tree: distinguish UDFs and builtins that use a SQL string body

This refactor changes the meaning of the `Overload.IsUDF` field to
be true only for user-defined functions - meaning those created using
`CREATE FUNCTION`. This is contrasted with builtin functions that are
defined with a SQL string set in `Overload.Body`. Logic that cares only
about user-defined functions can continue checking `Overload.IsUDF`,
while cases that deal with the SQL body should use `Overload.HasSQLBody()`.
Note that it is insufficient to check whether `Overload.Body` is empty
because it is possible to define a UDF with an empty body.

Informs cockroachdb#95214

Release note: None

pkg/ccl/changefeedccl/cdceval/func_resolver.go

@@ -73,10 +73,9 @@ func (rs *cdcFunctionResolver) ResolveFunction(
 		return nil, err
 	}
 
-	// Since we may be dealing with UDFs, ensure it is something
-	// that's supported.
+	// Ensure that any overloads defined using a SQL string are supported.
 	for _, overload := range funcDef.Overloads {
-		if overload.IsUDF {
+		if overload.HasSQLBody() {
 			if err := checkOverloadSupported(fnName, overload.Overload); err != nil {
 				return nil, err
 			}

pkg/sql/drop_function.go

@@ -142,6 +142,8 @@ func (p *planner) matchUDF(
 		}
 		return nil, err
 	}
+	// Note that we don't check ol.HasSQLBody() here, because builtin functions
+	// can't be dropped even if they are defined using a SQL string.
 	if !ol.IsUDF {
 		return nil, errors.Errorf(
 			"cannot drop function %s%s because it is required by the database system",

pkg/sql/opt/optbuilder/scalar.go

@@ -548,7 +548,7 @@ func (b *Builder) buildFunction(
 	}
 
 	overload := f.ResolvedOverload()
-	if overload.IsUDF {
+	if overload.HasSQLBody() {
 		return b.buildUDF(f, def, inScope, outScope, outCol, colRefs)
 	}
 

pkg/sql/schemachanger/scbuild/builder_state.go

@@ -1094,6 +1094,8 @@ func (b *builderState) ResolveUDF(
 		panic(err)
 	}
 
+	// ResolveUDF is not concerned with builtin functions that are defined using
+	// a SQL string, so we don't check ol.HasSQLBody() here.
 	if !ol.IsUDF {
 		panic(
 			errors.Errorf(

pkg/sql/sem/builtins/builtins.go

@@ -4940,7 +4940,6 @@ value if you rely on the HLC for accuracy.`,
 				{Name: "id", Typ: types.Int},
 			},
 			ReturnType: tree.FixedReturnType(types.Int),
-			IsUDF:      true,
 			Body: `SELECT crdb_internal.create_tenant(json_build_object('id', $1, 'service_mode',
  'external'))`,
 			Info:       `create_tenant(id) is an alias for create_tenant('{"id": id, "service_mode": "external"}'::jsonb)`,
@@ -4953,7 +4952,6 @@ value if you rely on the HLC for accuracy.`,
 				{Name: "name", Typ: types.String},
 			},
 			ReturnType: tree.FixedReturnType(types.Int),
-			IsUDF:      true,
 			Body:       `SELECT crdb_internal.create_tenant(json_build_object('id', $1, 'name', $2))`,
 			Info:       `create_tenant(id, name) is an alias for create_tenant('{"id": id, "name": name}'::jsonb)`,
 			Volatility: volatility.Volatile,
@@ -4964,7 +4962,6 @@ value if you rely on the HLC for accuracy.`,
 				{Name: "name", Typ: types.String},
 			},
 			ReturnType: tree.FixedReturnType(types.Int),
-			IsUDF:      true,
 			Body:       `SELECT crdb_internal.create_tenant(json_build_object('name', $1))`,
 			Info: `create_tenant(name) is an alias for create_tenant('{"name": name}'::jsonb).
 DO NOT USE -- USE 'CREATE TENANT' INSTEAD`,
@@ -5017,7 +5014,6 @@ DO NOT USE -- USE 'CREATE TENANT' INSTEAD`,
 				{Name: "id", Typ: types.Int},
 			},
 			ReturnType: tree.FixedReturnType(types.Int),
-			IsUDF:      true,
 			Body:       `SELECT crdb_internal.destroy_tenant($1, false)`,
 			Info:       "DO NOT USE -- USE 'DROP TENANT' INSTEAD.",
 			Volatility: volatility.Volatile,
@@ -6361,7 +6357,6 @@ DO NOT USE -- USE 'CREATE TENANT' INSTEAD`,
 				{Name: "number", Typ: types.Int},
 			},
 			ReturnType: tree.FixedReturnType(types.Jsonb),
-			IsUDF:      true,
 			Body: `SELECT crdb_internal.generate_test_objects(
 json_build_object('names', $1, 'counts', array[$2]))`,
 			Info: `Generates a number of objects whose name follow the provided pattern.
@@ -6377,7 +6372,6 @@ generate_test_objects('{"names":pat, "counts":[num]}'::jsonb)
 				{Name: "counts", Typ: types.IntArray},
 			},
 			ReturnType: tree.FixedReturnType(types.Jsonb),
-			IsUDF:      true,
 			Body: `SELECT crdb_internal.generate_test_objects(
 json_build_object('names', $1, 'counts', $2))`,
 			Info: `Generates a number of objects whose name follow the provided pattern.

