Re: bloated postgres data folder, clean up

Hi,

So, I still think the SQL function isnt really working well.
Here’s what I did:

/data/postgres # psql

postgres=# \copy ( select * from find_useless_postgres_file('live') ) to /tmp/useless_files.csv delimiter ';' csv header;
postgres=# \q

/data/postgres # wc -l /tmp/useless_files.csv
7422 /tmp/useless_files.csv

# filter out the .## files, e.g.:
# 48175847.37;/base/16398/48175847.37;/data/postgres/base/16398/48175847.37;1047420928
# 48175847.36;/base/16398/48175847.36;/data/postgres/base/16398/48175847.36;1073741824
# 48175847.35;/base/16398/48175847.35;/data/postgres/base/16398/48175847.35;1073741824
# 48175847.34;/base/16398/48175847.34;/data/postgres/base/16398/48175847.34;1073741824
# 48175847.33;/base/16398/48175847.33;/data/postgres/base/16398/48175847.33;1073741824
# 48175847.32;/base/16398/48175847.32;/data/postgres/base/16398/48175847.32;1073741824
# 48175847.31;/base/16398/48175847.31;/data/postgres/base/16398/48175847.31;1073741824
# 48175847.30;/base/16398/48175847.30;/data/postgres/base/16398/48175847.30;1073741824
#
# because oid2name doesn't like them, gives error:
# /data/postgres # oid2name -f 48175847.30 -i -S -q -d live
# oid2name: query failed: ERROR: invalid input syntax for type oid: "48175847.30"
# LINE 11: (pg_catalog.pg_relation_filenode(c.oid) IN ('48175847.30')...
# ^
#
# oid2name: query was: SELECT pg_catalog.pg_relation_filenode(c.oid) as "Filenode", relname as "Table Name"
# FROM pg_catalog.pg_class c
# LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
# LEFT JOIN pg_catalog.pg_database d ON d.datname = pg_catalog.current_database(),
# pg_catalog.pg_tablespace t
# WHERE relkind IN ('r', 'm', 'i', 'S', 't') AND
# t.oid = CASE
# WHEN reltablespace <> 0 THEN reltablespace
# ELSE dattablespace
# END AND
# (pg_catalog.pg_relation_filenode(c.oid) IN ('48175847.30'))
# ORDER BY relname

/data/postgres # cut -d ';' -f1 /tmp/useless_files.csv | cut -d'.' -f1 | sort -n | uniq >/tmp/potential_useless_oids.csv
/data/postgres # wc -l /tmp/potential_useless_oids.csv
1017 /tmp/potential_useless_oids.csv

# get a list of all used oids, instead of examing one by one
/data/postgres # oid2name -i -S -q -d live | awk '{print $1}' | sort -n | uniq >/tmp/used_oids.csv
/data/postgres # wc -l /tmp/used_oids.csv
940 /tmp/used_oids.csv

/data/postgres # while read i; do grep $i /tmp/used_oids.csv >/dev/null || (echo "$i" >>/tmp/not_in_use_oids.csv); done < /tmp/potential_useless_oids.csv
/data/postgres # wc -l /tmp/not_in_use_oids.csv
168 /tmp/not_in_use_oids.csv

/data/postgres # egrep -v 'fsm|vm' /tmp/not_in_use_oids.csv |wc -l
1
/data/postgres # egrep -v 'fsm|vm' /tmp/not_in_use_oids.csv
file_name
# The CSV header only

So, no bloated files.
But, using the function from https://wiki.postgresql.org/wiki/Show_database_bloat I get:

live=# select tbloat,wasted_space from table_bloat order by wasted_space desc limit 25;
tbloat │ wasted_space
────────┼──────────────
1.0 │ 9976 kB
1.2 │ 98 GB
1.0 │ 97 MB
1.4 │ 96 kB
1.2 │ 920 kB
1.2 │ 88 kB
1.1 │ 88 kB
2.0 │ 8192 bytes
0.0 │ 8192 bytes
1.3 │ 8192 bytes
2.0 │ 8192 bytes
1.3 │ 8192 bytes
1.5 │ 8192 bytes
1.5 │ 8192 bytes
2.0 │ 8192 bytes
1.1 │ 8192 bytes
1.0 │ 8192 bytes
1.1 │ 8192 bytes
1.3 │ 8192 bytes
1.5 │ 8192 bytes
1.1 │ 80 kB
1.0 │ 7584 kB
1.6 │ 71 MB
1.0 │ 704 kB
1.1 │ 6968 kB
(25 rows)

So actually, quite a lot of bloated data ☺
What am I doing wrong?

