v11-0006-Use-multibyte-aware-extraction-of-pattern-prefix.patch
text/x-patch
Filename: v11-0006-Use-multibyte-aware-extraction-of-pattern-prefix.patch
Type: text/x-patch
Part: 5
From bf07696da676482d874602bd0f267b979dea5b82 Mon Sep 17 00:00:00 2001
From: Jeff Davis <jeff@j-davis.com>
Date: Wed, 26 Nov 2025 10:28:45 -0800
Subject: [PATCH v11 6/9] Use multibyte-aware extraction of pattern prefixes.
Previously, like_fixed_prefix() used char-at-a-time logic, which
forced it to be too conservative for case-insensitive matching.
Now, use pg_wchar-at-a-time loop for text types, along with proper
detection of cased characters; and preserve and char-at-a-time logic
for bytea.
Removes the pg_locale_t char_is_cased() single-byte method and
replaces it with a proper multibyte pg_iswcased() method.
Discussion: https://postgr.es/m/450ceb6260cad30d7afdf155d991a9caafee7c0d.camel@j-davis.com
---
src/backend/utils/adt/like.c | 9 +-
src/backend/utils/adt/like_support.c | 128 ++++++++++++----------
src/backend/utils/adt/pg_locale.c | 15 ---
src/backend/utils/adt/pg_locale_builtin.c | 8 --
src/backend/utils/adt/pg_locale_icu.c | 8 --
src/backend/utils/adt/pg_locale_libc.c | 14 ---
src/include/utils/pg_locale.h | 3 -
7 files changed, 76 insertions(+), 109 deletions(-)
diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c
index 4a7fc583c71..772879f0a81 100644
--- a/src/backend/utils/adt/like.c
+++ b/src/backend/utils/adt/like.c
@@ -118,7 +118,7 @@ wchareq(const char *p1, const char *p2)
#include "like_match.c"
-/* setup to compile like_match.c for single byte case insensitive matches */
+/* setup to compile like_match.c for case-insensitive matches in C locale */
#define MATCH_LOWER
#define NextChar(p, plen) NextByte((p), (plen))
#define MatchText C_IMatchText
@@ -190,8 +190,11 @@ Generic_Text_IC_like(text *str, text *pat, Oid collation)
errmsg("nondeterministic collations are not supported for ILIKE")));
/*
- * For efficiency reasons, in the C locale we don't call lower() on the
- * pattern and text, but instead call SB_lower_char on each character.
+ * For efficiency reasons, in the C locale lowercase each character
+ * lazily. Otherwise, we lowercase the entire pattern and text strings
+ * prior to matching.
+ *
+ * XXX: use casefolding instead?
*/
if (locale->ctype_is_c)
diff --git a/src/backend/utils/adt/like_support.c b/src/backend/utils/adt/like_support.c
index 999f23f86d5..2db06bd1728 100644
--- a/src/backend/utils/adt/like_support.c
+++ b/src/backend/utils/adt/like_support.c
@@ -99,8 +99,6 @@ static Selectivity like_selectivity(const char *patt, int pattlen,
static Selectivity regex_selectivity(const char *patt, int pattlen,
bool case_insensitive,
int fixed_prefix_len);
-static int pattern_char_isalpha(char c, bool is_multibyte,
- pg_locale_t locale);
static Const *make_greater_string(const Const *str_const, FmgrInfo *ltproc,
Oid collation);
static Datum string_to_datum(const char *str, Oid datatype);
@@ -989,13 +987,11 @@ static Pattern_Prefix_Status
like_fixed_prefix(Const *patt_const, bool case_insensitive, Oid collation,
Const **prefix_const, Selectivity *rest_selec)
{
- char *match;
char *patt;
int pattlen;
Oid typeid = patt_const->consttype;
- int pos,
- match_pos;
- bool is_multibyte = (pg_database_encoding_max_length() > 1);
+ int pos;
+ int match_pos = 0;
pg_locale_t locale = 0;
/* the right-hand const is type text or bytea */
@@ -1023,60 +1019,94 @@ like_fixed_prefix(Const *patt_const, bool case_insensitive, Oid collation,
locale = pg_newlocale_from_collation(collation);
}
+ /* for text types, use pg_wchar; for BYTEA, use char */
if (typeid != BYTEAOID)
{
- patt = TextDatumGetCString(patt_const->constvalue);
- pattlen = strlen(patt);
+ text *val = DatumGetTextPP(patt_const->constvalue);
+ pg_wchar *wpatt;
+ pg_wchar *wmatch;
+ char *match;
+ int match_mblen;
+
+ patt = VARDATA_ANY(val);
+ pattlen = VARSIZE_ANY_EXHDR(val);
+ wpatt = palloc((pattlen + 1) * sizeof(pg_wchar));
+ pg_mb2wchar_with_len(patt, wpatt, pattlen);
+
+ wmatch = palloc((pattlen + 1) * sizeof(pg_wchar));
+ for (pos = 0; pos < pattlen; pos++)
+ {
+ /* % and _ are wildcard characters in LIKE */
+ if (wpatt[pos] == '%' ||
+ wpatt[pos] == '_')
+ break;
+
+ /* Backslash escapes the next character */
+ if (wpatt[pos] == '\\')
+ {
+ pos++;
+ if (pos >= pattlen)
+ break;
+ }
+
+ /*
+ * For ILIKE, stop if it's a case-varying character (it's sort of
+ * a wildcard).
