Re: Question on full vacuum clearing waste space - Mailing list pgsql-general

From Wenjun Che
Subject Re: Question on full vacuum clearing waste space
Date
Msg-id CACYkyiTG90jbA5mhE=auBoq_-gBZjsz2a_t9wJAomzCjb6L9NQ@mail.gmail.com
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In response to Re: Question on full vacuum clearing waste space  (Mohamed Wael Khobalatte <mkhobalatte@grubhub.com>)
Responses Re: Question on full vacuum clearing waste space  (Adrian Klaver <adrian.klaver@aklaver.com>)
List pgsql-general
Thank you for the quick response.

I ran the script from https://wiki.postgresql.org/wiki/Show_database_bloat, which shows "app_event_users" table has 3751936 as wastedbytes.

On Sun, Jun 7, 2020 at 12:32 AM Mohamed Wael Khobalatte <mkhobalatte@grubhub.com> wrote:

On Sat, Jun 6, 2020 at 11:24 PM Wenjun Che <wenjun@openfin.co> wrote:
Hi

I am testing full vacuum with pg 10.10 on AWS RDS.  I noticed for some tables, the number of waste bytes stays at a few MB after I run full vacuum.  I double-checked that there are no long running transactions, no orphaned prepared transactions and no abandoned replication slots. 

Here is output from full vacuum for one of the tables:

VACUUM(FULL, ANALYZE, VERBOSE) app_events_users
vacuuming "app_events_users"
"app_events_users": found 0 removable, 1198881 nonremovable row versions in 13369 pages
analyzing "licensing.app_events_users"
"app_events_users": scanned 13369 of 13369 pages, containing 1198881 live rows and 0 dead rows; 30000 rows in sample, 1198881 estimated total rows

What else can prevent full vacuum from reclaiming all waste space ?

Thank you 

What "waste query" are you running? Those tend to be estimates only. Vacuum Full clearly did its job from that log you shared. 


--
Wenjun Che
VP of Engineering | OpenFin

Move Fast.  Break Nothing.
www.openfin.co | @openfintech

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