From: | Ow Mun Heng <Ow(dot)Mun(dot)Heng(at)wdc(dot)com> |
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To: | pgsql-general(at)postgresql(dot)org, WDC - Ow Mun Heng <ow(dot)mun(dot)heng(at)wdc(dot)com> |
Subject: | Putting many related fields as an array |
Date: | 2009-05-12 05:23:14 |
Message-ID: | 1242105794.5457.59.camel@localhost.localdomain |
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Lists: | pgsql-general |
Hi,
Currently doing some level of aggregrate tables for some data. These
data will be used for slice/dice activity and we want to be able to
play/manipulate the data such that I can get means and stddev data.
Eg: For each Original Column eg:
population_in_town : (I get derivatives)
- mean # of ppl in each town
- stddev # of ppl in each town (stdev calc already uses 2 extra columns
for # of ppl squared and qty of ppl)
- count of ppl
- count of # of ppl is < 100 (to get a percentage of population)
- count of # of ppl is < 500
Hence, I'm seeing a 1:5 column growth here if I put them as column
based.
eg:
| sum of count | sum_of_count_squared | qty | qty < 100 | qty < 500 |
I'm thinking of lumping them into 1 column via an array instead of into
5 different columns. Not sure how to go about this, hence the email to
the list.
something like {244,455,1234,43,23}
query can be done like
sum_of_count / qty = Ave
(sum_of_count_squared * sum_qty ) / (qty * (qty-1)) = STDEV
(sum_qty<100 / sum_qty) = % < 100
(sum_qty<500 / sum_qty) = % < 500
Then there's the issue of speed/responsiveness on doing it.
Help would be appreciated in this.
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