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| author | Bruce Momjian <bruce@momjian.us> | 2005-05-25 22:59:33 +0000 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2005-05-25 22:59:33 +0000 |
| commit | 8c792fe9cbe1dcfdafcdc70b961be714631324ec (patch) | |
| tree | d9a4e8a4c5848634e4e5fe86db831f2a0d44af45 /src/backend/utils/adt/like.c | |
| parent | bbb586ff211c2d304db4a64e8c3ea715a4ecebb5 (diff) | |
| download | postgresql-8c792fe9cbe1dcfdafcdc70b961be714631324ec.tar.gz postgresql-8c792fe9cbe1dcfdafcdc70b961be714631324ec.zip | |
At the head of wchareq, length of (multibyte) character is compared by
using pg_mblen. Therefore, pg_mblen is executed many times, and it
becomes a bottleneck.
This patch makes a short cut, and reduces execution frequency of
pg_mblen by comparing the first byte first.
a_ogawa
Diffstat (limited to 'src/backend/utils/adt/like.c')
| -rw-r--r-- | src/backend/utils/adt/like.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c index 541bd0e629f..9289416ca46 100644 --- a/src/backend/utils/adt/like.c +++ b/src/backend/utils/adt/like.c @@ -11,7 +11,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/utils/adt/like.c,v 1.59 2004/12/31 22:01:22 pgsql Exp $ + * $PostgreSQL: pgsql/src/backend/utils/adt/like.c,v 1.60 2005/05/25 22:59:33 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -50,12 +50,18 @@ static text *MB_do_like_escape(text *, text *); static int wchareq(unsigned char *p1, unsigned char *p2) { - int l; + int p1_len; - l = pg_mblen(p1); - if (pg_mblen(p2) != l) + /* Optimization: quickly compare the first byte. */ + if(*p1 != *p2) return (0); - while (l--) + + p1_len = pg_mblen(p1); + if (pg_mblen(p2) != p1_len) + return (0); + + /* They are the same length */ + while (p1_len--) { if (*p1++ != *p2++) return (0); |