Skip to content

Commit f4f7f64

Browse files
ti-chi-botti-chi-bot
authored
TiDB functions: update command output (#18349) (#18423)
1 parent 042b32b commit f4f7f64

File tree

1 file changed

+30
-30
lines changed

1 file changed

+30
-30
lines changed

‎functions-and-operators/tidb-functions.md

Lines changed: 30 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -11,49 +11,49 @@ The following functions are TiDB extensions, and are not present in MySQL:
1111

1212
| Function name | Function description |
1313
| :-------------- | :------------------------------------- |
14-
| [`CURRENT_RESOURCE_GROUP()`](#current_resource_group) | Returns the resource group name that the current session is bound to. See also: [Use Resource Control to Achieve Resource Isolation](/tidb-resource-control.md). |
15-
| [`TIDB_BOUNDED_STALENESS()`](#tidb_bounded_staleness) | Instructs TiDB to read the data as new as possible within the time range. See also: [Read Historical Data Using the `AS OF TIMESTAMP` Clause](/as-of-timestamp.md). |
16-
| [`TIDB_CURRENT_TSO()`](#tidb_current_tso) | Returns the current [TSO](/tso.md). |
14+
| [`CURRENT_RESOURCE_GROUP()`](#current_resource_group) | Returns the name of the resource group that the current session is bound to. See [using resource control to achieve resource isolation](/tidb-resource-control.md). |
15+
| [`TIDB_BOUNDED_STALENESS()`](#tidb_bounded_staleness) | Instructs TiDB to read the most recent data within a specified time range. See [reading historical data using the `AS OF TIMESTAMP` clause](/as-of-timestamp.md). |
16+
| [`TIDB_CURRENT_TSO()`](#tidb_current_tso) | Returns the current [TimeStamp Oracle (TSO) in TiDB](/tso.md). |
1717
| [`TIDB_DECODE_BINARY_PLAN()`](#tidb_decode_binary_plan) | Decodes binary plans. |
1818
| [`TIDB_DECODE_KEY()`](#tidb_decode_key) | Decodes a TiDB-encoded key entry into a JSON structure containing `_tidb_rowid` and `table_id`. These encoded keys can be found in some system tables and logging outputs. |
1919
| [`TIDB_DECODE_PLAN()`](#tidb_decode_plan) | Decodes a TiDB execution plan. |
20-
| [`TIDB_DECODE_SQL_DIGESTS()`](#tidb_decode_sql_digests) | Queries the normalized SQL statements (a form without formats and arguments) corresponding to the set of SQL digests in the cluster. |
20+
| [`TIDB_DECODE_SQL_DIGESTS()`](#tidb_decode_sql_digests) | Queries the normalized SQL statements (a form without formats and arguments) corresponding to a set of SQL digests in the cluster. |
2121
| [`TIDB_ENCODE_SQL_DIGEST()`](#tidb_encode_sql_digest) | Gets a digest for a query string. |
22-
| [`TIDB_IS_DDL_OWNER()`](#tidb_is_ddl_owner) | Checks whether or not the TiDB instance you are connected to is the one that is the DDL Owner. The DDL Owner is the TiDB instance that is tasked with executing DDL statements on behalf of all other nodes in the cluster. |
22+
| [`TIDB_IS_DDL_OWNER()`](#tidb_is_ddl_owner) | Checks whether or not the TiDB instance you are connected to is the DDL Owner. The DDL Owner is the TiDB instance that is tasked with executing DDL statements on behalf of all other nodes in the cluster. |
2323
| [`TIDB_PARSE_TSO()`](#tidb_parse_tso) | Extracts the physical timestamp from a TiDB TSO timestamp. See also: [`tidb_current_ts`](/system-variables.md#tidb_current_ts). |
2424
| [`TIDB_PARSE_TSO_LOGICAL()`](#tidb_parse_tso_logical) | Extracts the logical timestamp from a TiDB TSO timestamp. |
2525
| [`TIDB_ROW_CHECKSUM()`](#tidb_row_checksum) | Queries the checksum value of a row. This function can only be used in `SELECT` statements within the FastPlan process. That is, you can query through statements like `SELECT TIDB_ROW_CHECKSUM() FROM t WHERE id = ?` or `SELECT TIDB_ROW_CHECKSUM() FROM t WHERE id IN (?, ?, ...)`. See also: [Data integrity validation for single-row data](/ticdc/ticdc-integrity-check.md). |
2626
| [`TIDB_SHARD()`](#tidb_shard) | Creates a shard index to scatter the index hotspot. A shard index is an expression index with a `TIDB_SHARD` function as the prefix.|
2727
| [`TIDB_VERSION()`](#tidb_version) | Returns the TiDB version with additional build information. |
28-
| [`VITESS_HASH()`](#vitess_hash) | Returns the hash of a number that is compatible with Vitess' `HASH` function. This is intended to help the data migration from Vitess. |
28+
| [`VITESS_HASH()`](#vitess_hash) | Returns the hash of a number. This function is compatible with the `HASH` function of Vitess, and is intended to help the data migration from Vitess. |
2929

