diff --git a/system-variables.md b/system-variables.md index 2503cefc4ea41..2b560fe6142d6 100644 --- a/system-variables.md +++ b/system-variables.md @@ -4114,7 +4114,7 @@ As shown in this diagram, when [`tidb_enable_paging`](#tidb_enable_paging-new-in - Type: Float - Range: `[0, 18446744073709551615]` - Default value: `3.0` -- Indicates the CPU cost of starting a Golang goroutine in TiDB. This variable is internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value. +- Indicates the CPU cost of starting a Golang goroutine in TiDB. This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. ### tidb_opt_copcpu_factor @@ -4124,7 +4124,7 @@ As shown in this diagram, when [`tidb_enable_paging`](#tidb_enable_paging-new-in - Type: Float - Range: `[0, 18446744073709551615]` - Default value: `3.0` -- Indicates the CPU cost for TiKV Coprocessor to process one row. This variable is internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value. +- Indicates the CPU cost for TiKV Coprocessor to process one row. This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. ### tidb_opt_correlation_exp_factor @@ -4158,7 +4158,7 @@ As shown in this diagram, when [`tidb_enable_paging`](#tidb_enable_paging-new-in - Type: Float - Range: `[0, 2147483647]` - Default value: `3.0` -- Indicates the CPU cost for TiDB to process one row. This variable is internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value. +- Indicates the CPU cost for TiDB to process one row. This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. ### `tidb_opt_derive_topn` New in v7.0.0 @@ -4177,7 +4177,7 @@ As shown in this diagram, when [`tidb_enable_paging`](#tidb_enable_paging-new-in - Type: Float - Range: `[0, 18446744073709551615]` - Default value: `3.0` -- Indicates the cost for TiKV to scan one row from the disk in descending order. This variable is internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value. +- Indicates the cost for TiKV to scan one row from the disk in descending order. This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. ### tidb_opt_disk_factor @@ -4187,7 +4187,7 @@ As shown in this diagram, when [`tidb_enable_paging`](#tidb_enable_paging-new-in - Type: Float - Range: `[0, 18446744073709551615]` - Default value: `1.5` -- Indicates the I/O cost for TiDB to read or write one byte of data from or to the temporary disk. This variable is internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value. +- Indicates the I/O cost for TiDB to read or write one byte of data from or to the temporary disk. This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. ### tidb_opt_distinct_agg_push_down @@ -4392,7 +4392,7 @@ mysql> desc select count(distinct a) from test.t; - Type: Float - Range: `[0, 2147483647]` - Default value: `0.001` -- Indicates the memory cost for TiDB to store one row. This variable is internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value. +- Indicates the memory cost for TiDB to store one row. This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. ### tidb_opt_mpp_outer_join_fixed_build_side New in v5.1.0 @@ -4411,7 +4411,7 @@ mysql> desc select count(distinct a) from test.t; - Type: Float - Range: `[0, 2147483647]` - Default value: `1.0` -- Indicates the net cost of transferring 1 byte of data through the network. This variable is internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value. +- Indicates the net cost of transferring 1 byte of data through the network. This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. ### tidb_opt_objective New in v7.4.0 @@ -4825,7 +4825,7 @@ SHOW WARNINGS; - Type: Float - Range: `[0, 2147483647]` - Default value: `1.5` -- Indicates the cost for TiKV to scan one row of data from the disk in ascending order. This variable is internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value. +- Indicates the cost for TiKV to scan one row of data from the disk in ascending order. This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. ### tidb_opt_seek_factor @@ -4835,7 +4835,7 @@ SHOW WARNINGS; - Type: Float - Range: `[0, 2147483647]` - Default value: `20` -- Indicates the start-up cost for TiDB to request data from TiKV. This variable is internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value. +- Indicates the start-up cost for TiDB to request data from TiKV. This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. ### tidb_opt_skew_distinct_agg New in v6.2.0 @@ -4890,6 +4890,210 @@ SHOW WARNINGS; - Default value: `OFF` - This variable is used to control whether to allow `INSERT`, `REPLACE`, and `UPDATE` statements to operate on the `_tidb_rowid` column. This variable can be used only when you import data using TiDB tools. +### tidb_opt_hash_agg_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_hash_join_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_index_join_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_index_lookup_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_index_merge_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_index_reader_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_index_scan_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_limit_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_merge_join_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_sort_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_stream_agg_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_table_full_scan_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_table_range_scan_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_table_reader_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_table_rowid_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_table_tiflash_scan_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + +### tidb_opt_topn_cost_factor New in v8.5.3 and v9.0.0 + +> **Warning:** +> +> This variable is used internally by the [cost model](/cost-model.md), and it is **NOT** recommended to modify its value. + +- Scope: SESSION | GLOBAL +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes +- Type: Float +- Range: `[0, 2147483647]` +- Default value: `1` + ### tidb_optimizer_selectivity_level - Scope: SESSION