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At the head of wchareq, length of (multibyte) character is compared by

using pg_mblen. Therefore, pg_mblen is executed many times, and itbecomes a bottleneck.This patch makes a short cut, and reduces execution frequency ofpg_mblen by comparing the first byte first.a_ogawa

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+11

-5

lines changed

src/backend/utils/adt
- like.c

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+11

-5

lines changed

`‎src/backend/utils/adt/like.c`

Lines changed: 11 additions & 5 deletions

Original file line number	Diff line number	Diff line change
`@@ -11,7 +11,7 @@`
`11`	`11`	`* Portions Copyright (c) 1994, Regents of the University of California`
`12`	`12`	`*`
`13`	`13`	`* IDENTIFICATION`
`14`		`- *$PostgreSQL: pgsql/src/backend/utils/adt/like.c,v 1.59 2004/12/31 22:01:22 pgsql Exp $`
	`14`	`+ *$PostgreSQL: pgsql/src/backend/utils/adt/like.c,v 1.60 2005/05/25 22:59:33 momjian Exp $`
`15`	`15`	`*`
`16`	`16`	`*-------------------------------------------------------------------------`
`17`	`17`	`*/`
`@@ -50,12 +50,18 @@ static text MB_do_like_escape(text , text *);`
`50`	`50`	`staticint`
`51`	`51`	`wchareq(unsignedcharp1,unsignedcharp2)`
`52`	`52`	`{`
`53`		`-intl;`
	`53`	`+intp1_len;`
`54`	`54`
`55`		`-l=pg_mblen(p1);`
`56`		`-if (pg_mblen(p2)!=l)`
	`55`	`+/* Optimization: quickly compare the first byte. */`
	`56`	`+if(p1!=p2)`
`57`	`57`	`return (0);`
`58`		`-while (l--)`
	`58`	`+`
	`59`	`+p1_len=pg_mblen(p1);`
	`60`	`+if (pg_mblen(p2)!=p1_len)`
	`61`	`+return (0);`
	`62`	`+`
	`63`	`+/* They are the same length */`
	`64`	`+while (p1_len--)`
`59`	`65`	`{`
`60`	`66`	`if (p1++!=p2++)`
`61`	`67`	`return (0);`

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Commit8c792fe

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`‎src/backend/utils/adt/like.c`

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