pkg/sql/sem/builtins/pg_builtins.go

@@ -209,7 +209,6 @@ func makePGGetViewDef(paramTypes tree.ParamTypes) tree.Overload {
 	return tree.Overload{
 		Types:      paramTypes,
 		ReturnType: tree.FixedReturnType(types.String),
-		IsUDF:      true,
 		Body: `SELECT definition
 		FROM pg_catalog.pg_views v
 		JOIN pg_catalog.pg_class c ON c.relname=v.viewname
@@ -229,7 +228,6 @@ func makePGGetConstraintDef(paramTypes tree.ParamTypes) tree.Overload {
 	return tree.Overload{
 		Types:      paramTypes,
 		ReturnType: tree.FixedReturnType(types.String),
-		IsUDF:      true,
 		Body:       `SELECT condef FROM pg_catalog.pg_constraint WHERE oid=$1 LIMIT 1`,
 		Info:       notUsableInfo,
 		Volatility: volatility.Stable,
@@ -597,7 +595,6 @@ var pgBuiltins = map[string]builtinDefinition{
 		tree.Overload{
 			Types:      tree.ParamTypes{{Name: "func_oid", Typ: types.Oid}},
 			ReturnType: tree.FixedReturnType(types.String),
-			IsUDF:      true,
 			Body: fmt.Sprintf(
 				`SELECT COALESCE(create_statement, prosrc)
              FROM pg_catalog.pg_proc
@@ -618,7 +615,6 @@ var pgBuiltins = map[string]builtinDefinition{
 		tree.Overload{
 			Types:      tree.ParamTypes{{Name: "func_oid", Typ: types.Oid}},
 			ReturnType: tree.FixedReturnType(types.String),
-			IsUDF:      true,
 			Body:       getFunctionArgStringQuery,
 			Info: "Returns the argument list (with defaults) necessary to identify a function, " +
 				"in the form it would need to appear in within CREATE FUNCTION.",
@@ -636,7 +632,6 @@ var pgBuiltins = map[string]builtinDefinition{
 		tree.Overload{
 			Types:      tree.ParamTypes{{Name: "func_oid", Typ: types.Oid}},
 			ReturnType: tree.FixedReturnType(types.String),
-			IsUDF:      true,
 			Body: `SELECT t.typname
              FROM pg_catalog.pg_proc p
              JOIN pg_catalog.pg_type t
@@ -657,7 +652,6 @@ var pgBuiltins = map[string]builtinDefinition{
 		tree.Overload{
 			Types:      tree.ParamTypes{{Name: "func_oid", Typ: types.Oid}},
 			ReturnType: tree.FixedReturnType(types.String),
-			IsUDF:      true,
 			Body:       getFunctionArgStringQuery,
 			Info: "Returns the argument list (without defaults) necessary to identify a function, " +
 				"in the form it would need to appear in within ALTER FUNCTION, for instance.",
@@ -671,7 +665,6 @@ var pgBuiltins = map[string]builtinDefinition{
 	"pg_get_indexdef": makeBuiltin(
 		tree.FunctionProperties{Category: builtinconstants.CategorySystemInfo, DistsqlBlocklist: true},
 		tree.Overload{
-			IsUDF:             true,
 			Types:             tree.ParamTypes{{Name: "index_oid", Typ: types.Oid}},
 			ReturnType:        tree.FixedReturnType(types.String),
 			Body:              `SELECT indexdef FROM pg_catalog.pg_indexes WHERE crdb_oid = $1`,
@@ -680,7 +673,6 @@ var pgBuiltins = map[string]builtinDefinition{
 			CalledOnNullInput: true,
 		},
 		tree.Overload{
-			IsUDF:      true,
 			Types:      tree.ParamTypes{{Name: "index_oid", Typ: types.Oid}, {Name: "column_no", Typ: types.Int}, {Name: "pretty_bool", Typ: types.Bool}},
 			ReturnType: tree.FixedReturnType(types.String),
 			Body: `SELECT CASE
@@ -852,7 +844,6 @@ var pgBuiltins = map[string]builtinDefinition{
 				{Name: "role_oid", Typ: types.Oid},
 			},
 			ReturnType:        tree.FixedReturnType(types.String),
-			IsUDF:             true,
 			Body:              `SELECT COALESCE((SELECT rolname FROM pg_catalog.pg_roles WHERE oid=$1 LIMIT 1), 'unknown (OID=' || $1 || ')')`,
 			Info:              notUsableInfo,
 			Volatility:        volatility.Stable,
@@ -872,7 +863,6 @@ var pgBuiltins = map[string]builtinDefinition{
 				[]*types.T{types.Int, types.Int, types.Int, types.Int, types.Bool, types.Int, types.Oid},
 				[]string{"start_value", "minimum_value", "maxmimum_value", "increment", "cycle_option", "cache_size", "data_type"},
 			)),
-			IsUDF: true,
 			Body: `SELECT COALESCE ((SELECT (seqstart, seqmin, seqmax, seqincrement, seqcycle, seqcache, seqtypid)
              FROM pg_catalog.pg_sequence WHERE seqrelid=$1 LIMIT 1),
              CASE WHEN crdb_internal.force_error('42P01', 'relation with OID ' || $1 || ' does not exist') > 0 THEN NULL ELSE NULL END)`,
@@ -931,7 +921,6 @@ var pgBuiltins = map[string]builtinDefinition{
 
