGCAwareMemoryTrack indicates whether to turn-on GC-aware memory track.
TiDBEnableGCAwareMemoryTrack = "tidb_enable_gc_aware_memory_track"
// TiDBEnableTmpStorageOnOOM controls whether to enable the temporary storage for some operators
// when a single SQL statement exceeds the memory quota specified by the memory quota.
TiDBEnableTmpStorageOnOOM = "tidb_enable_tmp_storage_on_oom"
// TiDBDDLEnableFastReorg indicates whether to use lighting backfill process for adding index.
TiDBDDLEnableFastReorg = "tidb_ddl_enable_fast_reorg"
// TiDBDDLDiskQuota used to set disk quota for lightning add index.
TiDBDDLDiskQuota = "tidb_ddl_disk_quota"
)
// TiDB intentional limits
// Can be raised in the future.
const (
// MaxConfigurableConcurrency is the maximum number of "threads" (goroutines) that can be specified
// for any type of configuration item that has concurrent workers.
MaxConfigurableConcurrency = 256
)
// Default TiDB system variable values.
const (
DefHostname = "localhost"
DefIndexLookupConcurrency = ConcurrencyUnset
DefIndexLookupJoinConcurrency = ConcurrencyUnset
DefIndexSerialScanConcurrency = 1
DefIndexJoinBatchSize = 25000
DefIndexLookupSize = 20000
DefDistSQLScanConcurrency = 15
DefBuildStatsConcurrency = 4
DefAutoAnalyzeRatio = 0.5
DefAutoAnalyzeStartTime = "00:00 +0000"
DefAutoAnalyzeEndTime = "23:59 +0000"
DefAutoIncrementIncrement = 1
DefAutoIncrementOffset = 1
DefChecksumTableConcurrency = 4
DefSkipUTF8Check = false
DefSkipASCIICheck = false
DefOptAggPushDown = false
DefOptCartesianBCJ = 1
DefOptMPPOuterJoinFixedBuildSide = false
DefOptWriteRowID = false
DefOptEnableCorrelationAdjustment = true
DefOptLimitPushDownThreshold = 100
DefOptCorrelationThreshold = 0.9
DefOptCorrelationExpFactor = 1
DefOptCPUFactor = 3.0
DefOptCopCPUFactor = 3.0
DefOptTiFlashConcurrencyFactor = 24.0
DefOptNetworkFactor = 1.0
DefOptScanFactor = 1.5
DefOptDescScanFactor = 3.0
DefOptSeekFactor = 20.0
DefOptMemoryFactor = 0.001
DefOptDiskFactor = 1.5
DefOptConcurrencyFactor = 3.0
DefOptCPUFactorV2 = 30.0
DefOptCopCPUFactorV2 = 30.0
DefOptTiFlashCPUFactorV2 = 2.0
DefOptNetworkFactorV2 = 4.0
DefOptScanFactorV2 = 100.0
DefOptDescScanFactorV2 = 150.0
DefOptTiFlashScanFactorV2 = 15.0
DefOptSeekFactorV2 = 9500000.0
DefOptMemoryFactorV2 = 0.001
DefOptDiskFactorV2 = 1.5
DefOptConcurrencyFactorV2 = 3.0
DefOptForceInlineCTE = false
DefOptInSubqToJoinAndAgg = true
DefOptPreferRangeScan = false
DefBatchInsert = false
DefBatchDelete = false
DefBatchCommit = false
DefCurretTS = 0
DefInitChunkSize = 32
DefMinPagingSize = int(paging.MinPagingSize)
DefMaxPagingSize = int(paging.MaxPagingSize)
DefMaxChunkSize = 1024
DefDMLBatchSize = 0
DefMaxPreparedStmtCount = -1
DefWaitTimeout = 28800
DefTiDBMemQuotaApplyCache = 32 << 20 // 32MB.
DefTiDBMemQuotaBindingCache = 64 << 20 // 64MB.
