expression：PostgreSQL system function support

expression/builtin.go

@@ -921,7 +921,10 @@ var funcs = map[string]functionClass{
 	ast.PgFuncIsWalReplayPaused:    &pgIsWalReplayPausedFunctionClass{baseFunctionClass{ast.PgFuncIsWalReplayPaused, 0, 0}},
 	ast.PgFuncGetUserById:          &pgGetUserByIDFunctionClass{baseFunctionClass{ast.PgFuncGetUserById, 1, 1}},
 	ast.PgFuncShobjDescription:     &pgShobjDescriptionFunctionClass{baseFunctionClass{ast.PgFuncShobjDescription, 2, 2}},
-	ast.PgFuncObjDescription:       &pgObjDescriptionFunctionClass{baseFunctionClass{ast.PgFuncObjDescription, 1, 1}},
+	ast.PgFuncObjDescription:       &pgObjDescriptionFunctionClass{baseFunctionClass{ast.PgFuncObjDescription, 2, 2}},
+	ast.PgFuncCurrentSchema:        &pgCurrentSchemaFunctionClass{baseFunctionClass{ast.PgFuncCurrentSchema, 0, 0}},
+	ast.PgFuncCurrentSchemas:       &pgCurrentSchemasFunctionClass{baseFunctionClass{ast.PgFuncCurrentSchemas, 1, 1}},
+	ast.PgFuncArrayPosition:        &pgArrayPositionFunctionClass{baseFunctionClass{ast.PgFuncArrayPosition, 2, 2}},
 }
 
 // IsFunctionSupported check if given function name is a builtin sql function.

expression/builtin_pg_func.go

@@ -18,11 +18,24 @@ import (
 	"github.com/pingcap/tidb/sessionctx"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/chunk"
+	"strings"
 )
 
 var (
 	_ functionClass = &currentDatabaseFunctionClass{}
 	_ functionClass = &pgSettingsDatabaseFunctionClass{}
+	_ functionClass = &pgEncodingToCharFunctionClass{}
+	_ functionClass = &pgHasDatabasePrivilegeFunctionClass{}
+	_ functionClass = &pgHasTablePrivilegeFunctionClass{}
+	_ functionClass = &pgHasSchemaPrivilegeFunctionClass{}
+	_ functionClass = &pgIsInRecoveryFunctionClass{}
+	_ functionClass = &pgIsWalReplayPausedFunctionClass{}
+	_ functionClass = &pgGetUserByIDFunctionClass{}
+	_ functionClass = &pgShobjDescriptionFunctionClass{}
+	_ functionClass = &pgObjDescriptionFunctionClass{}
+	_ functionClass = &pgCurrentSchemaFunctionClass{}
+	_ functionClass = &pgCurrentSchemasFunctionClass{}
+	_ functionClass = &pgArrayPositionFunctionClass{}
 )
 
 type currentDatabaseFunctionClass struct {
@@ -183,14 +196,14 @@ func (p *pgHasDatabasePrivilegeFunctionClass) getFunction(ctx sessionctx.Context
 	if err := p.verifyArgs(args); err != nil {
 		return nil, err
 	}
-	argTps := make([]types.EvalType, 0, 3)
-	argTps = append(argTps, types.ETInt, types.ETString)
+	argsTps := make([]types.EvalType, 0, 3)
+	argsTps = append(argsTps, types.ETString, types.ETString)
 	if len(args) > 2 {
-		idArgTp := make([]types.EvalType, 0, 1)
-		idArgTp = append(idArgTp, types.ETInt)
-		argTps = append(idArgTp, argTps...)
+		userArgTp := make([]types.EvalType, 0, 1)
+		userArgTp = append(userArgTp, types.ETString)
+		argsTps = append(userArgTp, argsTps...)
 	}
-	bf, err := newBaseBuiltinFuncWithTp(ctx, p.funcName, args, types.ETString, argTps...)
+	bf, err := newBaseBuiltinFuncWithTp(ctx, p.funcName, args, types.ETString, argsTps...)
 	if err != nil {
 		return nil, err
 	}
@@ -228,7 +241,9 @@ func (p *pgHasTablePrivilegeFunctionClass) getFunction(ctx sessionctx.Context, a
 	argsTps := make([]types.EvalType, 0, 3)
 	argsTps = append(argsTps, types.ETString, types.ETString)
 	if len(args) > 2 {
-		argsTps = append(argsTps)
+		userArgTp := make([]types.EvalType, 0, 1)
+		userArgTp = append(userArgTp, types.ETString)
+		argsTps = append(userArgTp, argsTps...)
 	}
 	bf, err := newBaseBuiltinFuncWithTp(ctx, p.funcName, args, types.ETString, argsTps...)
 	if err != nil {
@@ -418,7 +433,7 @@ type builtinPgShobjDescriptionSig struct {
 }
 
