## Saturday, December 18, 2004

### L-TREE a new datastructure for efficient hierarchy representation in a database.....

Hey don't say that you guys have never came across an LDAP server....hmm...ok its your directory within your organizaion.....since every organizaition is hierarchical in the sense a 'senior manager' has several 'managers' reporting to him and a 'manager' has 'developers' etc.....so all this data is hierarchical. So if I were to give you this problem and make a system which will report queries like 'gimme all the employees under employee X' how would you approach the problem ?....
One quick solution is create a table in the database
CREATE TABLE ORG_DIR (int EMP_ID NOT_NULL,VARCHAR(10) EMP_NAME, int SUP_ID);
To answer that you might query the database like
SELECT T1.EMP_NAME
FROM ORG_DIR T1, ORG_DIR T2
WHERE T1.SUP_ID == T2.EMP_ID && T2.EMP_ID = &INPUT

Finally you have got a workaround...Unfortunately this kind of workarounds seem to be very inefficient for storing and retriving Structured Hierarchical Data hmm...I know you are thinking about some thing right??? XML :)) Yes its XML. How can I store XML in my database and answer my queries on the Hierarchical data. My Idea is to make HIERARCHY as a datatype itself rather than some thing else. That is just as we have primitive datatype support within a database..ie every column in the database would be of some primitive datatype supported by the database...so The idea is can we make HIERARCHY a datatype.....hey wait a sec just figured out I'am not the only one who thought about it....yes Oleg has alreay added a great Contrib Module for postgresql. Oleg made is generic so that you can persist any label based HIERARCHY...now I have a good Idea in extending L-TREE to support XML....its really great to have such an optimized HIERARCHY representation for structured data...people have been talking about indexing and datastructures for XML Databases but this seems to me as a really good contribution from Oleg..... Vamsi

## Tuesday, December 14, 2004

### Useful unix command for finding all the files recusively which contain a string

peemt4:vamsik:(vamsi_aix_ns_port):/vobs/ETG_Repository/src>find . -name "*.c" -exec grep -i "Your Search String" \{\} \; -print
Sound simple but thought it would be useful....

GTL