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| author | Richard Guo <rguo@postgresql.org> | 2024-07-05 09:26:48 +0900 |
|---|---|---|
| committer | Richard Guo <rguo@postgresql.org> | 2024-07-05 09:26:48 +0900 |
| commit | aa86129e19d704afb93cb84ab9638f33d266ee9d (patch) | |
| tree | 0c1643a4ca9aaa321c08f4d896499aed3c961c2c /src/include/nodes/nodes.h | |
| parent | 5a519abeddfe34659a8c0478f04a0acfd0d80ec6 (diff) | |
Support "Right Semi Join" plan shapes
Hash joins can support semijoin with the LHS input on the right, using
the existing logic for inner join, combined with the assurance that only
the first match for each inner tuple is considered, which can be
achieved by leveraging the HEAP_TUPLE_HAS_MATCH flag. This can be very
useful in some cases since we may now have the option to hash the
smaller table instead of the larger.
Merge join could likely support "Right Semi Join" too. However, the
benefit of swapping inputs tends to be small here, so we do not address
that in this patch.
Note that this patch also modifies a test query in join.sql to ensure it
continues testing as intended. With this patch the original query would
result in a right-semi-join rather than semi-join, compromising its
original purpose of testing the fix for neqjoinsel's behavior for
semi-joins.
Author: Richard Guo
Reviewed-by: wenhui qiu, Alena Rybakina, Japin Li
Discussion: https://postgr.es/m/CAMbWs4_X1mN=ic+SxcyymUqFx9bB8pqSLTGJ-F=MHy4PW3eRXw@mail.gmail.com
Diffstat (limited to 'src/include/nodes/nodes.h')
| -rw-r--r-- | src/include/nodes/nodes.h | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h index 855009fd6e2..0d71d821f71 100644 --- a/src/include/nodes/nodes.h +++ b/src/include/nodes/nodes.h @@ -306,6 +306,7 @@ typedef enum JoinType */ JOIN_SEMI, /* 1 copy of each LHS row that has match(es) */ JOIN_ANTI, /* 1 copy of each LHS row that has no match */ + JOIN_RIGHT_SEMI, /* 1 copy of each RHS row that has match(es) */ JOIN_RIGHT_ANTI, /* 1 copy of each RHS row that has no match */ /* @@ -322,10 +323,10 @@ typedef enum JoinType /* * OUTER joins are those for which pushed-down quals must behave differently - * from the join's own quals. This is in fact everything except INNER and - * SEMI joins. However, this macro must also exclude the JOIN_UNIQUE symbols - * since those are temporary proxies for what will eventually be an INNER - * join. + * from the join's own quals. This is in fact everything except INNER, SEMI + * and RIGHT_SEMI joins. However, this macro must also exclude the + * JOIN_UNIQUE symbols since those are temporary proxies for what will + * eventually be an INNER join. * * Note: semijoins are a hybrid case, but we choose to treat them as not * being outer joins. This is okay principally because the SQL syntax makes |