Hello, Could you let me go on with this topic?
It is hard to ignore this glitch for us using CJK - Chinese,
Japanese, and Korean - characters on databse.. Maybe..
Saying on Japanese under the standard usage, about a hundred
characters out of seven thousand make make_greater_string() fail.
This is not so frequent to happen but also not as rare as
ignorable.
I think this glitch is caused because the method to derive the
`next character' is fundamentally a secret of each encoding but
now it is done in make_greater_string() using the method extended
from that of 1 byte ASCII charset for all encodings together.
So, I think it is reasonable that encoding info table (struct
pg_wchar_tbl) holds the function to do that.
How about this idea?
Points to realize this follows,
- pg_wchar_tbl@pg_wchar.c has new element `charinc' that holds a
function to increment a character of this encoding.
- Basically, the value of charinc is a `generic' increment
function that does what make_greater_string() does in current
implement.
- make_greater_string() now uses charinc for database encoding to
increment characters instead of the code directly written in
it.
- Give UTF-8 a special increment function.
As a consequence of this modification, make_greater_string()
looks somewhat simple thanks to disappearing of the sequence that
handles bare bytes in string. And doing `increment character'
with the knowledge of the encoding can be straightforward and
light and backtrack-free, and have fewer glitches than the
generic method.
# But the process for BYTEAOID remains there dissapointingly.
There still remains some glitches but I think it is overdo to do
conversion that changes the length of the character. Only 5
points out of 17 thousands (in current method, roughly for all
BMP characters) remains, and none of them are not Japanese
character :-)
The attached patch is sample implement of this idea.
What do you think about this patch?
--
Kyotaro Horiguchi
NTT Open Source Software Center
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 10b73fb..4151ce2 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -5502,6 +5502,16 @@ pattern_selectivity(Const *patt, Pattern_Type ptype)
/*
+ * This function is "character increment" function for bytea used in
+ * make_greater_string() that has same interface with pg_wchar_tbl.charinc.
+ */
+static bool byte_increment(unsigned char *ptr, int len)
+{
+ (*ptr)--;
+ return true;
+}
+
+/*
* Try to generate a string greater than the given string or any
* string it is a prefix of. If successful, return a palloc'd string
* in the form of a Const node; else return NULL.
@@ -5540,6 +5550,7 @@ make_greater_string(const Const *str_const, FmgrInfo
*ltproc, Oid collation)
int len;
Datum cmpstr;
text *cmptxt = NULL;
+ character_incrementer charincfunc;
/*
* Get a modifiable copy of the prefix string in C-string format, and
set
@@ -5601,27 +5612,38 @@ make_greater_string(const Const *str_const, FmgrInfo
*ltproc, Oid collation)
}
}
+ if (datatype != BYTEAOID)
+ charincfunc = pg_database_encoding_character_incrementer();
+ else
+ charincfunc = &byte_increment;
+
while (len > 0)
{
- unsigned char *lastchar = (unsigned char *) (workstr + len - 1);
- unsigned char savelastchar = *lastchar;
+ int charlen;
+ unsigned char *lastchar;
+ unsigned char savelastbyte;
+ Const *workstr_const;
+
+ if (datatype == BYTEAOID)
+ charlen = 1;
+ else
+ charlen = len - pg_mbcliplen(workstr, len, len - 1);
+
+ lastchar = (unsigned char *) (workstr + len - charlen);
/*
- * Try to generate a larger string by incrementing the last
byte.
+ * savelastbyte has meaning only for datatype == BYTEAOID
*/
- while (*lastchar < (unsigned char) 255)
- {
- Const *workstr_const;
+ savelastbyte = *lastchar;
- (*lastchar)++;
+ /*
+ * Try to generate a larger string by incrementing the last
byte or
+ * character.
