Optimize numeric multiplication for one and two base-NBASE digit multiplicands.

Joel Jacobson <joel@compiler.org>

From: "Joel Jacobson" <joel@compiler.org>

To: pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2024-07-01T06:04:06Z

Lists: pgsql-hackers

Attachments

0001-optimize-numeric-mul_var-small-factors.patch (application/octet-stream) patch 0001

Hello hackers,

Attached patch introduces an optimization of mul_var() in numeric.c, targeting cases where the multiplicands consist of only one or two base-NBASE digits. Such small multiplicands can fit into an int64 and thus be computed directly, resulting in a significant performance improvement, between 26% - 34% benchmarked on Intel Core i9-14900K.

This optimization is similar to commit d1b307eef2, that also targeted one and two base-NBASE digit operands, but optimized div_var().

Regards,
Joel

Commits

Optimise numeric multiplication for short inputs.
- ca481d3c9ab7 18.0 landed
Optimise numeric division for 3 and 4 base-NBASE digit divisors.
- 0aa38db56bf4 16.0 cited
Optimise numeric division for one and two base-NBASE digit divisors.
- d1b307eef281 15.0 cited