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Community Blog Facebook LinkBench Tests PostgreSQL Social Relation Profile Scenario Performance

Facebook LinkBench Tests PostgreSQL Social Relation Profile Scenario Performance

This article introduces LinkBench for PostgreSQL and shows you how to use it to run benchmark test for your database.

Background

LinkBench is an open-source database benchmark developed by Google to evaluate database performance. LinkBench creates a set of test data around a social graph and then perform data operations such as querying, adding or disconnecting relationships.

For more information about LinkBench, refer to the following articles:

https://www.facebook.com/notes/facebook-engineering/linkbench-a-database-benchmark-for-the-social-graph/10151391496443920
http://www.oschina.net/translate/linkbench-a-database-benchmark-for-the-social-graph

The test model of LinkBench is very typical in the social relationships of users. I will provide a copy of PostgreSQL database performance test data under this model and the test method.

After seeing this test data, you can compare it with the test data of other databases to see the performance differences.

Test Model of LinkBench

This data can be represented in a social graph, where objects (graph nodes) such as people, posts, comments, and pages are connected by associations (directed edges of the graph) that model different relationships between the nodes.

Different types of associations can represent friendship between two users, a user liking another object, ownership of a post, or any other relationship.

1

LinkBench is a graph-serving benchmark, not a graph-processing benchmark - the difference being that the former simulates the transactional workload from an interactive social network service while the latter simulates an analytics workload.

This benchmark is not about finding graph communities or graph partitioning, but rather serving real-time queries and updates on a graph database.

For example, a general form of graph query would be to find all the edges of type A from node X into which update operations can insert, delete, or update graph nodes or edges.

An example graph update operation is "insert a friendship edge from user 4 to user 63459821."

By classifying database queries into a small number of core operations for associations (edges) and objects (nodes), we could break down and analyze the mix of social graph operations for a production database.

The simple graph retrieval and update operations listed below are used to store and retrieve social graph data.

2

Note that the workload is heavy on edge operations and reads, particularly edge range scans.

Examples of edge range scans are "retrieve all comments for a post order from most to least recent" or "retrieve all friends for a user."

Optimization Tips:
This question is about storing data. If comments of an article have been aggregated, a small number of blocks need to be scanned and the performance is good. Similarly, if friends of a user have been aggregated, retrieving friends of a user will not encounter performance problems.

Aggregation through clusters can also reduce rows to be scanned.

Introduction to LinkBench for PostgreSQL

The actual benchmark is driven by the LinkBench driver, a Java program that generates the social graph and the operation mix.

Originally this tool only supports MySQL. Currently this tool has extended support for PostgreSQL. However, make sure to use PostgreSQL 9.5 or later, because queries include UPSET(insert on conflict), a new feature in PostgreSQL 9.5.

https://github.com/mdcallag/linkbench

Install LinkBench

mkdir ~/app  
cd ~/app  

JDK

cd ~  
http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html  
get     
Java SE Development Kit 8u102  
Linux x64   173.03 MB   jdk-8u102-linux-x64.tar.gz  
  
tar -zxvf jdk-8u102-linux-x64.tar.gz  
mv jdk1.8.0_102 /home/digoal/app/  

apache-maven

http://maven.apache.org/download.cgi  
  
wget http://mirrors.cnnic.cn/apache/maven/maven-3/3.3.9/binaries/apache-maven-3.3.9-bin.tar.gz  
tar -zxvf apache-maven-3.3.9-bin.tar.gz  
mv apache-maven-3.3.9 /home/digoal/app/  

Set up the environment

export JAVA_HOME=/home/digoal/app/jdk1.8.0_102  
export PATH=/home/digoal/app/apache-maven-3.3.9/bin:/home/digoal/app/jdk1.8.0_102/bin:$PATH  
export LD_LIBRARY_PATH=/home/digoal/app/apache-maven-3.3.9/lib:$LD_LIBRARY_PATH  

Install LinkBench

git clone https://github.com/mdcallag/linkbench  

Pack linkbench

$ cd linkbench  
  
$ mvn clean package -P pgsql -D skipTests  
  
[INFO] ------------------------------------------------------------------------  
[INFO] BUILD SUCCESS  
[INFO] ------------------------------------------------------------------------  
[INFO] Total time: 5.146 s  
[INFO] Finished at: 2016-09-11T13:07:55+08:00  
[INFO] Final Memory: 39M/1582M  
[INFO] ------------------------------------------------------------------------  

