Fix performance issue with many duplicate ids#40
Merged
Conversation
DominicGBauer
approved these changes
Oct 15, 2024
2 tasks
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
2 participants
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
If you had a sync rules query like this:
select '' as id from mytable(all rows with the same id), the JOIN sync_local query would haveO(n^2)operations. For 10k rows, this is 100m operations, which takes a very long time.While this should never be the case in a production app (you'd typically have a max of 2 or 3 duplicates), it could easily lead to a "hanging" app during development if you had a mistake in the query, making it difficult to debug.
The change in query here takes it back to
O(n). It does use an additional "TEMP B-TREE" for the DISTINCT/UNION step, but does not seem to negatively affect sync performance in my testing.