DefTiDBGeneralLog = false
DefTiDBPProfSQLCPU = 0
DefTiDBRetryLimit = 10
DefTiDBDisableTxnAutoRetry = true
DefTiDBConstraintCheckInPlace = false
DefTiDBHashJoinConcurrency = ConcurrencyUnset
DefTiDBProjectionConcurrency = ConcurrencyUnset
DefBroadcastJoinThresholdSize = 100 * 1024 * 1024
DefBroadcastJoinThresholdCount = 10 * 1024
DefTiDBOptimizerSelectivityLevel = 0
DefTiDBOptimizerEnableNewOFGB = false
DefTiDBEnableOuterJoinReorder = false
DefTiDBAllowBatchCop = 1
DefTiDBAllowMPPExecution = true
DefTiDBHashExchangeWithNewCollation = true
DefTiDBEnforceMPPExecution = false
DefTiFlashMaxThreads = -1
DefTiDBMPPStoreFailTTL = "60s"
DefTiDBTxnMode = ""
DefTiDBRowFormatV1 = 1
DefTiDBRowFormatV2 = 2
DefTiDBDDLReorgWorkerCount = 4
DefTiDBDDLReorgBatchSize = 256
DefTiDBDDLFlashbackConcurrency = 64
DefTiDBDDLErrorCountLimit = 512
DefTiDBMaxDeltaSchemaCount = 1024
DefTiDBPlacementMode = PlacementModeStrict
DefTiDBEnableAutoIncrementInGenerated = false
DefTiDBHashAggPartialConcurrency = ConcurrencyUnset
DefTiDBHashAggFinalConcurrency = ConcurrencyUnset
DefTiDBWindowConcurrency = ConcurrencyUnset
DefTiDBMergeJoinConcurrency = 1 // disable optimization by default
DefTiDBStreamAggConcurrency = 1
DefTiDBForcePriority = mysql.NoPriority
DefEnableWindowFunction = true
DefEnablePipelinedWindowFunction = true
DefEnableStrictDoubleTypeCheck = true
DefEnableVectorizedExpression = true
DefTiDBOptJoinReorderThreshold = 0
DefTiDBDDLSlowOprThreshold = 300
DefTiDBUseFastAnalyze = false
DefTiDBSkipIsolationLevelCheck = false
DefTiDBExpensiveQueryTimeThreshold = 60 // 60s
DefTiDBScatterRegion = false
DefTiDBWaitSplitRegionFinish = true
DefWaitSplitRegionTimeout = 300 // 300s
DefTiDBEnableNoopFuncs = Off
DefTiDBEnableNoopVariables = true
DefTiDBAllowRemoveAutoInc = false
DefTiDBUsePlanBaselines = true
DefTiDBEvolvePlanBaselines = false
DefTiDBEvolvePlanTaskMaxTime = 600 // 600s
DefTiDBEvolvePlanTaskStartTime = "00:00 +0000"
DefTiDBEvolvePlanTaskEndTime = "23:59 +0000"
DefInnodbLockWaitTimeout = 50 // 50s
DefTiDBStoreLimit = 0
DefTiDBMetricSchemaStep = 60 // 60s
DefTiDBMetricSchemaRangeDuration = 60 // 60s
DefTiDBFoundInPlanCache = false
DefTiDBFoundInBinding = false
DefTiDBEnableCollectExecutionInfo = true
DefTiDBAllowAutoRandExplicitInsert = false
DefTiDBEnableClusteredIndex = ClusteredIndexDefModeOn
DefTiDBRedactLog = false
DefTiDBRestrictedReadOnly = false
DefTiDBSuperReadOnly = false
DefTiDBShardAllocateStep = math.MaxInt64
DefTiDBEnableTelemetry = true
DefTiDBEnableParallelApply = false
DefTiDBEnableAmendPessimisticTxn = false
DefTiDBPartitionPruneMode = "dynamic"
DefTiDBEnableRateLimitAction = false
DefTiDBEnableAsyncCommit = false
DefTiDBEnable1PC = false
DefTiDBGuaranteeLinearizability = true
DefTiDBAnalyzeVersion = 2
DefTiDBEnableIndexMergeJoin = false
DefTiDBTrackAggregateMemoryUsage = true
DefTiDBEnableExchangePartition = true
DefCTEMaxRecursionDepth = 1000
DefTiDBTmpTableMaxSize = 64 << 20 // 64MB.