+ */
+ if (charincfunc(lastchar, charlen)) {
if (datatype != BYTEAOID)
- {
- /* do not generate invalid encoding sequences */
- if (!pg_verifymbstr(workstr, len, true))
- continue;
workstr_const = string_to_const(workstr,
datatype);
- }
else
workstr_const = string_to_bytea_const(workstr,
len);
@@ -5636,26 +5658,17 @@ make_greater_string(const Const *str_const, FmgrInfo
*ltproc, Oid collation)
pfree(workstr);
return workstr_const;
}
-
+
/* No good, release unusable value and try again */
pfree(DatumGetPointer(workstr_const->constvalue));
pfree(workstr_const);
}
- /* restore last byte so we don't confuse pg_mbcliplen */
- *lastchar = savelastchar;
-
/*
- * Truncate off the last character, which might be more than 1
byte,
- * depending on the character encoding.
+ * Truncate off the last character or restore last byte for
BYTEA.
*/
- if (datatype != BYTEAOID && pg_database_encoding_max_length() >
1)
- len = pg_mbcliplen(workstr, len, len - 1);
- else
- len -= 1;
-
- if (datatype != BYTEAOID)
- workstr[len] = '\0';
+ len -= charlen;
+ workstr[len] = (datatype != BYTEAOID ? '\0' : savelastbyte);
}
/* Failed... */
diff --git a/src/backend/utils/mb/wchar.c b/src/backend/utils/mb/wchar.c
index 5b0cf62..1d6aee0 100644
--- a/src/backend/utils/mb/wchar.c
+++ b/src/backend/utils/mb/wchar.c
@@ -935,6 +935,85 @@ pg_gb18030_dsplen(const unsigned char *s)
/*
*-------------------------------------------------------------------
+ * multibyte character incrementer
+ *
+ * These functions accept "charptr", a pointer to the first byte of a
+ * maybe-multibyte character. Try `increment' the character and return true if
+ * successed. If these functions returns false, the character is not modified.
+ * -------------------------------------------------------------------
+ */
+
+static bool pg_generic_charinc(unsigned char *charptr, int len)
+{
+ unsigned char *lastchar = (unsigned char *) (charptr + len - 1);
+ unsigned char savelastchar = *lastchar;
+ const char *const_charptr = (const char *)charptr;
+
+ while (*lastchar < (unsigned char) 255)
+ {
+ (*lastchar)++;
+ if (!pg_verifymbstr(const_charptr, len, true))
+ continue;
+ return true;
+ }
+
+ *lastchar = savelastchar;
+ return false;
+}
+
+static bool pg_utf8_increment(unsigned char *charptr, int length)
+{
+ unsigned char a;
+ unsigned char bak[4];
+
+ memcpy(bak, charptr, length);
+ switch (length)
+ {
+ default:
+ /* reject lengths 5 and 6 for now */
+ return false;
+ case 4:
+ a = charptr[3];
+ if (a < 0xBF)
+ {
+ charptr[3]++;
+ break;
+ }
+ charptr[3] = 0x80;
+ /* FALL THRU */
+ case 3:
+ a = charptr[2];
+ if (a < 0xBF)
+ {
+ charptr[2]++;
+ break;
+ }
+ charptr[2] = 0x80;
+ /* FALL THRU */
+ case 2:
+ a = charptr[1];
+ if ((*charptr == 0xed && a < 0x9F) || a < 0xBF)
+ {
+ charptr[1]++;
+ break;
+ }
+ charptr[1] = 0x80;
+ /* FALL THRU */
+ case 1:
+ a = *charptr;
+ if (a == 0x7F || a == 0xDF || a == 0xEF || a == 0xF7) {
+ memcpy(charptr, bak, length);
+ return false;
+ }
+ charptr[0]++;
+ break;
+ }
+
+ return pg_utf8_islegal(charptr, length);
+}
+
+/*
+ *-------------------------------------------------------------------
* multibyte sequence validators
*
* These functions accept "s", a pointer to the first byte of a string,
@@ -1341,48 +1420,48 @@ pg_utf8_islegal(const unsigned char *source, int length)
*-------------------------------------------------------------------
*/
pg_wchar_tbl pg_wchar_table[] = {
- {pg_ascii2wchar_with_len, pg_ascii_mblen, pg_ascii_dsplen,
pg_ascii_verifier, 1}, /* PG_SQL_ASCII */
- {pg_eucjp2wchar_with_len, pg_eucjp_mblen, pg_eucjp_dsplen,
pg_eucjp_verifier, 3}, /* PG_EUC_JP */
- {pg_euccn2wchar_with_len, pg_euccn_mblen, pg_euccn_dsplen,
pg_euccn_verifier, 2}, /* PG_EUC_CN */
- {pg_euckr2wchar_with_len, pg_euckr_mblen, pg_euckr_dsplen,
pg_euckr_verifier, 3}, /* PG_EUC_KR */
- {pg_euctw2wchar_with_len, pg_euctw_mblen, pg_euctw_dsplen,
