[SQL] Query tuning

[kapil.munish]

Hi,





I have a query which is run across 3 tables JOB_TYPE_FIRST,
JOB_TYPE_SECOND and JOB_ALLOCATION_WORKLIST.



The column JOBID is referenced in JOB_ALLOCATION_WORKLIST table and
primary key in both JOB_TYPE_FIRST, JOB_TYPE_SECOND tables.



There is one more column BOOK_ID which is supplied as the binding
parameter to the query. The query looks like:



select count(distinct(j.JOBID)) as jobCount

from  JOB_TYPE_FIRST a, JOB_TYPE_SECOND b, JOB_ALLOCATION_WORKLIST j

where (( a.JOBID = j.JOBID)

and (a.BOOK_ID = :bookId))

or ((b.JOBID = j.JOBID)

and (b.BOOK_ID = :bookId));



As the records in the database are too large it is having huge cost and
stalling the server and takes lot of time.



Can anyone suggest a better way to fetch the results for the query or
tune it? Any help would be highly appreciated.





Thanks  Regards,

Kapil


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[SQL] xpath_table

[Thomas Kellerer]

Hi, 

I am using xpath_table to convert elements from an XML column to rows. 

Now according to 
http://www.postgresql.org/docs/8.3/static/xml2.html
this function will be removed in a future version. 


That chapter also claims that the new XML syntax covers the functionality of 
the xml2 module, but I cannot find a way to return the elements of an XML 
document as rows (as xpath_table does)

Suppose I have the following content in my xml column:

team
 member id=10 name=Arthur Dent/
 member id=11 name=Ford Prefect/
/team


I am using a statement similar to this:

select member_id, member_name
from xpath_table('id', 'xml_text', 'xmltest', 
'/team/member/@id|/team/member/@name', 'true')
as t(id integer, member_id varchar, member_name varchar)

to get the following output

member_id   member_name
10  Arthur Dent
11  Ford Prefect

How would I achieve the same without using the deprecated xml2 module?

Thanks in advance
Thomas


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