Generate the environment variable configuration file

$ vi ~/.bash_profile

# append  
export JAVA_HOME=/home/digoal/app/jdk1.8.0_102  
export PATH=/home/digoal/app/linkbench/bin:/home/digoal/app/apache-maven-3.3.9/bin:/home/digoal/app/jdk1.8.0_102/bin:$PATH  
export LD_LIBRARY_PATH=/home/digoal/app/apache-maven-3.3.9/lib:$LD_LIBRARY_PATH  
export CLASSPATH=.:/home/digoal/app/linkbench/target/FacebookLinkBench.jar  

$ linkbench

Using java at: /home/digoal/app/jdk1.8.0_102/bin/java  
Did not select benchmark mode  
usage: linkbench [-c <file>] [-csvstats <file>] [-csvstream <file>] [-D  
       <property=value>] [-L <file>] [-l] [-r]  
 -c <file>                       Linkbench config file  
 -csvstats,--csvstats <file>     CSV stats output  
 -csvstream,--csvstream <file>   CSV streaming stats output  
 -D <property=value>             Override a config setting  
 -L <file>                       Log to this file  
 -l                              Execute loading stage of benchmark  
 -r                              Execute request stage of benchmark  

The benchmark runs in two phases:

1.  The load phase, where an initial graph is generated and loaded in bulk;

2.  The request phase, where many request threads concurrently access the database with a mix of operations. During the request phase latency and throughput statistics for operations are collected and reported.

The exact behavior of the driver in both phases is controlled by a configuration file, and many aspects of the benchmark can be easily altered using this file.

The configuration file template is config/LinkConfigPgsql.properties.

3

PostgreSQL Deployment

This article does not include OS parameter optimization.

$ wget https://ftp.postgresql.org/pub/source/v9.6rc1/postgresql-9.6rc1.tar.bz2      
$ tar -jxvf postgresql-9.6rc1.tar.bz2      
$ cd postgresql-9.6rc1      
$ ./configure --prefix=/home/postgres/pgsql9.6rc1 --enable-debug       
$ gmake world -j 32      
$ gmake install-world      

Environment variable configuration

$ vi ~/env_pg.sh      
# add by digoal      
export PS1="$USER@`/bin/hostname -s`-> "      
export PGPORT=1921      
export PGDATA=/data01/pgdata/pg_root_96      
export LANG=en_US.utf8      
export PGHOME=/home/postgres/pgsql9.6rc1      
export LD_LIBRARY_PATH=$PGHOME/lib:/lib64:/usr/lib64:/usr/local/lib64:/lib:/usr/lib:/usr/local/lib:$LD_LIBRARY_PATH      
export DATE=`date +"%Y%m%d%H%M"`      
export PATH=$PGHOME/bin:$PATH:.      
export MANPATH=$PGHOME/share/man:$MANPATH      
export PGHOST=$PGDATA      
export PGDATABASE=postgres      
alias rm='rm -i'      
alias ll='ls -lh'      
unalias vi      
$ . ~/env_pg.sh     

Create a Test Database

1.  Initialize the database

initdb -D $PGDATA -E UTF8 --locale=C -U postgres

2.  Create a database

    $> psql   
    DROP DATABASE IF EXISTS linkdb;  
    CREATE DATABASE linkdb ENCODING='latin1' template template0;  
  
    --drop user linkbench to create new one  
    DROP USER  IF EXISTS linkdb;  
  
    --  You may want to set up a special database user account for benchmarking:  
    CREATE USER linkdb password 'password';  
    -- Grant all privileges on linkdb to this user  
    GRANT ALL ON database linkdb TO linkdb;  

3.  Connect to linkdb and create tables and index

    $> \c linkdb linkdb  
  
    --add Schema keep the same query style (dbid.table_name)  
    DROP SCHEMA IF EXISTS linkdb CASCADE;   
    CREATE SCHEMA linkdb;  
  
    -- FIXME:Need to make it partitioned by key id1 %16  
    -- Partition tables are recommended, or you can directly use a single table  
    -- For partition tables, the constraint check(mod(id1,16)=0) is required for the sub-table ID1...
    -- src/main/java/com/facebook/LinkBench/LinkStorePgsql.java needs to be modified and re-compiled  
    -- In addition to id1=... add the same query criterion as the constraint, for example, where id1=val and mod(id1,16) = mod(val,16) ... 
    -- This allows the optimizer of PostgreSQL to filter id1=val
    CREATE TABLE linkdb.linktable (  
            id1 numeric(20) NOT NULL DEFAULT '0',  
            id2 numeric(20) NOT NULL DEFAULT '0',  
            link_type numeric(20) NOT NULL DEFAULT '0',  
            visibility smallint NOT NULL DEFAULT '0',  
            data varchar(255) NOT NULL DEFAULT '',  
            time numeric(20) NOT NULL DEFAULT '0',  
            version bigint NOT NULL DEFAULT '0',  
            PRIMARY KEY (link_type, id1,id2)  
            );  
  
