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Re: questions on toast tables

From: Warren Little <warren(dot)little(at)meridiascapital(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: questions on toast tables
Date: 2006-04-29 14:34:18
Message-ID: 1146321258.4995.22.camel@wjlnotebook (view raw or flat)
Thread:
Lists: pgsql-admin
selecting pg_attributes for the casedocument table shows
there is column with the following attributes

24216115|"........pg.dropped.2........"|0|0|-1|2|0|-1|-1|f|"x"|"i"|f|f|
t|t|

I also noticed a few other tables have a similar "dropped" column.

Could this be the reference to the toast table that is preventing the
vacuum from deleting the toast data?  And what purges "dropped" columns
if not a full vacuum.



On Sat, 2006-04-29 at 06:52 -0600, Warren Little wrote:
> I am now a little confused.
> 
> I ran the following with all but localhost connections disabled
> 
> vacuumdb --full --verbose -t casedocument -d tigris > vacfull.log 2>&1
> 
> which produced the following output:
> 
> INFO:  vacuuming "public.casedocument"
> INFO:  "casedocument": found 0 removable, 39663 nonremovable row
> versions in 852 pages
> DETAIL:  0 dead row versions cannot be removed yet.
> Nonremovable row versions range from 138 to 1953 bytes long.
> There were 1855 unused item pointers.
> Total free space (including removable row versions) is 65168 bytes.
> 0 pages are or will become empty, including 0 at the end of the table.
> 90 pages containing 14644 free bytes are potential move destinations.
> CPU 0.02s/0.00u sec elapsed 0.24 sec.
> INFO:  index "copycasedoc_pkey" now contains 39663 row versions in 387
> pages
> DETAIL:  0 index row versions were removed.
> 0 index pages have been deleted, 0 are currently reusable.
> CPU 0.01s/0.00u sec elapsed 0.56 sec.
> INFO:  "casedocument": moved 0 row versions, truncated 852 to 852 pages
> DETAIL:  CPU 0.00s/0.01u sec elapsed 0.03 sec.
> INFO:  vacuuming "pg_toast.pg_toast_24216115"
> INFO:  "pg_toast_24216115": found 0 removable, 23125332 nonremovable row
> versions in 5781284 pages
> DETAIL:  0 dead row versions cannot be removed yet.
> Nonremovable row versions range from 45 to 2030 bytes long.
> There were 1 unused item pointers.
> Total free space (including removable row versions) is 185874460 bytes.
> 0 pages are or will become empty, including 0 at the end of the table.
> 24019 pages containing 24668944 free bytes are potential move
> destinations.
> CPU 217.21s/16.97u sec elapsed 1745.04 sec.
> INFO:  index "pg_toast_24216115_index" now contains 23125332 row
> versions in 94046 pages
> DETAIL:  0 index row versions were removed.
> 1427 index pages have been deleted, 1427 are currently reusable.
> CPU 4.60s/1.05u sec elapsed 49.34 sec.
> INFO:  "pg_toast_24216115": moved 0 row versions, truncated 5781284 to
> 5781284 pages
> DETAIL:  CPU 0.00s/0.00u sec elapsed 0.00 sec.
> VACUUM
> 
> Not sure if I'm reading the output correctly, but it appears no rows in
> the toast table were removed.   
> What else could be holding onto the data in "pg_toast_24216115" ???
> 
> 
> 
> 
> 
> 
> 
> On Fri, 2006-04-28 at 16:03 -0400, Tom Lane wrote:
> > Warren Little <warren(dot)little(at)meridiascapital(dot)com> writes:
> > > 3) I know that once upon a time the table had a bytea column, but that
> > > was dropped.  Do I need to do a full vacuum on that table to get rid of
> > > the related toast data?
> > 
> > Yup.  (I take it it was a pretty darn bulky bytea column, too)
> > 
> > 			regards, tom lane
-- 
Warren Little
Chief Technology Officer
Meridias Capital Inc
1018 W Atherton Dr 
SLC, UT 84123
ph 866.369.7763

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