[jira] [Assigned] (FLINK-40353) Leverage RocksDB ordered MapState TemporalRowTimeJoinOperator

["Piotr Nowojski (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-40353?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Piotr Nowojski reassigned FLINK-40353:
--------------------------------------

    Assignee: Piotr Nowojski

> Leverage RocksDB ordered MapState TemporalRowTimeJoinOperator
> -------------------------------------------------------------
>
>                 Key: FLINK-40353
>                 URL: https://issues.apache.org/jira/browse/FLINK-40353
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table SQL / Runtime
>            Reporter: Piotr Nowojski
>            Assignee: Piotr Nowojski
>            Priority: Major
>
> Some state backends (e.g. RocksDB) always iterate a map state's keys in a well-defined order (their serialized/binary representation); others (e.g. the heap backend) don't. For example TemporalRowTimeJoinOperator could benefit from ordered iteration have currently no way today to detect this at runtime. 
> TemporalRowTimeJoinOperator (row-time FOR SYSTEM_TIME AS OF temporal joins) does a full scan of its left/probe-side state plus a fresh sort of its right/build-side state on every watermark-triggered timer firing, regardless of how many rows actually need processing on that firing. For a join with substantial buffered state, this is a recurring, cost that can be avoided once we expose the information that the underlying state is binary ordered.



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