Mit freundlichen Grüßen / With kind regards,
Johnny Morano
____________________________________________________

Johnny Morano | Principal Systems Engineer

PAY.ON GmbH | AN ACI WORLDWIDE COMPANY | WWW.PAYON.COM<http://www.payon.com/>
Jakob-Haringer-Str. 1 | 5020 Salzburg | Austria

This email message and any attachments may contain confidential, proprietary or non-public information. This information is intended solely for the designated recipient(s). If an addressing or transmission error has misdirected this email, please notify the sender immediately and destroy this email. Any review, dissemination, use or reliance upon this information by unintended recipients is prohibited. Any opinions expressed in this email are those of the author personally.

From: Rémi Cura [mailto:remi(dot)cura(at)gmail(dot)com]
Sent: Mittwoch, 2. März 2016 17:49
To: Johnny Morano
Cc: Alvaro Herrera; PostgreSQL General
Subject: Re: [GENERAL] bloated postgres data folder, clean up

Hey,
this is quite the *opposite*.
The function find files in the postgres database folder that are not used by the database.
To use it :
* connect to the database you want to analyse ( **mandatory** ).
* create the function (execute function definition)
* Execute `SELECT * FROM find_useless_postgres_file('your_database_name')`

This will output a list of files that are on the disk but not used by postgres,
and so can be removed.
To be extra sure, you should use oid2name programme to check that the useless files are really useless.

For this :
* output the list of potential useless files with copy for instance
ex :
COPY ( SELECT file_name
FROM find_useless_postgres_file('your_database_name')
) TO 'path_to_you_database_folder/potential_useless.txt'
now you've got a file with a list of potential erroneous files.
* Then use oid2name
`$su postgres
$cd path_to_you_database_folder
$while read i; do oid2name -f "$i" -i -S -q -d your_database_name; done < potential_useless.txt
`
Nothing should show, meaning that every potential erroneous file
has not been recognized by oid2name !
If you feel unconvinced, you can manually try oid2name on some
of the potential erroneous files, to be extra sure.
It should not find anything.

* Now delete all the files in `potential_useless.txt`.
It could be wiser to not delete the files but rename those
(for instance, adding `.potentially_useless` as a postfix)
so if it breaks something, you have an easy way to revert everything.

Anyway, use *-*extra extra*-* caution if you delete.
Except a backup, there would be no easy way to correct a mistake.
Cheers,
Rémi-C

2016-03-02 15:38 GMT+01:00 Johnny Morano <johnny(dot)morano(at)payon(dot)com<mailto:johnny(dot)morano(at)payon(dot)com>>:
Hi Remi!

This SQL function you have provided, seems to return all valid files, is that correct? In my case, it returned all my ‘base/’ files. Is that normal?
If yes, maybe you rename the function to ‘find_useful_postgres_files’ ;-)

Could you explain in steps how to use this function to make a cleanup of bloated data? (like in an example with commands and example output, if possible of course)

Thanks!

Mit besten Grüßen / With best regards,
Johnny Morano
____________________________________________________

Johnny Morano | Principal Systems Engineer

PAY.ON GmbH | AN ACI WORLDWIDE COMPANY | WWW.PAYON.COM<http://www.payon.com/>
Jakob-Haringer-Str. 1 | 5020 Salzburg | Austria
Registered at: LG Salzburg | Company number: FN 315081 f | VAT-ID: ATU64439405
Managing Director: Christian Bamberger

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From: pgsql-general-owner(at)postgresql(dot)org<mailto:pgsql-general-owner(at)postgresql(dot)org> [mailto:pgsql-general-owner(at)postgresql(dot)org<mailto:pgsql-general-owner(at)postgresql(dot)org>] On Behalf Of Rémi Cura
Sent: Mittwoch, 2. März 2016 14:58
To: Alvaro Herrera
Cc: PostgreSQL General
Subject: Re: [GENERAL] bloated postgres data folder, clean up

Would gladly do it,
but still this "wiki cooloff" stuff,
can't create a page
Cheers,
Rémi-C

2016-02-29 20:44 GMT+01:00 Alvaro Herrera <alvherre(at)2ndquadrant(dot)com<mailto:alvherre(at)2ndquadrant(dot)com>>:
Rémi Cura wrote:
> Hey dear list,
> after a fex years of experiments and crash,
> I ended up with a grossly bloated postgres folder.
> I had about 8 Go of useless files.

Would you add a new page to the wiki with this?

https://wiki.postgresql.org/wiki/Category:Administrative_Snippets

--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services