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Posted to derby-user@db.apache.org by 鲍少明 <io...@gmail.com> on 2011/09/01 14:30:58 UTC
new feature request of Derby
Hi Guys,
Is there any feature in Derby in its memory mode like Cache table in hsql?
I find this feature very important to us , especially there is some table
which holds a lot of table,
not suitable to be a pure memory table. But I want to still keep the other
tables in memory mode.
Is that possible?
Thanks,
Clark
Re: new feature request of Derby
Posted by Matt Pouttu-Clarke <Ma...@icrossing.com>.
Something as simple as using the buffer cache with a "NOCACHE" query hint
would probably work. However, I do not see a NOCACHE hint in Derby, but it
would be nice to have one...
On 9/1/11 5:55 AM, "Rick Hillegas" <ri...@oracle.com> wrote:
> Hi Clark,
>
> Derby does not have this feature. You might try putting your big tables
> in a separate, on-disk Derby database and select from them using
> restricted table functions. See the ForeignTableVTI attached to
> https://issues.apache.org/jira/browse/DERBY-4962
>
> Hope this helps,
> -Rick
>
> On 9/1/11 5:33 AM, 鲍少明 wrote:
>> I mean if one table holds a lot of data, then it cannot be all in memory.
>> the latest version of hsql of its memory mode allows only keep like 8M
>> data in memory but others
>> be kept in disk. This feature looks very useful.
>>
>> 2011/9/1 鲍少明 <iokerica@gmail.com <ma...@gmail.com>>
>>
>> Hi Guys,
>> Is there any feature in Derby in its memory mode like Cache table
>> in hsql?
>> I find this feature very important to us , especially there is
>> some table which holds a lot of table,
>> not suitable to be a pure memory table. But I want to still keep
>> the other tables in memory mode.
>> Is that possible?
>> Thanks,
>> Clark
>>
>>
>
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Re: new feature request of Derby
Posted by Rick Hillegas <ri...@oracle.com>.
Hi Clark,
Derby does not have this feature. You might try putting your big tables
in a separate, on-disk Derby database and select from them using
restricted table functions. See the ForeignTableVTI attached to
https://issues.apache.org/jira/browse/DERBY-4962
Hope this helps,
-Rick
On 9/1/11 5:33 AM, 鲍少明 wrote:
> I mean if one table holds a lot of data, then it cannot be all in memory.
> the latest version of hsql of its memory mode allows only keep like 8M
> data in memory but others
> be kept in disk. This feature looks very useful.
>
> 2011/9/1 鲍少明 <iokerica@gmail.com <ma...@gmail.com>>
>
> Hi Guys,
> Is there any feature in Derby in its memory mode like Cache table
> in hsql?
> I find this feature very important to us , especially there is
> some table which holds a lot of table,
> not suitable to be a pure memory table. But I want to still keep
> the other tables in memory mode.
> Is that possible?
> Thanks,
> Clark
>
>
Re: new feature request of Derby
Posted by Matt Pouttu-Clarke <Ma...@icrossing.com>.
Yes, there is a configurable page cache. It is a nice feature of Derby that
it does not hog all of the JVM memory by default: it is polite. You have to
ask it to use more memory. Also make sure to set –Xmx on the jvm so all the
data fits. Here is an example:
stmt.execute("CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY(" +
"'derby.storage.pageCacheSize'," +
"'131072')");
I believe you can also set in derby.properties as well. If you want to
pre-load the cache, simply query all the rows in the table.
Cheers,
Matt
On 9/1/11 5:33 AM, "鲍少明" <io...@gmail.com> wrote:
> I mean if one table holds a lot of data, then it cannot be all in memory.
> the latest version of hsql of its memory mode allows only keep like 8M data in
> memory but others
> be kept in disk. This feature looks very useful.
>
> 2011/9/1 鲍少明 <io...@gmail.com>
>> Hi Guys,
>>
>> Is there any feature in Derby in its memory mode like Cache table in hsql?
>> I find this feature very important to us , especially there is some table
>> which holds a lot of table,
>> not suitable to be a pure memory table. But I want to still keep the other
>> tables in memory mode.
>>
>> Is that possible?
>>
>> Thanks,
>> Clark
>
>
iCrossing Privileged and Confidential Information
This email message is for the sole use of the intended recipient(s) and may contain confidential and privileged information of iCrossing. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message.
Re: new feature request of Derby
Posted by 鲍少明 <io...@gmail.com>.
I mean if one table holds a lot of data, then it cannot be all in memory.
the latest version of hsql of its memory mode allows only keep like 8M data
in memory but others
be kept in disk. This feature looks very useful.
2011/9/1 鲍少明 <io...@gmail.com>
> Hi Guys,
>
> Is there any feature in Derby in its memory mode like Cache table in hsql?
> I find this feature very important to us , especially there is some table
> which holds a lot of table,
> not suitable to be a pure memory table. But I want to still keep the other
> tables in memory mode.
>
> Is that possible?
>
> Thanks,
> Clark
>
Re: new feature request of Derby
Posted by 鲍少明 <io...@gmail.com>.
I mean if one table holds a lot of data, then it cannot be all in memory.
the latest version of hsql of its memory mode allows only keep like 8M data
in memory but others
be kept in disk. This feature looks very useful.
2011/9/1 鲍少明 <io...@gmail.com>
> Hi Guys,
>
> Is there any feature in Derby in its memory mode like Cache table in hsql?
> I find this feature very important to us , especially there is some table
> which holds a lot of table,
> not suitable to be a pure memory table. But I want to still keep the other
> tables in memory mode.
>
> Is that possible?
>
> Thanks,
> Clark
>