Add fill to select statements.

CHANGELOG.md

@@ -6,6 +6,7 @@
 ### Features
 - [#1902](https://github.com/influxdb/influxdb/pull/1902): Enforce retention policies to have a minimum duration.
 - [#1906](https://github.com/influxdb/influxdb/pull/1906): Add show servers to query language.
+- [#1925](https://github.com/influxdb/influxdb/pull/1925): Add `fill(none)`, `fill(previous)`, and `fill(<num>)` to queries.
 
 ## v0.9.0-rc10 [2015-03-09]
 

cmd/influxd/server_integration_test.go

@@ -431,6 +431,34 @@ func runTestsData(t *testing.T, testName string, nodes Cluster, database, retent
 			expected: `{"results":[{"series":[{"name":"limit","columns":["time","foo"]}]}]}`,
 		},
 
+		// Fill tests
+		{
+			name: "fill with value",
+			write: `{"database" : "%DB%", "retentionPolicy" : "%RP%", "points": [
+				{"name": "fills", "timestamp": "2009-11-10T23:00:02Z","fields": {"val": 3}},
+				{"name": "fills", "timestamp": "2009-11-10T23:00:03Z","fields": {"val": 5}},
+				{"name": "fills", "timestamp": "2009-11-10T23:00:06Z","fields": {"val": 4}},
+				{"name": "fills", "timestamp": "2009-11-10T23:00:16Z","fields": {"val": 10}}
+			]}`,
+			query:    `select mean(val) from "%DB%"."%RP%".fills where time >= '2009-11-10T23:00:00Z' and time < '2009-11-10T23:00:20Z' group by time(5s) fill(1)`,
+			expected: `{"results":[{"series":[{"name":"fills","columns":["time","mean"],"values":[["2009-11-10T23:00:00Z",4],["2009-11-10T23:00:05Z",4],["2009-11-10T23:00:10Z",1],["2009-11-10T23:00:15Z",10]]}]}]}`,
+		},
+		{
+			name:     "fill with previous",
+			query:    `select mean(val) from "%DB%"."%RP%".fills where time >= '2009-11-10T23:00:00Z' and time < '2009-11-10T23:00:20Z' group by time(5s) fill(previous)`,
+			expected: `{"results":[{"series":[{"name":"fills","columns":["time","mean"],"values":[["2009-11-10T23:00:00Z",4],["2009-11-10T23:00:05Z",4],["2009-11-10T23:00:10Z",4],["2009-11-10T23:00:15Z",10]]}]}]}`,
+		},
+		{
+			name:     "fill with none, i.e. clear out nulls",
+			query:    `select mean(val) from "%DB%"."%RP%".fills where time >= '2009-11-10T23:00:00Z' and time < '2009-11-10T23:00:20Z' group by time(5s) fill(none)`,
+			expected: `{"results":[{"series":[{"name":"fills","columns":["time","mean"],"values":[["2009-11-10T23:00:00Z",4],["2009-11-10T23:00:05Z",4],["2009-11-10T23:00:15Z",10]]}]}]}`,
+		},
+		{
+			name:     "fill defaults to null",
+			query:    `select mean(val) from "%DB%"."%RP%".fills where time >= '2009-11-10T23:00:00Z' and time < '2009-11-10T23:00:20Z' group by time(5s)`,
+			expected: `{"results":[{"series":[{"name":"fills","columns":["time","mean"],"values":[["2009-11-10T23:00:00Z",4],["2009-11-10T23:00:05Z",4],["2009-11-10T23:00:10Z",null],["2009-11-10T23:00:15Z",10]]}]}]}`,
+		},
+
 		// Metadata display tests
 
