On 2013-10-28 12:27, Herouth Maoz wrote:
I have a rather large and slow table in Postgresql 9.1. I'm thinking of
partitioning it by months, but I don't like the idea of creating and dropping
tables all the time.
I'm thinking of simply creating 12 child tables, in which the check condition
will be, for example, date_part('month'', time_arrived) = 1 (or 2 for February,
3 for March etc.).
I'll just be deleting records rather than dropping tables, the same way I do in
my current setup. I delete a week's worth every time.
So, I have two questions.
First, is constraint exclusion going to work with that kind of condition? I mean, if my WHERE clause says
something like "time_arrived >= '2013-04-05' and time_arrived < '2013-04-17'", will it be
able to tell that date_part("month",time_arrived) for all the records is 4, and therefore avoid
selecting from any partitions other than the april one?
Second, when I delete (not drop!) from the mother table, are records deleted
automatically from the child tables or do I need to create rules/triggers for
that?
TIA,
Herouth
1. No - you'd need a condition like "where date_part("month",
time_arrived) = 1" in your select statements in order for the constraint
exclusion to kick in
2. Yes - there is no need to create rules or triggers for deletes on the
parent table (check out the syntax for "delete from <table>" versus
"delete from only <table>)
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