junmuz opened a new pull request, #29808:
URL: https://github.com/apache/flink/pull/29808
…a ALTER TABLE
<!--
*Thank you very much for contributing to Apache Flink - we are happy that
you want to help us improve Flink. To help the community review your
contribution in the best possible way, please go through the checklist below,
which will get the contribution into a shape in which it can be best reviewed.*
*Please understand that we do not do this to make contributions to Flink a
hassle. In order to uphold a high standard of quality for code contributions,
while at the same time managing a large number of contributions, we need
contributors to prepare the contributions well, and give reviewers enough
contextual information for the review. Please also understand that
contributions that do not follow this guide will take longer to review and thus
typically be picked up with lower priority by the community.*
## Contribution Checklist
- Make sure that the pull request corresponds to a [JIRA
issue](https://issues.apache.org/jira/projects/FLINK/issues). Exceptions are
made for typos in JavaDoc or documentation files, which need no JIRA issue.
- Name the pull request in the form "[FLINK-XXXX] [component] Title of the
pull request", where *FLINK-XXXX* should be replaced by the actual issue
number. Skip *component* if you are unsure about which is the best component.
Typo fixes that have no associated JIRA issue should be named following
this pattern: `[hotfix] [docs] Fix typo in event time introduction` or
`[hotfix] [javadocs] Expand JavaDoc for PuncuatedWatermarkGenerator`.
- Fill out the template below to describe the changes contributed by the
pull request. That will give reviewers the context they need to do the review.
- Make sure that the change passes the automated tests, i.e., `mvn clean
verify` passes. You can set up Azure Pipelines CI to do that following [this
guide](https://cwiki.apache.org/confluence/display/FLINK/Azure+Pipelines#AzurePipelines-Tutorial:SettingupAzurePipelinesforaforkoftheFlinkrepository).
- Each pull request should address only one issue, not mix up code from
multiple issues.
- Each commit in the pull request has a meaningful commit message
(including the JIRA id)
- Once all items of the checklist are addressed, remove the above text and
this checklist, leaving only the filled out template below.
**(The sections below can be removed for hotfixes of typos)**
-->
## What is the purpose of the change
Adds `IF NOT EXISTS` support when adding columns with `ALTER TABLE`,
allowing schema setup statements to be repeated before an `INSERT` without
failing on existing columns.
Existing columns retain their definitions and positions. For column lists,
each existing column is skipped independently while missing columns are added.
## Brief change log
- Support `ADD COLUMN IF NOT EXISTS`, `ADD IF NOT EXISTS column_definition`,
and `ADD IF NOT EXISTS (column_definition, ...)`.
- Preserve the conditional addition flag in SQL node reconstruction and
unparsing.
- Filter existing columns before converting schema changes and return a
no-op operation when all specified columns already exist.
- Document the supported syntax, repeatable schema setup, and interaction
with `ALTER TABLE IF EXISTS`.
## Verifying this change
This change adds the following test coverage:
- `FlinkSqlParserImplTest`: supported syntax, unparsing, quoted identifiers,
column definitions, and rejection of unsupported guarded lists.
- `SqlAlterTableAddColumnConverterTest`: adding missing columns, preserving
existing columns, mixed column lists, no-op behavior, and validation failures.
- `CatalogITCase`: repeated `CREATE TABLE IF NOT EXISTS` and conditional
column additions across separate table environments sharing a catalog, followed
by successful inserts.
- SQL Gateway `table.q`: repeated conditional additions and verification
that existing column types, comments, and positions are preserved.
Tests were not run while preparing this PR description.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): no
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: no
- The serializers: no
- The runtime per-record code paths (performance sensitive): no
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
- The S3 file system connector: no
## Documentation
- Does this pull request introduce a new feature? yes
- If yes, how is the feature documented? docs — the SQL ALTER TABLE
reference includes updated syntax, examples, and behavior for existing columns
and missing tables.
---
##### Was generative AI tooling used to co-author this PR?
- [X] Yes (please specify the tool below)
Generated-by: Codex (GPT-6)
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
