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README_GPDB_en.md

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This manual describes how to compile pgBackRest, use it to create a backup copy of the Greenplum cluster and recover from it.

1. Supported versions of Greenplum

Currently, Greenplum 6 and Greenplum 7 are supported.

2. pgBackRest compilation

  • Install dependencies

The following installation commands must be executed as root.

Command on CentOS 7 
yum install git gcc openssl-devel libxml2-devel bzip2-devel libzstd-devel lz4-devel libyaml-devel zlib-devel libssh2-devel
Command on ALT Linux p10 
apt-get update
apt-get install git gcc openssl-devel libxml2-devel bzip2-devel libzstd-devel liblz4-devel libyaml-devel zlib-devel libssh2-devel
Command on Ubuntu 22.04 
apt-get update
apt-get install gcc git libbz2-dev liblz4-dev libssh2-1-dev libssl-dev libxml2-dev libyaml-dev libzstd-dev pkg-config zlib1g-dev
  • Set environment variables

The PATH variable should contain a path to pg_config of Greenplum, and LD_LIBRARY_PATH should contain a path to libpq.so.5.

source <GPDB_DIR>/greenplum_path.sh
  • Download the repository
git clone https://github.com/arenadata/pgbackrest -b 2.52-ci
  • Go to the source code directory
cd pgbackrest/src/
  • Run the configuration script

Optimization (-O2) and vectorization of page checksum calculations will be enabled without parameters.

./configure

For debugging, it is recommended to run the command

CFLAGS="-O0 -g3" ./configure --disable-optimize --enable-test
  • Build

The command to build using all available cores and without displaying executable commands

make -j`nproc` -s

As a result, an executable file named pgbackrest will appear in the current directory.

  • Install
sudo make install

By default, the pgbackrest executable file will be placed in the /usr/local/bin directory. This is the only action that is performed during the installation phase.

3. Configuration

  • Create directories for backup and log. For the test, let it be /tmp/backup and /tmp/backup/log.
mkdir -p /tmp/backup/log
  • Create a configuration file

In the following command examples, it is assumed that the configuration file has a standard name - /etc/pgbackrest.conf. If you need to use another file, its name can be passed through the --config parameter. For standard demo cluster created with DATADIRS=/tmp/gpdb the command to create a configuration file will require superuser rights and will look like this:

Command for Greenplum 6 
sudo tee /etc/pgbackrest.conf <<EOF
[seg-1]
pg1-path=/tmp/gpdb/qddir/demoDataDir-1
pg1-port=6000

[seg0]
pg1-path=/tmp/gpdb/dbfast1/demoDataDir0
pg1-port=6002

[seg1]
pg1-path=/tmp/gpdb/dbfast2/demoDataDir1
pg1-port=6003

[seg2]
pg1-path=/tmp/gpdb/dbfast3/demoDataDir2
pg1-port=6004

[global]
repo1-path=/tmp/backup
log-path=/tmp/backup/log
start-fast=y
fork=GPDB
EOF
Command for Greenplum 7 
sudo tee /etc/pgbackrest.conf <<EOF
[seg-1]
pg1-path=/tmp/gpdb/qddir/demoDataDir-1
pg1-port=7000

[seg0]
pg1-path=/tmp/gpdb/dbfast1/demoDataDir0
pg1-port=7002

[seg1]
pg1-path=/tmp/gpdb/dbfast2/demoDataDir1
pg1-port=7003

[seg2]
pg1-path=/tmp/gpdb/dbfast3/demoDataDir2
pg1-port=7004

[global]
repo1-path=/tmp/backup
log-path=/tmp/backup/log
start-fast=y
fork=GPDB
EOF

This version of pgBackRest can be used for both PostgreSQL and Greenplum backups, so you should specify in the fork parameter which DBMS is backed up. Description of the remaining parameters can be found in the documentation or in build/help/help.xml.

