From: | Liron Shiri <lirons(at)checkpoint(dot)com> |
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To: | "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
Subject: | Investigating the reason for a very big TOAST table size |
Date: | 2012-08-26 12:46:31 |
Message-ID: | 6B9568EED16BA541BE4A0F3108351E6301BEA8FE0F1E@il-ex01.ad.checkpoint.com |
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Lists: | pgsql-performance |
Hi,
We have a table which its TOAST table size is 66 GB, and we believe should be smaller.
The table size is 472 kb. And the table has 4 columns that only one of them should be toasted.
The table has only 8 dead tuples, so apparently this is not the problem.
This table contains a column with bytea type data (kept as TOAST). We tried to check what is the size of the toasted data in each row by using the following query (the data_blob is the bytea column):
SELECT nid, octet_length(data_blob) FROM my_table ORDER BY octet_length(data_blob) DESC;
This result contain 1782 rows. The sizes I get from each row are between 35428 to 42084.
1782 * 38000 = 67716000 byte = 64.579 MB .
What can be the reason for a table size of 66 GB? What else should I check?
Thanks in advance,
Liron
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