pingcap / pingcap/tidb

Support to use the outer side of the (Anti) Semi Join to build the hash table

Open
#32,335 9 comments 4 reactions 1 assignee Claimed by @winoros View on GitHub
help wanted sig/planner type/enhancement
Dominant language
Go
Stars
40.5k
Forks
6.2k
PR merge metrics
PR metrics pending

Description

## Enhancement

Currently, when TiDB meets a(an) (Anti) Semi join, it would always choose the inner side to build the hash table.
When the inner side is extremely large compared with the outer side, our current strategy would cost a lot on building the hash table by the inner side.

So we should support constructing the hash table by the outer side to speed up the execution when the data distribution is like the above case.

It's something the same with supporting constructing hash table by the outer side of the outer join, which is implemented in TiDB.

Contributor guide

Open the contributing guide

Assessment

This issue has not been assessed yet.

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.