From ebb7d70268be38f49db34ebdc115e18eed3e1dff Mon Sep 17 00:00:00 2001
From: chAnge <50198008+chAngeZhaoZhanBo@users.noreply.github.com>
Date: Thu, 5 Aug 2021 14:55:13 +0800
Subject: [PATCH] expression: Support mathematical functions pushdown to
 tiflash (#25596)

---
 expression/expr_to_pb_test.go | 56 +++++++++++++++++++++++++++++++++--
 expression/expression.go      |  3 +-
 2 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/expression/expr_to_pb_test.go b/expression/expr_to_pb_test.go
index 8f7c328118..6024503cc3 100644
--- a/expression/expr_to_pb_test.go
+++ b/expression/expr_to_pb_test.go
@@ -755,7 +755,7 @@ func (s *testEvaluatorSuite) TestExprPushDownToFlash(c *C) {
 	c.Assert(err, IsNil)
 	exprs = append(exprs, function)
 
-	// ScalarFuncSig_CeilDecimalToDecimal
+	// ScalarFuncSig_CeilDecToDec
 	function, err = NewFunction(mock.NewContext(), ast.Ceil, types.NewFieldType(mysql.TypeNewDecimal), decimalColumn)
 	c.Assert(err, IsNil)
 	exprs = append(exprs, function)
@@ -770,16 +770,66 @@ func (s *testEvaluatorSuite) TestExprPushDownToFlash(c *C) {
 	c.Assert(err, IsNil)
 	exprs = append(exprs, function)
 
-	// ScalarFuncSig_FloorDecimalToInt
+	// ScalarFuncSig_FloorDecToInt
 	function, err = NewFunction(mock.NewContext(), ast.Floor, types.NewFieldType(mysql.TypeLonglong), decimalColumn)
 	c.Assert(err, IsNil)
 	exprs = append(exprs, function)
 
-	// ScalarFuncSig_FloorDecimalToDecimal
+	// ScalarFuncSig_FloorDecToDec
 	function, err = NewFunction(mock.NewContext(), ast.Floor, types.NewFieldType(mysql.TypeNewDecimal), decimalColumn)
 	c.Assert(err, IsNil)
 	exprs = append(exprs, function)
 
+	// ScalarFuncSig_Log1Arg
+	function, err = NewFunction(mock.NewContext(), ast.Log, types.NewFieldType(mysql.TypeDouble), realColumn)
+	c.Assert(err, IsNil)
+	exprs = append(exprs, function)
+
+	// ScalarFuncSig_Log2Args
+	function, err = NewFunction(mock.NewContext(), ast.Log, types.NewFieldType(mysql.TypeDouble), realColumn, realColumn)
+	c.Assert(err, IsNil)
+	exprs = append(exprs, function)
+
+	// ScalarFuncSig_Log2
+	function, err = NewFunction(mock.NewContext(), ast.Log2, types.NewFieldType(mysql.TypeDouble), realColumn)
+	c.Assert(err, IsNil)
+	exprs = append(exprs, function)
+
+	// ScalarFuncSig_Log10
+	function, err = NewFunction(mock.NewContext(), ast.Log10, types.NewFieldType(mysql.TypeDouble), realColumn)
+	c.Assert(err, IsNil)
+	exprs = append(exprs, function)
+
+	// ScalarFuncSig_Exp
+	function, err = NewFunction(mock.NewContext(), ast.Exp, types.NewFieldType(mysql.TypeDouble), realColumn)
+	c.Assert(err, IsNil)
+	exprs = append(exprs, function)
+
+	// ScalarFuncSig_Pow
+	function, err = NewFunction(mock.NewContext(), ast.Pow, types.NewFieldType(mysql.TypeDouble), realColumn, realColumn)
+	c.Assert(err, IsNil)
+	exprs = append(exprs, function)
+
+	// ScalarFuncSig_Radians
+	function, err = NewFunction(mock.NewContext(), ast.Radians, types.NewFieldType(mysql.TypeDouble), realColumn)
+	c.Assert(err, IsNil)
+	exprs = append(exprs, function)
+
+	// ScalarFuncSig_Degrees
+	function, err = NewFunction(mock.NewContext(), ast.Degrees, types.NewFieldType(mysql.TypeDouble), realColumn)
+	c.Assert(err, IsNil)
+	exprs = append(exprs, function)
+
+	// ScalarFuncSig_CRC32
+	function, err = NewFunction(mock.NewContext(), ast.CRC32, types.NewFieldType(mysql.TypeLonglong), stringColumn)
+	c.Assert(err, IsNil)
+	exprs = append(exprs, function)
+
+	// ScalarFuncSig_Conv
+	function, err = NewFunction(mock.NewContext(), ast.Conv, types.NewFieldType(mysql.TypeDouble), stringColumn, intColumn, intColumn)
+	c.Assert(err, IsNil)
+	exprs = append(exprs, function)
+
 	// Replace
 	function, err = NewFunction(mock.NewContext(), ast.Replace, types.NewFieldType(mysql.TypeString), stringColumn, stringColumn, stringColumn)
 	c.Assert(err, IsNil)
diff --git a/expression/expression.go b/expression/expression.go
index a73c6df8ba..f84f75cb90 100644
--- a/expression/expression.go
+++ b/expression/expression.go
@@ -1017,7 +1017,8 @@ func scalarExprSupportedByFlash(function *ScalarFunction) bool {
 		ast.Concat, ast.ConcatWS,
 		ast.Year, ast.Month, ast.Day,
 		ast.DateDiff, ast.TimestampDiff, ast.DateFormat, ast.FromUnixTime,
-		ast.Sqrt,
+		ast.Sqrt, ast.Log, ast.Log2, ast.Log10, ast.Ln, ast.Exp, ast.Pow, ast.Sign,
+		ast.Radians, ast.Degrees, ast.Conv, ast.CRC32,
 		ast.JSONLength:
 		return true
 	case ast.Substr, ast.Substring, ast.Left, ast.Right, ast.CharLength: