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* Rewrite multiple joins...
@ 2009-08-21 03:17 tripplowe <tripplowe@gmail.com>
0 siblings, 1 reply; 2+ messages in thread
From: tripplowe @ 2009-08-21 03:17 UTC (permalink / raw)
To: pgsql-sql
Hey Folks,
I have a query that seems like it will never end. I'm hoping you can help
me rewrite it.
I have 4 tables that contain information about house sales within the state
(sale, taxes, property, buyer). Each table has an 'id' field that links
each record. I am just trying to flatten these files so I will have all of
the information in a single file. Below is my attempt to do so. Is there a
more efficient way to rewrite the joins?
select * from sale, taxes, property, buyer
where sale.id = taxes.id and sale.id = property.id and sale.id = buyer.id
I'm using postgresql 8.3 on a Windows 7 machine.
Thank You,
-Tripp
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* Re: Rewrite multiple joins...
@ 2009-08-21 15:15 Rob Sargent <robjsargent@gmail.com>
parent: tripplowe <tripplowe@gmail.com>
0 siblings, 0 replies; 2+ messages in thread
From: Rob Sargent @ 2009-08-21 15:15 UTC (permalink / raw)
To: tripplowe <tripplowe@gmail.com>; +Cc: pgsql-sql
Well indexing (or lack thereof) could be the real problem but you could
try "chaining" the tables
select * from sale s, taxes t, property p, buyer b
where s.id = t.id and t.id = p.id and p.id = b.id
and see if that (or other combination) changes the query plan appreciably.
(I would have to wonder if all those records are really unique per
sale.id? e.g. multiple buyers per unit sold or school and property tax
in separate records. And wondering further why, if you have sql access,
do you need a single table. Maybe you want a view for convenience (e.g.
select * from view_of_sales where lower(county) like 'a%' )?
tripplowe wrote:
> Hey Folks,
>
> I have a query that seems like it will never end. I'm hoping you can help
> me rewrite it.
>
> I have 4 tables that contain information about house sales within the state
> (sale, taxes, property, buyer). Each table has an 'id' field that links
> each record. I am just trying to flatten these files so I will have all of
> the information in a single file. Below is my attempt to do so. Is there a
> more efficient way to rewrite the joins?
>
> select * from sale, taxes, property, buyer
> where sale.id = taxes.id and sale.id = property.id and sale.id = buyer.id
>
> I'm using postgresql 8.3 on a Windows 7 machine.
>
> Thank You,
> -Tripp
>
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