From f8111cef0ecf6e778a15406a622687f8099c947d Mon Sep 17 00:00:00 2001
From: Fabian Reinartz <fab.reinartz@gmail.com>
Date: Mon, 26 Dec 2016 16:55:44 +0100
Subject: [PATCH] Fix chunk series iterator seeking

---
 db.go      |  8 +++++---
 querier.go | 16 +++++++++-------
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/db.go b/db.go
index 90d944f23..e04bdd3c2 100644
--- a/db.go
+++ b/db.go
@@ -22,12 +22,14 @@ import (
 // DefaultOptions used for the DB. They are sane for setups using
 // millisecond precision timestamps.
 var DefaultOptions = &Options{
-	Retention: 15 * 24 * 3600 * 1000, // 15 days
+	Retention:  15 * 24 * 3600 * 1000, // 15 days
+	DisableWAL: false,
 }
 
 // Options of the DB storage.
 type Options struct {
-	Retention int64
+	Retention  int64
+	DisableWAL bool
 }
 
 // DB is a time series storage.
@@ -41,7 +43,7 @@ type DB struct {
 
 // TODO(fabxc): make configurable
 const (
-	shardShift   = 3
+	shardShift   = 0
 	numShards    = 1 << shardShift
 	maxChunkSize = 1024
 )
diff --git a/querier.go b/querier.go
index 4c6a877de..f92e3d1ae 100644
--- a/querier.go
+++ b/querier.go
@@ -72,7 +72,6 @@ func (q *querier) Select(ms ...labels.Matcher) SeriesSet {
 }
 
 func (q *querier) LabelValues(n string) ([]string, error) {
-	// TODO(fabxc): return returned merged result.
 	res, err := q.shards[0].LabelValues(n)
 	if err != nil {
 		return nil, err
@@ -570,15 +569,18 @@ func newChunkSeriesIterator(mints []int64, cs []chunks.Chunk) *chunkSeriesIterat
 }
 
 func (it *chunkSeriesIterator) Seek(t int64) (ok bool) {
-	x := sort.Search(len(it.mints), func(i int) bool { return it.mints[i] >= t })
+	// Only do binary search forward to stay in line with other iterators
+	// that can only move forward.
+	x := sort.Search(len(it.mints[it.i:]), func(i int) bool { return it.mints[i] >= t })
+	x += it.i
 
+	// If the timestamp was not found, it might be in the last chunk.
 	if x == len(it.mints) {
-		return false
+		x--
 	}
-	if it.mints[x] == t {
-		if x == 0 {
-			return false
-		}
+	// Go to previous chunk if the chunk doesn't exactly start with t.
+	// If we are already at the first chunk, we use it as it's the best we have.
+	if x > 0 && it.mints[x] > t {
 		x--
 	}