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help / color / mirror / Atom feedFrom: Jeff Davis <[email protected]>
To: [email protected]
Subject: pgsql: Optimization for lower(), upper(), casefold() functions.
Date: Sat, 15 Mar 2025 20:04:41 +0000
Message-ID: <[email protected]> (raw)
Optimization for lower(), upper(), casefold() functions.
Improve performance and reduce table sizes for case mapping.
The main case mapping table stores only 16-bit offsets, which can be
used to look up the mapped code point in any of the case tables (fold,
lower, upper, or title case). Simple case pairs point to the same
offsets.
Generate a function in generate-unicode_case_table.pl that consists of
a nested branches to test for specific codepoint ranges that determine
the offset in the main table.
Other approaches were considered, such as representing these ranges as
another structure (rather than branches in a generated function), or a
different approach such as a radix tree, or perfect hashing. The
author implemented and tested these alternatives and settled on the
generated branches.
Author: Alexander Borisov <[email protected]>
Reviewed-by: Heikki Linnakangas <[email protected]>
Discussion: https://postgr.es/m/7cac7e66-9a3b-4e3f-a997-42aa0c401f80%40gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/27bdec06841d1bb004ca7627eac97808b08a7ac7
Modified Files
--------------
src/common/unicode/generate-unicode_case_table.pl | 388 +-
src/common/unicode_case.c | 80 +-
src/include/common/unicode_case_table.h | 16418 ++++++++++++++++----
3 files changed, 13671 insertions(+), 3215 deletions(-)
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