routing: improve dual and left joins #5551
Merged
Conversation
This file contains 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
Fixes vitessio#4772 Fixes vitessio#5508 Previously, vitess was conservative about using vindexes for tables involving left joins. After some reasoning, we've determined that it's actually safe (and more efficient) to use them. In existing functionality, a reference table had to be on the RHS of the analysis. There was no benefit if it was on the LHS. When we changed dual to be a Reference tables, it caused a regression. If dual was on the LHS of a join or subquery, then it would get treated as cross-shard. The new change handles the case of ref tables to be on the LHS. This also fixes the regression. Signed-off-by: Sugu Sougoumarane <ssougou@gmail.com>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
Fixes #4772
Fixes #5508
Previously, vitess was conservative about using vindexes for tables
involving left joins. After some reasoning, we've determined that it's
actually safe (and more efficient) to use them.
In existing functionality, a reference table had to be on the RHS
of the analysis. There was no benefit if it was on the LHS. When
we changed dual to be a Reference tables, it caused a regression.
If dual was on the LHS of a join or subquery, then it would get
treated as cross-shard. The new change handles the case of ref
tables to be on the LHS. This also fixes the regression.
Signed-off-by: Sugu Sougoumarane ssougou@gmail.com