simplify the code

Signed-off-by: Andres Taylor <andres@planetscale.com>

go/vt/servenv/mysql.go

@@ -40,7 +40,6 @@ func MySQLServerVersion() string {
 // flag. It is intended for use in tests that require a specific MySQL server
 // version (for example, collations) that cannot specify that via the command
 // line.
-// Please note that semantics.ClearCachedInfoSchemaInfo() should be called any time this method is called
 func SetMySQLServerVersionForTest(version string) {
 	mySQLServerVersion = version
 }

go/vt/vtgate/engine/memory_sort_test.go

@@ -28,14 +28,12 @@ import (
 	querypb "vitess.io/vitess/go/vt/proto/query"
 	"vitess.io/vitess/go/vt/servenv"
 	"vitess.io/vitess/go/vt/vtgate/evalengine"
-	"vitess.io/vitess/go/vt/vtgate/semantics"
 )
 
 func init() {
 	// We require MySQL 8.0 collations for the comparisons in the tests
 	mySQLVersion := "8.0.0"
 	servenv.SetMySQLServerVersionForTest(mySQLVersion)
-	semantics.ClearCachedInfoSchemaInfo()
 	collationEnv = collations.NewEnvironment(mySQLVersion)
 }
 

go/vt/vtgate/engine/ordered_aggregate_test.go

@@ -32,7 +32,6 @@ import (
 	querypb "vitess.io/vitess/go/vt/proto/query"
 	"vitess.io/vitess/go/vt/servenv"
 	. "vitess.io/vitess/go/vt/vtgate/engine/opcode"
-	"vitess.io/vitess/go/vt/vtgate/semantics"
 )
 
 var collationEnv *collations.Environment
@@ -41,7 +40,6 @@ func init() {
 	// We require MySQL 8.0 collations for the comparisons in the tests
 	mySQLVersion := "8.0.0"
 	servenv.SetMySQLServerVersionForTest(mySQLVersion)
-	semantics.ClearCachedInfoSchemaInfo()
 	collationEnv = collations.NewEnvironment(mySQLVersion)
 }
 

go/vt/vtgate/engine/route_test.go

@@ -35,7 +35,6 @@ import (
 	"vitess.io/vitess/go/vt/sqlparser"
 	"vitess.io/vitess/go/vt/vterrors"
 	"vitess.io/vitess/go/vt/vtgate/evalengine"
-	"vitess.io/vitess/go/vt/vtgate/semantics"
 	"vitess.io/vitess/go/vt/vtgate/vindexes"
 )
 
@@ -51,7 +50,6 @@ func init() {
 	// We require MySQL 8.0 collations for the comparisons in the tests
 	mySQLVersion := "8.0.0"
 	servenv.SetMySQLServerVersionForTest(mySQLVersion)
-	semantics.ClearCachedInfoSchemaInfo()
 	collationEnv = collations.NewEnvironment(mySQLVersion)
 }
 

go/vt/vtgate/evalengine/api_compare_test.go

@@ -23,8 +23,6 @@ import (
 	"testing"
 	"time"
 
-	"vitess.io/vitess/go/vt/vtgate/semantics"
-
 	"github.com/stretchr/testify/require"
 
 	"vitess.io/vitess/go/mysql/collations"
@@ -58,7 +56,6 @@ func init() {
 	// We require MySQL 8.0 collations for the comparisons in the tests
 	mySQLVersion := "8.0.0"
 	servenv.SetMySQLServerVersionForTest(mySQLVersion)
-	semantics.ClearCachedInfoSchemaInfo()
 	collationEnv = collations.NewEnvironment(mySQLVersion)
 }
 

go/vt/vtgate/evalengine/integration/comparison_test.go

@@ -27,8 +27,6 @@ import (
 	"testing"
 	"time"
 
-	"vitess.io/vitess/go/vt/vtgate/semantics"
-
 	"github.com/spf13/pflag"
 
 	"vitess.io/vitess/go/mysql/format"
@@ -258,7 +256,6 @@ func TestMySQL(t *testing.T) {
 	// We require MySQL 8.0 collations for the comparisons in the tests
 
 	servenv.SetMySQLServerVersionForTest(conn.ServerVersion)
-	semantics.ClearCachedInfoSchemaInfo()
 	collationEnv = collations.NewEnvironment(conn.ServerVersion)
 	servenv.OnParse(registerFlags)
 	initTimezoneData(t, conn)

go/vt/vtgate/planbuilder/plan_test.go

@@ -104,10 +104,8 @@ func TestSystemTables57(t *testing.T) {
 	// first we move everything to use 5.7 logic
 	oldVer := servenv.MySQLServerVersion()
 	servenv.SetMySQLServerVersionForTest("5.7")
-	semantics.ClearCachedInfoSchemaInfo()
 	defer func() {
 		servenv.SetMySQLServerVersionForTest(oldVer)
-		semantics.ClearCachedInfoSchemaInfo()
 	}()
 	vschemaWrapper := &vschemaWrapper{v: loadSchema(t, "vschemas/schema.json", true)}
 	testOutputTempDir := makeTestOutput(t)
@@ -200,10 +198,8 @@ func TestOneWith57Version(t *testing.T) {
 	// first we move everything to use 5.7 logic
 	oldVer := servenv.MySQLServerVersion()
 	servenv.SetMySQLServerVersionForTest("5.7")
-	semantics.ClearCachedInfoSchemaInfo()
 	defer func() {
 		servenv.SetMySQLServerVersionForTest(oldVer)
-		semantics.ClearCachedInfoSchemaInfo()
 	}()
 	vschema := &vschemaWrapper{v: loadSchema(t, "vschemas/schema.json", true)}
 

go/vt/vtgate/semantics/info_schema.go

@@ -1671,30 +1671,22 @@ type infoSchemaWithColumns struct {
 	infoSchemaData map[string][]vindexes.Column
 }
 
-// We cache this information. If the version is changed in a test, this field also needs to be cleared
-var cacheSchemaInfo map[string][]vindexes.Column
+// We cache this information, since these are maps that are not changed
+var infoSchema57 = getInfoSchema57()
+var infoSchema80 = getInfoSchema80()
 
 // newSchemaInfo returns a SchemaInformation that has the column information for all info_schema tables
 func newSchemaInfo(inner SchemaInformation) SchemaInformation {
-	if cacheSchemaInfo == nil {
-		// yes, this is slightly racy, but the worst that can happen is that we build it more times
-		// than needed. It's not going to lead to any actual issues
-		loadSchemaInfo()
-	}
-	return &infoSchemaWithColumns{inner: inner, infoSchemaData: cacheSchemaInfo}
-}
-
-func ClearCachedInfoSchemaInfo() {
-	cacheSchemaInfo = nil
+	return &infoSchemaWithColumns{inner: inner, infoSchemaData: loadSchemaInfo()}
 }
 
-func loadSchemaInfo() {
+func loadSchemaInfo() map[string][]vindexes.Column {
 	version := servenv.MySQLServerVersion()
 	if strings.HasPrefix(version, "5.7") {
-		cacheSchemaInfo = getInfoSchema57()
-	} else {
-		cacheSchemaInfo = getInfoSchema80()
+		return infoSchema57
 	}
+
+	return infoSchema80
 }
 
 // FindTableOrVindex implements the SchemaInformation interface