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Posted to derby-user@db.apache.org by S <s....@gmail.com> on 2006/11/01 07:00:11 UTC
storage estimation
Hi, how do I estimate the average record length of a table. Actually, I have
a fast growing table and I need to understand the disk size requirement of
it. In Oracle, the all_tables table provides this information.
Re: storage estimation
Posted by Stanley Bradbury <St...@gmail.com>.
S wrote:
> Hi, how do I estimate the average record length of a table. Actually,
> I have a fast growing table and I need to understand the disk size
> requirement of it. In Oracle, the all_tables table provides this
> information.
I couldn't find this in the documentation but it still works - no
promises that it will not be removed at some point - the following shows
the space (pages and pagesize) for the tables and indexes of a table.
Average records size can be computed by summing all the sizes (pages x
pagesize), divide by the rows in the table.
select * from NEW org.apache.derby.diag.SpaceTable('SYS','SYSTABLES') AS x;
CONGLOMERATENAME
|ISIND&|NUMALLOCATEDPAGES |NUMFREEPAGES
|NUMUNFILLEDPAGES |PAGESIZE |ESTIMSPACESAVING
------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------
SYSTABLES_INDEX1
|1 |1 |0
|1 |4096 |0
SYSTABLES_INDEX2
|1 |1 |0
|1 |4096 |0
SYSTABLES
|0 |1 |0
|1 |4096 |0