Thread: Autovaccum
Hi list, I would like to know if it is necessary to set my database to autovaccum if the intent of my DB Manager is do not make any deletion in any time. If there is no deletions why autovaccum ok ? Regards Ezequias
Ezequias Rodrigues da Rocha wrote: > Hi list, > > I would like to know if it is necessary to set my database to > autovaccum if the intent of my DB Manager is do not make any deletion > in any time. > > If there is no deletions why autovaccum ok ? You need to vacuum from time to time anyway, even if you don't delete anything. The easiest way to do it is let autovacuum do it for you. -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc.
On 30/11/06, Alvaro Herrera <alvherre@commandprompt.com> wrote: > Ezequias Rodrigues da Rocha wrote: > > Hi list, > > > > I would like to know if it is necessary to set my database to > > autovaccum if the intent of my DB Manager is do not make any deletion > > in any time. > > > > If there is no deletions why autovaccum ok ? > > You need to vacuum from time to time anyway, even if you don't delete > anything. The easiest way to do it is let autovacuum do it for you. > Complete Answer. 1. If you do any updates or deletes you need to vacuum. 2. If you do any update, deletes or inserts you need to analyse. 3. If you never change anything No Updates, No Inserts, No Deletes you need to vacuum once ever 2 billion transactions due to wrap around if you don't your data will disappear. But depending on how busy your database is this could be once a year. 4. Auto Vacuum does all this automatically. Which is kind of useful. 5. You can do this manually via cron or by hand if you wish. Peter.
It is possible to set this up on PgAdmin ? I need to shutdown the postgresql service to change this parameters ? ps: Your information was very clear for me. Thank you very much. Ezequias 2006/11/30, Peter Childs <peterachilds@gmail.com>: > On 30/11/06, Alvaro Herrera <alvherre@commandprompt.com> wrote: > > Ezequias Rodrigues da Rocha wrote: > > > Hi list, > > > > > > I would like to know if it is necessary to set my database to > > > autovaccum if the intent of my DB Manager is do not make any deletion > > > in any time. > > > > > > If there is no deletions why autovaccum ok ? > > > > You need to vacuum from time to time anyway, even if you don't delete > > anything. The easiest way to do it is let autovacuum do it for you. > > > > Complete Answer. > > 1. If you do any updates or deletes you need to vacuum. > > 2. If you do any update, deletes or inserts you need to analyse. > > 3. If you never change anything No Updates, No Inserts, No Deletes you > need to vacuum once ever 2 billion transactions due to wrap around if > you don't your data will disappear. But depending on how busy your > database is this could be once a year. > > 4. Auto Vacuum does all this automatically. Which is kind of useful. > > 5. You can do this manually via cron or by hand if you wish. > > Peter. > > ---------------------------(end of broadcast)--------------------------- > TIP 7: You can help support the PostgreSQL project by donating at > > http://www.postgresql.org/about/donate > -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Atenciosamente (Sincerely) Ezequias Rodrigues da Rocha=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- A pior das democracias ainda é melhor do que a melhor das ditaduras The worst of democracies is still better than the better of dictatorships http://ezequiasrocha.blogspot.com/
Alvaro Herrera wrote: > Ezequias Rodrigues da Rocha wrote: >> Hi list, >> >> I would like to know if it is necessary to set my database to >> autovaccum if the intent of my DB Manager is do not make any deletion >> in any time. >> >> If there is no deletions why autovaccum ok ?> > You need to vacuum from time to time anyway, even if you don't delete > anything. The easiest way to do it is let autovacuum do it for you. > One thing that vacuum/autovacuum does is mark space used by deleted rows to be reused. Without deletes this won't be necessary in table data files. But when you update a record an index may also be updated and have the same effect within the index storage space. There are other things that vacuum does to keep your database running optimally. One is to update planner statistics about how many rows are in each table which effects the query planning and optimizing. Without deletes a plain vacuum won't achieve a great deal, but a regular VACUUM ANALYZE (as done by autovacuum) will make a difference to the performance of your database. If no data in your db changes then you won't have to bother vacuuming. -- Shane Ambler pgSQL@007Marketing.com Get Sheeky @ http://Sheeky.Biz
Ezequias Rodrigues da Rocha wrote: > It is possible to set this up on PgAdmin ? I don't know. > I need to shutdown the postgresql service to change this parameters ? No, you can just modify the params in postgresql.conf and HUP the server so that it re-reads the config file, no restart required.
