Make sure the query string has valid regex and add a test

coordinator/coordinator.go

@@ -279,14 +279,11 @@ func (self *Coordinator) expandRegex(spec *parser.QuerySpec) {
 	}
 
 	if f := q.FromClause; f.Type == parser.FromClauseMergeFun {
-		series := self.clusterConfiguration.MetaStore.GetSeriesForDatabaseAndRegex(spec.Database(), q.FromClause.Regex)
-		f.Type = parser.FromClauseMerge
-		f.Regex = nil
-		for _, s := range series {
-			f.Names = append(f.Names, &parser.TableName{
-				Name: &parser.Value{Name: s, Type: parser.ValueTableName},
-			})
+		f := func(r *regexp.Regexp) []string {
+			return self.clusterConfiguration.MetaStore.GetSeriesForDatabaseAndRegex(spec.Database(), r)
 		}
+
+		parser.RewriteMergeQuery(q, f)
 	}
 }
 

parser/from_clause.go

@@ -48,14 +48,14 @@ func (self *FromClause) GetString() string {
 	buffer := bytes.NewBufferString("")
 	switch self.Type {
 	case FromClauseMerge:
-		fmt.Fprintf(buffer, "merge(")
+		fmt.Fprintf(buffer, "merge(/")
 		for i, n := range self.Names {
 			if i > 0 {
 				buffer.WriteRune('|')
 			}
 			buffer.WriteString(n.Name.GetString())
 		}
-		buffer.WriteRune(')')
+		buffer.WriteString("/)")
 	case FromClauseInnerJoin:
 		fmt.Fprintf(buffer, "%s%s inner join %s%s", self.Names[0].Name.GetString(), self.Names[0].GetAliasString(),
 			self.Names[1].Name.GetString(), self.Names[1].GetAliasString())

parser/parser_test.go

@@ -32,6 +32,25 @@ func (self *QueryParserSuite) TestInvalidFromClause(c *C) {
 	c.Assert(err, ErrorMatches, ".*\\$undefined.*")
 }
 
+func (self *QueryParserSuite) TestParseMergeGetString(c *C) {
+	f := func(r *regexp.Regexp) []string {
+		return []string{"foobar"}
+	}
+
+	query := "select * from merge(/.*foo.*/)"
+	qs, err := ParseQuery(query)
+	c.Assert(err, IsNil)
+	c.Assert(qs, HasLen, 1)
+	RewriteMergeQuery(qs[0].SelectQuery, f)
+	fmt.Printf("Parsing %s\n", qs[0].GetQueryStringWithTimeCondition())
+	actualQs, err := ParseQuery(qs[0].GetQueryStringWithTimeCondition())
+	c.Assert(err, IsNil)
+	c.Assert(actualQs, HasLen, 1)
+	RewriteMergeQuery(actualQs[0].SelectQuery, f)
+	actualQs[0].SelectQuery.startTimeSpecified = false
+	c.Assert(actualQs[0].SelectQuery, DeepEquals, qs[0].SelectQuery)
+}
+
 func (self *QueryParserSuite) TestInvalidExplainQueries(c *C) {
 	query := "explain select foo, baz group by time(1d)"
 	_, err := ParseQuery(query)

parser/rewrite.go

@@ -0,0 +1,21 @@
+package parser
+
+import "regexp"
+
+type RegexMatcher func(r *regexp.Regexp) []string
+
+func RewriteMergeQuery(query *SelectQuery, rm RegexMatcher) {
+	if query.FromClause.Type != FromClauseMergeFun {
+		return
+	}
+
+	series := rm(query.FromClause.Regex)
+	f := query.FromClause
+	f.Type = FromClauseMerge
+	f.Regex = nil
+	for _, s := range series {
+		f.Names = append(f.Names, &TableName{
+			Name: &Value{Name: s, Type: ValueTableName},
+		})
+	}
+}