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From Rick Hillegas <rick.hille...@oracle.com>
Subject Re: Data Compression for Query Processing
Date Tue, 06 Sep 2011 17:34:33 GMT
Hi Reka,

I would recommend looking at the Derby logic for encrypting databases. 
You can probably get column compression to work by putting your 
(de)compression logic alongside the (de)encryption touchpoints.

Hope this helps,
-Rick

On 9/6/11 9:21 AM, Reka Thirunavukkarasu wrote:
> Hi Rick,
> Thank you for your immediate reply.We are trying to achieve attribute
> level compression
> (in your words more compact storage of columns).Attribute level
> compression is best
> from the query processing point of view.Attributes fall in to three
> major category Integer,
> floating point and character string.We have to apply three different
> compression techniques
> for each data types.But for demonstration purpose we will apply
> compression to only character
> string attributes.We will test it in a database which has only
> character string.This is our main goal.
> Thank you.
>
> On Tue, Sep 6, 2011 at 8:19 PM, Rick Hillegas<rick.hillegas@oracle.com>  wrote:
>> Hi Reka,
>>
>> Can you give us more detail about what you are trying to achieve? That may
>> help us figure out what the right touchpoints are. Are you trying to achieve
>> any of the following:
>>
>> 1) More aggressive garbage-collection of deleted rows...
>>
>> 2) More compact storage of columns...
>>
>> 3) More compact storage of rows...
>>
>> 4) More compact storage of pages...
>>
>> 5) Something else...
>>
>> Thanks,
>> -Rick
>>
>>
>> On 9/6/11 7:07 AM, Reka Thirunavukkarasu wrote:
>>> Hi all,
>>>
>>> We are from university of Moratuwa,Sri lanka.We are willing to apply
>>> data compression to Derby in query processing
>>> as requirement of our Advanced Database course project.
>>>
>>>
>>> Currently Derby has facility to trim the free space in raw data
>>> container(using SYSCS_UTIL.SYSCS_COMPRESS_TABLE
>>> system procedure).Our goal is to apply data compression(Run-length
>>> encoding Compression) for each of values(not field name)
>>> of a query before executing and decompressing the data
>>>   when the execution finishes.
>>>
>>>
>>> Initially we went through the code base and identified that the data
>>> compression can be applied within the executeStatement()
>>>
>>> method of org.apache.derby.impl.jdbc.EmbedStatement class before
>>> calling ps.execute(),and we thought Using getParameterValueSet()
>>> method of Activation class the the attribute values of the parsed
>>> query can be obtained.But when we try to print the contents of the
>>> ParameterValueSet for typical insert query
>>> ,it is printing null(it is just empty set).
>>>
>>>
>>> We are expecting help from community regarding following questions.
>>>
>>>
>>> 1)What is wrong with point we identified to apply compression?
>>>
>>> 2)By applying compression before executing query,will the query
>>> execution process be affected?
>>>
>>> 3)Are there any possible place to apply compression and decompression
>>> before executing query?
>>>
>>>
>>> Thank you.
>>> -Reka
>>>
>>
>
>


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