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Re: Need to calculate total size of a table along with BLOB data assosciated with it. - Mailing list pgsql-admin

From girish R G peetle
Subject Re: Need to calculate total size of a table along with BLOB data assosciated with it.
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Msg-id CAKKd0641+_vFKiRM4GNxO3bEaqM9JevtsuW1fr-rNAiYfqxP3Q@mail.gmail.com
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In response to Re: Need to calculate total size of a table along with BLOB data assosciated with it.  (Albe Laurenz <laurenz.albe@wien.gv.at>)
Responses Re: Need to calculate total size of a table along with BLOB data assosciated with it.
Re: Need to calculate total size of a table along with BLOB data assosciated with it.
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Got it. Thanks Laurenz. 
One thing is little confusing, if large objects don't belong to a table, then how does restriction of 8GB table size for TAR format is applicable if BLOB data is involved.
Is it  (Regular Table Data size) + (BLOB data held by OID stored in the table) ?  

If just OID of a large object is copied to a different table say 'Table2'. Then for 'Table2' as well should I calculate the total size as (Regular Table Data size) + (BLOB data held by OID stored in the table) ? 


Thanks
Girish

On Fri, Sep 18, 2015 at 5:23 PM, Albe Laurenz <laurenz.albe@wien.gv.at> wrote:
girish R G peetle wrote:
> PostgreSQL system function, pg_total_relation_size() doesn't include BLOB data size that is associated
> with the table.
>
> TAR dump restore fails if the BLOB data size associated with a table is more than 8GB. (Which is
> limitation of TAR format).
>
> I know we can switch to compressed dump format. But wanted to know if there a way to know true size of
> a table.

Not easily, because technically, large objects don't belong to a table.

You'd have to write your own that scans the table and adds the size of
all referenced large objects.
It can probably be done in one SELECT using lo_lseek.

Yours,
Laurenz Albe

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