From: David Rowley <drowley@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Speedup Hash Joins with dedicated functions for ExprState hashin
Date: Tue, 10 Dec 2024 22:32:37 +0000
Message-ID: <E1tL8mS-0026L0-Cj@gemulon.postgresql.org> (raw)
Speedup Hash Joins with dedicated functions for ExprState hashing
Hashing of a single Var is a very common operation for ExprState to
perform. Here we add dedicated ExecJust* functions which helps speed up
Hash Joins by removing the interpretation overhead in ExecInterpExpr().
This change currently only affects Hash Joins on a single column. Hash
Joins with multiple join keys or an expression still run through
ExecInterpExpr().
Some testing has shown up to 10% query performance increases on recent AMD
hardware and nearly 7% increase on an Apple M2 for a query performing a
hash join with a large number of lookups on a small hash table.
This change was extracted from a larger patch which adjusts GROUP BY /
hashed subplans / hashed set operations to use ExprState hashing.
Discussion: https://postgr.es/m/CAApHDvr8Zc0ZgzVoCZLdHGOFNhiJeQ6vrUcS9V7N23zMWQb-eA@mail.gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/50416cc4843a85fcb53507e21577cce16c75c65f
Modified Files
--------------
src/backend/executor/execExprInterp.c | 206 +++++++++++++++++++++++++++++++++-
1 file changed, 205 insertions(+), 1 deletion(-)
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To: pgsql-committers@postgresql.org
Cc: drowley@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Speedup Hash Joins with dedicated functions for ExprState hashin
In-Reply-To: <E1tL8mS-0026L0-Cj@gemulon.postgresql.org>
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