 func (b *builtinPgShobjDescriptionSig) Clone() builtinFunc {
-	newSig := &builtinPgGetUserByIDSig{}
+	newSig := &builtinPgShobjDescriptionSig{}
 	newSig.cloneFrom(&b.baseBuiltinFunc)
 	return newSig
 }
@@ -437,7 +452,7 @@ func (p *pgObjDescriptionFunctionClass) getFunction(ctx sessionctx.Context, args
 	if err := p.verifyArgs(args); err != nil {
 		return nil, err
 	}
-	bf, err := newBaseBuiltinFuncWithTp(ctx, p.funcName, args, types.ETString, types.ETInt)
+	bf, err := newBaseBuiltinFuncWithTp(ctx, p.funcName, args, types.ETString, types.ETInt, types.ETString)
 	if err != nil {
 		return nil, err
 	}
@@ -452,11 +467,111 @@ type builtinPgObjDescriptionSig struct {
 }
 
 func (b *builtinPgObjDescriptionSig) Clone() builtinFunc {
-	newSig := &builtinPgGetUserByIDSig{}
+	newSig := &builtinPgObjDescriptionSig{}
 	newSig.cloneFrom(&b.baseBuiltinFunc)
 	return newSig
 }
 
 func (b *builtinPgObjDescriptionSig) evalString(row chunk.Row) (string, bool, error) {
 	return "[null]", false, nil
 }
+
+// PgFuncCurrentSchema
+// TODO: Since the specific schema logic is not implemented, it is tentatively designated as "public" here
+type pgCurrentSchemaFunctionClass struct {
+	baseFunctionClass
+}
+
+func (p *pgCurrentSchemaFunctionClass)getFunction(ctx sessionctx.Context, args []Expression) (builtinFunc, error)  {
+	if err := p.verifyArgs(args); err != nil {
+		return nil, err
+	}
+	bf, err := newBaseBuiltinFuncWithTp(ctx, p.funcName, args, types.ETString)
+	if err != nil {
+		return nil, err
+	}
+	bf.tp.Charset, bf.tp.Collate = ctx.GetSessionVars().GetCharsetInfo()
+	bf.tp.Flen = 64
+	sig := &builtinPgCurrentSchemaSig{bf}
+	return sig, nil
+}
+
+type builtinPgCurrentSchemaSig struct {
+	baseBuiltinFunc
+}
+
+func (b *builtinPgCurrentSchemaSig) evalString(row chunk.Row) (string, bool, error) {
+	return "public", false, nil
+}
+
+// PgFuncCurrentSchemas
+type pgCurrentSchemasFunctionClass struct {
+	baseFunctionClass
+}
+
+func (p *pgCurrentSchemasFunctionClass)getFunction(ctx sessionctx.Context, args []Expression) (builtinFunc, error)  {
+	if err := p.verifyArgs(args); err != nil {
+		return nil, err
+	}
+	bf, err := newBaseBuiltinFuncWithTp(ctx, p.funcName, args, types.ETString, types.ETInt)
+	if err != nil {
+		return nil, err
+	}
+	bf.tp.Charset, bf.tp.Collate = ctx.GetSessionVars().GetCharsetInfo()
+	bf.tp.Flen = 64
+	sig := &builtinPgCurrentSchemasSig{bf}
+	return sig, nil
+}
+
+type builtinPgCurrentSchemasSig struct {
+	baseBuiltinFunc
+}
+
+func (b *builtinPgCurrentSchemasSig) evalString(row chunk.Row) (string, bool, error) {
+	return "{pg_catalog,public}", false, nil
+}
+
+type pgArrayPositionFunctionClass struct {
+	baseFunctionClass
+}
+
+func (p *pgArrayPositionFunctionClass) getFunction(ctx sessionctx.Context, args []Expression) (builtinFunc, error) {
+	if err := p.verifyArgs(args); err != nil {
+		return nil, err
+	}
+	bf, err := newBaseBuiltinFuncWithTp(ctx, p.funcName, args, types.ETInt, types.ETString, types.ETString)
+	if err != nil {
+		return nil, err
+	}
+	bf.tp.Charset, bf.tp.Collate = ctx.GetSessionVars().GetCharsetInfo()
+	bf.tp.Flen = 64
+	sig := &builtinPgArrayPositionSig{bf}
+	return sig, nil
+}
+
+type builtinPgArrayPositionSig struct {
+	baseBuiltinFunc
+}
+
+func (b *builtinPgArrayPositionSig) Clone() builtinFunc {
+	newSig := &builtinPgArrayPositionSig{}
+	newSig.cloneFrom(&b.baseBuiltinFunc)
+	return newSig
+}
+
+func (b *builtinPgArrayPositionSig) evalInt(row chunk.Row) (int64, bool, error) {
+	arrayList, isNull, err := b.args[0].EvalString(b.ctx, row)
+	if isNull || err != nil {
+		return 0, isNull, err
+	}
+	array, isNull, err := b.args[0].EvalString(b.ctx, row)
+	if isNull || err != nil {
+		return 0, isNull, err
+	}
+	var res int64 = 0
+	strExist := strings.Contains(arrayList, array)
+	if strExist {
+		res =1
+	}
+	return res, false, nil
+}