  • Create and initialize directories for the coordinator and each primary segment in which files for recovery will be stored
for i in -1 0 1 2
do 
    PGOPTIONS="-c gp_session_role=utility" pgbackrest --stanza=seg$i stanza-create
done
  • Configure Greenplum
gpconfig -c archive_mode -v on
gpconfig -c archive_command -v "'PGOPTIONS=\"-c gp_session_role=utility\" /usr/local/bin/pgbackrest --stanza=seg%c archive-push %p'" --skipvalidation
gpstop -ar
  • Install the gp_pitr extension (skip this step for Greenplum 7)

Run the query below in any client application, for example in psql.

create extension gp_pitr;

This extension is necessary to work with restore points.

  • Check that the backup and the WAL archiving are configured correctly
for i in -1 0 1 2
do 
	PGOPTIONS="-c gp_session_role=utility" pgbackrest --stanza=seg$i check
done

The command should not output an error message

4. Backup of the Greenplum cluster

4.1 Save files from primary segments and coordinator

for i in -1 0 1 2
do 
    PGOPTIONS="-c gp_session_role=utility" pgbackrest --stanza=seg$i backup
done

If you need to stop an interrupted backup, you can do this with the query

select pg_stop_backup() from gp_dist_random('gp_id');

4.2 Сreate a named restore point

Run the query

select gp_create_restore_point('backup1');

The record of the restore point will be stored in WAL.

4.3 Archive the files that store the created restore point.

Sending to the archive is carried out by switching WALs on coordinator and segments to new files using the query

select gp_switch_wal();

5. Restoring the Greenplum cluster

  • Stop the cluster and delete the contents of the directories of all cluster components
gpstop -a
rm -rf /tmp/gpdb/qddir/demoDataDir-1/* /tmp/gpdb/dbfast1/demoDataDir0/* /tmp/gpdb/dbfast2/demoDataDir1/* /tmp/gpdb/dbfast3/demoDataDir2/* /tmp/gpdb/dbfast_mirror1/demoDataDir0/* /tmp/gpdb/dbfast_mirror2/demoDataDir1/* /tmp/gpdb/dbfast_mirror3/demoDataDir2/* /tmp/gpdb/standby/*
  • Restore the contents of the coordinator's and primary segment directories from a backup

The name of the restore point from point 4.2 is passed in the --target parameter.

Command for Greenplum 6 
for i in -1 0 1 2
do 
    pgbackrest --stanza=seg$i --type=name --target=backup1 restore
done
Command for Greenplum 7 
for i in -1 0 1 2
do 
    pgbackrest --stanza=seg$i --type=name --target=backup1 --target-action=promote restore
done

In Greenplum 7, the recovery_target_action configuration parameter has been introduced to dictate the system's action upon reaching a specified recovery point. The default setting, pause, halts the recovery process, waiting for further instructions. To ensure the cluster automatically resumes operation post-recovery, this parameter should be changed to promote.

  • Run only the coordinator
gpstart -am
  • Remove the secondary coordinator from the cluster
gpinitstandby -ar
  • Mark mirror segments as unavailable
PGOPTIONS="-c gp_session_role=utility" psql postgres -c "
set allow_system_table_mods to true;
update gp_segment_configuration 
 set status = case when role='m' then 'd' else status end, 
     mode = 'n'
 where content >= 0;"
  • Restart the cluster in normal mode
gpstop -ar
  • Restore mirrors by primary segments
gprecoverseg -aF
  • Restore the secondary coordinator
Command for Greenplum 6 
gpinitstandby -as $HOSTNAME -S /tmp/gpdb/standby -P 6001
Command for Greenplum 7 
gpinitstandby -as $HOSTNAME -S /tmp/gpdb/standby -P 7001
  • Make sure that all cluster components are restored and working

Run the query

select * from gp_segment_configuration order by content, role;

One line should be output for the coordinator, backup coordinator, and each primary and mirror segment. All rows in the status column must have the u value.