Get best of the week

Introducing PostgreSQL wal-g backup system

WAL-G is a simple and effective tool for backing up PostgreSQL to the cloud. By its basic functionality, it is the heir to the popular WAL-E tool , but rewritten in Go. But there is one important new feature in WAL-G - delta copies. WAL-G delta copies store file pages that have changed from a previous backup version. WAL-G implements quite a few technologies for parallelizing backups. WAL-G is much faster than WAL-E.


Details of wal-g can be found in the article: Overclocking backup. Yandex lecture


The S3 storage protocol has become popular for data storage. One of the advantages of S3 is the ability to access via the API, which allows for flexible interaction with the repository, including public read access, while information is updated in the repository only by authorized persons.


There are several both open and private implementations of storages operating under the S3 protocol. Today we are going to look at a popular solution for organizing small storage - Minio.


For testing wal-g, one PostgreSQL server is suitable, and Minio is used as a replacement for S3.


Minio Server


Minio Installation


yum -y install yum-plugin-copr
yum copr enable -y lkiesow/minio
yum install -y minio mc

Edit AccessKey and SecretKey in /etc/minio/minio.conf


vi /etc/minio/minio.conf

If you will not use nginx before Minio, then you need to change


--address 127.0.0.1:9000

--address 0.0.0.0:9000

Generate and add to MINIO_ACCESS_KEY and MINIO_SECRET_KEY in /etc/minio/minio.conf


# Custom username or access key of minimum 3 characters in length.
#MINIO_ACCESS_KEY=

# Custom password or secret key of minimum 8 characters in length.
#MINIO_SECRET_KEY=

Launch Minio


systemctl start minio

web- Minio http://ip---minio:9000 (, pg-backups).



WAL-G rpm ( ). Github, Fedora COPR.


RPM-based .


wal-g rpm , /etc/wal-g.d/server-s3.conf.


backup-fetch.sh
backup-list.sh
backup-push.sh
wal-fetch.sh
wal-g-run.sh
wal-push.sh

wal-g.


yum -y install yum-plugin-copr
yum copr enable -y antonpatsev/wal-g
yum install -y wal-g

wal-g.


wal-g --version
wal-g version v0.2.14

/etc/wal-g.d/server-s3.conf .


, , , PGDATA


#!/bin/bash

export PG_VER="9.6"

export WALE_S3_PREFIX="s3://pg-backups" # ,     S3
export AWS_ACCESS_KEY_ID="xxxx" # AccessKey  /etc/minio/minio.conf 
export AWS_ENDPOINT="http://ip---minio:9000"
export AWS_S3_FORCE_PATH_STYLE="true"
export AWS_SECRET_ACCESS_KEY="yyyy" # SecretKey  /etc/minio/minio.conf

export PGDATA=/var/lib/pgsql/$PG_VER/data/
export PGHOST=/var/run/postgresql/.s.PGSQL.5432 #     PostgreSQL

export WALG_UPLOAD_CONCURRENCY=2 # -    
export WALG_DOWNLOAD_CONCURRENCY=2 # -   
export WALG_UPLOAD_DISK_CONCURRENCY=2 # -     
export WALG_DELTA_MAX_STEPS=7
export WALG_COMPRESSION_METHOD=brotli #    .

WAL-G WALG_DELTA_MAX_STEPS — , base- -, -. , . , , .


.


yum install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-7-x86_64/pgdg-redhat-repo-latest.noarch.rpm
yum install -y postgresql96 postgresql96-server mc

.


/usr/pgsql-9.6/bin/postgresql96-setup initdb
Initializing database ... OK

1 , wal_level archive PostgreSQL 10 , replica PostgreSQL 10 .


wal_level = archive

WAL 60 PostgreSQL. archive_timeout.


archive_mode = on
archive_command = '/usr/local/bin/wal-push.sh %p'
archive_timeout = 60 #  60     archive_command.

PostgreSQL


systemctl start postgresql-9.6

PostgreSQL : (postgresql-Wed.log ).


tail -fn100 /var/lib/pgsql/9.6/data/pg_log/postgresql-Wed.log

psql.


su - postgres
psql

psql .


test1.


create database test1;

test.


postgres=# \c test1;

indexing_table.


test1=# CREATE TABLE indexing_table(created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW());

.


