Merge branch 'master' into able-perf

executor.go

@@ -1529,6 +1529,8 @@ func (e *executor) executeDistinctShard(ctx context.Context, qcx *Qcx, index str
 			Index: index,
 			Field: fieldName,
 		}
+	} else if field.Options().Type == FieldTypeTimestamp {
+		result = DistinctTimestamp{Name: fieldName}
 	} else {
 		result = SignedRow{}
 	}
@@ -1564,11 +1566,19 @@ func (e *executor) executeDistinctShard(ctx context.Context, qcx *Qcx, index str
 		if err != nil {
 			return nil, err
 		}
-		results := make([]string, len(r.Pos.Columns()))
-		for i, val := range r.Pos.Columns() {
+		// If we have a filter, or there's just no content for this shard, we
+		// can end up with empty results. Rather than trying to synthesize
+		// a result from this empty set, we just go ahead and use that.
+		if r.Pos == nil {
+			return result, nil
+		}
+		cols := r.Pos.Columns()
+		results := make([]string, len(cols))
+		for i, val := range cols {
 			results[i] = FormatTimestampNano(int64(val), bsig.Base, field.options.TimeUnit)
 		}
-		return DistinctTimestamp{Name: fieldName, Values: results}, nil
+		result = DistinctTimestamp{Name: fieldName, Values: results}
+		return result, nil
 	}
 	return executeDistinctShardBSI(ctx, qcx, idx, fieldName, shard, bsig, filterBitmap)
 }

executor_test.go

@@ -6789,13 +6789,16 @@ func variousQueriesCountDistinctTimestamp(t *testing.T, c *test.Cluster) {
 
 	// create an index and timestamp field
 	c.CreateField(t, index, pilosa.IndexOptions{TrackExistence: true}, field, pilosa.OptFieldTypeTimestamp(time.Unix(0, 0), "s"))
+	c.CreateField(t, index, pilosa.IndexOptions{TrackExistence: true}, "set")
 
 	// add some data
 	data := []string{"2010-01-02T12:32:00Z", "2010-04-20T12:32:00Z", "2011-04-20T12:59:00Z", "2011-04-20T12:40:00Z", "2011-04-20T12:32:00Z"}
 
 	for i, datum := range data {
-		c.Query(t, index, fmt.Sprintf("Set(%d, ts=\"%s\")", i*(1<<20), datum))
+		c.Query(t, index, fmt.Sprintf("Set(%d, ts=\"%s\")", i*ShardWidth, datum))
 	}
+	// set something in shard 8 so there's a shard present with no timestamp data
+	c.Query(t, index, fmt.Sprintf("Set(%d, set=0)", 8*ShardWidth))
 
 	// query the Count of Distinct vals in field ts
 	count := c.Query(t, index, "Count(Distinct(field=ts))").Results[0]
@@ -6803,6 +6806,13 @@ func variousQueriesCountDistinctTimestamp(t *testing.T, c *test.Cluster) {
 		t.Fatalf("expected %v got %v", len(data), count)
 	}
 
+	// query the ones that are in or after 2011, expecting 3. this helps us
+	// hit an edge case that only happens if you have no data *because of
+	// a filter*.
+	count = c.Query(t, index, "Count(Distinct(Row(ts > \"2011-01-01T00:00:00Z\"), field=ts))").Results[0]
+	if count != uint64(3) {
+		t.Fatalf("expected %v got %v", 3, count)
+	}
 }
 
 // Ensure that a top-level, bare distinct on multiple nodes

row.go

@@ -463,6 +463,11 @@ func (r *Row) MarshalJSON() ([]byte, error) {
 
 // Columns returns the columns in r as a slice of ints.
 func (r *Row) Columns() []uint64 {
+	// We occasionally hit cases where we want to call Columns on something
+	// that might not exist, but a nil slice would be fine.
+	if r == nil {
+		return nil
+	}
 	a := make([]uint64, 0, r.Count())
 	for i := range r.segments {
 		a = append(a, r.segments[i].Columns()...)