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From Pavel Bortnovskiy <pbortnovs...@jefferies.com>
Subject RE: concurrent execution of Statement's .addBatch() and .executeBatch()
Date Mon, 10 Dec 2012 19:56:20 GMT
Does Derby use some kind of PrepStatement pooling?

-----Original Message-----
From: Dag Wanvik [mailto:dag.wanvik@oracle.com]
Sent: Monday, December 10, 2012 2:53 PM
To: derby-user@db.apache.org
Subject: Re: concurrent execution of Statement's .addBatch() and .executeBatch()


On 07.12.2012 16:53, Pavel Bortnovskiy wrote:
> Thank you, Knut.
> It has been my assumption that creation of PreparedStatement is expensive. Thus I create
cached Prepared Statements (such as INSERT, UPDATE, DELETE, SELECT COUNT(*) FROM <table>)
and then use them. Would it be an improvement in my design to create multiple PreparedStatements
for those (assuring proper addition of objects and execution)? Would you still recommend caching
and reusing them or creating them anew?
Please also note that as long as the statements are textually the same, i.e. arguments are
given dynamically as "?" , Derby is able to use its internal cache to avoid SQL compilation
for more than the first thread, even if each of the thread has a created a separate PreparedStatement
in its own connection. Cf.
http://db.apache.org/derby/docs/10.9/ref/rrefproperstatementcachesize.html

Thanks,
Dag

>
> For instance, if I have 3,000 records to insert, I could split them into 6x500 batches,
create 6 PreparedStatements and have each of them execute their corresponding batches in parallel.
>
> Thank you,
> Pavel.
>
> -----Original Message-----
> From: Knut Anders Hatlen [mailto:knut.hatlen@oracle.com]
> Sent: Friday, December 07, 2012 7:01 AM
> To: Derby Discussion
> Subject: Re: concurrent execution of Statement's .addBatch() and
> .executeBatch()
>
> Pavel Bortnovskiy <pbortnovskiy@jefferies.com> writes:
>
>> Hello:
>>
>> Is it safe to call .addBatch() and .executeBatch() methods from
>> multiple threads on the same PreparedStatement?
>>
>> Simple example: batching and executing a large number of the same
>> statements (with the same PreparedStatement) by using ExecutorService.
> Hi Pavel,
>
> Both addBatch() and executeBatch() do their work in a block synchronized on the connection,
so in theory it should work to have many threads adding batches to the same PreparedStatement.
I don't think it has been heavily tested, though.
>
> And if the threads set any parameters on the PreparedStatement, your
> application needs to synchronize the threads manually. For example, if
> two threads call
>
>   ps.setInt(1, id);
>   ps.setObject(2, value);
>   ps.addBatch();
>
> on the same statement, you need to add synchronization to ensure that the addBatch()
call in one thread doesn't end up using one or more parameter values set by the other thread.
>
> --
> Knut Anders
>
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including any attachments, are confidential to the ordinary user of the email address to which
it was addressed. If you are not the addressee of this email you may not copy, forward, disclose
or otherwise use it or any part of it in any form whatsoever. This email may be produced at
the request of regulators or in connection with civil litigation. Jefferies accepts no liability
for any errors or omissions arising as a result of transmission. Use by other than intended
recipients is prohibited. In the United Kingdom, Jefferies operates as Jefferies International
Limited; registered in England: no. 1978621; registered office: Vintners Place, 68 Upper Thames
Street, London EC4V 3BJ. Jefferies International Limited is authorised and regulated by the
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