diff --git a/contrib/fuzzystrmatch/fuzzystrmatch.c b/contrib/fuzzystrmatch/fuzzystrmatch.c
index 92a2f1b92a67d191b0cf0624cb66a89d57ffd805..cbac1f2381fdd067e7b06d430bd3b392e4ebf832 100644
--- a/contrib/fuzzystrmatch/fuzzystrmatch.c
+++ b/contrib/fuzzystrmatch/fuzzystrmatch.c
@@ -171,12 +171,12 @@ levenshtein_with_costs(PG_FUNCTION_ARGS)
/* Extract a pointer to the actual character data */
s_data = VARDATA_ANY(src);
t_data = VARDATA_ANY(dst);
- /* Determine length of each string in bytes and characters */
+ /* Determine length of each string in bytes */
s_bytes = VARSIZE_ANY_EXHDR(src);
t_bytes = VARSIZE_ANY_EXHDR(dst);
- PG_RETURN_INT32(varstr_levenshtein(s_data, s_bytes, t_data, t_bytes, ins_c,
- del_c, sub_c));
+ PG_RETURN_INT32(varstr_levenshtein(s_data, s_bytes, t_data, t_bytes,
+ ins_c, del_c, sub_c, false));
}
@@ -194,12 +194,12 @@ levenshtein(PG_FUNCTION_ARGS)
/* Extract a pointer to the actual character data */
s_data = VARDATA_ANY(src);
t_data = VARDATA_ANY(dst);
- /* Determine length of each string in bytes and characters */
+ /* Determine length of each string in bytes */
s_bytes = VARSIZE_ANY_EXHDR(src);
t_bytes = VARSIZE_ANY_EXHDR(dst);
- PG_RETURN_INT32(varstr_levenshtein(s_data, s_bytes, t_data, t_bytes, 1, 1,
- 1));
+ PG_RETURN_INT32(varstr_levenshtein(s_data, s_bytes, t_data, t_bytes,
+ 1, 1, 1, false));
}
@@ -221,13 +221,14 @@ levenshtein_less_equal_with_costs(PG_FUNCTION_ARGS)
/* Extract a pointer to the actual character data */
s_data = VARDATA_ANY(src);
t_data = VARDATA_ANY(dst);
- /* Determine length of each string in bytes and characters */
+ /* Determine length of each string in bytes */
s_bytes = VARSIZE_ANY_EXHDR(src);
t_bytes = VARSIZE_ANY_EXHDR(dst);
- PG_RETURN_INT32(varstr_levenshtein_less_equal(s_data, s_bytes, t_data,
- t_bytes, ins_c, del_c,
- sub_c, max_d));
+ PG_RETURN_INT32(varstr_levenshtein_less_equal(s_data, s_bytes,
+ t_data, t_bytes,
+ ins_c, del_c, sub_c,
+ max_d, false));
}
@@ -246,12 +247,14 @@ levenshtein_less_equal(PG_FUNCTION_ARGS)
/* Extract a pointer to the actual character data */
s_data = VARDATA_ANY(src);
t_data = VARDATA_ANY(dst);
- /* Determine length of each string in bytes and characters */
+ /* Determine length of each string in bytes */
s_bytes = VARSIZE_ANY_EXHDR(src);
t_bytes = VARSIZE_ANY_EXHDR(dst);
- PG_RETURN_INT32(varstr_levenshtein_less_equal(s_data, s_bytes, t_data,
- t_bytes, 1, 1, 1, max_d));
+ PG_RETURN_INT32(varstr_levenshtein_less_equal(s_data, s_bytes,
+ t_data, t_bytes,
+ 1, 1, 1,
+ max_d, false));
}
diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c
index 632eb29312ebd649e69aedac145ed3efd5732fbf..81332b57d9311c2a04afe2200fe842f179850576 100644
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -550,7 +550,8 @@ updateFuzzyAttrMatchState(int fuzzy_rte_penalty,
varstr_levenshtein_less_equal(actual, strlen(actual), match, matchlen,
1, 1, 1,
fuzzystate->distance + 1
- - fuzzy_rte_penalty);
+ - fuzzy_rte_penalty,
+ true);
/*
* If more than half the characters are different, don't treat it as a
@@ -843,10 +844,12 @@ searchRangeTableForCol(ParseState *pstate, const char *alias, char *colname,
*/
if (alias != NULL)
fuzzy_rte_penalty =
- varstr_levenshtein(alias, strlen(alias),
- rte->eref->aliasname,
- strlen(rte->eref->aliasname),
- 1, 1, 1);
+ varstr_levenshtein_less_equal(alias, strlen(alias),
+ rte->eref->aliasname,
+ strlen(rte->eref->aliasname),
+ 1, 1, 1,
+ MAX_FUZZY_DISTANCE + 1,
+ true);
/*
* Scan for a matching column; if we find an exact match, we're
diff --git a/src/backend/utils/adt/levenshtein.c b/src/backend/utils/adt/levenshtein.c
index a499a20df9dd99a829c4583ea50c15f5a47c7691..f40557b847e3f0bb88c1e38dfd874788dff5e3db 100644
--- a/src/backend/utils/adt/levenshtein.c
+++ b/src/backend/utils/adt/levenshtein.c
@@ -26,9 +26,16 @@
#define MAX_LEVENSHTEIN_STRLEN 255
/*
- * Calculates Levenshtein distance metric between supplied csrings, which are
- * not necessarily null-terminated. Generally (1, 1, 1) penalty costs suffices
- * for common cases, but your mileage may vary.
