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.hille...@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