pg_euctw_verifier, 4}, /* PG_EUC_TW */
- {pg_eucjp2wchar_with_len, pg_eucjp_mblen, pg_eucjp_dsplen,
pg_eucjp_verifier, 3}, /* PG_EUC_JIS_2004 */
- {pg_utf2wchar_with_len, pg_utf_mblen, pg_utf_dsplen, pg_utf8_verifier,
4}, /* PG_UTF8 */
- {pg_mule2wchar_with_len, pg_mule_mblen, pg_mule_dsplen,
pg_mule_verifier, 4}, /* PG_MULE_INTERNAL */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_LATIN1 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_LATIN2 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_LATIN3 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_LATIN4 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_LATIN5 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_LATIN6 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_LATIN7 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_LATIN8 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_LATIN9 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_LATIN10 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_WIN1256 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_WIN1258 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_WIN866 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_WIN874 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_KOI8R */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_WIN1251 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_WIN1252 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* ISO-8859-5 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* ISO-8859-6 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* ISO-8859-7 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* ISO-8859-8 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_WIN1250 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_WIN1253 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_WIN1254 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_WIN1255 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_WIN1257 */
- {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_latin1_verifier, 1}, /* PG_KOI8U */
- {0, pg_sjis_mblen, pg_sjis_dsplen, pg_sjis_verifier, 2}, /*
PG_SJIS */
- {0, pg_big5_mblen, pg_big5_dsplen, pg_big5_verifier, 2}, /*
PG_BIG5 */
- {0, pg_gbk_mblen, pg_gbk_dsplen, pg_gbk_verifier, 2}, /*
PG_GBK */
- {0, pg_uhc_mblen, pg_uhc_dsplen, pg_uhc_verifier, 2}, /*
PG_UHC */
- {0, pg_gb18030_mblen, pg_gb18030_dsplen, pg_gb18030_verifier, 4},
/* PG_GB18030 */
- {0, pg_johab_mblen, pg_johab_dsplen, pg_johab_verifier, 3}, /* PG_JOHAB
*/
- {0, pg_sjis_mblen, pg_sjis_dsplen, pg_sjis_verifier, 2} /*
PG_SHIFT_JIS_2004 */
+ {pg_ascii2wchar_with_len, pg_ascii_mblen, pg_ascii_dsplen,
pg_generic_charinc, pg_ascii_verifier, 1}, /* PG_SQL_ASCII */
+ {pg_eucjp2wchar_with_len, pg_eucjp_mblen, pg_eucjp_dsplen,
pg_generic_charinc, pg_eucjp_verifier, 3}, /* PG_EUC_JP */
+ {pg_euccn2wchar_with_len, pg_euccn_mblen, pg_euccn_dsplen,
pg_generic_charinc, pg_euccn_verifier, 2}, /* PG_EUC_CN */
+ {pg_euckr2wchar_with_len, pg_euckr_mblen, pg_euckr_dsplen,
pg_generic_charinc, pg_euckr_verifier, 3}, /* PG_EUC_KR */
+ {pg_euctw2wchar_with_len, pg_euctw_mblen, pg_euctw_dsplen,
pg_generic_charinc, pg_euctw_verifier, 4}, /* PG_EUC_TW */
+ {pg_eucjp2wchar_with_len, pg_eucjp_mblen, pg_eucjp_dsplen,
pg_generic_charinc, pg_eucjp_verifier, 3}, /* PG_EUC_JIS_2004 */
+ {pg_utf2wchar_with_len, pg_utf_mblen, pg_utf_dsplen, pg_utf8_increment,
pg_utf8_verifier, 4}, /* PG_UTF8 */
+ {pg_mule2wchar_with_len, pg_mule_mblen, pg_mule_dsplen,