+ * Calculates Levenshtein distance metric between supplied strings, which are
+ * not necessarily null-terminated.
+ *
+ * source: source string, of length slen bytes.
+ * target: target string, of length tlen bytes.
+ * ins_c, del_c, sub_c: costs to charge for character insertion, deletion,
+ * and substitution respectively; (1, 1, 1) costs suffice for common
+ * cases, but your mileage may vary.
+ * max_d: if provided and >= 0, maximum distance we care about; see below.
+ * trusted: caller is trusted and need not obey MAX_LEVENSHTEIN_STRLEN.
*
* One way to compute Levenshtein distance is to incrementally construct
* an (m+1)x(n+1) matrix where cell (i, j) represents the minimum number
@@ -43,7 +50,7 @@
* array.
*
* If max_d >= 0, we only need to provide an accurate answer when that answer
- * is less than or equal to the bound. From any cell in the matrix, there is
+ * is less than or equal to max_d. From any cell in the matrix, there is
* theoretical "minimum residual distance" from that cell to the last column
* of the final row. This minimum residual distance is zero when the
* untransformed portions of the strings are of equal length (because we might
@@ -58,12 +65,15 @@
*/
int
#ifdef LEVENSHTEIN_LESS_EQUAL
-varstr_levenshtein_less_equal(const char *source, int slen, const char *target,
- int tlen, int ins_c, int del_c, int sub_c,
- int max_d)
+varstr_levenshtein_less_equal(const char *source, int slen,
+ const char *target, int tlen,
+ int ins_c, int del_c, int sub_c,
+ int max_d, bool trusted)
#else
-varstr_levenshtein(const char *source, int slen, const char *target, int tlen,
- int ins_c, int del_c, int sub_c)
+varstr_levenshtein(const char *source, int slen,
+ const char *target, int tlen,
+ int ins_c, int del_c, int sub_c,
+ bool trusted)
#endif
{
int m,
@@ -95,15 +105,7 @@ varstr_levenshtein(const char *source, int slen, const char *target, int tlen,
#define STOP_COLUMN m
#endif
- /*
- * A common use for Levenshtein distance is to match attributes when
- * building diagnostic, user-visible messages. Restrict the size of
- * MAX_LEVENSHTEIN_STRLEN at compile time so that this is guaranteed to
- * work.
- */
- StaticAssertStmt(NAMEDATALEN <= MAX_LEVENSHTEIN_STRLEN,
- "Levenshtein hinting mechanism restricts NAMEDATALEN");
-
+ /* Convert string lengths (in bytes) to lengths in characters */
m = pg_mbstrlen_with_len(source, slen);
n = pg_mbstrlen_with_len(target, tlen);
@@ -118,14 +120,18 @@ varstr_levenshtein(const char *source, int slen, const char *target, int tlen,
/*
* For security concerns, restrict excessive CPU+RAM usage. (This
- * implementation uses O(m) memory and has O(mn) complexity.)
+ * implementation uses O(m) memory and has O(mn) complexity.) If
+ * "trusted" is true, caller is responsible for not making excessive
+ * requests, typically by using a small max_d along with strings that are
+ * bounded, though not necessarily to MAX_LEVENSHTEIN_STRLEN exactly.
*/
- if (m > MAX_LEVENSHTEIN_STRLEN ||
- n > MAX_LEVENSHTEIN_STRLEN)
+ if (!trusted &&
+ (m > MAX_LEVENSHTEIN_STRLEN ||
+ n > MAX_LEVENSHTEIN_STRLEN))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
- errmsg("argument exceeds the maximum length of %d bytes",
- MAX_LEVENSHTEIN_STRLEN)));
+ errmsg("levenshtein argument exceeds maximum length of %d characters",
+ MAX_LEVENSHTEIN_STRLEN)));
#ifdef LEVENSHTEIN_LESS_EQUAL
/* Initialize start and stop columns. */
diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index 477fde1f81dbbc601aedd46893fff57b2ac3968d..3c134a3aa9688cef8970d75a59ff6b2c09286ddf 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -810,11 +810,14 @@ extern Datum textoverlay_no_len(PG_FUNCTION_ARGS);
extern Datum name_text(PG_FUNCTION_ARGS);
extern Datum text_name(PG_FUNCTION_ARGS);
extern int varstr_cmp(char *arg1, int len1, char *arg2, int len2, Oid collid);
-extern int varstr_levenshtein(const char *source, int slen, const char *target,
- int tlen, int ins_c, int del_c, int sub_c);
+extern int varstr_levenshtein(const char *source, int slen,
+ const char *target, int tlen,
+ int ins_c, int del_c, int sub_c,
+ bool trusted);
extern int varstr_levenshtein_less_equal(const char *source, int slen,
- const char *target, int tlen, int ins_c,
- int del_c, int sub_c, int max_d);
+ const char *target, int tlen,
+ int ins_c, int del_c, int sub_c,
+ int max_d, bool trusted);
extern List *textToQualifiedNameList(text *textval);
extern bool SplitIdentifierString(char *rawstring, char separator,
List **namelist);