Hi,

I had some time in the evening and implemented this solution. It is
available via github. The branch is feature/dbi_indexing_lob_columns.

https://github.com/bellmich/openxpki/commits/feature/dbi_indexing_lob_columns

Now I'm looking for somebody who can and is willing to test it with Oracle.

Any volunteers?

Best regards, Michael


Am 12.04.2012 10:42, schrieb Michael Bell:
> Hi,
> 
> I would like to propose a new solution which is quite the same as the
> one from Martin. The basic idea is that we manage a digest column for
> every TEXT column - fully transparent and automatic.
> 
> 1. Data definition
> 
> Every table column of type TEXT or LONGTEXT is supplement with a column
> of type TEXT_KEY which is used for an SHA2-512 of the original column.
> 
> 2. Functions
> 
> 2.1 create_table
> 
> If a column is of type TEXT or LONGTEXT then automatically an additional
> column for the digest is created.
> 
> 2.2 update and insert
> 
> If a TEXT or LONGTEXT column is written then the digest column is
> written too.
> 
> 2.3 select and update
> 
> If a join or an EQUAL operator is used then this is automatically
> replaced by the same operation on the digest column.
> 
> If a LIKE operator is used then nothing is changed. Can Oracle handle
> LIKE on columns of type CLOB? If Oracle does not support this then we
> should forbid LIKE on TEXT and LONGTEXT columns.
> 
> 3. Index handling
> 
> If an index is requested on a TEXT or LONGTEXT column then this index is
> automatically migrated to the digest column.
> 
> Any comments please?
> 
> The important thing is for me, that the whole thing is transparent for
> the database drivers and for the users of the database layer. Nobody has
> to take care.
> 
> Conclusion: We need the data in the database but we don't want to use
> the data for operations in the database.
> 
> Best regards
> 
> Michael

-- 
___________________________________________________________________

Michael Bell                        Humboldt-Universitaet zu Berlin

Tel.: +49 (0)30-2093 70143          ZE Computer- und Medienservice
Fax:  +49 (0)30-2093 70135          Unter den Linden 6
[email protected]       D-10099 Berlin
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