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Speed up byteain by not parsing traditional-style input twice.

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Instead of laboriously computing the exact output length, use strlen
to get an upper bound cheaply.  (This is still O(N) of course, but
the constant factor is a lot less.)  This will typically result in
overallocating the output datum, but that's of little concern since
it's a short-lived allocation in just about all use-cases.

A simple microbenchmark showed about 40% speedup for long input
strings.

While here, make some cosmetic cleanups and add a test case that
covers the double-backslash code path in byteain and byteaout.

Author: Steven Niu <niushiji@gmail.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Stepan Neretin <slpmcf@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/ca315729-140b-426e-81a6-6cd5cfe7ecc5@gmail.com
This commit is contained in:
Tom Lane
2025-07-18 16:42:02 -04:00
parent 84409ed640
commit 3683af6170
3 changed files with 39 additions and 54 deletions
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12
src/test/regress/expected/strings.out
View File

@@ -236,6 +236,12 @@ SELECT E'De\\678dBeEf'::bytea;
ERROR: invalid input syntax for type bytea
LINE 1: SELECT E'De\\678dBeEf'::bytea;
^
SELECT E'DeAd\\\\BeEf'::bytea;
bytea
----------------------
\x446541645c42654566
(1 row)
SELECT reverse(''::bytea);
reverse
---------
@@ -291,6 +297,12 @@ SELECT E'De\\123dBeEf'::bytea;
DeSdBeEf
(1 row)
SELECT E'DeAd\\\\BeEf'::bytea;
bytea
------------
DeAd\\BeEf
(1 row)
-- Test non-error-throwing API too
SELECT pg_input_is_valid(E'\\xDeAdBeE', 'bytea');
pg_input_is_valid

2
src/test/regress/sql/strings.sql
View File

@@ -76,6 +76,7 @@ SELECT E'De\\000dBeEf'::bytea;
SELECT E'De\123dBeEf'::bytea;
SELECT E'De\\123dBeEf'::bytea;
SELECT E'De\\678dBeEf'::bytea;
SELECT E'DeAd\\\\BeEf'::bytea;
SELECT reverse(''::bytea);
SELECT reverse('\xaa'::bytea);
@@ -88,6 +89,7 @@ SELECT E'\\xDe00BeEf'::bytea;
SELECT E'DeAdBeEf'::bytea;
SELECT E'De\\000dBeEf'::bytea;
SELECT E'De\\123dBeEf'::bytea;
SELECT E'DeAd\\\\BeEf'::bytea;
-- Test non-error-throwing API too
SELECT pg_input_is_valid(E'\\xDeAdBeE', 'bytea');