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| author | Michael Paquier <michael@paquier.xyz> | 2024-02-22 10:02:55 +0900 |
|---|---|---|
| committer | Michael Paquier <michael@paquier.xyz> | 2024-02-22 10:02:55 +0900 |
| commit | 011d60c4352c5c48c0f1a185e8a12833c22a58db (patch) | |
| tree | 3c4bf5dc8bcebb6b101300f50d06c40e3d665939 | |
| parent | 943f7ae1c8693cf3ea59d103aaf9590ea062fb9c (diff) | |
| download | postgresql-011d60c4352c5c48c0f1a185e8a12833c22a58db.tar.gz postgresql-011d60c4352c5c48c0f1a185e8a12833c22a58db.zip | |
Speed up uuid_out() by not relying on a StringInfo
Since the size of the string representation of an uuid is fixed, there
is no benefit in using a StringInfo. This commit simplifies uuid_oud()
to not rely on a StringInfo, where avoiding the overhead of the string
manipulation makes the function substantially faster.
A COPY TO on a relation with one UUID attribute can show up to a 40%
speedup when the bottleneck is the COPY computation with uuid_out()
showing up at the top of the profiles (numbered measure here, Laurenz
has mentioned something closer to 20% faster runtimes), for example when
the data is fully in shared buffers or the OS cache.
Author: Laurenz Albe
Reviewed-by: Andres Freund, Michael Paquier
Description: https://postgr.es/m/679d5455cbbb0af667ccb753da51a475bae1eaed.camel@cybertec.at
| -rw-r--r-- | src/backend/utils/adt/uuid.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/src/backend/utils/adt/uuid.c b/src/backend/utils/adt/uuid.c index 73dfd711c73..2ca8fc69943 100644 --- a/src/backend/utils/adt/uuid.c +++ b/src/backend/utils/adt/uuid.c @@ -53,10 +53,13 @@ uuid_out(PG_FUNCTION_ARGS) { pg_uuid_t *uuid = PG_GETARG_UUID_P(0); static const char hex_chars[] = "0123456789abcdef"; - StringInfoData buf; + char *buf, + *p; int i; - initStringInfo(&buf); + /* counts for the four hyphens and the zero-terminator */ + buf = palloc(2 * UUID_LEN + 5); + p = buf; for (i = 0; i < UUID_LEN; i++) { int hi; @@ -68,16 +71,17 @@ uuid_out(PG_FUNCTION_ARGS) * ("-"). Therefore, add the hyphens at the appropriate places here. */ if (i == 4 || i == 6 || i == 8 || i == 10) - appendStringInfoChar(&buf, '-'); + *p++ = '-'; hi = uuid->data[i] >> 4; lo = uuid->data[i] & 0x0F; - appendStringInfoChar(&buf, hex_chars[hi]); - appendStringInfoChar(&buf, hex_chars[lo]); + *p++ = hex_chars[hi]; + *p++ = hex_chars[lo]; } + *p = '\0'; - PG_RETURN_CSTRING(buf.data); + PG_RETURN_CSTRING(buf); } /* |