## Esteban Zimanyi (ezima...@ulb.ac.be): > Is there a step-by-step procedure specified somewhere?
The first step is not to disable autovacuum... (why would you want to do that?). > For example, before launching the tests there is a load.sql file that loads > all the test tables. The file starts as follows > > SET statement_timeout = 0; That's all session parameters. The general principle here is: We have parameters which can be set inside a session - "SET ..." - or even inside a transaction - "SET LOCAL" - and reset again ("RESET ..."). These parameters are also in the server configuration - I like to think of those settings as the defaults for new sessions (except when overridden on a user/database/function level, etc.). Other parameters have to be set on the server level - that is, added to the configuration file(s). ("ALTER SYSTEM" is just a way to add configuration directives via the postgresql.auto.conf file). Changes the the configuration files become active after a server reload (or restart, of course). Some of these settings can only be set on server start (not reload) or even have to match the data directory. In any case, the documentation is very clear if a restart is required for changing a parameter, e.g. in https://www.postgresql.org/docs/13/runtime-config-autovacuum.html "This parameter can only be set in the postgresql.conf file or on the server command line" And some parameters can be set as storage parameters on a per-object (table, index, ...) base, but that's the next can of worms. The takeaways of this are: 1. ALTER SYSTEM only edits the configuration, reloads and restarts have to be handled by the operator as usual. Documentation: https://www.postgresql.org/docs/13/sql-altersystem.html "Values set with ALTER SYSTEM will be effective after the next server configuration reload, or after the next server restart in the case of parameters that can only be changed at server start. A server configuration reload can be commanded by calling the SQL function pg_reload_conf(), running pg_ctl reload, or sending a SIGHUP signal to the main server process." 2. Different parameters can have different contexts, which you should be aware of when changing them. Session and object ("storage") parameters take their defaults from the server configuration. Check parameter documentation and the pg_settings view (documented here: https://www.postgresql.org/docs/13/view-pg-settings.html ) for parameter contexts. 3. Don't disable autovacuum unless you really know what you're doing. Gruß, Christoph -- Spare Space