    -- this is index for linktable  
    CREATE INDEX id1_type on linkdb.linktable(  
            id1,link_type,visibility,time,id2,version,data);  
  
    CREATE TABLE linkdb.counttable (  
            id numeric(20) NOT NULL DEFAULT '0',  
            link_type numeric(20) NOT NULL DEFAULT '0',  
            count int NOT NULL DEFAULT '0',  
            time numeric(20) NOT NULL DEFAULT '0',  
            version numeric(20) NOT NULL DEFAULT '0',  
            PRIMARY KEY (id,link_type)  
            );  
  
    CREATE TABLE linkdb.nodetable (  
            id BIGSERIAL NOT NULL,  
            type int NOT NULL,  
            version numeric NOT NULL,  
            time int NOT NULL,  
            data text NOT NULL,  
            PRIMARY KEY(id)  
            );  

Configure the Load Template

Note that each value cannot have a trailing space in the configuration file of LinkBench. Otherwise parsing errors may occur.

Configure how much test data is to be imported

$ vi ~/app/linkbench/config/FBWorkload.properties

# end node id for initial load (exclusive)  
# With default config and MySQL/InnoDB, 1M ids ~= 1GB  
maxid1 = 1000000001  
# Configure about 1 billion node records (about 1 TB)  

Configure the database connection method, report frequency, thread, operations tested on each thread, maximum test duration, and stress testing

$ vi ~/app/linkbench/config/LinkConfigPgsql.properties

workload_file = config/FBWorkload.properties  
linkstore = com.facebook.LinkBench.LinkStorePgsql  
nodestore = com.facebook.LinkBench.LinkStorePgsql  
# Database connection information  
host = xxx.xxx.xxx.xxx  
user = linkdb  
password = linkdb  
port = 1922  
dbid = linkdb  
# Database tables  
linktable = linktable  
counttable = counttable  
nodetable = nodetable  
# INFO output level  
debuglevel = INFO  
# Print frequency  
progressfreq = 300  
displayfreq = 1800  
# Number of records allowed to be loaded and requested on each thread  
load_progress_interval = 500000  
req_progress_interval = 500000  
maxsamples = 10000  
# Number of threads to be loaded  
loaders = 64  
generate_nodes = true  
loader_chunk_size = 2048  
# Number of requests enabled (Multiplying by 2 to get the number of connections)    
requesters = 192  
# Number of requests for each thread  
requests = 5000000  
requestrate = 0  
maxtime = 100000  
warmup_time = 0  
max_failed_requests = 100  

Load Benchmark Data

$ cd ~/app/linkbench  
  
$ ./bin/linkbench -c config/LinkConfigPgsql.properties -l  

Configure Benchmark Template

The steps are the same as those described in the preceding "Configure the load template" section

Stress Testing

./bin/linkbench -c config/LinkConfigPgsql.properties -r  

Benchmark Result

Data load Result

INFO 2016-09-12 01:19:07,229 [main]: LOAD_NODE_BULK count = 390625  p25 = [8000,9000]ms  p50 = [8000,9000]ms  p75 = [9000,10000]ms  p95 = [10000,100000]ms  p99 = [10000,100000]ms  max = 1259341.029ms  mean = 9759.494ms
INFO 2016-09-12 01:19:07,229 [main]: LOAD_LINKS_BULK count = 1708831  p25 = [10000,100000]ms  p50 = [10000,100000]ms  p75 = [10000,100000]ms  p95 = [10000,100000]ms  p99 = [10000,100000]ms  max = 1292335.24ms  mean = 33558.09ms
INFO 2016-09-12 01:19:07,229 [main]: LOAD_COUNTS_BULK count = 301615  p25 = [10000,100000]ms  p50 = [10000,100000]ms  p75 = [10000,100000]ms  p95 = [10000,100000]ms  p99 = [10000,100000]ms  max = 1318474.297ms  mean = 66637.2ms
INFO 2016-09-12 01:19:07,229 [main]: LOAD PHASE COMPLETED.  Loaded 100000000 nodes (Expected 100000000). Loaded 437452202 links (4.37 links per node).  Took 4060.6 seconds.  Links/second = 107731 

