Update badger to commit e7b6e76f96e8 (#5538)

Also enables storing indices in the cache.

Author: Ibrahim Jarif

go.mod

@@ -16,7 +16,7 @@ require (
 	github.com/blevesearch/segment v0.0.0-20160915185041-762005e7a34f // indirect
 	github.com/blevesearch/snowballstem v0.0.0-20180110192139-26b06a2c243d // indirect
 	github.com/codahale/hdrhistogram v0.0.0-20161010025455-3a0bb77429bd
-	github.com/dgraph-io/badger/v2 v2.0.1-rc1.0.20200522174526-6eaa5009af27
+	github.com/dgraph-io/badger/v2 v2.0.1-rc1.0.20200528205344-e7b6e76f96e8
 	github.com/dgraph-io/dgo/v2 v2.1.1-0.20191127085444-c7a02678e8a6
 	github.com/dgraph-io/ristretto v0.0.2-0.20200115201040-8f368f2f2ab3
 	github.com/dgrijalva/jwt-go v3.2.0+incompatible

go.sum

@@ -62,8 +62,8 @@ github.com/d4l3k/messagediff v1.2.1/go.mod h1:Oozbb1TVXFac9FtSIxHBMnBCq2qeH/2KkE
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/dgraph-io/badger/v2 v2.0.1-rc1.0.20200522174526-6eaa5009af27 h1:2oSyH418QYuj2IhW5XWvSJqu5S2wT6czY2ZmPcLhgB4=
-github.com/dgraph-io/badger/v2 v2.0.1-rc1.0.20200522174526-6eaa5009af27/go.mod h1:3KY8+bsP8wI0OEnQJAKpd4wIJW/Mm32yw2j/9FUVnIM=
+github.com/dgraph-io/badger/v2 v2.0.1-rc1.0.20200528205344-e7b6e76f96e8 h1:TDpSSjrjipVJHEpcimd7uRYqiIeMc1LsM7p2tgEl+s8=
+github.com/dgraph-io/badger/v2 v2.0.1-rc1.0.20200528205344-e7b6e76f96e8/go.mod h1:3KY8+bsP8wI0OEnQJAKpd4wIJW/Mm32yw2j/9FUVnIM=
 github.com/dgraph-io/dgo/v2 v2.1.1-0.20191127085444-c7a02678e8a6 h1:5leDFqGys055YO3TbghBhk/QdRPEwyLPdgsSJfiR20I=
 github.com/dgraph-io/dgo/v2 v2.1.1-0.20191127085444-c7a02678e8a6/go.mod h1:LJCkLxm5fUMcU+yb8gHFjHt7ChgNuz3YnQQ6MQkmscI=
 github.com/dgraph-io/ristretto v0.0.2-0.20200115201040-8f368f2f2ab3 h1:MQLRM35Pp0yAyBYksjbj1nZI/w6eyRY/mWoM1sFf4kU=

worker/server_state.go

@@ -149,8 +149,12 @@ func (s *ServerState) initStorage() {
 		// All the writes to posting store should be synchronous. We use batched writers
 		// for posting lists, so the cost of sync writes is amortized.
 		x.Check(os.MkdirAll(Config.PostingDir, 0700))
-		opt := badger.DefaultOptions(Config.PostingDir).WithValueThreshold(1 << 10 /* 1KB */).
-			WithNumVersionsToKeep(math.MaxInt32).WithMaxCacheSize(1 << 30)
+		opt := badger.DefaultOptions(Config.PostingDir).
+			WithValueThreshold(1 << 10 /* 1KB */).
+			WithNumVersionsToKeep(math.MaxInt32).
+			WithMaxCacheSize(1 << 30).
+			WithKeepBlockIndicesInCache(true).
+			WithKeepBlocksInCache(true)
 		opt = setBadgerOptions(opt)
 
 		// Print the options w/o exposing key.