DefTiDBEnableLocalTxn = false
DefTiDBTSOClientBatchMaxWaitTime = 0.0 // 0ms
DefTiDBEnableTSOFollowerProxy = false
DefTiDBEnableOrderedResultMode = false
DefTiDBEnablePseudoForOutdatedStats = false
DefTiDBRegardNULLAsPoint = true
DefEnablePlacementCheck = true
DefTimestamp = "0"
DefTimestampFloat = 0.0
DefTiDBEnableStmtSummary = true
DefTiDBStmtSummaryInternalQuery = false
DefTiDBStmtSummaryRefreshInterval = 1800
DefTiDBStmtSummaryHistorySize = 24
DefTiDBStmtSummaryMaxStmtCount = 3000
DefTiDBStmtSummaryMaxSQLLength = 4096
DefTiDBCapturePlanBaseline = Off
DefTiDBEnableIndexMerge = true
DefEnableLegacyInstanceScope = true
DefTiDBTableCacheLease = 3 // 3s
DefTiDBPersistAnalyzeOptions = true
DefTiDBEnableColumnTracking = false
DefTiDBStatsLoadSyncWait = 0
DefTiDBStatsLoadPseudoTimeout = true
DefSysdateIsNow = false
DefTiDBEnableMutationChecker = false
DefTiDBTxnAssertionLevel = AssertionOffStr
DefTiDBIgnorePreparedCacheCloseStmt = false
DefTiDBBatchPendingTiFlashCount = 4000
DefRCReadCheckTS = false
DefTiDBRemoveOrderbyInSubquery = false
DefTiDBSkewDistinctAgg = false
DefTiDB3StageDistinctAgg = true
DefTiDBReadStaleness = 0
DefTiDBGCMaxWaitTime = 24 * 60 * 60
DefMaxAllowedPacket uint64 = 67108864
DefTiDBEnableBatchDML = false
DefTiDBMemQuotaQuery = 1073741824 // 1GB
DefTiDBStatsCacheMemQuota = 0
MaxTiDBStatsCacheMemQuota = 1024 * 1024 * 1024 * 1024 // 1TB
DefTiDBQueryLogMaxLen = 4096
DefRequireSecureTransport = false
DefTiDBCommitterConcurrency = 128
DefTiDBBatchDMLIgnoreError = false
DefTiDBMemQuotaAnalyze = -1
DefTiDBEnableAutoAnalyze = true
DefTiDBMemOOMAction = "CANCEL"
DefTiDBMaxAutoAnalyzeTime = 12 * 60 * 60
DefTiDBEnablePrepPlanCache = true
DefTiDBPrepPlanCacheSize = 100
DefTiDBPrepPlanCacheMemoryGuardRatio = 0.1
DefTiDBEnableConcurrentDDL = concurrencyddl.TiDBEnableConcurrentDDL
DefTiDBSimplifiedMetrics = false
DefTiDBEnablePaging = false
DefTiFlashFineGrainedShuffleStreamCount = 0
DefStreamCountWhenMaxThreadsNotSet = 8
DefTiFlashFineGrainedShuffleBatchSize = 8192
DefAdaptiveClosestReadThreshold = 4096
DefTiDBEnableAnalyzeSnapshot = false
DefTiDBGenerateBinaryPlan = true
DefEnableTiDBGCAwareMemoryTrack = true
DefTiDBDefaultStrMatchSelectivity = 0.8
DefTiDBEnableTmpStorageOnOOM = true
DefTiDBEnableMDL = false
DefTiFlashFastScan = false
DefTiDBEnableFastReorg = false
DefTiDBDDLDiskQuota = 100 * 1024 * 1024 * 1024 // 100GB
DefExecutorConcurrency = 5
DefTiDBEnableGeneralPlanCache = false
DefTiDBGeneralPlanCacheSize = 100
DefTiDBEnableTiFlashReadForWriteStmt = false
// MaxDDLReorgBatchSize is exported for testing.
MaxDDLReorgBatchSize int32 = 10240
MinDDLReorgBatchSize int32 = 32
MinExpensiveQueryTimeThreshold uint64 = 10 // 10s
DefTiDBRcWriteCheckTs = false
DefTiDBConstraintCheckInPlacePessimistic = true
DefTiDBForeignKeyChecks = false
DefTiDBOptRangeMaxSize = 0
DefTiDBCostModelVer = 1
)
// Process global variables.
var (
ProcessGeneralLog = atomic.NewBool(false)
RunAutoAnalyze = atomic.NewBool(DefTiDBEnableAutoAnalyze)
GlobalLogMaxDays = atomic.NewInt32(int32(config.GetGlobalConfig().Log.File.MaxDays))
QueryLogMaxLen = atomic.NewInt32(DefTiDBQueryLogMaxLen)
EnablePProfSQLCPU = atomic.NewBool(false)
EnableBatchDML = atomic.NewBool(false)
EnableTmpStorageOnOOM = atomic.NewBool(DefTiDBEnableTmpStorageOnOOM)
ddlReorgWorkerCounter int32 = DefTiDBDDLReorgWorkerCount
ddlReorgBatchSize int32 = DefTiDBDDLReorgBatchSize
ddlFlashbackConcurrency int32 = DefTiDBDDLFlashbackConcurrency
ddlErrorCountLimit int64 = DefTiDBDDLErrorCountLimit
ddlReorgRowFormat int64 = DefTiDBRowFormatV2
maxDeltaSchemaCount int64 = DefTiDBMaxDeltaSchemaCount
// DDLSlowOprThreshold is the threshold for ddl slow operations, uint is millisecond.