3030
</CustomContent>
3131

3232
<CustomContent platform="tidb-cloud">
3333

3434
| Function name | Function description |
3535
| :-------------- | :------------------------------------- |
36-
| [`CURRENT_RESOURCE_GROUP()`](#current_resource_group) | Returns the resource group name that the current session is bound to. See also: [Use Resource Control to Achieve Resource Isolation](/tidb-resource-control.md). |
37-
| [`TIDB_BOUNDED_STALENESS()`](#tidb_bounded_staleness) | Instructs TiDB to read the data as new as possible within the time range. See also: [Read Historical Data Using the `AS OF TIMESTAMP` Clause](/as-of-timestamp.md). |
38-
| [`TIDB_CURRENT_TSO()`](#tidb_current_tso) | Returns the current [TSO](/tso.md). |
36+
| [`CURRENT_RESOURCE_GROUP()`](#current_resource_group) | Returns the resource group name that the current session is bound to. See [using resource control to achieve resource isolation](/tidb-resource-control.md). |
37+
| [`TIDB_BOUNDED_STALENESS()`](#tidb_bounded_staleness) | Instructs TiDB to read most recent data within a specified time range. See [reading historical data using the `AS OF TIMESTAMP` clause](/as-of-timestamp.md). |
38+
| [`TIDB_CURRENT_TSO()`](#tidb_current_tso) | Returns the current [TimeStamp Oracle (TSO) in TiDB](/tso.md). |
3939
| [`TIDB_DECODE_BINARY_PLAN()`](#tidb_decode_binary_plan) | Decodes binary plans. |
40-
| [`TIDB_DECODE_KEY()`](#tidb_decode_key) | Decodes a TiDB-encoded key entry into a JSON structure containing `_tidb_rowid` and `table_id`. These encoded keys can be found in some system tables and in logging outputs. |
40+
| [`TIDB_DECODE_KEY()`](#tidb_decode_key) | Decodes a TiDB-encoded key entry into a JSON structure containing `_tidb_rowid` and `table_id`. These encoded keys can be found in some system tables and logging outputs. |
4141
| [`TIDB_DECODE_PLAN()`](#tidb_decode_plan) | Decodes a TiDB execution plan. |
42-
| [`TIDB_DECODE_SQL_DIGESTS()`](#tidb_decode_sql_digests) | Queries the normalized SQL statements (a form without formats and arguments) corresponding to the set of SQL digests in the cluster. |
42+
| [`TIDB_DECODE_SQL_DIGESTS()`](#tidb_decode_sql_digests) | Queries the normalized SQL statements (a form without formats and arguments) corresponding to a set of SQL digests in the cluster. |
4343
| [`TIDB_ENCODE_SQL_DIGEST()`](#tidb_encode_sql_digest) | Gets a digest for a query string. |
44-
| [`TIDB_IS_DDL_OWNER()`](#tidb_is_ddl_owner) | Checks whether or not the TiDB instance you are connected to is the one that is the DDL Owner. The DDL Owner is the TiDB instance that is tasked with executing DDL statements on behalf of all other nodes in the cluster. |
44+
| [`TIDB_IS_DDL_OWNER()`](#tidb_is_ddl_owner) | Checks whether or not the TiDB instance you are connected to is the DDL Owner. The DDL Owner is the TiDB instance that is tasked with executing DDL statements on behalf of all other nodes in the cluster. |
4545
| [`TIDB_PARSE_TSO()`](#tidb_parse_tso) | Extracts the physical timestamp from a TiDB TSO timestamp. See also: [`tidb_current_ts`](/system-variables.md#tidb_current_ts). |
4646
| [`TIDB_PARSE_TSO_LOGICAL()`](#tidb_parse_tso_logical) | Extracts the logical timestamp from a TiDB TSO timestamp. |
4747
| [`TIDB_ROW_CHECKSUM()`](#tidb_row_checksum) | Queries the checksum value of a row. This function can only be used in `SELECT` statements within the FastPlan process. That is, you can query through statements like `SELECT TIDB_ROW_CHECKSUM() FROM t WHERE id = ?` or `SELECT TIDB_ROW_CHECKSUM() FROM t WHERE id IN (?, ?, ...)`. See also: [Data integrity validation for single-row data](https://docs.pingcap.com/tidb/stable/ticdc-integrity-check). |
4848
| [`TIDB_SHARD()`](#tidb_shard) | Creates a shard index to scatter the index hotspot. A shard index is an expression index with a `TIDB_SHARD` function as the prefix.|
4949
| [`TIDB_VERSION()`](#tidb_version) | Returns the TiDB version with additional build information. |
50-
| [`VITESS_HASH()`](#vitess_hash) | Returns the hash of a number that is compatible with Vitess' `HASH` function. This is intended to help the data migration from Vitess. |
50+
| [`VITESS_HASH()`](#vitess_hash) | Returns the hash of a number. This function is compatible with the `HASH` function of Vitess, and is intended to help the data migration from Vitess. |
5151

