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https://issues.apache.org/jira/browse/FLINK-40962?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18126757#comment-18126757
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ChenZhuo edited comment on FLINK-40962 at 10/13/26 1:56 PM:
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Hi, I would like to work on this issue. My proposed approach is to add a
precision-preserving TIMESTAMP_LTZ implementation to the existing batch
LeadLagAggFunction and wire it into AggFunctionFactory. Since LAG and LEAD
share this path, I will cover both with batch regression tests, including
null/default handling and timestamp precision.
Two scope questions before I prepare the patch:
1. The missing type branch appears to affect batch LEAD as well as LAG. Would
covering both under this ticket be appropriate?
2. Should the initial PR target master only, or are there maintained release
branches where you would like this fix backported?
Could a committer please assign this issue to me (JIRA username: chenzhuo)?
Thanks!
was (Author: chenzhuo):
Hi, I would like to work on this issue. My proposed approach is to add a
precision-preserving TIMESTAMP_LTZ implementation to the existing batch
LeadLagAggFunction and wire it into AggFunctionFactory. Since LAG and LEAD
share this path, I will cover both with batch regression tests, including
null/default handling and timestamp precision.
Could a committer please assign this issue to me (JIRA username: chenzhuo)?
Thanks!
> LAG() unsupported for TIMESTAMP_LTZ arguments in batch mode
> -----------------------------------------------------------
>
> Key: FLINK-40962
> URL: https://issues.apache.org/jira/browse/FLINK-40962
> Project: Flink
> Issue Type: Improvement
> Components: Table SQL / Planner
> Reporter: Saketh Kurnool
> Priority: Major
>
> h1. Issue
> The `LAG()` window function is rejected for `TIMESTAMP_LTZ` argument types in
> batch/snapshot mode. It works in streaming mode. Concretely:
>
> {code:java}
> Failed to (re)submit Job to Flink: {"errors":["Unsupported call:
> LAG(TIMESTAMP_LTZ(3)) \nIf you think this function should be supported, you
> can create an issue and start a discussion for it."]}{code}
> h1. Proposal
> Add the missing `TIMESTAMP_LTZ` case to
> `AggFunctionFactory.createBatchLeadLagAggFunction`
> h2. Files to modify
> * LeadLagAggFunction.java: add a `LocalZonedTimestampLeadLagAggFunction`
> static inner class that returns `DataTypes.TIMESTAMP_LTZ` as the result type
> * AggFunctionFactory.scala: add a case for `TIMESTAMP_LTZ` to
> `createBatchLeadLagAggFunction` to return a
> `LocalZonedTimestampLeadLagAggFunction`
> * TimestampITCase.scala: add IT coverage for LAG(TIMESTAMP_LTZ)
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