Support timezone offsets for queries

The timezone for a query can now be added to the end with something like
`TZ("America/Los_Angeles")` and it will localize the results of the
query to be in that timezone. The offset will automatically be set to
the offset for that timezone and offsets will automatically adjust for
daylight savings time so grouping by a day will result in a 25 hour day
once a year and a 23 hour day another day of the year.

The automatic adjustment of intervals for timezone offsets changing will
only happen if the group by period is greater than the timezone offset
would be. That means grouping by an hour or less will not be affected by
daylight savings time, but a 2 hour or 1 day interval will be.

The default timezone is UTC and existing queries are unaffected by this
change.

When times are returned as strings (when `epoch=1` is not used), the
results will be returned using the requested timezone format in RFC3339
format.

CHANGELOG.md

@@ -11,6 +11,7 @@
 - [#7856](https://github.com/influxdata/influxdb/issues/7856): Failed points during an import now result in a non-zero exit code.
 - [#7821](https://github.com/influxdata/influxdb/issues/7821): Expose some configuration settings via SHOW DIAGNOSTICS
 - [#8025](https://github.com/influxdata/influxdb/issues/8025): Support single and multiline comments in InfluxQL.
+- [#6541](https://github.com/influxdata/influxdb/issues/6541): Support timezone offsets for queries.
 
 ### Bugfixes
 

coordinator/statement_executor.go

@@ -438,6 +438,9 @@ func (e *StatementExecutor) executeSelectStatement(stmt *influxql.SelectStatemen
 	// Generate a row emitter from the iterator set.
 	em := influxql.NewEmitter(itrs, stmt.TimeAscending(), ctx.ChunkSize)
 	em.Columns = stmt.ColumnNames()
+	if stmt.Location != nil {
+		em.Location = stmt.Location
+	}
 	em.OmitTime = stmt.OmitTime
 	defer em.Close()
 

influxql/README.md

@@ -787,7 +787,8 @@ REVOKE READ ON "mydb" FROM "jdoe"
 ```
 select_stmt = "SELECT" fields from_clause [ into_clause ] [ where_clause ]
               [ group_by_clause ] [ order_by_clause ] [ limit_clause ]
-              [ offset_clause ] [ slimit_clause ] [ soffset_clause ] .
+              [ offset_clause ] [ slimit_clause ] [ soffset_clause ]
+              [ timezone_clause ] .
 ```
 
 #### Examples:
@@ -798,6 +799,9 @@ SELECT mean("value") FROM "cpu" WHERE "region" = 'uswest' GROUP BY time(10m) fil
 
 -- select from all measurements beginning with cpu into the same measurement name in the cpu_1h retention policy
 SELECT mean("value") INTO "cpu_1h".:MEASUREMENT FROM /cpu.*/
+
+-- select from measurements grouped by the day with a timezone
+SELECT mean("value") FROM "cpu" GROUP BY region, time(1d) fill(0) tz("America/Chicago")
 ```
 
 ## Clauses
@@ -817,6 +821,8 @@ slimit_clause   = "SLIMIT" int_lit .
 
 soffset_clause  = "SOFFSET" int_lit .
 
+timezone_clause = tz(identifier) .
+
 on_clause       = "ON" db_name .
 
 order_by_clause = "ORDER BY" sort_fields .

influxql/ast.go

@@ -984,6 +984,9 @@ type SelectStatement struct {
 	// The value to fill empty aggregate buckets with, if any.
 	FillValue interface{}
 
+	// The timezone for the query, if any.
+	Location *time.Location
+
 	// Renames the implicit time field name.
 	TimeAlias string
 
@@ -1650,6 +1653,9 @@ func (s *SelectStatement) String() string {
 	if s.SOffset > 0 {
 		_, _ = fmt.Fprintf(&buf, " SOFFSET %d", s.SOffset)
 	}
+	if s.Location != nil {
+		_, _ = fmt.Fprintf(&buf, ` TZ("%s")`, s.Location)
+	}
 	return buf.String()
 }
 

influxql/emitter.go

@@ -20,6 +20,9 @@ type Emitter struct {
 	// The columns to attach to each row.
 	Columns []string
 
+	// The time zone location.
+	Location *time.Location
+
 	// Removes the "time" column from output.
 	// Used for meta queries where time does not apply.
 	OmitTime bool
@@ -32,6 +35,7 @@ func NewEmitter(itrs []Iterator, ascending bool, chunkSize int) *Emitter {
 		itrs:      itrs,
 		ascending: ascending,
 		chunkSize: chunkSize,
+		Location:  time.UTC,
 	}
 }
 
@@ -154,7 +158,7 @@ func (e *Emitter) readAt(t int64, name string, tags Tags) []interface{} {
 
 	values := make([]interface{}, len(e.itrs)+offset)
 	if !e.OmitTime {
-		values[0] = time.Unix(0, t).UTC()
+		values[0] = time.Unix(0, t).In(e.Location)
 	}
 	e.readInto(t, name, tags, values[offset:])
 	return values

influxql/internal/internal.proto

@@ -38,6 +38,7 @@ message IteratorOptions {
     optional string      Condition  = 8;
     optional int64       StartTime  = 9;
     optional int64       EndTime    = 10;
+    optional string      Location   = 21;
     optional bool        Ascending  = 11;
     optional int64       Limit      = 12;
     optional int64       Offset     = 13;