\dt+ sizes don't include TOAST data

Florian Weimer wrote:

The sizes displayed by \dt+ in version 8.4.2 do not take TOAST tables
into account, presumably because the pg_relation_size does not reflect
that, either. I think this is a bit surprising. From a user
perspective, these are part of the table storage (I understand that
the indices might be a different story, but TOAST table are a fairly
deep implementation detail and should perhaps be hidden here).

As of last week there's a new pg_table_size available that does what you
want here:
http://archives.postgresql.org/pgsql-committers/2010-01/msg00288.php

I don't believe \dt+ has been updated yet to use that though; that's
worth considering for a minute, not sure anybody thought about it yet.

--
Greg Smith 2ndQuadrant Baltimore, MD
PostgreSQL Training, Services and Support
greg@2ndQuadrant.com www.2ndQuadrant.com

Greg Smith <greg@2ndquadrant.com> writes:

Florian Weimer wrote:

The sizes displayed by \dt+ in version 8.4.2 do not take TOAST tables
into account, presumably because the pg_relation_size does not reflect
that, either. I think this is a bit surprising. From a user
perspective, these are part of the table storage (I understand that
the indices might be a different story, but TOAST table are a fairly
deep implementation detail and should perhaps be hidden here).

As of last week there's a new pg_table_size available that does what you
want here:
http://archives.postgresql.org/pgsql-committers/2010-01/msg00288.php

I don't believe \dt+ has been updated yet to use that though; that's
worth considering for a minute, not sure anybody thought about it yet.

We could only use pg_table_size against a backend >= 9.0, which would
mean that the displayed results mean something different depending on
which backend version psql is being used with. That's not necessarily
a deal-breaker, but it does seem a bit evil.

An alternative worth thinking about is to make it use
pg_total_relation_size instead of pg_relation_size. That's available,
with similar semantics, in all versions that have pg_relation_size
either (ie, >= 8.1). Also, this is arguably more nearly the right thing
since at the level of \dt+ I think people would expect indexes to get
folded in too.

regards, tom lane

Tom Lane wrote:

Greg Smith <greg@2ndquadrant.com> writes:

Florian Weimer wrote:

The sizes displayed by \dt+ in version 8.4.2 do not take TOAST tables
into account, presumably because the pg_relation_size does not reflect
that, either. I think this is a bit surprising. From a user
perspective, these are part of the table storage (I understand that
the indices might be a different story, but TOAST table are a fairly
deep implementation detail and should perhaps be hidden here).

As of last week there's a new pg_table_size available that does what you
want here:
http://archives.postgresql.org/pgsql-committers/2010-01/msg00288.php

I don't believe \dt+ has been updated yet to use that though; that's
worth considering for a minute, not sure anybody thought about it yet.

We could only use pg_table_size against a backend >= 9.0, which would
mean that the displayed results mean something different depending on
which backend version psql is being used with. That's not necessarily
a deal-breaker, but it does seem a bit evil.

Perhaps we can emulate pg_table_size on earlier server versions, using a
query which provides the sum of table plus toast items. It would be a
bit slower, but the normal case of using the same server version would
be fast.

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

Alvaro Herrera wrote:

Tom Lane wrote:

Greg Smith <greg@2ndquadrant.com> writes:

Florian Weimer wrote:

The sizes displayed by \dt+ in version 8.4.2 do not take TOAST tables
into account, presumably because the pg_relation_size does not reflect
that, either. I think this is a bit surprising. From a user
perspective, these are part of the table storage (I understand that
the indices might be a different story, but TOAST table are a fairly
deep implementation detail and should perhaps be hidden here).

As of last week there's a new pg_table_size available that does what you
want here:
http://archives.postgresql.org/pgsql-committers/2010-01/msg00288.php

I don't believe \dt+ has been updated yet to use that though; that's
worth considering for a minute, not sure anybody thought about it yet.

We could only use pg_table_size against a backend >= 9.0, which would
mean that the displayed results mean something different depending on
which backend version psql is being used with. That's not necessarily
a deal-breaker, but it does seem a bit evil.

Perhaps we can emulate pg_table_size on earlier server versions, using a
query which provides the sum of table plus toast items. It would be a
bit slower, but the normal case of using the same server version would
be fast.

Added to TODO:

Consider showing TOAST and index sizes in \dt+

* http://archives.postgresql.org/pgsql-general/2010-01/msg00912.php

--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +