pg_repack -- Reorganize tables in PostgreSQL databases with minimal locks

pg_repack is a PostgreSQL extension which lets you remove bloat from tables and indexes, and optionally restore the physical order of clustered indexes. Unlike CLUSTER and VACUUM FULL it works online, without holding an exclusive lock on the processed tables during processing. pg_repack is efficient to boot, with performance comparable to using CLUSTER directly.

pg_repack is a fork of the previous pg_reorg project. Please check the project page for bug report and development information.

You can choose one of the following methods to reorganize:

  • Online CLUSTER (ordered by cluster index)
  • Ordered by specified columns
  • Online VACUUM FULL (packing rows only)

NOTICE:

  • Only superusers can use the utility.
  • Target table must have a PRIMARY KEY, or at least a UNIQUE total index on a NOT NULL column.

Requirements

PostgreSQL versions
PostgreSQL 8.2, 8.3, 8.4, 9.0, 9.1, 9.2
OS
RHEL 5.2, Windows XP SP3
Disks
Requires free disk space twice as large as the target table(s) and indexes. For example, if the total size of the tables and indexes to be reorganized is 1GB, an additional 2GB of disk space is required.

Download

You can download pg_repack from the PGXN website. Unpack the archive and follow the installation instructions.

Alternatively you can use the PGXN Client to download, compile and install the package; use:

$ pgxn install pg_repack

Check the pgxn install documentation for the options available.

Installation

pg_repack can be built with make on UNIX or Linux. The PGXS build framework is used automatically. Before building, you might need to install the PostgreSQL development packages (postgresql-devel, etc.) and add the directory containing pg_config to your $PATH. Then you can run:

$ cd pg_repack
$ make
$ sudo make install

You can also use Microsoft Visual C++ 2010 to build the program on Windows. There are project files in the msvc folder.

After installation, load the pg_repack extension in the database you want to process. On PostgreSQL 9.1 and following pg_repack is packaged as an extension, so you can execute:

$ psql -c "CREATE EXTENSION pg_repack" -d your_database

For previous PostgreSQL versions you should load the script $SHAREDIR/contrib/pg_repack.sql in the database to process; you can get $SHAREDIR using pg_config --sharedir, e.g.

$ psql -f "$(pg_config --sharedir)/contrib/pg_repack.sql" -d your_database

You can remove pg_repack from a PostgreSQL 9.1 and following database using DROP EXTENSION pg_repack. For previous Postgresql versions load the $SHAREDIR/contrib/uninstall_pg_repack.sql script or just drop the repack schema.

If you are upgrading from a previous version of pg_repack or pg_reorg, just drop the old version from the database as explained above and install the new version.

Usage

pg_repack [OPTION]... [DBNAME]

The following options can be specified in OPTIONS.

Options:
-a, --all repack all databases
-n, --no-order do vacuum full instead of cluster
-o, --order-by=COLUMNS
 order by columns instead of cluster keys
-t, --table=TABLE
 repack specific table only
-T, --wait-timeout=SECS
 timeout to cancel other backends on conflict
-Z, --no-analyze
 don't analyze at end
Connection options:
-d, --dbname=DBNAME
 database to connect
-h, --host=HOSTNAME
 database server host or socket directory
-p, --port=PORT
 database server port
-U, --username=USERNAME
 user name to connect as
-w, --no-password
 never prompt for password
-W, --password force password prompt
Generic options:
-e, --echo echo queries
-E, --elevel=LEVEL
 set output message level
--help show this help, then exit
--version output version information, then exit

Reorg Options

Options to order rows. If not specified, pg_repack performs an online CLUSTER using cluster indexes. Only one option can be specified. You may also specify target tables or databases.

-n, --no-order
Do online VACUUM FULL.
-o COLUMNS [,...], --order-by=COLUMNS [,...]
Do online CLUSTER ordered by specified columns.
-t TABLE, --table=TABLE
Reorganize table only. If you don't specify this option, all tables in specified databases are reorganized.
-T SECS, --wait-timeout=SECS
pg_repack needs to take an exclusive lock at the end of the reorganization. This setting controls how long it wait for acquiring the lock in seconds. If the lock cannot be taken even after the duration, pg_repack forces to cancel conflicted queries. Also, if the server version is 8.4 or newer, pg_repack forces to disconnect conflicted backends after twice time passed. The default is 60 seconds.
-Z, --no-analyze
Disable ANALYZE after the reorganization. If not specified, run ANALYZE after the reorganization.

Connection Options

Options to connect to servers. You cannot use --all and --dbname or --table together.

-a, --all
Reorganize all databases.
-d DBNAME, --dbname=DBNAME
Specifies the name of the database to be reorganized. If this is not specified and -a (or --all) is not used, the database name is read from the environment variable PGDATABASE. If that is not set, the user name specified for the connection is used.
-h HOSTNAME, --host=HOSTNAME
Specifies the host name of the machine on which the server is running. If the value begins with a slash, it is used as the directory for the Unix domain socket.
-p PORT, --port=PORT
Specifies the TCP port or local Unix domain socket file extension on which the server is listening for connections.
-U USERNAME, --username=USERNAME
User name to connect as.
-w, --no-password
Never issue a password prompt. If the server requires password authentication and a password is not available by other means such as a .pgpass file, the connection attempt will fail. This option can be useful in batch jobs and scripts where no user is present to enter a password.
-W, --password

Force the program to prompt for a password before connecting to a database.

