WAL compression enabled by default

Signed-off-by: Chris Marchbanks <csmarchbanks@gmail.com>

db.go

@@ -81,8 +81,8 @@ type Options struct {
 	// This in-turn enables vertical compaction and vertical query merge.
 	AllowOverlappingBlocks bool
 
-	// WALCompression will turn on Snappy compression for records on the WAL.
-	WALCompression bool
+	// DisableWALCompression will turn off Snappy compression for records on the WAL.
+	DisableWALCompression bool
 }
 
 // Appender allows appending a batch of data. It must be completed with a
@@ -303,7 +303,7 @@ func Open(dir string, l log.Logger, r prometheus.Registerer, opts *Options) (db
 		if opts.WALSegmentSize > 0 {
 			segmentSize = opts.WALSegmentSize
 		}
-		wlog, err = wal.NewSize(l, r, filepath.Join(dir, "wal"), segmentSize, opts.WALCompression)
+		wlog, err = wal.NewSize(l, r, filepath.Join(dir, "wal"), segmentSize, !opts.DisableWALCompression)
 		if err != nil {
 			return nil, err
 		}