expression/builtin_pg_func_test.go

@@ -0,0 +1,49 @@
+// Copyright 2021 Digital China Group Co.,Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package expression
+
+import (
+	"github.com/DigitalChinaOpenSource/DCParser/ast"
+	. "github.com/pingcap/check"
+	"github.com/pingcap/tidb/types"
+	"github.com/pingcap/tidb/util/chunk"
+	"github.com/pingcap/tidb/util/mock"
+)
+
+// TestCurrentDatabase test PostgreSQL system function current_database().
+func (s *testEvaluatorSuite) TestCurrentDatabase(c *C) {
+	fc := funcs[ast.PgFuncCurrentDatabase]
+	ctx := mock.NewContext()
+	f, err := fc.getFunction(ctx, nil)
+	c.Assert(err, IsNil)
+	d, err := evalBuiltinFunc(f, chunk.Row{})
+	c.Assert(err, IsNil)
+	c.Assert(d.Kind(), Equals, types.KindNull)
+	ctx.GetSessionVars().CurrentDB = "test"
+	d, err = evalBuiltinFunc(f, chunk.Row{})
+	c.Assert(err, IsNil)
+	c.Assert(d.GetString(), Equals, "test")
+	c.Assert(f.Clone().PbCode(), Equals, f.PbCode())
+}
+
+// TestCurrentSchema test PostgreSQL system function current_schema()
+func (s *testEvaluatorSuite) TestCurrentSchema(c *C) {
+	fc := funcs[ast.PgFuncCurrentSchema]
+	ctx := mock.NewContext()
+	f, err := fc.getFunction(ctx, nil)
+	c.Assert(err, NotNil)
+	d, err := evalBuiltinFunc(f, chunk.Row{})
+	c.Assert(err, IsNil)
+	c.Assert(d.GetString(), Equals, "public")
+}

go.mod

@@ -3,7 +3,7 @@ module github.com/pingcap/tidb
 require (
 	cloud.google.com/go v0.51.0 // indirect
 	github.com/BurntSushi/toml v0.3.1
-	github.com/DigitalChinaOpenSource/DCParser v0.0.0-20210906032539-5020c84eb0ab
+	github.com/DigitalChinaOpenSource/DCParser v0.0.0-20210913013152-bbeff4b1e131
 	github.com/DigitalChinaOpenSource/dcbr v4.0.11+incompatible
 	github.com/Jeffail/gabs/v2 v2.5.1
 	github.com/aws/aws-sdk-go v1.30.24 // indirect

go.sum

@@ -25,6 +25,10 @@ github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
 github.com/DigitalChinaOpenSource/DCParser v0.0.0-20210906032539-5020c84eb0ab h1:H25pUoHH6J1OPNIZjFeHgeCsKvdpBL0iiMSMAt8SlTo=
 github.com/DigitalChinaOpenSource/DCParser v0.0.0-20210906032539-5020c84eb0ab/go.mod h1:3n404SkCabBM0pYRgCyXEKttOLdrmMyBaWMGvaRs/ns=
+github.com/DigitalChinaOpenSource/DCParser v0.0.0-20210909034839-f401b2c4f4dd h1:kYpjLNIuJSIBS7i9tSAcTaBH+/hGfN4+PnfVj1BbCL4=
+github.com/DigitalChinaOpenSource/DCParser v0.0.0-20210909034839-f401b2c4f4dd/go.mod h1:3n404SkCabBM0pYRgCyXEKttOLdrmMyBaWMGvaRs/ns=
+github.com/DigitalChinaOpenSource/DCParser v0.0.0-20210913013152-bbeff4b1e131 h1:PsGgaMEO+FUkIzheFAimGQF1xBVhKzub5Y6WarRS2es=
+github.com/DigitalChinaOpenSource/DCParser v0.0.0-20210913013152-bbeff4b1e131/go.mod h1:3n404SkCabBM0pYRgCyXEKttOLdrmMyBaWMGvaRs/ns=
 github.com/DigitalChinaOpenSource/dcbr v4.0.11+incompatible h1:ICQTYSnJC7i3Ns4xXGS5DMi1wTfg44woW4eWQi2ZNTQ=
 github.com/DigitalChinaOpenSource/dcbr v4.0.11+incompatible/go.mod h1:sIm2Eayjb84BFeHrWkkA+4Zdt+4CRSs1HhrlosPwRNk=
 github.com/HdrHistogram/hdrhistogram-go v0.9.0 h1:dpujRju0R4M/QZzcnR1LH1qm+TVG3UzkWdp5tH1WMcg=