Am 05.08.19 um 22:47 schrieb Mariel Cherkassky:
Hey,
I have a very big query that consist from 3-4 subqueries that use
windows functions. There is a chance that I'll need to rewrite the
query but first I'm trying to search for other ways to improve it and
I'll be happy to hear if one of u have an idea.
Basically my table has the following structure :
(objid,first_num,last_num) and each record is a range from the first
number to the last one for that specific obj. I'm trying to unite
ranges that overlaps. For example :
for the following table :
objid first_num last_num
1 5 7
1 8 10
2 4 6
2 9 10
I would like to get :
objid first_num last_num
1 5 10
2 4 6
2 9 10
I have a query that does it but takes about 4s for 1.5M records. I
created an index on (objid,first_num,last_num) in order to use only
index scan instead of seq scan on this table. I wanted to here if u
guys have any other ideas.
you should provide more information, for instance:
* used version
* table-structure
* real query
* execution plan (using explain analyse)
Andreas
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