This option is never essential, since the program will automatically prompt for a password if the server demands password authentication. However, pg_repack will waste a connection attempt finding out that the server wants a password. In some cases it is worth typing -W to avoid the extra connection attempt.

Generic Options

-e, --echo
Echo commands sent to server.
-E LEVEL, --elevel=LEVEL
Choose the output message level from DEBUG, INFO, NOTICE, WARNING, ERROR, LOG, FATAL, and PANIC. The default is INFO.
--help
Show usage of the program.
--version
Show the version number of the program.

Environment

PGDATABASE, PGHOST, PGPORT, PGUSER

Default connection parameters

This utility, like most other PostgreSQL utilities, also uses the environment variables supported by libpq (see Environment Variables).

Examples

Execute the following command to perform an online CLUSTER of all tables in test database:

$ pg_repack test

Execute the following command to perform an online VACUUM FULL to foo table in test database:

$ pg_repack --no-order --table foo -d test

Diagnostics

Error messages are reported when pg_repack fails. The following list shows the cause of errors.

You need to cleanup by hand after fatal errors. To cleanup, just remove pg_repack from the database and install it again: for PostgreSQL 9.1 and following execute DROP EXTENSION pg_repack CASCADE in the database where the error occurred, followed by CREATE EXTENSION pg_repack; for previous version load the script $SHAREDIR/contrib/uninstall_pg_repack.sql into the database where the error occured and then load $SHAREDIR/contrib/pg_repack.sql again.

pg_repack: reorg database "template1" ... skipped: pg_repack is not installed in the database

pg_repack is not installed in the database when --all option is specified.

Do register pg_repack to the database.

ERROR: pg_repack is not installed

pg_repack is not installed in the database specified by --dbname.

Do register pg_repack to the database.

ERROR: program 'pg_repack V1' does not match database library 'pg_repack V2'

There is a mismatch between the pg_repack binary and the database library (.so or .dll).

The mismatch could be due to the wrong binary in the $PATH or the wrong database being addressed. Check the program directory and the database; if they are what expected you may need to repeat pg_repack installation.

ERROR: extension 'pg_repack V1' required, found extension 'pg_repack V2'

The SQL extension found in the database does not match the version required by the pg_repack program.

You should drop the extension from the database and reload it as described in the installation section.

ERROR: relation "table" has no primary key

The target table doesn't have PRIMARY KEY.

Define PRIMARY KEY to the table. (ALTER TABLE ADD PRIMARY KEY)

ERROR: relation "table" has no cluster key

The target table doesn't have CLUSTER KEY.

Define CLUSTER KEY to the table. (ALTER TABLE CLUSTER)

pg_repack: query failed: ERROR: column "col" does not exist

The target table doesn't have columns specified by --order-by option.

Specify existing columns.

ERROR: permission denied for schema repack

Permission error.

pg_repack must be executed by superusers.

pg_repack: query failed: ERROR: trigger "z_repack_trigger" for relation "tbl" already exists

The target table already has a trigger named z_repack_trigger.

Delete or rename the trigger.

pg_repack: trigger conflicted for tbl

The target table already has a trigger which follows by z_repack_trigger in alphabetical order.

Delete or rename the trigger.

Restrictions

pg_repack has the following restrictions. Be careful to avoid data corruptions.

Temp tables

pg_repack cannot reorganize temp tables.

GiST indexes

pg_repack cannot reorganize tables using GiST indexes.

DDL commands

You cannot do DDL commands except VACUUM and ANALYZE during pg_repack. In many cases pg_repack will fail and rollback correctly, but there are some cases which may result in data corruption.

TRUNCATE
TRUNCATE is lost. Deleted rows still exist after pg_repack.
CREATE INDEX
It causes index corruption.
ALTER TABLE ... ADD COLUMN
It causes loss of data. Newly added columns are initialized with NULLs.
ALTER TABLE ... ALTER COLUMN TYPE
It causes data corruption.
ALTER TABLE ... SET TABLESPACE
It causes data corruption by wrong relfilenode.

Details

pg_repack creates a work table in the repack schema and sorts the rows in this table. Then, it updates the system catalogs directly to swap the work table and the original one.

Releases

  • pg_repack 1.1.8
    • Added support for PostgreSQL 9.2.
    • Added support for CREATE EXTENSION on PostgreSQL 9.1 and following.
    • Give user feedback while waiting for transactions to finish (pg_reorg issue #5).
    • Bugfix: Allow running on newly promoted streaming replication slaves (pg_reorg issue #1).
    • Bugfix: Fix interaction between pg_repack and Slony 2.0/2.1 (pg_reorg issue #4)
    • Bugfix: Properly escape column names (pg_reorg issue #6).
    • Bugfix: Avoid recreating invalid indexes, or choosing them as key (pg_reorg issue #9).
    • Bugfix: Never choose a partial index as primary key (pg_reorg issue #22).
  • pg_reorg 1.1.7 (2011-08-07)
    • Bugfix: VIEWs and FUNCTIONs could be corrupted that used a reorganized table which has a dropped column.
    • Supports PostgreSQL 9.1 and 9.2dev. (but EXTENSION is not yet)

See Also