sql: implement oidvectortypes builtin

docs/generated/sql/functions.md

@@ -3303,6 +3303,8 @@ may increase either contention or retry errors, or both.</p>
 </span></td><td>Stable</td></tr>
 <tr><td><a name="obj_description"></a><code>obj_description(object_oid: oid, catalog_name: <a href="string.html">string</a>) &rarr; <a href="string.html">string</a></code></td><td><span class="funcdesc"><p>Returns the comment for a database object specified by its OID and the name of the containing system catalog. For example, obj_description(123456, ‘pg_class’) would retrieve the comment for the table with OID 123456.</p>
 </span></td><td>Stable</td></tr>
+<tr><td><a name="oidvectortypes"></a><code>oidvectortypes(vector: oidvector) &rarr; <a href="string.html">string</a></code></td><td><span class="funcdesc"><p>Generates a comma seperated string of type names from an oidvector.</p>
+</span></td><td>Stable</td></tr>
 <tr><td><a name="pg_backend_pid"></a><code>pg_backend_pid() &rarr; <a href="int.html">int</a></code></td><td><span class="funcdesc"><p>Returns a numerical ID attached to this session. This ID is part of the query cancellation key used by the wire protocol. This function was only added for compatibility, and unlike in Postgres, the returned value does not correspond to a real process ID.</p>
 </span></td><td>Stable</td></tr>
 <tr><td><a name="pg_collation_for"></a><code>pg_collation_for(str: anyelement) &rarr; <a href="string.html">string</a></code></td><td><span class="funcdesc"><p>Returns the collation of the argument</p>

pkg/sql/logictest/testdata/logic_test/builtin_function

@@ -4197,3 +4197,19 @@ query T
 SELECT bitmask_xor(B'001'::VARBIT, '101'::STRING);
 ----
 100
+
+# Query `percentile_disc_impl(arg1: float, arg2: bool) -> bool` from pg_proc
+query T rowsort
+SELECT oidvectortypes(proargtypes) FROM pg_proc WHERE oid=263
+----
+float, bool
+
+# Query a custom type and function.
+statement ok
+CREATE TYPE custom_typ AS ENUM ('good', 'bad');
+CREATE OR REPLACE FUNCTION custom_fn(c custom_typ) RETURNS custom_typ AS 'SELECT c' LANGUAGE SQL;
+
+query T rowsort
+SELECT oidvectortypes(proargtypes) FROM pg_proc WHERE proname='custom_fn'
+----
+custom_typ

pkg/sql/sem/builtins/builtins.go

@@ -3993,6 +3993,41 @@ value if you rely on the HLC for accuracy.`,
 		},
 	),
 
+	"oidvectortypes": makeBuiltin(
+		tree.FunctionProperties{
+			Category: builtinconstants.CategoryCompatibility,
+		},
+		tree.Overload{
+			Types: tree.ParamTypes{
+				{Name: "vector", Typ: types.OidVector},
+			},
+			ReturnType: tree.FixedReturnType(types.String),
+			Fn: func(ctx context.Context, evalCtx *eval.Context, args tree.Datums) (tree.Datum, error) {
+				var err error
+				oidVector := args[0].(*tree.DArray)
+				result := strings.Builder{}
+				for idx, datum := range oidVector.Array {
+					oidDatum := datum.(*tree.DOid)
+					var typ *types.T
+					if resolvedTyp, ok := types.OidToType[oidDatum.Oid]; ok {
+						typ = resolvedTyp
+					} else {
+						typ, err = evalCtx.Planner.ResolveTypeByOID(ctx, oidDatum.Oid)
+						if err != nil {
+							return nil, err
+						}
+					}
+					result.WriteString(typ.Name())
+					if idx != len(oidVector.Array)-1 {
+						result.WriteString(", ")
+					}
+				}
+				return tree.NewDString(result.String()), nil
+			},
+			Info:       "Generates a comma seperated string of type names from an oidvector.",
+			Volatility: volatility.Stable,
+		}),
+
 	"crdb_internal.pb_to_json": makeBuiltin(
 		jsonProps(),
 		func() []tree.Overload {

pkg/sql/sem/builtins/fixed_oids.go

@@ -2452,6 +2452,7 @@ var builtinOidsArray = []string{
 	2481: `bitmask_xor(a: string, b: string) -> varbit`,
 	2482: `bitmask_xor(a: varbit, b: string) -> varbit`,
 	2483: `bitmask_xor(a: string, b: varbit) -> varbit`,
+	2484: `oidvectortypes(vector: oidvector) -> string`,
 }
 
 var builtinOidsBySignature map[string]oid.Oid