 	"col_description": makeBuiltin(defProps(),
 		tree.Overload{
-			IsUDF:      true,
 			Types:      tree.ParamTypes{{Name: "table_oid", Typ: types.Oid}, {Name: "column_number", Typ: types.Int}},
 			ReturnType: tree.FixedReturnType(types.String),
 			// Note: the following is equivalent to:
@@ -962,7 +951,6 @@ var pgBuiltins = map[string]builtinDefinition{
 
 	"obj_description": makeBuiltin(defProps(),
 		tree.Overload{
-			IsUDF:      true,
 			Types:      tree.ParamTypes{{Name: "object_oid", Typ: types.Oid}},
 			ReturnType: tree.FixedReturnType(types.String),
 			Body: `SELECT description
@@ -977,7 +965,6 @@ var pgBuiltins = map[string]builtinDefinition{
 			CalledOnNullInput: true,
 		},
 		tree.Overload{
-			IsUDF:      true,
 			Types:      tree.ParamTypes{{Name: "object_oid", Typ: types.Oid}, {Name: "catalog_name", Typ: types.String}},
 			ReturnType: tree.FixedReturnType(types.String),
 			Body: `SELECT d.description
@@ -1012,7 +999,6 @@ var pgBuiltins = map[string]builtinDefinition{
 
