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selfuncs.c: use pg_strxfrm() instead of strxfrm().

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pg_strxfrm() takes a pg_locale_t, so it works properly with all
providers. This improves estimates for ICU when performing linear
interpolation within a histogram bin.

Previously, convert_string_datum() always used strxfrm() and relied on
setlocale(). That did not produce good estimates for non-default or
non-libc collations.

Discussion: https://postgr.es/m/89475ee5487d795124f4e25118ea8f1853edb8cb.camel@j-davis.com
This commit is contained in:
Jeff Davis 2024-08-06 11:55:21 -07:00
parent a54d4ed183
commit a890ad2149
2 changed files with 25 additions and 11 deletions
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23
src/backend/utils/adt/pg_locale.c
View File

@ -2124,14 +2124,7 @@ pg_strxfrm_libc(char *dest, const char *src, size_t destsize,
pg_locale_t locale)
{
Assert(locale->provider == COLLPROVIDER_LIBC);
#ifdef TRUST_STRXFRM
return strxfrm_l(dest, src, destsize, locale->info.lt);
#else
/* shouldn't happen */
PGLOCALE_SUPPORT_ERROR(locale->provider);
return 0; /* keep compiler quiet */
#endif
}
static size_t
@ -2340,6 +2333,10 @@ pg_strxfrm_enabled(pg_locale_t locale)
* The provided 'src' must be nul-terminated. If 'destsize' is zero, 'dest'
* may be NULL.
*
* Not all providers support pg_strxfrm() safely. The caller should check
* pg_strxfrm_enabled() first, otherwise this function may return wrong
* results or an error.
*
* Returns the number of bytes needed (or more) to store the transformed
* string, excluding the terminating nul byte. If the value returned is
* 'destsize' or greater, the resulting contents of 'dest' are undefined.
@ -2372,6 +2369,10 @@ pg_strxfrm(char *dest, const char *src, size_t destsize, pg_locale_t locale)
* 'src' does not need to be nul-terminated. If 'destsize' is zero, 'dest' may
* be NULL.
*
* Not all providers support pg_strnxfrm() safely. The caller should check
* pg_strxfrm_enabled() first, otherwise this function may return wrong
* results or an error.
*
* Returns the number of bytes needed (or more) to store the transformed
* string, excluding the terminating nul byte. If the value returned is
* 'destsize' or greater, the resulting contents of 'dest' are undefined.
@ -2426,6 +2427,10 @@ pg_strxfrm_prefix_enabled(pg_locale_t locale)
*
* The provided 'src' must be nul-terminated.
*
* Not all providers support pg_strxfrm_prefix() safely. The caller should
* check pg_strxfrm_prefix_enabled() first, otherwise this function may return
* wrong results or an error.
*
* If destsize is not large enough to hold the resulting byte sequence, stores
* only the first destsize bytes in 'dest'. Returns the number of bytes
* actually copied to 'dest'.
@ -2455,6 +2460,10 @@ pg_strxfrm_prefix(char *dest, const char *src, size_t destsize,
*
* The provided 'src' must be nul-terminated.
*
* Not all providers support pg_strnxfrm_prefix() safely. The caller should
* check pg_strxfrm_prefix_enabled() first, otherwise this function may return
* wrong results or an error.
*
* If destsize is not large enough to hold the resulting byte sequence, stores
* only the first destsize bytes in 'dest'. Returns the number of bytes
* actually copied to 'dest'.

13
src/backend/utils/adt/selfuncs.c
View File

@ -4639,7 +4639,7 @@ convert_one_string_to_scalar(char *value, int rangelo, int rangehi)
* On failure (e.g., unsupported typid), set *failure to true;
* otherwise, that variable is not changed. (We'll return NULL on failure.)
*
* When using a non-C locale, we must pass the string through strxfrm()
* When using a non-C locale, we must pass the string through pg_strxfrm()
* before continuing, so as to generate correct locale-specific results.
*/
static char *
@ -4673,20 +4673,25 @@ convert_string_datum(Datum value, Oid typid, Oid collid, bool *failure)
if (!lc_collate_is_c(collid))
{
pg_locale_t mylocale = pg_newlocale_from_collation(collid);
char *xfrmstr;
size_t xfrmlen;
size_t xfrmlen2 PG_USED_FOR_ASSERTS_ONLY;
/*
* XXX: We could guess at a suitable output buffer size and only call
* strxfrm twice if our guess is too small.
* pg_strxfrm() twice if our guess is too small.
*
* XXX: strxfrm doesn't support UTF-8 encoding on Win32, it can return
* bogus data or set an error. This is not really a problem unless it
* crashes since it will only give an estimation error and nothing
* fatal.
*
* XXX: we do not check pg_strxfrm_enabled(). On some platforms and in
* some cases, libc strxfrm() may return the wrong results, but that
* will only lead to an estimation error.
*/
xfrmlen = strxfrm(NULL, val, 0);
xfrmlen = pg_strxfrm(NULL, val, 0, mylocale);
#ifdef WIN32
/*
@ -4698,7 +4703,7 @@ convert_string_datum(Datum value, Oid typid, Oid collid, bool *failure)
return val;
#endif
xfrmstr = (char *) palloc(xfrmlen + 1);
xfrmlen2 = strxfrm(xfrmstr, val, xfrmlen + 1);
xfrmlen2 = pg_strxfrm(xfrmstr, val, xfrmlen + 1, mylocale);
/*
* Some systems (e.g., glibc) can return a smaller value from the