+ */
+ if (case_insensitive && pg_iswcased(wpatt[pos], locale))
+ break;
+
+ wmatch[match_pos++] = wpatt[pos];
+ }
+
+ wmatch[match_pos] = '\0';
+
+ match_mblen = pg_database_encoding_max_length() * match_pos + 1;
+ match = palloc(match_mblen);
+ pg_wchar2mb_with_len(wmatch, match, match_pos);
+
+ pfree(wpatt);
+ pfree(wmatch);
+
+ *prefix_const = string_to_const(match, typeid);
+ pfree(match);
}
else
{
bytea *bstr = DatumGetByteaPP(patt_const->constvalue);
+ char *match;
+ patt = VARDATA_ANY(bstr);
pattlen = VARSIZE_ANY_EXHDR(bstr);
- patt = (char *) palloc(pattlen);
- memcpy(patt, VARDATA_ANY(bstr), pattlen);
- Assert((Pointer) bstr == DatumGetPointer(patt_const->constvalue));
- }
-
- match = palloc(pattlen + 1);
- match_pos = 0;
- for (pos = 0; pos < pattlen; pos++)
- {
- /* % and _ are wildcard characters in LIKE */
- if (patt[pos] == '%' ||
- patt[pos] == '_')
- break;
- /* Backslash escapes the next character */
- if (patt[pos] == '\\')
+ match = palloc(pattlen + 1);
+ for (pos = 0; pos < pattlen; pos++)
{
- pos++;
- if (pos >= pattlen)
+ /* % and _ are wildcard characters in LIKE */
+ if (patt[pos] == '%' ||
+ patt[pos] == '_')
break;
- }
- /* Stop if case-varying character (it's sort of a wildcard) */
- if (case_insensitive &&
- pattern_char_isalpha(patt[pos], is_multibyte, locale))
- break;
-
- match[match_pos++] = patt[pos];
- }
+ /* Backslash escapes the next character */
+ if (patt[pos] == '\\')
+ {
+ pos++;
+ if (pos >= pattlen)
+ break;
+ }
- match[match_pos] = '\0';
+ match[match_pos++] = patt[pos];
+ }
- if (typeid != BYTEAOID)
- *prefix_const = string_to_const(match, typeid);
- else
*prefix_const = string_to_bytea_const(match, match_pos);
+ pfree(match);
+ }
+
if (rest_selec != NULL)
*rest_selec = like_selectivity(&patt[pos], pattlen - pos,
case_insensitive);
- pfree(patt);
- pfree(match);
-
/* in LIKE, an empty pattern is an exact match! */
if (pos == pattlen)
return Pattern_Prefix_Exact; /* reached end of pattern, so exact */
@@ -1481,24 +1511,6 @@ regex_selectivity(const char *patt, int pattlen, bool case_insensitive,
return sel;
}
-/*
- * Check whether char is a letter (and, hence, subject to case-folding)
- *
- * In multibyte character sets or with ICU, we can't use isalpha, and it does
- * not seem worth trying to convert to wchar_t to use iswalpha or u_isalpha.
- * Instead, just assume any non-ASCII char is potentially case-varying, and
- * hard-wire knowledge of which ASCII chars are letters.
- */
-static int
-pattern_char_isalpha(char c, bool is_multibyte,
- pg_locale_t locale)
-{
- if (locale->ctype_is_c)
- return (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z');
- else
- return char_is_cased(c, locale);
-}
-
/*
* For bytea, the increment function need only increment the current byte
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index e5e75ca2c2c..c4e89502f85 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1625,21 +1625,6 @@ pg_towlower(pg_wchar wc, pg_locale_t locale)
return locale->ctype->wc_tolower(wc, locale);
}
-/*
- * char_is_cased()
- *
- * Fuzzy test of whether the given char is case-varying or not. The argument
- * is a single byte, so in a multibyte encoding, just assume any non-ASCII
- * char is case-varying.