 		{

influxql/INFLUXQL.md

@@ -576,15 +576,15 @@ select_stmt = fields from_clause [ into_clause ] [ where_clause ]
 
 ```sql
 -- select mean value from the cpu measurement where region = 'uswest' grouped by 10 minute intervals
-SELECT mean(value) FROM cpu WHERE region = 'uswest' GROUP BY time(10m);
+SELECT mean(value) FROM cpu WHERE region = 'uswest' GROUP BY time(10m) fill(0);
 ```
 
 ## Clauses
 
 ```
 from_clause     = "FROM" measurements .
 
-group_by_clause = "GROUP BY" dimensions .
+group_by_clause = "GROUP BY" dimensions fill(<option>).
 
 limit_clause    = "LIMIT" int_lit .
 

influxql/ast.go

@@ -529,6 +529,19 @@ func (s *AlterRetentionPolicyStatement) RequiredPrivileges() ExecutionPrivileges
 	return ExecutionPrivileges{{Name: "", Privilege: AllPrivileges}}
 }
 
+type FillOption int
+
+const (
+	// NullFill means that empty aggregate windows will just have null values.
+	NullFill FillOption = iota
+	// NoFill means that empty aggregate windows will be purged from the result.
+	NoFill
+	// NumberFill means that empty aggregate windwos will be filled with the given number
+	NumberFill
+	// PreviousFill means that empty aggregate windows will be filled with whatever the previous aggregate window had
+	PreviousFill
+)
+
 // SelectStatement represents a command for extracting data from the database.
 type SelectStatement struct {
 	// Expressions returned from the selection.
@@ -566,6 +579,12 @@ type SelectStatement struct {
 
 	// if it's a query for raw data values (i.e. not an aggregate)
 	RawQuery bool
+
+	// What fill option the select statement uses, if any
+	Fill FillOption
+
+	// The value to fill empty aggregate buckets with, if any
+	FillValue interface{}
 }
 
 // Clone returns a deep copy of the statement.

influxql/engine.go

@@ -182,6 +182,9 @@ func (m *MapReduceJob) Execute(out chan *Row, filterEmptyResults bool) {
 	// processes the result values if there's any math in there
 	resultValues = m.processResults(resultValues)
 
+	// handle any fill options
+	resultValues = m.processFill(resultValues)
+
 	row := &Row{
 		Name:    m.MeasurementName,
 		Tags:    m.TagSet.Tags,
@@ -226,6 +229,52 @@ func (m *MapReduceJob) processResults(results [][]interface{}) [][]interface{} {
 	return mathResults
 }
 
+// processFill will take the results and return new reaults (or the same if no fill modifications are needed) with whatever fill options the query has.
+func (m *MapReduceJob) processFill(results [][]interface{}) [][]interface{} {
+	// don't do anything if it's raw query results or we're supposed to leave the nulls
+	if m.stmt.RawQuery || m.stmt.Fill == NullFill {
+		return results
+	}
+
+	if m.stmt.Fill == NoFill {
+		// remove any rows that have even one nil value. This one is tricky because they could have multiple
+		// aggregates, but this option means that any row that has even one nil gets purged.
+		newResults := make([][]interface{}, 0, len(results))
+		for _, vals := range results {
+			hasNil := false
+			// start at 1 because the first value is always time
+			for j := 1; j < len(vals); j++ {
+				if vals[j] == nil {
+					hasNil = true
+					break
+				}
+			}
+			if !hasNil {
+				newResults = append(newResults, vals)
+			}
+		}
+		return newResults
+	}
+
+	// they're either filling with previous values or a specific number
+	for i, vals := range results {
+		// start at 1 because the first value is always time
