builtins: add metaphone() sql built-in

docs/generated/sql/functions.md

@@ -986,6 +986,8 @@ available replica will error.</p>
 </span></td><td>Immutable</td></tr>
 <tr><td><a name="levenshtein"></a><code>levenshtein(source: <a href="string.html">string</a>, target: <a href="string.html">string</a>, ins_cost: <a href="int.html">int</a>, del_cost: <a href="int.html">int</a>, sub_cost: <a href="int.html">int</a>) &rarr; <a href="int.html">int</a></code></td><td><span class="funcdesc"><p>Calculates the Levenshtein distance between two strings. The cost parameters specify how much to charge for each edit operation. Maximum input length is 255 characters.</p>
 </span></td><td>Immutable</td></tr>
+<tr><td><a name="metaphone"></a><code>metaphone(source: <a href="string.html">string</a>) &rarr; <a href="string.html">string</a></code></td><td><span class="funcdesc"><p>Compute ‘sound-like’ string from the input string.</p>
+</span></td><td>Immutable</td></tr>
 <tr><td><a name="soundex"></a><code>soundex(source: <a href="string.html">string</a>) &rarr; <a href="string.html">string</a></code></td><td><span class="funcdesc"><p>Convert a string to its Soundex code.</p>
 </span></td><td>Immutable</td></tr></tbody>
 </table>

pkg/sql/sem/builtins/builtins.go

@@ -3915,10 +3915,30 @@ value if you rely on the HLC for accuracy.`,
 			Info: "Calculates the Levenshtein distance between two strings. The cost parameters specify how much to " +
 				"charge for each edit operation. Maximum input length is 255 characters.",
 			Volatility: volatility.Immutable,
-		}),
+		},
+	),
 	"levenshtein_less_equal": makeBuiltin(tree.FunctionProperties{UnsupportedWithIssue: 56820, Category: builtinconstants.CategoryFuzzyStringMatching}),
-	"metaphone":              makeBuiltin(tree.FunctionProperties{UnsupportedWithIssue: 56820, Category: builtinconstants.CategoryFuzzyStringMatching}),
-	"dmetaphone_alt":         makeBuiltin(tree.FunctionProperties{UnsupportedWithIssue: 56820, Category: builtinconstants.CategoryFuzzyStringMatching}),
+	"metaphone":              makeBuiltin(
+		tree.FunctionProperties{Category: builtinconstants.CategoryFuzzyStringMatching},
+		tree.Overload{
+			Types:      tree.ParamTypes{{Name: "source", Typ: types.String}},
+			ReturnType: tree.FixedReturnType(types.String),
+			Fn: func(_ context.Context, _ *eval.Context, args tree.Datums) (tree.Datum, error) {
+				const maxLen = 255
+				s := string(tree.MustBeDString(args[0]))
+				if (len(s) > maxLen) {
+					return nil, pgerror.Newf(pgcode.InvalidParameterValue,
+						"metaphone argument exceeds maximum length of %d characters", maxLen)
+				}
+				m := fuzzystrmatch.Metaphone(s)
+				return tree.NewDString(m), nil
+			},
+			Info: 		"Compute 'sound-like' string from the input string.",
+			Volatility: volatility.Immutable,
+		},
+	),
+	"dmetaphone":			makeBuiltin(tree.FunctionProperties{UnsupportedWithIssue: 56820, Category: builtinconstants.CategoryFuzzyStringMatching}),
+	"dmetaphone_alt":		makeBuiltin(tree.FunctionProperties{UnsupportedWithIssue: 56820, Category: builtinconstants.CategoryFuzzyStringMatching}),
 
 	// JSON functions.
 	// The behavior of both the JSON and JSONB data types in CockroachDB is

pkg/sql/sem/builtins/fixed_oids.go

@@ -2463,6 +2463,7 @@ var builtinOidsArray = []string{
 	2492: `make_timestamptz(year: int, month: int, day: int, hour: int, min: int, sec: float, timezone: string) -> timestamptz`,
 	2493: `date_trunc(element: string, input: timestamptz, timezone: string) -> timestamptz`,
 	2494: `make_date(year: int, month: int, day: int) -> date`,
+	2495: `metaphone(source: string) -> string`,
 }
 
 var builtinOidsBySignature map[string]oid.Oid

pkg/util/fuzzystrmatch/BUILD.bazel

@@ -4,6 +4,7 @@ go_library(
     name = "fuzzystrmatch",
     srcs = [
         "leven.go",
+        "metaphone.go",
         "soundex.go",
     ],
     importpath = "github.com/cockroachdb/cockroach/pkg/util/fuzzystrmatch",
@@ -15,6 +16,7 @@ go_test(
     size = "small",
     srcs = [
         "leven_test.go",
+        "metaphone_test.go",
         "soundex_test.go",
     ],
     args = ["-test.timeout=55s"],