Extend DDL/MDL info (#20329) #20705
Extend DDL/MDL info (#20329) #20705
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Co-authored-by: xixirangrang <[email protected]>
Co-authored-by: xixirangrang <[email protected]>
Co-authored-by: xixirangrang <[email protected]>
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Hello @ti-chi-bot, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!
Summary of Changes
This pull request extends the DDL/MDL (Data Definition Language/Metadata Lock) information available in the TiDB documentation. It adds a new entry for tidb_mdl_view in the table of contents and in the mysql schema documentation, and also adds a section about DDL-related tables in ddl-introduction.md, including information_schema.DDL_JOBS and mysql.tidb_mdl_view. The example in metadata-lock.md is also updated to use TABLE mysql.tidb_mdl_view\G instead of SELECT * FROM mysql.tidb_mdl_view\G, and the example values are updated.
Highlights
- TOC Updates: The table of contents (both
TOC-tidb-cloud.mdandTOC.md) are updated to include a link to the documentation fortidb_mdl_view. - DDL Introduction: The
ddl-introduction.mdfile is updated to include a section on DDL-related tables, specificallyinformation_schema.DDL_JOBSandmysql.tidb_mdl_view. - Metadata Lock Documentation: The
metadata-lock.mdfile is updated to useTABLE mysql.tidb_mdl_view\Ginstead ofSELECT * FROM mysql.tidb_mdl_view\Gin the examples, and the example output is updated. - New Documentation File: A new documentation file
mysql-schema/mysql-schema-tidb-mdl-view.mdis added to describe themysql.tidb_mdl_viewtable. - mysql schema documentation: The
mysql-schema/mysql-schema.mdfile is updated to include a link to the newtidb_mdl_viewdocumentation.
Changelog
Click here to see the changelog
- TOC-tidb-cloud.md
- Added a link to
tidb_mdl_viewdocumentation undermysqlSchema.
- Added a link to
- TOC.md
- Added a link to
tidb_mdl_viewdocumentation undermysqlSchema.
- Added a link to
- ddl-introduction.md
- Added a section about DDL-related tables, including
information_schema.DDL_JOBSandmysql.tidb_mdl_view.
- Added a section about DDL-related tables, including
- metadata-lock.md
- Updated the example to use
TABLE mysql.tidb_mdl_view\Ginstead ofSELECT * FROM mysql.tidb_mdl_view\G. - Updated the example output to reflect current values.
- Updated the example to use
- mysql-schema/mysql-schema-tidb-mdl-view.md
- Created a new file to document the
mysql.tidb_mdl_viewtable, including its fields and purpose.
- Created a new file to document the
- mysql-schema/mysql-schema.md
- Added a link to the new
tidb_mdl_viewdocumentation.
- Added a link to the new
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Code Review
The pull request extends DDL/MDL information by adding documentation for tidb_mdl_view and linking it in relevant places. The changes seem reasonable and improve the discoverability of this feature. However, there are a few inconsistencies and potential issues that need to be addressed.
Summary of Findings
- Inconsistent SQL example: The SQL example in
metadata-lock.mdusesALTER TABLE t ADD COLUMN c INTwhich does not match the surrounding text that refers to adding an index. This inconsistency could confuse users. - SQL_DIGESTS field length: The
SQL_DIGESTSfield inmysql-schema-tidb-mdl-view.mdis defined asvarchar(5), which seems too short to store meaningful digests. This might lead to truncation and loss of information.
Merge Readiness
The pull request introduces valuable documentation for tidb_mdl_view. However, the identified inconsistencies and potential issues should be addressed before merging to ensure accuracy and prevent user confusion. I am unable to approve this pull request, and recommend that the author address the issues raised in the review comments before merging.
| job_id: 118 | ||
| db_name: test | ||
| table_name: t | ||
| query: ALTER TABLE t ADD COLUMN c INT |
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The query shown here is ALTER TABLE t ADD COLUMN c INT, but the surrounding text refers to adding an index (ALTER TABLE t ADD INDEX idx(a)). This is inconsistent and might confuse users. Should this be updated to match the surrounding text, or vice versa?
| query: ALTER TABLE t ADD COLUMN c INT | |
| query: ALTER TABLE t ADD INDEX idx(a) |
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This looks like a correct comment that needs addressing.
|
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/approve |
|
[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: hfxsd The full list of commands accepted by this bot can be found here. The pull request process is described here
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Approvers can indicate their approval by writing |
This is an automated cherry-pick of #20329
What is changed, added or deleted? (Required)
https://docs.pingcap.com/tidb/stable/metadata-lock#observability gives some useful info, but it is hard to find and this table lacks documentation.
Which TiDB version(s) do your changes apply to? (Required)
Tips for choosing the affected version(s):
By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.
For details, see tips for choosing the affected versions.
What is the related PR or file link(s)?
Do your changes match any of the following descriptions?