Change default to memorymap and update recommendation to one-third RAM in docs. (#2315)

Author: Pawan Rawal

dgraph/cmd/server/run.go

@@ -62,7 +62,7 @@ func init() {
 		"Directory to store posting lists.")
 	flag.String("posting_tables", defaults.PostingTables,
 		"Specifies how Badger LSM tree is stored. Options are loadtoram, memorymap and "+
-			"fileio; which consume most to least RAM while providing best to worst "+
+			"fileio; which consume most to least RAM while providing best to worst read"+
 			"performance respectively.")
 	flag.StringP("wal", "w", defaults.WALDir,
 		"Directory to store raft write-ahead logs.")

edgraph/config.go

@@ -42,7 +42,7 @@ var Config Options
 
 var DefaultConfig = Options{
 	PostingDir:    "p",
-	PostingTables: "loadtoram",
+	PostingTables: "memorymap",
 	WALDir:        "w",
 	Nomutations:   false,
 

wiki/content/deploy/index.md

@@ -198,8 +198,8 @@ Dgraph cluster nodes use different ports to communicate over gRPC and http. User
 If you are using Dgraph v1.0.2 (or older) then the default ports are 7080, 8080 for zero, so when following instructions for different setup guides below override zero port using `--port_offset`.
 
 ```sh
-dgraph zero --idx=1 --lru_mb=<typically half the RAM> --port_offset -2000
-dgraph zero --idx=2 --lru_mb=<typically half the RAM> --port_offset -1999
+dgraph zero --idx=1 --lru_mb=<typically one-third the RAM> --port_offset -2000
+dgraph zero --idx=2 --lru_mb=<typically one-third the RAM> --port_offset -1999
 ```
 Ratel's default port is 8081, so override it using -p 8000.
 
@@ -258,8 +258,8 @@ For all other various flags, run `dgraph zero --help`.
 **Run dgraph server**
 
 ```sh
-dgraph server --lru_mb=<typically half the RAM> --my=IPADDR:7080 --zero=localhost:5080
-dgraph server --lru_mb=<typically half the RAM> --my=IPADDR:7081 --zero=localhost:5080 -o=1
+dgraph server --lru_mb=<typically one-third the RAM> --my=IPADDR:7080 --zero=localhost:5080
+dgraph server --lru_mb=<typically one-third the RAM> --my=IPADDR:7081 --zero=localhost:5080 -o=1
 ```
 Notice the use of -o for the second server to add offset to the default ports used by server. Zero automatically assigns an unique ID to each Dgraph server, which is persisted in the write ahead log (wal) directory, users can specify the index using `--idx` option. Dgraph servers use two location to persist data and wal logs and have to be different for each server if they are running on the same host. User can use `-p` and `-w` to change the location of data and WAL. For all other flags, run
 
@@ -293,11 +293,11 @@ docker run -it -p 5080:5080 -p 6080:6080 -v ~/zero:/dgraph dgraph/dgraph:latest
 ```sh
 mkdir ~/server1 # Or any other directory where data should be stored.
 
-docker run -it -p 7080:7080 -p 8080:8080 -p 9080:9080 -v ~/server1:/dgraph dgraph/dgraph:latest dgraph server --lru_mb=<typically half the RAM> --zero=HOSTIPADDR:5080 --my=HOSTIPADDR:7080
+docker run -it -p 7080:7080 -p 8080:8080 -p 9080:9080 -v ~/server1:/dgraph dgraph/dgraph:latest dgraph server --lru_mb=<typically one-third the RAM> --zero=HOSTIPADDR:5080 --my=HOSTIPADDR:7080
 
 mkdir ~/server2 # Or any other directory where data should be stored.
 
-docker run -it -p 7081:7081 -p 8081:8081 -p 9081:9081 -v ~/server2:/dgraph dgraph/dgraph:latest dgraph server --lru_mb=<typically half the RAM> --zero=HOSTIPADDR:5080 --my=HOSTIPADDR:7081  -o=1
+docker run -it -p 7081:7081 -p 8081:8081 -p 9081:9081 -v ~/server2:/dgraph dgraph/dgraph:latest dgraph server --lru_mb=<typically one-third the RAM> --zero=HOSTIPADDR:5080 --my=HOSTIPADDR:7081  -o=1
 ```
 Notice the use of -o for server2 to override the default ports for server2.
 
@@ -1416,7 +1416,7 @@ During bulk loading of data, Dgraph can consume more memory than usual, due to h
 
 The recommended minimum RAM to run on desktops and laptops is 16GB. Dgraph can take up to 7-8 GB with the default setting `-lru_mb` set to 4096; so having the rest 8GB for desktop applications should keep your machine humming along.
 
-On EC2/GCE instances, the recommended minimum is 8GB. It's recommended to set `-lru_mb` to half of RAM size.
+On EC2/GCE instances, the recommended minimum is 8GB. It's recommended to set `-lru_mb` to one-third of RAM size.
 
 ## See Also
 

wiki/content/get-started/index.md

@@ -150,7 +150,7 @@ Run 'dgraph-ratel' to start Dgraph UI. This can be used to do mutations and quer
 dgraph-ratel
 ```
 
-{{% notice "tip" %}}You need to set the estimated memory Dgraph server can take through `lru_mb` flag. This is just a hint to the Dgraph server and actual usage would be higher than this. It's recommended to set lru_mb to half the available RAM.{{% /notice %}}
+{{% notice "tip" %}}You need to set the estimated memory Dgraph server can take through `lru_mb` flag. This is just a hint to the Dgraph server and actual usage would be higher than this. It's recommended to set lru_mb to one-third the available RAM.{{% /notice %}}
 
 #### Windows
 
@@ -211,7 +211,7 @@ docker exec -it diggy dgraph-ratel
 If you are using Dgraph v1.0.2 (or older) then the default ports are 7080, 8080 for zero, so when following instructions for different setup guides override zero port using `--port_offset`.
 
 ```sh
-dgraph zero --lru_mb=<typically half the RAM> --port_offset -2000
+dgraph zero --lru_mb=<typically one-third the RAM> --port_offset -2000
 ```
 Ratel's default port is 8081, so override it using -p 8000.