DDLSlowOprThreshold = config.GetGlobalConfig().Instance.DDLSlowOprThreshold
ForcePriority = int32(DefTiDBForcePriority)
MaxOfMaxAllowedPacket uint64 = 1073741824
ExpensiveQueryTimeThreshold uint64 = DefTiDBExpensiveQueryTimeThreshold
MemoryUsageAlarmRatio = atomic.NewFloat64(config.GetGlobalConfig().Instance.MemoryUsageAlarmRatio)
EnableLocalTxn = atomic.NewBool(DefTiDBEnableLocalTxn)
MaxTSOBatchWaitInterval = atomic.NewFloat64(DefTiDBTSOClientBatchMaxWaitTime)
EnableTSOFollowerProxy = atomic.NewBool(DefTiDBEnableTSOFollowerProxy)
RestrictedReadOnly = atomic.NewBool(DefTiDBRestrictedReadOnly)
VarTiDBSuperReadOnly = atomic.NewBool(DefTiDBSuperReadOnly)
PersistAnalyzeOptions = atomic.NewBool(DefTiDBPersistAnalyzeOptions)
TableCacheLease = atomic.NewInt64(DefTiDBTableCacheLease)
EnableColumnTracking = atomic.NewBool(DefTiDBEnableColumnTracking)
StatsLoadSyncWait = atomic.NewInt64(DefTiDBStatsLoadSyncWait)
StatsLoadPseudoTimeout = atomic.NewBool(DefTiDBStatsLoadPseudoTimeout)
MemQuotaBindingCache = atomic.NewInt64(DefTiDBMemQuotaBindingCache)
GCMaxWaitTime = atomic.NewInt64(DefTiDBGCMaxWaitTime)
StatsCacheMemQuota = atomic.NewInt64(DefTiDBStatsCacheMemQuota)
OOMAction = atomic.NewString(DefTiDBMemOOMAction)
MaxAutoAnalyzeTime = atomic.NewInt64(DefTiDBMaxAutoAnalyzeTime)
// variables for plan cache
PreparedPlanCacheMemoryGuardRatio = atomic.NewFloat64(DefTiDBPrepPlanCacheMemoryGuardRatio)
EnableConcurrentDDL = atomic.NewBool(DefTiDBEnableConcurrentDDL)
DDLForce2Queue = atomic.NewBool(false)
EnableNoopVariables = atomic.NewBool(DefTiDBEnableNoopVariables)
EnableMDL = atomic.NewBool(DefTiDBEnableMDL)
// EnableFastReorg indicates whether to use lightning to enhance DDL reorg performance.
EnableFastReorg = atomic.NewBool(DefTiDBEnableFastReorg)
// DDLDiskQuota is the temporary variable for set disk quota for lightning
DDLDiskQuota = atomic.NewUint64(DefTiDBDDLDiskQuota)
// EnableForeignKey indicates whether to enable foreign key feature.
EnableForeignKey = atomic.NewBool(false)
EnableRCReadCheckTS = atomic.NewBool(false)
)
var (
// SetMemQuotaAnalyze is the func registered by global/subglobal tracker to set memory quota.
SetMemQuotaAnalyze func(quota int64) = nil
// GetMemQuotaAnalyze is the func registered by global/subglobal tracker to get memory quota.
GetMemQuotaAnalyze func() int64 = nil
// SetStatsCacheCapacity is the func registered by domain to set statsCache memory quota.
SetStatsCacheCapacity atomic.Value
// SwitchConcurrentDDL is the func registered by DDL to switch concurrent DDL.
SwitchConcurrentDDL func(bool) error = nil
// SwitchMDL is the func registered by DDL to switch MDL.
SwitchMDL func(bool2 bool) error = nil
// EnableDDL is the func registered by ddl to enable running ddl in this instance.
EnableDDL func() error = nil
// DisableDDL is the func registered by ddl to disable running ddl in this instance.
DisableDDL func() error = nil
)
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