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Thread: Where does vacuum FULL write temp-files?

Where does vacuum FULL write temp-files?

From
Andreas Joseph Krogh
Date:
Hi all.
 
I'm planning to vacuum FULL a pg_largeobject relation (after vacuumlo'ing it). The relation is 300GB large so I'm concerned the operation will write full my pg_xlog directory which is on a 200GB (net) RAID1 SSD.
 
Where does vacuum FULL rewrite to, does it use pg_xlog or some other directory?
 
Thanks.
 
--
Andreas Joseph Krogh
CTO / Partner - Visena AS
Mobile: +47 909 56 963
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Re: Where does vacuum FULL write temp-files?

From
Venkata Balaji N
Date:
 
I'm planning to vacuum FULL a pg_largeobject relation (after vacuumlo'ing it). The relation is 300GB large so I'm concerned the operation will write full my pg_xlog directory which is on a 200GB (net) RAID1 SSD.
 
Where does vacuum FULL rewrite to, does it use pg_xlog or some other directory?

 
Which version of PostgreSQL is this ?

If i got your question correctly, VACUUM FULL would rewrite the data to a new data file associated with that particular relation (Table) in the "$PGDATA/base" directory. This needs an extra disk space at the OS level (this is not related to pg_xlog directory).

As VACUUMING is a data change operation, "pg_xlog" will also have only the WAL data (modifications) written at the time of VACUUMING.

http://www.postgresql.org/docs/9.4/static/sql-vacuum.html

Regards,
Venkata Balaji N

Fujitsu Australia

Re: Where does vacuum FULL write temp-files?

From
Andreas Joseph Krogh
Date:
På onsdag 15. april 2015 kl. 04:34:31, skrev Venkata Balaji N <nag1010@gmail.com>:
 
I'm planning to vacuum FULL a pg_largeobject relation (after vacuumlo'ing it). The relation is 300GB large so I'm concerned the operation will write full my pg_xlog directory which is on a 200GB (net) RAID1 SSD.
 
Where does vacuum FULL rewrite to, does it use pg_xlog or some other directory?
 
Which version of PostgreSQL is this ?
 
If i got your question correctly, VACUUM FULL would rewrite the data to a new data file associated with that particular relation (Table) in the "$PGDATA/base" directory. This needs an extra disk space at the OS level (this is not related to pg_xlog directory).

As VACUUMING is a data change operation, "pg_xlog" will also have only the WAL data (modifications) written at the time of VACUUMING.

http://www.postgresql.org/docs/9.4/static/sql-vacuum.html
 
This is PG-9.3
 
So I understand that VACUUM FULL writes the new table to the same tablespace as the original table (also for system-catalogs like pg_largeobject), and doesn't use any temp-space outside the location of that tablespace?
 
Thanks.
 
--
Andreas Joseph Krogh
CTO / Partner - Visena AS
Mobile: +47 909 56 963
 
Attachment

Re: Where does vacuum FULL write temp-files?

From
Guillaume Lelarge
Date:
2015-04-15 10:46 GMT+02:00 Andreas Joseph Krogh <andreas@visena.com>:
På onsdag 15. april 2015 kl. 04:34:31, skrev Venkata Balaji N <nag1010@gmail.com>:
 
I'm planning to vacuum FULL a pg_largeobject relation (after vacuumlo'ing it). The relation is 300GB large so I'm concerned the operation will write full my pg_xlog directory which is on a 200GB (net) RAID1 SSD.
 
Where does vacuum FULL rewrite to, does it use pg_xlog or some other directory?
 
Which version of PostgreSQL is this ?
 
If i got your question correctly, VACUUM FULL would rewrite the data to a new data file associated with that particular relation (Table) in the "$PGDATA/base" directory. This needs an extra disk space at the OS level (this is not related to pg_xlog directory).

As VACUUMING is a data change operation, "pg_xlog" will also have only the WAL data (modifications) written at the time of VACUUMING.

http://www.postgresql.org/docs/9.4/static/sql-vacuum.html
 
This is PG-9.3
 
So I understand that VACUUM FULL writes the new table to the same tablespace as the original table (also for system-catalogs like pg_largeobject), and doesn't use any temp-space outside the location of that tablespace?

You're right.


--

Re: Where does vacuum FULL write temp-files?

From
Andreas Joseph Krogh
Date:
På fredag 17. april 2015 kl. 00:05:47, skrev Guillaume Lelarge <guillaume@lelarge.info>:
2015-04-15 10:46 GMT+02:00 Andreas Joseph Krogh <andreas@visena.com>:
På onsdag 15. april 2015 kl. 04:34:31, skrev Venkata Balaji N <nag1010@gmail.com>:
 
I'm planning to vacuum FULL a pg_largeobject relation (after vacuumlo'ing it). The relation is 300GB large so I'm concerned the operation will write full my pg_xlog directory which is on a 200GB (net) RAID1 SSD.
 
Where does vacuum FULL rewrite to, does it use pg_xlog or some other directory?
 
Which version of PostgreSQL is this ?
 
If i got your question correctly, VACUUM FULL would rewrite the data to a new data file associated with that particular relation (Table) in the "$PGDATA/base" directory. This needs an extra disk space at the OS level (this is not related to pg_xlog directory).

As VACUUMING is a data change operation, "pg_xlog" will also have only the WAL data (modifications) written at the time of VACUUMING.

http://www.postgresql.org/docs/9.4/static/sql-vacuum.html
 
This is PG-9.3
 
So I understand that VACUUM FULL writes the new table to the same tablespace as the original table (also for system-catalogs like pg_largeobject), and doesn't use any temp-space outside the location of that tablespace?
 
 
You're right.
 
Thanks.
 
--
Andreas Joseph Krogh
CTO / Partner - Visena AS
Mobile: +47 909 56 963
 
Attachment