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From Bryan Pendleton <bpendleton.de...@gmail.com>
Subject Re: Can someone tell me if "syscs_util.update_statistics" locks table/indexes being updated
Date Wed, 01 Dec 2010 14:32:15 GMT
On 12/01/2010 05:26 AM, Bergquist, Brett wrote:
> If I have a table with millions of rows and I invoke syscs_util.update_statistics on
it, will the table/indexes be lock such that inserts or updates will fail while this is being
done.  The documentation is not clear if this is the case (at least to me).

I'm pretty sure that the scan of the data happens using the
READ_UNCOMMITTED isolation level, which is the lowest-level of
locking (that is, the highest concurrency)
http://db.apache.org/derby/docs/10.6/devguide/cdevconcepts15366.html

However, that's based on looking at the code in the updateStatistics()
method in AlterTableConstantAction.java, not on actually trying it,
so if you could set up a test environment and try it, that would be great!

thanks,

bryan


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