Merge pull request #7295 from Akilan1999/version_variable_vitess

added vitess_version as variable

go/vt/sqlparser/ast_rewriting.go

@@ -237,6 +237,7 @@ func (er *expressionRewriter) sysVarRewrite(cursor *Cursor, node *ColName) {
 		sysvars.SessionUUID.Name,
 		sysvars.ReadAfterWriteGTID.Name,
 		sysvars.ReadAfterWriteTimeOut.Name,
+		sysvars.VitessVersion.Name,
 		sysvars.SessionTrackGTIDs.Name:
 		cursor.Replace(bindVarExpression("__vt" + lowered))
 		er.bindVars.AddSysVar(lowered)

go/vt/sqlparser/ast_rewriting_test.go

@@ -32,14 +32,18 @@ type myTestCase struct {
 	ddlStrategy, sessionUUID                                          bool
 	udv                                                               int
 	autocommit, clientFoundRows, skipQueryPlanCache                   bool
-	sqlSelectLimit, transactionMode, workload                         bool
+	sqlSelectLimit, transactionMode, workload, vitessVersion          bool
 }
 
 func TestRewrites(in *testing.T) {
 	tests := []myTestCase{{
 		in:       "SELECT 42",
 		expected: "SELECT 42",
 		// no bindvar needs
+	}, {
+		in:            "SELECT @@vitess_version",
+		expected:      "SELECT :__vtvitess_version as `@@vitess_version`",
+		vitessVersion: true,
 	}, {
 		in:       "SELECT last_insert_id()",
 		expected: "SELECT :__lastInsertId as `last_insert_id()`",
@@ -198,6 +202,7 @@ func TestRewrites(in *testing.T) {
 			assert.Equal(tc.rawGTID, result.NeedsSysVar(sysvars.ReadAfterWriteGTID.Name), "should need rawGTID")
 			assert.Equal(tc.rawTimeout, result.NeedsSysVar(sysvars.ReadAfterWriteTimeOut.Name), "should need rawTimeout")
 			assert.Equal(tc.sessTrackGTID, result.NeedsSysVar(sysvars.SessionTrackGTIDs.Name), "should need sessTrackGTID")
+			assert.Equal(tc.vitessVersion, result.NeedsSysVar(sysvars.VitessVersion.Name), "should need Vitess version")
 		})
 	}
 }

go/vt/sysvars/sysvars.go

@@ -55,7 +55,8 @@ var (
 	Names               = SystemVariable{Name: "names", Default: utf8, IdentifierAsString: true}
 	SessionUUID         = SystemVariable{Name: "session_uuid", IdentifierAsString: true}
 	// Online DDL
-	DDLStrategy = SystemVariable{Name: "ddl_strategy", IdentifierAsString: true}
+	DDLStrategy   = SystemVariable{Name: "ddl_strategy", IdentifierAsString: true}
+	VitessVersion = SystemVariable{Name: "vitess_version", IdentifierAsString: true}
 
 	// Read After Write settings
 	ReadAfterWriteGTID    = SystemVariable{Name: "read_after_write_gtid"}

go/vt/vtgate/executor.go

@@ -29,6 +29,8 @@ import (
 	"sync"
 	"time"
 
+	"vitess.io/vitess/go/vt/servenv"
+
 	"vitess.io/vitess/go/vt/sysvars"
 
 	"context"
@@ -315,6 +317,8 @@ func (e *Executor) addNeededBindVars(bindVarNeeds *sqlparser.BindVarNeeds, bindV
 				}
 			})
 			bindVars[key] = sqltypes.StringBindVariable(v)
+		case sysvars.VitessVersion.Name:
+			bindVars[key] = sqltypes.StringBindVariable(servenv.AppVersion.String())
 		}
 	}