pg_generic_charinc, pg_mule_verifier, 4}, /* PG_MULE_INTERNAL */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_LATIN1 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_LATIN2 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_LATIN3 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_LATIN4 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_LATIN5 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_LATIN6 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_LATIN7 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_LATIN8 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_LATIN9 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_LATIN10 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_WIN1256 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_WIN1258 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_WIN866 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_WIN874 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_KOI8R */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_WIN1251 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_WIN1252 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* ISO-8859-5 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* ISO-8859-6 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* ISO-8859-7 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* ISO-8859-8 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_WIN1250 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_WIN1253 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_WIN1254 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_WIN1255 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_WIN1257 */
+ {pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen,
pg_generic_charinc, pg_latin1_verifier, 1}, /* PG_KOI8U */
+ {0, pg_sjis_mblen, pg_sjis_dsplen, pg_generic_charinc,
pg_sjis_verifier, 2}, /* PG_SJIS */
+ {0, pg_big5_mblen, pg_big5_dsplen, pg_generic_charinc,
pg_big5_verifier, 2}, /* PG_BIG5 */
+ {0, pg_gbk_mblen, pg_gbk_dsplen, pg_generic_charinc, pg_gbk_verifier,
2}, /* PG_GBK */
+ {0, pg_uhc_mblen, pg_uhc_dsplen, pg_generic_charinc, pg_uhc_verifier,
2}, /* PG_UHC */
+ {0, pg_gb18030_mblen, pg_gb18030_dsplen, pg_generic_charinc,
pg_gb18030_verifier, 4}, /* PG_GB18030 */
+ {0, pg_johab_mblen, pg_johab_dsplen, pg_generic_charinc,
pg_johab_verifier, 3}, /* PG_JOHAB */
+ {0, pg_sjis_mblen, pg_sjis_dsplen, pg_generic_charinc,
pg_sjis_verifier, 2} /* PG_SHIFT_JIS_2004 */
};
/* returns the byte length of a word for mule internal code */
@@ -1459,6 +1538,15 @@ pg_database_encoding_max_length(void)
}
/*
+ * fetch maximum length of the encoding for the current database
+ */
+character_incrementer
+pg_database_encoding_character_incrementer(void)
+{
+ return pg_wchar_table[GetDatabaseEncoding()].charinc;
+}
+
+/*
* Verify mbstr to make sure that it is validly encoded in the current
* database encoding. Otherwise same as pg_verify_mbstr().
*/
diff --git a/src/include/mb/pg_wchar.h b/src/include/mb/pg_wchar.h
index 826c7af..356703a 100644
--- a/src/include/mb/pg_wchar.h
+++ b/src/include/mb/pg_wchar.h
@@ -284,6 +284,8 @@ typedef int (*mblen_converter) (const unsigned char *mbstr);
typedef int (*mbdisplaylen_converter) (const unsigned char *mbstr);
+typedef bool (*character_incrementer) (unsigned char *mbstr, int len);
+
typedef int (*mbverifier) (const unsigned char *mbstr, int len);
typedef struct
@@ -292,6 +294,7 @@ typedef struct
* string to a wchar */
mblen_converter mblen; /* get byte length of a char */
mbdisplaylen_converter dsplen; /* get display width of a char
*/
+ character_incrementer charinc; /* Character code incrementer if not
null */
mbverifier mbverify; /* verify multibyte sequence */
int maxmblen; /* max bytes for a char
in this encoding */
} pg_wchar_tbl;
@@ -389,6 +392,7 @@ extern int pg_encoding_mbcliplen(int encoding, const char
*mbstr,
extern int pg_mbcharcliplen(const char *mbstr, int len, int imit);
extern int pg_encoding_max_length(int encoding);
extern int pg_database_encoding_max_length(void);
+extern character_incrementer pg_database_encoding_character_incrementer(void);
extern int PrepareClientEncoding(int encoding);
extern int SetClientEncoding(int encoding);
--
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