From 3f9eacf24cd052bbfec593e2838c598f6a741cd2 Mon Sep 17 00:00:00 2001
From: Cory LaNou <cory@lanou.com>
Date: Tue, 12 May 2015 14:30:01 -0600
Subject: [PATCH] add validations to parser for distinct

---
 influxql/ast.go         | 31 +++++++++++++++++++++++++++++++
 influxql/parser_test.go |  5 +++++
 2 files changed, 36 insertions(+)

diff --git a/influxql/ast.go b/influxql/ast.go
index b2b837284d..ca7cf7ad04 100644
--- a/influxql/ast.go
+++ b/influxql/ast.go
@@ -893,6 +893,22 @@ func (s *SelectStatement) hasTimeDimensions(node Node) bool {
 
 // Validate checks certain edge conditions to determine if this is a valid select statment
 func (s *SelectStatement) Validate(tr targetRequirement) error {
+	if err := s.ValidateAggregates(tr); err != nil {
+		return err
+	}
+
+	if err := s.ValidateDistinct(); err != nil {
+		return err
+	}
+
+	if err := s.validateDerivative(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (s *SelectStatement) ValidateAggregates(tr targetRequirement) error {
 	// fetch the group by duration
 	groupByDuration, _ := s.GroupByInterval()
 
@@ -907,6 +923,21 @@ func (s *SelectStatement) Validate(tr targetRequirement) error {
 			return fmt.Errorf("aggregate functions with GROUP BY time require a WHERE time clause")
 		}
 	}
+	return nil
+}
+
+func (s *SelectStatement) ValidateDistinct() error {
+	if !s.Distinct {
+		return nil
+	}
+
+	if len(s.Fields) > 1 {
+		return fmt.Errorf("select DISTINCT may only have one field")
+	}
+
+	if !s.IsRawQuery {
+		return fmt.Errorf("select DISTINCT does not allow for aggregate functions")
+	}
 
 	if err := s.validateDerivative(); err != nil {
 		return err
diff --git a/influxql/parser_test.go b/influxql/parser_test.go
index 43a5fde8fb..cbbe6d9b8b 100644
--- a/influxql/parser_test.go
+++ b/influxql/parser_test.go
@@ -1063,6 +1063,11 @@ func TestParser_ParseStatement(t *testing.T) {
 		{s: `SELECT 1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 FROM myseries`, err: `unable to parse number at line 1, char 8`},
 		{s: `SELECT 10.5h FROM myseries`, err: `found h, expected FROM at line 1, char 12`},
 		{s: `SELECT derivative(field1), field1 FROM myseries`, err: `derivative cannot be used with other fields`},
+		{s: `SELECT DISTINCT FROM myseries`, err: `found FROM, expected identifier, string, number, bool at line 1, char 17`},
+		{s: `SELECT DISTINCT field1, field2 FROM myseries`, err: `select DISTINCT may only have one field`},
+		{s: `SELECT DISTINCT field1, sum(field1) FROM myseries`, err: `select DISTINCT may only have one field`},
+		{s: `SELECT DISTINCT field1, count(field2) FROM myseries`, err: `select DISTINCT may only have one field`},
+		{s: `SELECT DISTINCT sum(field1) FROM myseries`, err: `select DISTINCT does not allow for aggregate functions`},
 		{s: `DELETE`, err: `found EOF, expected FROM at line 1, char 8`},
 		{s: `DELETE FROM`, err: `found EOF, expected identifier at line 1, char 13`},
 		{s: `DELETE FROM myseries WHERE`, err: `found EOF, expected identifier, string, number, bool at line 1, char 28`},