. 10-20 .


#!/bin/bash
# postgres
while true; do
psql -U postgres -d test1 -c "INSERT INTO indexing_table(created_at) VALUES (CURRENT_TIMESTAMP);"
sleep 60;
done

test1


select * from indexing_table;
2020-01-29 09:41:25.226198+
2020-01-29 09:42:25.336989+
2020-01-29 09:43:25.356069+
2020-01-29 09:44:25.37381+
2020-01-29 09:45:25.392944+
2020-01-29 09:46:25.412327+
2020-01-29 09:47:25.432564+
2020-01-29 09:48:25.451985+
2020-01-29 09:49:25.472653+
2020-01-29 09:50:25.491974+
2020-01-29 09:51:25.510178+

.


WAL:


select pg_switch_xlog();
 PostgreSQL  10:
select pg_switch_wal();

.


su - postgres
/usr/local/bin/backup-push.sh


/usr/local/bin/backup-list.sh


WAL.


Postgresql.


/var/lib/pgsql/9.6/data.


/usr/local/bin/backup-fetch.sh postgres.


su - postgres
/usr/local/bin/backup-fetch.sh

Backup extraction complete.


recovery.conf /var/lib/pgsql/9.6/data .


restore_command = '/usr/local/bin/wal-fetch.sh "%f" "%p"'

PostgreSQL. PostgreSQL recovery WAL, .


systemctl start postgresql-9.6
tail -fn100 /var/lib/pgsql/9.6/data/pg_log/postgresql-Wed.log

.


, recovery.conf recovery_target_time — .


restore_command = '/usr/local/bin/wal-fetch.sh "%f" "%p"'
recovery_target_time = '2020-01-29 09:46:25'

indexing_table


 2020-01-29 09:41:25.226198+00
 2020-01-29 09:42:25.336989+00
 2020-01-29 09:43:25.356069+00
 2020-01-29 09:44:25.37381+00
 2020-01-29 09:45:25.392944+00

PostgreSQL. PostgreSQL recovery WAL, .


systemctl start postgresql-9.6
tail -fn100 /var/lib/pgsql/9.6/data/pg_log/postgresql-Wed.log

PostgreSQL 12 -:


  • restore_command recovery_target_time postgresql.conf
  • $PGDATA/recovery.signal


1GB https://gist.github.com/ololobus/5b25c432f208d7eb31051a5f238dffff


1GB .


postgres=# SELECT pg_size_pretty(pg_database_size('test1'));
pg_size_pretty
----------------
1003 MB

s4cmd is a free command line tool for working with data located in Amazon S3 storage. The utility is written in the python programming language, and due to this it can be used on both Windows and Linux operating systems.


Install s4cmd


pip install s4cmd

Lz4


s4cmd --endpoint-url=http://ip---minio:9000 --access-key=xxxx --secret-key=yyyy du -r s3://pg-backups
840540822       s3://pg-backups/wal_005/
840    lz4  WAL 

   lz4 - 1GB 
time backup_push.sh
real 0m18.582s

 S3    

581480085       s3://pg-backups/basebackups_005/
842374424   s3://pg-backups/wal_005
581

LZMA


  1 
338413694       s3://pg-backups/wal_005/
338     lzma

   
time backup_push.sh
real    5m25.054s

   S3
270310495       s3://pg-backups/basebackups_005/
433485092   s3://pg-backups/wal_005/

270       lzma

Brotli


  1 
459229886       s3://pg-backups/wal_005/
459     brotli

   
real    0m23.408s

   S3
312960942       s3://pg-backups/basebackups_005/
459309262   s3://pg-backups/wal_005/

312       brotli

Comparison of the results on the graph.



As you can see, Brotli is comparable in size to LZMA, but backup is performed during LZ4.


Chat of the Russian-speaking community PostgreSQL: https://t.me/pgsql


Please put a star on Github if you use wal-g

Source: https://habr.com/ru/post/undefined/

More articles:


All Articles