Avoid using text_to_cstring() in levenshtein functions.

Operating directly on the underlying varlena saves palloc and memcpy
overhead, which testing shows to be significant.

Extracted from a larger patch by Alexander Korotkov.

diff --git a/contrib/fuzzystrmatch/fuzzystrmatch.c b/contrib/fuzzystrmatch/fuzzystrmatch.c
index 0bf7c681a1873b0a6a1b9a0901a327051fc4dd0f..169081591888f67c08ebf242b8e4f6d9063d9229 100644 (file)
--- a/contrib/fuzzystrmatch/fuzzystrmatch.c
+++ b/contrib/fuzzystrmatch/fuzzystrmatch.c
@@ -5,7 +5,7 @@
  *
  * Joe Conway <mail@joeconway.com>
  *
- * $PostgreSQL: pgsql/contrib/fuzzystrmatch/fuzzystrmatch.c,v 1.32 2010/01/02 16:57:32 momjian Exp $
+ * $PostgreSQL: pgsql/contrib/fuzzystrmatch/fuzzystrmatch.c,v 1.33 2010/07/29 20:11:48 rhaas Exp $
  * Copyright (c) 2001-2010, PostgreSQL Global Development Group
  * ALL RIGHTS RESERVED;
  *
@@ -90,7 +90,7 @@ soundex_code(char letter)
  */
 #define MAX_LEVENSHTEIN_STRLEN         255
 
-static int levenshtein_internal(const char *s, const char *t,
+static int levenshtein_internal(text *s, text *t,
                                         int ins_c, int del_c, int sub_c);
 
 
@@ -191,7 +191,7 @@ getcode(char c)
  *                                               cases, but your mileage may vary.
  */
 static int
-levenshtein_internal(const char *s, const char *t,
+levenshtein_internal(text *s, text *t,
                                         int ins_c, int del_c, int sub_c)
 {
        int                     m,
@@ -203,8 +203,8 @@ levenshtein_internal(const char *s, const char *t,
        const char *x;
        const char *y;
 
-       m = strlen(s);
-       n = strlen(t);
+       m = VARSIZE_ANY_EXHDR(s);
+       n = VARSIZE_ANY_EXHDR(t);
 
        /*
         * We can transform an empty s into t with n insertions, or a non-empty t
@@ -244,7 +244,7 @@ levenshtein_internal(const char *s, const char *t,
                prev[i] = i * del_c;
 
        /* Loop through rows of the notional array */
-       for (y = t, j = 1; j < n; y++, j++)
+       for (y = VARDATA_ANY(t), j = 1; j < n; y++, j++)
        {
                int                *temp;
 
@@ -254,7 +254,7 @@ levenshtein_internal(const char *s, const char *t,
                 */
                curr[0] = j * ins_c;
 
-               for (x = s, i = 1; i < m; x++, i++)
+               for (x = VARDATA_ANY(s), i = 1; i < m; x++, i++)
                {
                        int                     ins;
                        int                     del;
@@ -288,8 +288,8 @@ PG_FUNCTION_INFO_V1(levenshtein_with_costs);
 Datum
 levenshtein_with_costs(PG_FUNCTION_ARGS)
 {
-       char       *src = TextDatumGetCString(PG_GETARG_DATUM(0));
-       char       *dst = TextDatumGetCString(PG_GETARG_DATUM(1));
+       text       *src = PG_GETARG_TEXT_PP(0);
+       text       *dst = PG_GETARG_TEXT_PP(1);
        int                     ins_c = PG_GETARG_INT32(2);
        int                     del_c = PG_GETARG_INT32(3);
        int                     sub_c = PG_GETARG_INT32(4);
@@ -302,8 +302,8 @@ PG_FUNCTION_INFO_V1(levenshtein);
 Datum
 levenshtein(PG_FUNCTION_ARGS)
 {
-       char       *src = TextDatumGetCString(PG_GETARG_DATUM(0));
-       char       *dst = TextDatumGetCString(PG_GETARG_DATUM(1));
+       text       *src = PG_GETARG_TEXT_PP(0);
+       text       *dst = PG_GETARG_TEXT_PP(1);
 
        PG_RETURN_INT32(levenshtein_internal(src, dst, 1, 1, 1));
 }