5252
</CustomContent>
5353

5454
## CURRENT_RESOURCE_GROUP
5555

56-
The `CURRENT_RESOURCE_GROUP` function is used to show the resource group name that the current session is bound to. When the [Resource control](/tidb-resource-control.md) feature is enabled, the available resources that can be used by SQL statements are restricted by the resource quota of the bound resource group.
56+
The `CURRENT_RESOURCE_GROUP()` function is used to show the resource group name that the current session is bound to. When the [Resource control](/tidb-resource-control.md) feature is enabled, the available resources that can be used by SQL statements are restricted by the resource quota of the bound resource group.
5757

5858
When a session is established, TiDB binds the session to the resource group that the login user is bound to by default. If the user is not bound to any resource groups, the session is bound to the `default` resource group. Once the session is established, the bound resource group will not change by default, even if the bound resource group of the user is changed via [modifying the resource group bound to the user](/sql-statements/sql-statement-alter-user.md#modify-basic-user-information). To change the bound resource group of the current session, you can use [`SET RESOURCE GROUP`](/sql-statements/sql-statement-set-resource-group.md).
5959

@@ -63,8 +63,8 @@ Create a user `user1`, create two resource groups `rg1` and `rg2`, and bind the
6363

6464
```sql
6565
CREATE USER 'user1';
66-
CREATE RESOURCE GROUP 'rg1' RU_PER_SEC = 1000;
67-
CREATE RESOURCE GROUP 'rg2' RU_PER_SEC = 2000;
66+
CREATE RESOURCE GROUP rg1 RU_PER_SEC = 1000;
67+
CREATE RESOURCE GROUP rg2 RU_PER_SEC = 2000;
6868
ALTER USER 'user1' RESOURCE GROUP `rg1`;
6969
```
7070

@@ -105,7 +105,7 @@ The `TIDB_BOUNDED_STALENESS()` function is used as part of [`AS OF TIMESTAMP`](/
105105

106106
## TIDB_CURRENT_TSO
107107

108-
The `TIDB_CURRENT_TSO()` function returns the [TSO](/tso.md) for the current transaction. This is similar to the [`tidb_current_ts`](/system-variables.md#tidb_current_ts) variable.
108+
The `TIDB_CURRENT_TSO()` function returns the [TSO](/tso.md) for the current transaction. This is similar to the [`tidb_current_ts`](/system-variables.md#tidb_current_ts) system variable.
109109

