Query: Always use INNER join to establish the outer query link - #173
Draft
nilmerg wants to merge 1 commit into
Draft
Conversation
A subquery always needs to establish a link, be it part of a WHERE or solely used to eager load (using `Query::derive`) a relation. Using an INNER join allows the database to apply optimizations it wouldn't be able to otherwise.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
A subquery always needs to establish a link, be it part of a WHERE or solely used to eager load (using
Query::derive) a relation. Using an INNER join allows the database to apply optimizations it wouldn't be able to otherwise.Since this affects
Query::derive(), any eager loaded relation will now return no result. But this should be usually not a problem, as a caller that iterates or callsfirst()without handling the never entered loop ornull-return is already bugged, IMHO. I've checked this with Icinga DB Web and found exactly two cases: Icinga/icingadb-web#1408Still attempting to prove this is actually of advantage, though…