Repair recently-introduced error in makeIndexable for LIKE:

a non-leading % would be put into the >=/<= patterns.  Also, repair
longstanding confusion about whether %% means a literal %%.  The SQL92
doesn't say any such thing, and textlike() knows that, but gram.y didn't.

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index c038f43caae9477680f0b01e19430aa21972f31d..bb36c6f0422bb1daa1893e957706d8e96930fc07 100644 (file)
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.83 1999/05/22 05:06:43 momjian Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.84 1999/06/07 14:28:25 tgl Exp $
  *
  * HISTORY
  *   AUTHOR            DATE            MAJOR EVENT
@@ -5357,6 +5357,7 @@ static Node *makeIndexable(char *opname, Node *lexpr, Node *rexpr)
            int pos, match_pos=0;
            bool found_special = false;
 
+           /* Cannot optimize if unquoted | { } is present in pattern */
            for (pos = 1; n->val.val.str[pos]; pos++)
            {
                if (n->val.val.str[pos] == '|' ||
@@ -5367,12 +5368,16 @@ static Node *makeIndexable(char *opname, Node *lexpr, Node *rexpr)
                    break;
                }
                if (n->val.val.str[pos] == '\\')
+               {
                    pos++;
+                   if (n->val.val.str[pos] == '\0')
+                       break;
+               }
            }
 
-           /* skip leading ^ */
            if (!found_special)
            {
+               /* note start at pos 1 to skip leading ^ */
                for (pos = 1; n->val.val.str[pos]; pos++)
                {
                    if (n->val.val.str[pos] == '.' ||
@@ -5383,9 +5388,11 @@ static Node *makeIndexable(char *opname, Node *lexpr, Node *rexpr)
                        (strcmp(opname,"~*") == 0 && isalpha(n->val.val.str[pos])))
                        break;
                    if (n->val.val.str[pos] == '\\')
+                   {
                        pos++;
-                   if (n->val.val.str[pos] == '\0')
-                       break;
+                       if (n->val.val.str[pos] == '\0')
+                           break;
+                   }
                    match_least[match_pos] = n->val.val.str[pos];
                    match_most[match_pos++] = n->val.val.str[pos];
                }
@@ -5430,16 +5437,22 @@ static Node *makeIndexable(char *opname, Node *lexpr, Node *rexpr)
    
            for (pos = 0; n->val.val.str[pos]; pos++)
            {
-               if (n->val.val.str[pos] == '%' &&
-                    n->val.val.str[pos+1] != '%')
-                   break;
-               if(n->val.val.str[pos] == '_')
+               /* % and _ are wildcard characters in LIKE */
+               if (n->val.val.str[pos] == '%' ||
+                   n->val.val.str[pos] == '_')
                    break;
-               if (n->val.val.str[pos] == '\\' ||
-                   n->val.val.str[pos+1] == '%')
+               /* Backslash quotes the next character */
+               if (n->val.val.str[pos] == '\\')
+               {
                    pos++;
-               if (n->val.val.str[pos] == '\0')
-                   break;
+                   if (n->val.val.str[pos] == '\0')
+                       break;
+               }
+               /*
+                * NOTE: this code used to think that %% meant a literal %,
+                * but textlike() itself does not think that, and the SQL92
+                * spec doesn't say any such thing either.
+                */
                match_least[match_pos] = n->val.val.str[pos];
                match_most[match_pos++] = n->val.val.str[pos];
            }

diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c
index 14fc5314d0c482132a25748eea2c377a8508e271..2d35bfabaca8acbe66be17660106b5406daa420f 100644 (file)
--- a/src/backend/utils/adt/like.c
+++ b/src/backend/utils/adt/like.c
@@ -111,7 +111,7 @@ textnlike(struct varlena * s, struct varlena * p)
 }
 
 
-/* $Revision: 1.24 $
+/* $Revision: 1.25 $
 ** "like.c" A first attempt at a LIKE operator for Postgres95.
 **
 ** Originally written by Rich $alz, mirror!rs, Wed Nov 26 19:03:17 EST 1986.
@@ -191,7 +191,9 @@ DoMatch(pg_wchar * text, pg_wchar * p)
    else
    {
        /* End of input string.  Do we have matching string remaining? */
-       if (p[0] == '\0' || (p[0] == '%' && p[1] == '\0'))
+       while (*p == '%')       /* allow multiple %'s at end of pattern */
+           p++;
+       if (*p == '\0')
            return LIKE_TRUE;
        else
            return LIKE_ABORT;