Stress Test Result

Query performance for one-way metrics

INFO 2016-09-11 21:49:47,069 [main]: 
ADD_NODE 
count = 2471774  
p25 = [0.4,0.5]ms  Less than 0.5 milliseconds for 25% requests
p50 = [0.5,0.6]ms  Less than 0.6 milliseconds for 50% requests
p75 = [0.6,0.7]ms  Less than 0.7 milliseconds for 75% requests
p95 = [1,2]ms Less than 2 milliseconds for 95% requests
p99 = [4,5]ms  Less than 5 milliseconds for 99% requests
max = 213.324ms  Maximum RT
mean = 0.715ms   Average RT

p25 indicates that the RT for 0-25% of requests is between a and b (milliseconds) and p50 indicates that the RT for 25-50% of requests is between a and b (milliseconds)

Overall test statistics (including QPS)

INFO 2016-09-11 21:49:47,070 [main]: 
REQUEST PHASE COMPLETED. 
96000000 requests done in 796 seconds. 
Requests/second = 120482 

The test result for a 32-core machine

INFO 2016-09-11 21:49:47,069 [main]: ADD_NODE count = 2471774  p25 = [0.4,0.5]ms  p50 = [0.5,0.6]ms  p75 = [0.6,0.7]ms  p95 = [1,2]ms  p99 = [4,5]ms  max = 213.324ms  mean = 0.715ms  
INFO 2016-09-11 21:49:47,069 [main]: UPDATE_NODE count = 7073914  p25 = [0.4,0.5]ms  p50 = [0.5,0.6]ms  p75 = [0.7,0.8]ms  p95 = [2,3]ms  p99 = [5,6]ms  max = 154.589ms  mean = 0.813ms  
INFO 2016-09-11 21:49:47,069 [main]: DELETE_NODE count = 971421  p25 = [0.3,0.4]ms  p50 = [0.4,0.5]ms  p75 = [0.6,0.7]ms  p95 = [2,3]ms  p99 = [4,5]ms  max = 80.185ms  mean = 0.731ms  
INFO 2016-09-11 21:49:47,070 [main]: GET_NODE count = 12414612  p25 = [0.4,0.5]ms  p50 = [0.6,0.7]ms  p75 = [0.9,1]ms  p95 = [2,3]ms  p99 = [5,6]ms  max = 78.739ms  mean = 0.943ms  
INFO 2016-09-11 21:49:47,070 [main]: ADD_LINK count = 8631075  p25 = [1,2]ms  p50 = [2,3]ms  p75 = [3,4]ms  p95 = [5,6]ms  p99 = [9,10]ms  max = 103.442ms  mean = 2.657ms  
INFO 2016-09-11 21:49:47,070 [main]: DELETE_LINK count = 2870975  p25 = [1,2]ms  p50 = [2,3]ms  p75 = [3,4]ms  p95 = [6,7]ms  p99 = [14,15]ms  max = 134.991ms  mean = 3.197ms  
INFO 2016-09-11 21:49:47,070 [main]: UPDATE_LINK count = 7694028  p25 = [1,2]ms  p50 = [2,3]ms  p75 = [3,4]ms  p95 = [5,6]ms  p99 = [9,10]ms  max = 91.146ms  mean = 2.654ms  
INFO 2016-09-11 21:49:47,070 [main]: COUNT_LINK count = 4690047  p25 = [0.4,0.5]ms  p50 = [0.6,0.7]ms  p75 = [1,2]ms  p95 = [2,3]ms  p99 = [5,6]ms  max = 79.349ms  mean = 1.026ms  
INFO 2016-09-11 21:49:47,070 [main]: MULTIGET_LINK count = 504147  p25 = [0.7,0.8]ms  p50 = [0.9,1]ms  p75 = [1,2]ms  p95 = [3,4]ms  p99 = [6,7]ms  max = 59.272ms  mean = 1.325ms  
INFO 2016-09-11 21:49:47,070 [main]: GET_LINKS_LIST count = 48678007  p25 = [0.7,0.8]ms  p50 = [0.9,1]ms  p75 = [1,2]ms  p95 = [3,4]ms  p99 = [6,7]ms  max = 117.932ms  mean = 1.386ms  
INFO 2016-09-11 21:49:47,070 [main]: REQUEST PHASE COMPLETED. 96000000 requests done in 796 seconds. Requests/second = 120482  

Each item represents a test case and the last row indicates the overall performance. For more information, see the preceding figures.

The result shows that LinkBench reaches 120,000 QPS.

A 32-core host is used in this test example.

References

https://github.com/mdcallag/linkbench
https://www.facebook.com/notes/facebook-engineering/linkbench-a-database-benchmark-for-the-social-graph/10151391496443920

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