110110
```sql
111111
BEGIN;
@@ -303,14 +303,14 @@ This function returns a string, which is in the format of a JSON string array. T
303303
> * This function has a high overhead because every time it is called, it internally queries the `STATEMENTS_SUMMARY`, `STATEMENTS_SUMMARY_HISTORY`, `CLUSTER_STATEMENTS_SUMMARY`, and `CLUSTER_STATEMENTS_SUMMARY_HISTORY` tables, and the query involves the `UNION` operation. This function currently does not support vectorization, that is, when calling this function for multiple rows of data, the above query is performed separately for each row.
304304
305305
```sql
306-
set @digests = '["e6f07d43b5c21db0fbb9a31feac2dc599787763393dd5acbfad80e247eb02ad5","38b03afa5debbdf0326a014dbe5012a62c51957f1982b3093e748460f8b00821","e5796985ccafe2f71126ed6c0ac939ffa015a8c0744a24b7aee6d587103fd2f7"]';
306+
SET @digests = '["e6f07d43b5c21db0fbb9a31feac2dc599787763393dd5acbfad80e247eb02ad5","38b03afa5debbdf0326a014dbe5012a62c51957f1982b3093e748460f8b00821","e5796985ccafe2f71126ed6c0ac939ffa015a8c0744a24b7aee6d587103fd2f7"]';
307307
308-
select tidb_decode_sql_digests(@digests);
308+
SELECT TIDB_DECODE_SQL_DIGESTS(@digests);
309309
```
310310
311311
```sql
312312
+------------------------------------+
313-
| tidb_decode_sql_digests(@digests) |
313+
| TIDB_DECODE_SQL_DIGESTS(@digests) |
314314
+------------------------------------+
315315
| ["begin",null,"select * from `t`"] |
316316
+------------------------------------+
@@ -320,12 +320,12 @@ select tidb_decode_sql_digests(@digests);
320320
In the above example, the parameter is a JSON array containing 3 SQL digests, and the corresponding SQL statements are the three items in the query results. But the SQL statement corresponding to the second SQL digest cannot be found from the cluster, so the second item in the result is `null`.
321321
322322
```sql
323-
select tidb_decode_sql_digests(@digests, 10);
323+
SELECT TIDB_DECODE_SQL_DIGESTS(@digests, 10);
324324
```
325325
326326
```sql
327327
+---------------------------------------+
328-
| tidb_decode_sql_digests(@digests, 10) |
328+
| TIDB_DECODE_SQL_DIGESTS(@digests, 10) |
329329
+---------------------------------------+
330330
| ["begin",null,"select * f..."] |
331331
+---------------------------------------+
@@ -336,7 +336,7 @@ The above call specifies the second parameter (that is, the truncation length) a
336336
337337
See also:
338338
339-
- [`Statement Summary Tables`](/statement-summary-tables.md)
339+
- [Statement summary tables](/statement-summary-tables.md)
340340
- [`INFORMATION_SCHEMA.TIDB_TRX`](/information-schema/information-schema-tidb-trx.md)
341341
342342
## TIDB_ENCODE_SQL_DIGEST
@@ -461,7 +461,7 @@ Create table `t` and insert data:
461461
```sql
462462
USE test;
463463
CREATE TABLE t (id INT PRIMARY KEY, k INT, c CHAR(1));
464-
INSERT INTO t values (1, 10, 'a');
464+
INSERT INTO t VALUES (1, 10, 'a');
465465
```
466466
467467
The following statement shows how to query the checksum value of the row where `id = 1` in table `t`:
@@ -544,15 +544,15 @@ SELECT TIDB_VERSION()\G
544544

545545
```sql
546546
*************************** 1. row ***************************
547-
TIDB_VERSION(): Release Version: v5.1.0-alpha-13-gd5e0ed0aa-dirty
547+
TIDB_VERSION(): Release Version: v8.2.0
548548
Edition: Community
549-
Git Commit Hash: d5e0ed0aaed72d2f2dfe24e9deec31cb6cb5fdf0
550-
Git Branch: master
551-
UTC Build Time: 2021-05-24 14:39:20
552-
GoVersion: go1.13
549+
Git Commit Hash: 821e491a20fbab36604b36b647b5bae26a2c1418
550+
Git Branch: HEAD
551+
UTC Build Time: 2024-07-11 19:16:25
552+
GoVersion: go1.21.10
553553
Race Enabled: false
554-
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
555554
Check Table Before Drop: false
555+
Store: tikv
556556
1 row in set (0.00 sec)
557557
```
558558

0 commit comments

Comments
 (0)