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Posted to ojb-user@db.apache.org by Tino Schöllhorn <t....@tiscali.de> on 2004/07/26 13:17:54 UTC
Debugging Queries
Hi,
I am using MySQL and OJB and now I want to create a Query over a large
table. For performance reason I want to use the "pageing"-feature - but
I have the feeling that currently OJB is somehow ommitting this (the
result is fine - but the SQL seems not to include the LIMIT-clause).
Is there a way to get the native SQL from a query which OJB would send
to the database (this would help for other, complex queries too).
With regards
Tino
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Re: Debugging Queries
Posted by Craig Andrews <cr...@simplyspiffing.com>.
Tino Schöllhorn wrote:
> I am using MySQL and OJB and now I want to create a Query over a large
> table. For performance reason I want to use the "pageing"-feature - but
> I have the feeling that currently OJB is somehow ommitting this (the
> result is fine - but the SQL seems not to include the LIMIT-clause).
>
> Is there a way to get the native SQL from a query which OJB would send
> to the database (this would help for other, complex queries too).
A database specific way would be to add the line:
log=/path/to/some/file.log
to my.cnf, which would cause MySQL to write each and every query it
receives out to file.log. You can then just monitor what goes in there.
Unfortunately, there is a large performance penalty, but it can be handy
for debugging whole transactions.
--
Craig
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Re: Debugging Queries
Posted by Tino Schöllhorn <t....@tiscali.de>.
Hi Thomas,
I am perfectly aware of that - but in my opinion you're already doing
the right thing: emulate the behaviour of paging when the underlying db
isn't supporting it. But if the underlying db is supporting this feature
(many db implement this: mysql, mssql, oracle...) it should be used
because one can have dramatically network and performance increases.
With regards
Tino
Thomas Dudziak wrote:
> Jakob Braeuchi wrote:
>
>> hi tino,
>>
>> i do have an implementation using limit, but i think it's not finished
>> yet.
>
>
> Please be aware that not all databases support limits in sql (e.g. McKoi).
> Btw, do we use paging resultsets ? In that case, we might not need
> limits as the driver can optimize via cursors, or not ?
>
> Tom
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Re: Debugging Queries
Posted by Thomas Dudziak <to...@first.fhg.de>.
Jakob Braeuchi wrote:
> hi tino,
>
> i do have an implementation using limit, but i think it's not finished
> yet.
Please be aware that not all databases support limits in sql (e.g. McKoi).
Btw, do we use paging resultsets ? In that case, we might not need
limits as the driver can optimize via cursors, or not ?
Tom
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Re: Debugging Queries
Posted by Jakob Braeuchi <jb...@gmx.ch>.
hi tino,
i do have an implementation using limit, but i think it's not finished yet.
jakob
Tino Schöllhorn schrieb:
> Hi Jakob,
>
> thanks for your answer. Will that feature be implemented in OJB 1.1? We
> have some queries where that feature is important for us. If this is
> just a matter of the MySQLPlatform-Implementation I could help out....or
> is this a general problem?
>
> With regards Tino
>
> Jakob Braeuchi wrote:
>
>> hi tino,
>>
>> ojb does not use the limit-clause yet. the paging is implemented by
>> positioning the cursor in the resultset.
>>
>> jakob
>>
>> Tino Schöllhorn schrieb:
>>
>>> Hi,
>>>
>>> I am using MySQL and OJB and now I want to create a Query over a
>>> large table. For performance reason I want to use the
>>> "pageing"-feature - but I have the feeling that currently OJB is
>>> somehow ommitting this (the result is fine - but the SQL seems not to
>>> include the LIMIT-clause).
>>>
>>> Is there a way to get the native SQL from a query which OJB would
>>> send to the database (this would help for other, complex queries too).
>>>
>>> With regards
>>> Tino
>>>
>>>
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>>> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
>>> For additional commands, e-mail: ojb-user-help@db.apache.org
>>>
>>>
>
>
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>
>
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Re: Debugging Queries
Posted by Tino Schöllhorn <t....@tiscali.de>.
Hi Jakob,
thanks for your answer. Will that feature be implemented in OJB 1.1? We
have some queries where that feature is important for us. If this is
just a matter of the MySQLPlatform-Implementation I could help out....or
is this a general problem?
With regards Tino
Jakob Braeuchi wrote:
> hi tino,
>
> ojb does not use the limit-clause yet. the paging is implemented by
> positioning the cursor in the resultset.
>
> jakob
>
> Tino Schöllhorn schrieb:
>
>> Hi,
>>
>> I am using MySQL and OJB and now I want to create a Query over a large
>> table. For performance reason I want to use the "pageing"-feature -
>> but I have the feeling that currently OJB is somehow ommitting this
>> (the result is fine - but the SQL seems not to include the LIMIT-clause).
>>
>> Is there a way to get the native SQL from a query which OJB would send
>> to the database (this would help for other, complex queries too).
>>
>> With regards
>> Tino
>>
>>
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>> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
>> For additional commands, e-mail: ojb-user-help@db.apache.org
>>
>>
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Re: Debugging Queries
Posted by Jakob Braeuchi <jb...@gmx.ch>.
hi tino,
ojb does not use the limit-clause yet. the paging is implemented by positioning
the cursor in the resultset.
jakob
Tino Schöllhorn schrieb:
> Hi,
>
> I am using MySQL and OJB and now I want to create a Query over a large
> table. For performance reason I want to use the "pageing"-feature - but
> I have the feeling that currently OJB is somehow ommitting this (the
> result is fine - but the SQL seems not to include the LIMIT-clause).
>
> Is there a way to get the native SQL from a query which OJB would send
> to the database (this would help for other, complex queries too).
>
> With regards
> Tino
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> For additional commands, e-mail: ojb-user-help@db.apache.org
>
>
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