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functions-and-operators, releases: clarify TIDB_DECODE_SQL_DIGESTS wording (#23686) #23754

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functions-and-operators, releases: clarify TIDB_DECODE_SQL_DIGESTS wording (#23686) #23754

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functions-and-operators, releases: clarify TIDB_DECODE_SQL_DIGESTS wo…
yahonda Sep 1, 2026
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Update functions-and-operators/tidb-functions.md
yahonda Sep 3, 2026
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Update functions-and-operators/tidb-functions.md
yahonda Sep 3, 2026
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Update releases/release-5.2.0.md
yahonda Sep 3, 2026
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Update functions-and-operators/tidb-functions.md
yahonda Sep 3, 2026
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6 changes: 3 additions & 3 deletions functions-and-operators/tidb-functions.md
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Expand Up @@ -17,7 +17,7 @@ The following functions are TiDB extensions, and are not present in MySQL:
| [`TIDB_DECODE_BINARY_PLAN()`](#tidb_decode_binary_plan) | Decodes binary plans. |
| [`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. |
| [`TIDB_DECODE_PLAN()`](#tidb_decode_plan) | Decodes a TiDB execution plan. |
| [`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. |
| [`TIDB_DECODE_SQL_DIGESTS()`](#tidb_decode_sql_digests) | Queries the normalized SQL statements (in which literal values are replaced with placeholders such as `?` or `...`) corresponding to a set of SQL digests in the cluster. |
| [`TIDB_ENCODE_INDEX_KEY()`](#tidb_encode_index_key) | Encodes an index key. |
| [`TIDB_ENCODE_RECORD_KEY()`](#tidb_encode_record_key) | Encodes a record key. |
| [`TIDB_ENCODE_SQL_DIGEST()`](#tidb_encode_sql_digest) | Gets a digest for a query string. |
Expand All @@ -42,7 +42,7 @@ The following functions are TiDB extensions, and are not present in MySQL:
| [`TIDB_DECODE_BINARY_PLAN()`](#tidb_decode_binary_plan) | Decodes binary plans. |
| [`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. |
| [`TIDB_DECODE_PLAN()`](#tidb_decode_plan) | Decodes a TiDB execution plan. |
| [`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. |
| [`TIDB_DECODE_SQL_DIGESTS()`](#tidb_decode_sql_digests) | Queries the normalized SQL statements (in which literal values are replaced with placeholders such as `?` or `...`) corresponding to a set of SQL digests in the cluster. |
| [`TIDB_ENCODE_INDEX_KEY()`](#tidb_encode_index_key) | Encodes an index key. |
| [`TIDB_ENCODE_RECORD_KEY()`](#tidb_encode_record_key) | Encodes a record key. |
| [`TIDB_ENCODE_SQL_DIGEST()`](#tidb_encode_sql_digest) | Gets a digest for a query string. |
Expand Down Expand Up @@ -294,7 +294,7 @@ SELECT tidb_decode_plan('8QIYMAkzMV83CQEH8E85LjA0CWRhdGE6U2VsZWN0aW9uXzYJOTYwCXR

## TIDB_DECODE_SQL_DIGESTS

The `TIDB_DECODE_SQL_DIGESTS()` function is used to query the normalized SQL statements (a form without formats and arguments) corresponding to the set of SQL digests in the cluster. This function accepts 1 or 2 arguments:
The `TIDB_DECODE_SQL_DIGESTS()` function is used to query the normalized SQL statements (in which literal values are replaced with placeholders such as `?` or `...`) corresponding to the set of SQL digests in the cluster. This function accepts 1 or 2 arguments:

@coderabbitai coderabbitai Bot Sep 7, 2026

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📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win

Align the linked TIDB_TRX description.

information-schema/information-schema-tidb-trx.md still says that normalized SQL is “without arguments and format”. This page now defines the same output as literal values replaced with placeholders. Update the linked sentence in this backport, or confirm that the older wording is intentional.


* `digests`: A string. This parameter is in the format of a JSON string array, and each string in the array is a SQL digest.
* `stmtTruncateLength`: An integer (optional). It is used to limit the length of each SQL statement in the returned result. If a SQL statement exceeds the specified length, the statement is truncated. `0` means that the length is unlimited.
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2 changes: 1 addition & 1 deletion releases/release-5.2.0.md
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Expand Up @@ -113,7 +113,7 @@ In v5.2, the key new features and improvements are as follows:
In v5.2, the following enhancements are made to Lock View:

- In addition to the SQL digest column in the Lock View-related tables, add a column to these tables that shows the corresponding normalized SQL text. You do not have to manually query the statement corresponding to a SQL digest.
- Add the `TIDB_DECODE_SQL_DIGESTS` function to query the normalized SQL statements (a form without formats and arguments) corresponding to a set of SQL digests in the cluster. This simplifies the operation of querying the statements that have been historically executed by a transaction.
- Add the `TIDB_DECODE_SQL_DIGESTS` function to query the normalized SQL statements (in which literal values are replaced with placeholders such as `?` or `...`) corresponding to a set of SQL digests in the cluster. This simplifies the operation of querying the statements that have been historically executed by a transaction.
- Add a column in the `DATA_LOCK_WAITS` and `DEADLOCKS` system tables to show the table name, row ID, index value, and other key information interpreted from a key. This simplifies the operations such as locating the table to which a key belongs and interpreting the key information.
- Support collecting the information of retryable deadlock errors in the `DEADLOCKS` table, which makes it easier to troubleshoot issues caused by such errors. The error collection is disabled by default and can be enabled using the `pessimistic-txn.deadlock-history-collect-retryable` configuration.
- Support distinguishing query-executing transactions from idle transactions on the `TIDB_TRX` system table. The `Normal` state is now divided into `Running` and `Idle` states.
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