- */
-bool
-char_is_cased(char ch, pg_locale_t locale)
-{
- if (locale->ctype == NULL)
- return (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z');
- return locale->ctype->char_is_cased(ch, locale);
-}
-
/*
* Return required encoding ID for the given locale, or -1 if any encoding is
* valid for the locale.
diff --git a/src/backend/utils/adt/pg_locale_builtin.c b/src/backend/utils/adt/pg_locale_builtin.c
index 0d4c754a267..0c2920112bb 100644
--- a/src/backend/utils/adt/pg_locale_builtin.c
+++ b/src/backend/utils/adt/pg_locale_builtin.c
@@ -191,13 +191,6 @@ wc_iscased_builtin(pg_wchar wc, pg_locale_t locale)
return pg_u_prop_cased(to_char32(wc));
}
-static bool
-char_is_cased_builtin(char ch, pg_locale_t locale)
-{
- return IS_HIGHBIT_SET(ch) ||
- (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z');
-}
-
static pg_wchar
wc_toupper_builtin(pg_wchar wc, pg_locale_t locale)
{
@@ -225,7 +218,6 @@ static const struct ctype_methods ctype_methods_builtin = {
.wc_ispunct = wc_ispunct_builtin,
.wc_isspace = wc_isspace_builtin,
.wc_isxdigit = wc_isxdigit_builtin,
- .char_is_cased = char_is_cased_builtin,
.wc_iscased = wc_iscased_builtin,
.wc_tolower = wc_tolower_builtin,
.wc_toupper = wc_toupper_builtin,
diff --git a/src/backend/utils/adt/pg_locale_icu.c b/src/backend/utils/adt/pg_locale_icu.c
index e8820666b2d..18d026deda8 100644
--- a/src/backend/utils/adt/pg_locale_icu.c
+++ b/src/backend/utils/adt/pg_locale_icu.c
@@ -121,13 +121,6 @@ static int32_t u_strFoldCase_default(UChar *dest, int32_t destCapacity,
const char *locale,
UErrorCode *pErrorCode);
-static bool
-char_is_cased_icu(char ch, pg_locale_t locale)
-{
- return IS_HIGHBIT_SET(ch) ||
- (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z');
-}
-
/*
* XXX: many of the functions below rely on casts directly from pg_wchar to
* UChar32, which is correct for the UTF-8 encoding, but not in general.
@@ -244,7 +237,6 @@ static const struct ctype_methods ctype_methods_icu = {
.wc_ispunct = wc_ispunct_icu,
.wc_isspace = wc_isspace_icu,
.wc_isxdigit = wc_isxdigit_icu,
- .char_is_cased = char_is_cased_icu,
.wc_iscased = wc_iscased_icu,
.wc_toupper = toupper_icu,
.wc_tolower = tolower_icu,
diff --git a/src/backend/utils/adt/pg_locale_libc.c b/src/backend/utils/adt/pg_locale_libc.c
index cd54198f0c7..4cb3c64b4a6 100644
--- a/src/backend/utils/adt/pg_locale_libc.c
+++ b/src/backend/utils/adt/pg_locale_libc.c
@@ -262,17 +262,6 @@ wc_iscased_libc_mb(pg_wchar wc, pg_locale_t locale)
iswlower_l((wint_t) wc, locale->lt);
}
-static bool
-char_is_cased_libc(char ch, pg_locale_t locale)
-{
- bool is_multibyte = pg_database_encoding_max_length() > 1;
-
- if (is_multibyte && IS_HIGHBIT_SET(ch))
- return true;
- else
- return isalpha_l((unsigned char) ch, locale->lt);
-}
-
static pg_wchar
toupper_libc_sb(pg_wchar wc, pg_locale_t locale)
{
@@ -345,7 +334,6 @@ static const struct ctype_methods ctype_methods_libc_sb = {
.wc_ispunct = wc_ispunct_libc_sb,
.wc_isspace = wc_isspace_libc_sb,
.wc_isxdigit = wc_isxdigit_libc_sb,
- .char_is_cased = char_is_cased_libc,
.wc_iscased = wc_iscased_libc_sb,
.wc_toupper = toupper_libc_sb,
.wc_tolower = tolower_libc_sb,
@@ -371,7 +359,6 @@ static const struct ctype_methods ctype_methods_libc_other_mb = {
.wc_ispunct = wc_ispunct_libc_sb,
.wc_isspace = wc_isspace_libc_sb,
.wc_isxdigit = wc_isxdigit_libc_sb,
- .char_is_cased = char_is_cased_libc,
.wc_iscased = wc_iscased_libc_sb,
.wc_toupper = toupper_libc_sb,
.wc_tolower = tolower_libc_sb,
@@ -393,7 +380,6 @@ static const struct ctype_methods ctype_methods_libc_utf8 = {
.wc_ispunct = wc_ispunct_libc_mb,
.wc_isspace = wc_isspace_libc_mb,
.wc_isxdigit = wc_isxdigit_libc_mb,
- .char_is_cased = char_is_cased_libc,
.wc_iscased = wc_iscased_libc_mb,
.wc_toupper = toupper_libc_mb,
.wc_tolower = tolower_libc_mb,
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 832007385d8..01f891def7a 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -125,9 +125,6 @@ struct ctype_methods
bool (*wc_iscased) (pg_wchar wc, pg_locale_t locale);
pg_wchar (*wc_toupper) (pg_wchar wc, pg_locale_t locale);
pg_wchar (*wc_tolower) (pg_wchar wc, pg_locale_t locale);
-
- /* required */
- bool (*char_is_cased) (char ch, pg_locale_t locale);
};
/*
--
2.43.0