On 30.05.2011 21:51, Nick Raj wrote:
Hi,
Cube code provided by postgres contrib folder. It uses the NDBOX structure.
On creating index, it's size increase at a high rate.
On inserting some tuple and creating indexes its behaviour is shown below.
1. When there is only one tuple
select pg_size_pretty(pg_relation_
size('cubtest')); //Table size without index
pg_size_pretty
----------------
8192 bytes
(1 row)
select pg_size_pretty(pg_total_relation_size('cubtest')); //Table size with
index
pg_size_pretty
----------------
16 kB
(1 row)
i.e. Index size in nearly 8kB
2. When tuples are 20,000
Table Size without index - 1.6 MB
Table Size with index - 11 MB
i.e. Index size is nearly 9.4 MB
3. When tuples are 5 lakh
Table Size without index - 40 MB
Table Size with index - 2117 MB
i.e. Index size is nearly 2077 MB ~ 2GB
It is taking nearly 20-25 min for creating index for 5 lakh tuples.
Can some one tell me why index is becoming so large?
How to compress or reduce its size?
Which version of PostgreSQL are you using? I wonder if this could be due
to the bug in cube's picksplit algorithm that was fixed a while ago:
http://archives.postgresql.org/message-id/aanlktimc8w6guhpwjewdjqa6wgovh-7qg9ar4pem2...@mail.gmail.com
If not, please post a self-contained test case to create and populate
the table, so that others can easily try to reproduce it.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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