From: Tom Lane Date: Tue, 18 Jan 2011 19:09:22 +0000 (-0500) Subject: Avoid detoast in texteq/textne/byteaeq/byteane for unequal-length strings. X-Git-Tag: REL9_1_ALPHA4~427 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1b393f4e5db4fd6bbc86a4e88785b6945a1541d0;p=postgresql Avoid detoast in texteq/textne/byteaeq/byteane for unequal-length strings. We can get the length of a compressed or out-of-line datum without actually detoasting it. If the lengths of two strings are unequal, we can then conclude they are unequal without detoasting. That saves considerable work in an admittedly less-common case, without costing anything much when the optimization doesn't apply. Noah Misch --- diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c index ed57685a18..e111d2650b 100644 --- a/src/backend/utils/adt/varlena.c +++ b/src/backend/utils/adt/varlena.c @@ -1451,22 +1451,34 @@ text_cmp(text *arg1, text *arg2) Datum texteq(PG_FUNCTION_ARGS) { - text *arg1 = PG_GETARG_TEXT_PP(0); - text *arg2 = PG_GETARG_TEXT_PP(1); + Datum arg1 = PG_GETARG_DATUM(0); + Datum arg2 = PG_GETARG_DATUM(1); bool result; + Size len1, + len2; /* * Since we only care about equality or not-equality, we can avoid all the - * expense of strcoll() here, and just do bitwise comparison. + * expense of strcoll() here, and just do bitwise comparison. In fact, + * we don't even have to do a bitwise comparison if we can show the + * lengths of the strings are unequal; which might save us from having + * to detoast one or both values. */ - if (VARSIZE_ANY_EXHDR(arg1) != VARSIZE_ANY_EXHDR(arg2)) + len1 = toast_raw_datum_size(arg1); + len2 = toast_raw_datum_size(arg2); + if (len1 != len2) result = false; else - result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), - VARSIZE_ANY_EXHDR(arg1)) == 0); + { + text *targ1 = DatumGetTextPP(arg1); + text *targ2 = DatumGetTextPP(arg2); - PG_FREE_IF_COPY(arg1, 0); - PG_FREE_IF_COPY(arg2, 1); + result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2), + len1 - VARHDRSZ) == 0); + + PG_FREE_IF_COPY(targ1, 0); + PG_FREE_IF_COPY(targ2, 1); + } PG_RETURN_BOOL(result); } @@ -1474,22 +1486,28 @@ texteq(PG_FUNCTION_ARGS) Datum textne(PG_FUNCTION_ARGS) { - text *arg1 = PG_GETARG_TEXT_PP(0); - text *arg2 = PG_GETARG_TEXT_PP(1); + Datum arg1 = PG_GETARG_DATUM(0); + Datum arg2 = PG_GETARG_DATUM(1); bool result; + Size len1, + len2; - /* - * Since we only care about equality or not-equality, we can avoid all the - * expense of strcoll() here, and just do bitwise comparison. - */ - if (VARSIZE_ANY_EXHDR(arg1) != VARSIZE_ANY_EXHDR(arg2)) + /* See comment in texteq() */ + len1 = toast_raw_datum_size(arg1); + len2 = toast_raw_datum_size(arg2); + if (len1 != len2) result = true; else - result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), - VARSIZE_ANY_EXHDR(arg1)) != 0); + { + text *targ1 = DatumGetTextPP(arg1); + text *targ2 = DatumGetTextPP(arg2); - PG_FREE_IF_COPY(arg1, 0); - PG_FREE_IF_COPY(arg2, 1); + result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2), + len1 - VARHDRSZ) != 0); + + PG_FREE_IF_COPY(targ1, 0); + PG_FREE_IF_COPY(targ2, 1); + } PG_RETURN_BOOL(result); } @@ -2358,23 +2376,31 @@ SplitIdentifierString(char *rawstring, char separator, Datum byteaeq(PG_FUNCTION_ARGS) { - bytea *arg1 = PG_GETARG_BYTEA_PP(0); - bytea *arg2 = PG_GETARG_BYTEA_PP(1); - int len1, - len2; + Datum arg1 = PG_GETARG_DATUM(0); + Datum arg2 = PG_GETARG_DATUM(1); bool result; + Size len1, + len2; - len1 = VARSIZE_ANY_EXHDR(arg1); - len2 = VARSIZE_ANY_EXHDR(arg2); - - /* fast path for different-length inputs */ + /* + * We can use a fast path for unequal lengths, which might save us from + * having to detoast one or both values. + */ + len1 = toast_raw_datum_size(arg1); + len2 = toast_raw_datum_size(arg2); if (len1 != len2) result = false; else - result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) == 0); + { + bytea *barg1 = DatumGetByteaPP(arg1); + bytea *barg2 = DatumGetByteaPP(arg2); - PG_FREE_IF_COPY(arg1, 0); - PG_FREE_IF_COPY(arg2, 1); + result = (memcmp(VARDATA_ANY(barg1), VARDATA_ANY(barg2), + len1 - VARHDRSZ) == 0); + + PG_FREE_IF_COPY(barg1, 0); + PG_FREE_IF_COPY(barg2, 1); + } PG_RETURN_BOOL(result); } @@ -2382,23 +2408,31 @@ byteaeq(PG_FUNCTION_ARGS) Datum byteane(PG_FUNCTION_ARGS) { - bytea *arg1 = PG_GETARG_BYTEA_PP(0); - bytea *arg2 = PG_GETARG_BYTEA_PP(1); - int len1, - len2; + Datum arg1 = PG_GETARG_DATUM(0); + Datum arg2 = PG_GETARG_DATUM(1); bool result; + Size len1, + len2; - len1 = VARSIZE_ANY_EXHDR(arg1); - len2 = VARSIZE_ANY_EXHDR(arg2); - - /* fast path for different-length inputs */ + /* + * We can use a fast path for unequal lengths, which might save us from + * having to detoast one or both values. + */ + len1 = toast_raw_datum_size(arg1); + len2 = toast_raw_datum_size(arg2); if (len1 != len2) result = true; else - result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) != 0); + { + bytea *barg1 = DatumGetByteaPP(arg1); + bytea *barg2 = DatumGetByteaPP(arg2); - PG_FREE_IF_COPY(arg1, 0); - PG_FREE_IF_COPY(arg2, 1); + result = (memcmp(VARDATA_ANY(barg1), VARDATA_ANY(barg2), + len1 - VARHDRSZ) != 0); + + PG_FREE_IF_COPY(barg1, 0); + PG_FREE_IF_COPY(barg2, 1); + } PG_RETURN_BOOL(result); }