apache / apache/druid

Add back Query ID verification check from MSQ workers

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#16,894 0 comments 0 reactions 0 assignees View on GitHub
Area - MSQ Refactoring Starter
Dominant language
Java
Stars
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Forks
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Avg merge
2d 58m
Merged PRs (30d)
233

Description

### Description
Until and before Druid 30, the query IDs of different stages in MSQ were populated randomly, but we never really relied on them. It was incorrect behavior which was fixed in https://github.com/apache/druid/pull/16168. Later, a query ID verification check was added to make sure that different stages of a query have the same query ID. However, it isn't safe to do so till we have to maintain backward compatibility with Druid 30, which would be till Druid 34 is released. https://github.com/apache/druid/pull/16886 removed the query id verification check, that should be added back once that happens.

Contributor guide

Open the contributing guide

Research direction

Read PRs 16168 and 16886 first to understand how MSQ stage query IDs were populated and why verification was removed. Locate the prior verification check and its tests, then restore it only after the Druid 34 compatibility window; done means different stages are verified to use the same query ID without breaking Druid 30 compatibility.

Written by the indexing model from the issue text.

Assessment

Tech stack
java
Domain
databases, distributed-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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