+		for j := 1; j < len(vals); j++ {
+			if vals[j] == nil {
+				switch m.stmt.Fill {
+				case PreviousFill:
+					if i != 0 {
+						vals[j] = results[i-1][j]
+					}
+				case NumberFill:
+					vals[j] = m.stmt.FillValue
+				}
+			}
+		}
+	}
+	return results
+}
+
 func getProcessor(expr Expr, startIndex int) (processor, int) {
 	switch expr := expr.(type) {
 	case *VarRef:

influxql/parser.go

@@ -553,6 +553,11 @@ func (p *Parser) parseSelectStatement(tr targetRequirement) (*SelectStatement, e
 		return nil, err
 	}
 
+	// Parse fill options: "fill(<option>)"
+	if stmt.Fill, stmt.FillValue, err = p.parseFill(); err != nil {
+		return nil, err
+	}
+
 	// Parse sort: "ORDER BY FIELD+".
 	if stmt.SortFields, err = p.parseOrderBy(); err != nil {
 		return nil, err
@@ -1370,6 +1375,42 @@ func (p *Parser) parseDimension() (*Dimension, error) {
 	return &Dimension{Expr: expr}, nil
 }
 
+// parseFill parses the fill call and its optios.
+func (p *Parser) parseFill() (FillOption, interface{}, error) {
+	// Parse the expression first.
+	expr, err := p.ParseExpr()
+	if err != nil {
+		p.unscan()
+		return NullFill, nil, nil
+	}
+	if lit, ok := expr.(*Call); !ok {
+		p.unscan()
+		return NullFill, nil, nil
+	} else {
+		if lit.Name != "fill" {
+			p.unscan()
+			return NullFill, nil, nil
+		}
+		if len(lit.Args) != 1 {
+			return NullFill, nil, errors.New("fill requires an argument, e.g.: 0, null, none, previous")
+		}
+		switch lit.Args[0].String() {
+		case "null":
+			return NullFill, nil, nil
+		case "none":
+			return NoFill, nil, nil
+		case "previous":
+			return PreviousFill, nil, nil
+		default:
+			num, ok := lit.Args[0].(*NumberLiteral)
+			if !ok {
+				return NullFill, nil, fmt.Errorf("expected number argument in fill()")
+			}
+			return NumberFill, num.Val, nil
+		}
+	}
+}
+
 // parseOptionalTokenAndInt parses the specified token followed
 // by an int, if it exists.
 func (p *Parser) parseOptionalTokenAndInt(t Token) (int, error) {

influxql/parser_test.go

@@ -170,6 +170,49 @@ func TestParser_ParseStatement(t *testing.T) {
 			},
 		},
 
+		// SELECT statement with fill
+		{
+			s: `SELECT mean(value) FROM cpu GROUP BY time(5m) fill(1)`,
+			stmt: &influxql.SelectStatement{
+				Fields: []*influxql.Field{{
+					Expr: &influxql.Call{
+						Name: "mean",
+						Args: []influxql.Expr{&influxql.VarRef{Val: "value"}}}}},
+				Source: &influxql.Measurement{Name: "cpu"},
+				Dimensions: []*influxql.Dimension{
+					{Expr: &influxql.Call{
+						Name: "time",
+						Args: []influxql.Expr{
+							&influxql.DurationLiteral{Val: 5 * time.Minute},
+						},
+					}},
+				},
+				Fill:      influxql.NumberFill,
+				FillValue: float64(1),
+			},
+		},
+
+		// SELECT statement with previous fill
+		{
+			s: `SELECT mean(value) FROM cpu GROUP BY time(5m) fill(previous)`,
+			stmt: &influxql.SelectStatement{
+				Fields: []*influxql.Field{{
+					Expr: &influxql.Call{
+						Name: "mean",
+						Args: []influxql.Expr{&influxql.VarRef{Val: "value"}}}}},
+				Source: &influxql.Measurement{Name: "cpu"},
+				Dimensions: []*influxql.Dimension{
+					{Expr: &influxql.Call{
+						Name: "time",
+						Args: []influxql.Expr{
+							&influxql.DurationLiteral{Val: 5 * time.Minute},
+						},
+					}},
+				},
+				Fill: influxql.PreviousFill,
+			},
+		},
+
 		// DELETE statement
 		{
 			s: `DELETE FROM myseries WHERE host = 'hosta.influxdb.org'`,