Just a little question. What is the interval of time the vacuum will run on my database ? Ezequias 2006/11/30, Matthew T. O'Connor <matthew@zeut.net>: > Ezequias Rodrigues da Rocha wrote: > > It is possible to set this up on PgAdmin ? > > I don't know. > > > I need to shutdown the postgresql service to change this parameters ? > > No, you can just modify the params in postgresql.conf and HUP the server > so that it re-reads the config file, no restart required. > > > -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Atenciosamente (Sincerely) Ezequias Rodrigues da Rocha=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- A pior das democracias ainda é melhor do que a melhor das ditaduras The worst of democracies is still better than the better of dictatorships http://ezequiasrocha.blogspot.com/
Ezequias Rodrigues da Rocha wrote: > Could you tell me if only this both options are ok (attach) ? > > If I don't mark the interval of vacuuns what will be the interval of > each vacuum ? The default settings may be fine for you, it depends a bit on how many insert/updates you get in a given time frame. http://www.postgresql.org/docs/8.1/interactive/runtime-config-autovacuum.html will give a definition of each parameter that can be set. http://www.postgresql.org/docs/8.1/interactive/maintenance.html#AUTOVACUUM will explain in more detail. Basically every autovacuum_naptime seconds autovacuum looks at estimates of how much the database has changed since the last run. If the amount of change is greater than the thresholds determined from the other settings then a vacuum/analyze will be done. If you have 100 records added/updated per day then you may only need it to run 1 or 2 times a day using smaller thresholds. If you are adding 10,000 records an hour then you will want it to run more often. > 2006/11/30, Shane Ambler <pgsql@007marketing.com>: >> Alvaro Herrera wrote: >> > Ezequias Rodrigues da Rocha wrote: >> >> Hi list, >> >> >> >> I would like to know if it is necessary to set my database to >> >> autovaccum if the intent of my DB Manager is do not make any deletion >> >> in any time. >> >> >> >> If there is no deletions why autovaccum ok ? >> > >> > You need to vacuum from time to time anyway, even if you don't delete >> > anything. The easiest way to do it is let autovacuum do it for you. >> > >> >> One thing that vacuum/autovacuum does is mark space used by deleted rows >> to be reused. Without deletes this won't be necessary in table data >> files. But when you update a record an index may also be updated and >> have the same effect within the index storage space. >> >> There are other things that vacuum does to keep your database running >> optimally. One is to update planner statistics about how many rows are >> in each table which effects the query planning and optimizing. >> >> Without deletes a plain vacuum won't achieve a great deal, but a regular >> VACUUM ANALYZE (as done by autovacuum) will make a difference to the >> performance of your database. >> >> If no data in your db changes then you won't have to bother vacuuming. >> >> -- >> >> Shane Ambler >> pgSQL@007Marketing.com >> >> Get Sheeky @ http://Sheeky.Biz >> > > -- Shane Ambler pgSQL@007Marketing.com Get Sheeky @ http://Sheeky.Biz
Hi, Ezequias, "Ezequias Rodrigues da Rocha" <ezequias.rocha@gmail.com> wrote: > What is the interval of time the vacuum will run on my database ? That depends on your settings and load. Autovacuum looks at every table, and checks the number of modifications, as well as the total number of transactions since the last vacuum, and decides whether to VACUUM and/or ANALYZE. The thresholds for those settings can be configured per table, with the defaults in the postgresql.conf. Regards, Markus -- Markus Schaber | Logical Tracking&Tracing International AG Dipl. Inf. | Software Development GIS Fight against software patents in Europe! www.ffii.org www.nosoftwarepatents.org