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Co-authored-by: Aolin <aolinz@outlook.com>
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@TomShawn @Oreoxmt
TomShawn and Oreoxmt authored Aug 18, 2022
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Showing 1 changed file with 11 additions and 11 deletions.
22 changes: 11 additions & 11 deletions system-variables.md
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Expand Up @@ -347,7 +347,7 @@ This variable is an alias for `last_insert_id`.
- If you set the variable to a value that exceeds the upper limit `1048576`, `1048576` is used instead:

```sql
mysql> SET GLOBAL max_prepared_stmt_count=1048577;
mysql> SET GLOBAL max_prepared_stmt_count = 1048577;
Query OK, 0 rows affected, 1 warning (0.01 sec)

mysql> SHOW WARNINGS;
Expand Down Expand Up @@ -1773,7 +1773,7 @@ For a system upgraded to v5.0 from an earlier version, if you have not modified
- Range: `[0, 2]`
- Indicates whether to allow the Broadcast Cartesian Join.
- `0` means that the Broadcast Cartesian Join is not allowed. `1` means that it is allowed based on [`tidb_broadcast_join_threshold_count`](#tidb_broadcast_join_threshold_count-new-in-v50). `2` means that it is always allowed even if the table size exceeds the threshold.
- This variable is internally used in TiDB, and it is not recommended to modify its value.
- This variable is internally used in TiDB, and it is **NOT** recommended to modify its value.
### tidb_opt_concurrency_factor
Expand All @@ -1782,7 +1782,7 @@ For a system upgraded to v5.0 from an earlier version, if you have not modified
- Type: Float
- Range: `[0, 2147483647]`
- 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 internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value.
### tidb_opt_cop_cpu_factor
Expand All @@ -1791,7 +1791,7 @@ For a system upgraded to v5.0 from an earlier version, if you have not modified
- Type: Float
- Range: `[0, 2147483647]`
- 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 internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value.
### tidb_opt_correlation_exp_factor
Expand Down Expand Up @@ -1822,7 +1822,7 @@ For a system upgraded to v5.0 from an earlier version, if you have not modified
- 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 internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value.
### tidb_opt_desc_scan_factor
Expand All @@ -1831,7 +1831,7 @@ For a system upgraded to v5.0 from an earlier version, if you have not modified
- Type: Float
- Range: `[0, 2147483647]`
- 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 internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value.
### tidb_opt_disk_factor
Expand All @@ -1840,7 +1840,7 @@ For a system upgraded to v5.0 from an earlier version, if you have not modified
- Type: Float
- Range: `[0, 2147483647]`
- 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 internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value.
### tidb_opt_distinct_agg_push_down
Expand Down Expand Up @@ -1928,7 +1928,7 @@ 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 internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value.
### tidb_opt_mpp_outer_join_fixed_build_side <span class="version-mark">New in v5.1.0</span>
Expand All @@ -1945,7 +1945,7 @@ 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 internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value.
### tidb_opt_prefer_range_scan <span class="version-mark">New in v5.0</span>
Expand Down Expand Up @@ -1995,7 +1995,7 @@ explain select * from t where age=5;
- 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 internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value.
### tidb_opt_seek_factor
Expand All @@ -2004,7 +2004,7 @@ explain select * from t where age=5;
- 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 internally used in the [Cost Model](/cost-model.md), and it is **NOT** recommended to modify its value.
### tidb_opt_skew_distinct_agg <span class="version-mark">New in v6.2.0</span>
Expand Down

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