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flexible-freeze

Flexible freeze scripts for managing off-hours vacuuming and freezing of PostgreSQL databases.

/scripts/flexible_freeze.py

This script is designed for doing VACUUM FREEZE or VACUUM ANALYZE runs on your database during known slow traffic periods. Takes a timeout so that it won't overrun your slow traffic period.

Tested on Python 3.8, but should work on any supported Python 3.

Supports any non-EOL version of PostgreSQL.

Requires psycopg2

usage: flexible_freeze.py [-h] [-m RUN_MIN] [-s MINSIZEMB] [-d DBLIST] [-T TABLES_TO_EXCLUDE]
                          [--exclude-table-in-database EXCLUDE_TABLE_IN_DATABASE] [--no-freeze] [--no-analyze] [--vacuum]
                          [--pause PAUSE_TIME] [--freezeage FREEZEAGE] [--costdelay COSTDELAY] [--costlimit COSTLIMIT] [-t]
                          [--enforce-time] [-l LOGFILE] [-v] [--debug] [-U DBUSER] [-H DBHOST] [-p DBPORT] [-w DBPASS] [-st TABLE]

optional arguments:
  -h, --help            show this help message and exit
  -m RUN_MIN, --minutes RUN_MIN
                        Number of minutes to run before halting. Defaults to 2 hours
  -s MINSIZEMB, --minsizemb MINSIZEMB
                        Minimum table size to vacuum/freeze (in MB). Default is 0.
  -d DBLIST, --databases DBLIST
                        Comma-separated list of databases to vacuum, if not all of them
  -T TABLES_TO_EXCLUDE, --exclude-table TABLES_TO_EXCLUDE
                        Exclude any table with this name (in any database). You can pass this option multiple times to exclude
                        multiple tables.
  --exclude-table-in-database EXCLUDE_TABLE_IN_DATABASE
                        Argument is of form 'DATABASENAME.TABLENAME' exclude the named table, but only when processing the named
                        database. You can pass this option multiple times.
  --no-freeze           Do VACUUM ANALYZE instead of VACUUM ANALYZE FREEZE
  --no-analyze          Do not do an ANALYZE as part of the VACUUM operation
  --vacuum              Do VACUUM ANALYZE instead of VACUUM ANALYZE FREEZE (deprecated option; use --no-freeze instead)
  --pause PAUSE_TIME    seconds to pause between vacuums. Default is 10.
  --freezeage FREEZEAGE
                        minimum age for freezing. Default 10m XIDs
  --costdelay COSTDELAY
                        vacuum_cost_delay setting in ms. Default 20
  --costlimit COSTLIMIT
                        vacuum_cost_limit setting. Default 2000
  -t, --print-timestamps
  --enforce-time        enforce time limit by terminating vacuum
  -l LOGFILE, --log LOGFILE
  -v, --verbose
  --debug
  -U DBUSER, --user DBUSER
                        database user
  -H DBHOST, --host DBHOST
                        database hostname
  -p DBPORT, --port DBPORT
                        database port
  -w DBPASS, --password DBPASS
                        database password
  -st TABLE, --table TABLE
                        only process specified table

Notes:

The minutes time limit is normally only enforced at the start of vacuuming each table, allowing vacuums to continue past the end of the time window. If you set --enforce-time, however, it uses statement_timeout to terminate a running vacuum at the end of the time window (plus 30 seconds grace period).

If you do not specify a --enforce_time, flexible_freeze will issue a SET statement_timeout = 0 statement before each operation to avoid cancellation by a system- or role-wide statement_timeout value.

Normally flexible_freeze.py does VACUUM FREEZE ANALYZE, starting with the tables with the oldest transaction IDs. If you set --no-freeze, though, it will instead do VACUUM ANALYZE, starting with the tables with the most dead rows. If you are doing both, do the FREEZE first.

You can specify --no-analyze to skip the ANALYZE step.

The database user supplied is expected to have permissions on all tables (e.g. a superuser). If they do not, flexible_freeze will error out.

Currently, flexible_freeze will not respond to a CTRL-C until the current vacuum is done. If you need to halt flexible_freeze before then, we recommend using pg_cancel_backend() from the Postgres command line. This will cause flexible_freeze to error out and exit.