Allow setting key/value in a metadata stored in the topology

go/vt/sqlparser/analyzer.go

@@ -285,6 +285,9 @@ func ExtractSetValues(sql string) (keyValues map[SetKey]interface{}, scope strin
 		case strings.HasPrefix(key, "@@session."):
 			scope = SessionStr
 			key = strings.TrimPrefix(key, "@@session.")
+		case strings.HasPrefix(key, "@@vitess_metadata."):
+			scope = VitessMetadataStr
+			key = strings.TrimPrefix(key, "@@vitess_metadata.")
 		case strings.HasPrefix(key, "@@"):
 			key = strings.TrimPrefix(key, "@@")
 		}

go/vt/sqlparser/ast.go

@@ -662,9 +662,10 @@ type Set struct {
 
 // Set.Scope or Show.Scope
 const (
-	SessionStr  = "session"
-	GlobalStr   = "global"
-	ImplicitStr = ""
+	SessionStr        = "session"
+	GlobalStr         = "global"
+	VitessMetadataStr = "vitess_metadata"
+	ImplicitStr       = ""
 )
 
 // Format formats the node.

go/vt/sqlparser/like_filter.go

@@ -0,0 +1,34 @@
+package sqlparser
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+var (
+	re = regexp.MustCompile(`([^\\]?|[\\]{2})[%_]`)
+)
+
+func replacer(s string) string {
+	if strings.HasPrefix(s, `\\`) {
+		return s[2:]
+	}
+
+	result := strings.Replace(s, "%" ,".*", -1)
+	result = strings.Replace(result, "_", ".", -1)
+
+	return result
+}
+
+// LikeToRegexp converts a like sql expression to regular expression
+func LikeToRegexp(likeExpr string) *regexp.Regexp {
+	if likeExpr == "" {
+		return regexp.MustCompile("^.*$") // Can never fail
+	}
+
+	keyPattern := regexp.QuoteMeta(likeExpr)
+	keyPattern = re.ReplaceAllStringFunc(keyPattern, replacer)
+	keyPattern = fmt.Sprintf("^%s$", keyPattern)
+	return regexp.MustCompile(keyPattern) // Can never fail
+}

go/vt/sqlparser/like_filter_test.go

@@ -0,0 +1,73 @@
+package sqlparser
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestEmptyLike(t *testing.T) {
+	want := "^.*$"
+	got := LikeToRegexp("").String()
+
+	assert.Equal(t, want, got)
+}
+
+func TestLikePrefixRegexp(t *testing.T) {
+	show, e := Parse("show vitess_metadata variables like 'key%'")
+	if e != nil {
+		t.Error(e)
+	}
+
+	want := "^key.*$"
+	got := LikeToRegexp(show.(*Show).ShowTablesOpt.Filter.Like).String()
+
+	assert.Equal(t, want, got)
+}
+
+func TestLikeAnyCharsRegexp(t *testing.T) {
+	show, e := Parse("show vitess_metadata variables like '%val1%val2%'")
+	if e != nil {
+		t.Error(e)
+	}
+
+	want := "^.*val1.*val2.*$"
+	got := LikeToRegexp(show.(*Show).ShowTablesOpt.Filter.Like).String()
+
+	assert.Equal(t, want, got)
+}
+
+func TestSingleAndMultipleCharsRegexp(t *testing.T) {
+	show, e := Parse("show vitess_metadata variables like '_val1_val2%'")
+	if e != nil {
+		t.Error(e)
+	}
+
+	want := "^.val1.val2.*$"
+	got := LikeToRegexp(show.(*Show).ShowTablesOpt.Filter.Like).String()
+
+	assert.Equal(t, want, got)
+}
+
+func TestSpecialCharactersRegexp(t *testing.T) {
+	show, e := Parse("show vitess_metadata variables like '?.*?'")
+	if e != nil {
+		t.Error(e)
+	}
+
+	want := "^\\?\\.\\*\\?$"
+	got := LikeToRegexp(show.(*Show).ShowTablesOpt.Filter.Like).String()
+
+	assert.Equal(t, want, got)
+}
+
+func TestQuoteLikeSpecialCharacters(t *testing.T) {
+	show, e := Parse(`show vitess_metadata variables like 'part1_part2\\%part3_part4\\_part5%'`)
+	if e != nil {
+		t.Error(e)
+	}
+
+	want := "^part1.part2%part3.part4_part5.*$"
+	got := LikeToRegexp(show.(*Show).ShowTablesOpt.Filter.Like).String()
+
+	assert.Equal(t, want, got)
+}