 	"shobj_description": makeBuiltin(defProps(),
 		tree.Overload{
-			IsUDF:      true,
 			Types:      tree.ParamTypes{{Name: "object_oid", Typ: types.Oid}, {Name: "catalog_name", Typ: types.String}},
 			ReturnType: tree.FixedReturnType(types.String),
 			Body: `SELECT d.description
@@ -1075,7 +1061,6 @@ var pgBuiltins = map[string]builtinDefinition{
 	// https://www.postgresql.org/docs/9.6/static/functions-info.html
 	"pg_function_is_visible": makeBuiltin(defProps(),
 		tree.Overload{
-			IsUDF:      true,
 			Types:      tree.ParamTypes{{Name: "oid", Typ: types.Oid}},
 			ReturnType: tree.FixedReturnType(types.Bool),
 			Body: `SELECT n.nspname = any current_schemas(true)
@@ -1093,7 +1078,6 @@ var pgBuiltins = map[string]builtinDefinition{
 	// https://www.postgresql.org/docs/9.6/static/functions-info.html
 	"pg_table_is_visible": makeBuiltin(defProps(),
 		tree.Overload{
-			IsUDF:      true,
 			Types:      tree.ParamTypes{{Name: "oid", Typ: types.Oid}},
 			ReturnType: tree.FixedReturnType(types.Bool),
 			Body: `SELECT n.nspname = any current_schemas(true)
@@ -1115,7 +1099,6 @@ var pgBuiltins = map[string]builtinDefinition{
 	// https://www.postgresql.org/docs/9.6/static/functions-info.html
 	"pg_type_is_visible": makeBuiltin(defProps(),
 		tree.Overload{
-			IsUDF:      true,
 			Types:      tree.ParamTypes{{Name: "oid", Typ: types.Oid}},
 			ReturnType: tree.FixedReturnType(types.Bool),
 			Body: `SELECT n.nspname = any current_schemas(true)
@@ -1912,7 +1895,6 @@ var pgBuiltins = map[string]builtinDefinition{
 	// https://github.com/postgres/postgres/blob/master/src/backend/catalog/information_schema.sql
 	"information_schema._pg_index_position": makeBuiltin(defProps(),
 		tree.Overload{
-			IsUDF: true,
 			Types: tree.ParamTypes{
 				{Name: "oid", Typ: types.Oid},
 				{Name: "col", Typ: types.Int2},

pkg/sql/sem/tree/overload.go

@@ -208,15 +208,16 @@ type Overload struct {
 	// FunctionProperties are the properties of this overload.
 	FunctionProperties
 
-	// IsUDF is set to true when this is a user-defined function overload.
-	// Note: Body can be empty string even IsUDF is true.
+	// IsUDF is set to true when this is a user-defined function overload built
+	// using CREATE FUNCTION. Note: Body can be empty even if IsUDF is true.
 	IsUDF bool
+	// Body is the SQL string body of a function. It can be set even if IsUDF is
+	// false if a builtin function is defined using a SQL string.
+	Body string
 	// UDFContainsOnlySignature is only set to true for Overload signatures cached
 	// in a Schema descriptor, which means that the full UDF descriptor need to be
 	// fetched to get more info, e.g. function Body.
 	UDFContainsOnlySignature bool
-	// Body is the SQL string body of a user-defined function.
-	Body string
 	// ReturnSet is set to true when a user-defined function is defined to return
 	// a set of values.
 	ReturnSet bool
@@ -270,6 +271,12 @@ func (b Overload) IsGenerator() bool {
 	return b.Generator != nil || b.GeneratorWithExprs != nil
 }
 
+// HasSQLBody returns true if the function was defined using a SQL string body.
+// This is the case for user-defined functions and some builtins.
+func (b Overload) HasSQLBody() bool {
+	return b.IsUDF || b.Body != ""
+}
+
 // Signature returns a human-readable signature.
 // If simplify is bool, tuple-returning functions with just
 // 1 tuple element unwrap the return type in the signature.

pkg/sql/sem/tree/type_check.go

@@ -3123,6 +3123,9 @@ func getMostSignificantOverload(
 	for _, idx := range filter {
 		o := qualifiedOverloads[idx]
 		if o.IsUDF {
+			// This check is only concerned with user-defined functions, not with
+			// builtin functions defined with a SQL string body. For this reason we
+			// check o.IsUDF instead of o.HasSQLBody().
 			udfFound = true
 		}
 		if seenSchema != "" && o.Schema != seenSchema {

pkg/sql/sem/tree/udf.go

@@ -516,7 +516,7 @@ type UDFDisallowanceVisitor struct {
 
 // VisitPre implements the Visitor interface.
 func (v *UDFDisallowanceVisitor) VisitPre(expr Expr) (recurse bool, newExpr Expr) {
-	if funcExpr, ok := expr.(*FuncExpr); ok && funcExpr.ResolvedOverload().IsUDF {
+	if funcExpr, ok := expr.(*FuncExpr); ok && funcExpr.ResolvedOverload().HasSQLBody() {
 		v.FoundUDF = true
 		return false, expr
 	}