Re: Very specialised query

From: Matthew Wakeling
Subject: Re: Very specialised query
Date: ,
Msg-id: alpine.DEB.2.00.0904011924150.21772@aragorn.flymine.org
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In response to: Re: Very specialised query  (Matthew Wakeling)
Responses: Re: Very specialised query  (Matthew Wakeling)
List: pgsql-performance

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Very specialised query  (Matthew Wakeling, )
 Re: Very specialised query  ("Kevin Grittner", )
 Re: Very specialised query  (Tom Lane, )
  Re: Very specialised query  (Matthew Wakeling, )
 Re: Very specialised query  (Matthew Wakeling, )
  Re: Very specialised query  (Tom Lane, )
 Re: Very specialised query  (Віталій Тимчишин, )
  Re: Very specialised query  (Matthew Wakeling, )
   Re: Very specialised query  (Tom Lane, )
    Re: Very specialised query  (Matthew Wakeling, )
    Re: Very specialised query  (Matthew Wakeling, )
     Re: Very specialised query  (Віталій Тимчишин, )
      Re: Very specialised query  (Matthew Wakeling, )
       Re: Very specialised query  (Віталій Тимчишин, )
        Re: Very specialised query  (Matthew Wakeling, )
 Re: Very specialised query  (Dimitri Fontaine, )
  Re: Very specialised query  (Matthew Wakeling, )
 Re: Very specialised query  ("Marc Mamin", )
  Re: Very specialised query  (Matthew Wakeling, )
   Re: Very specialised query  ("Marc Mamin", )
    Re: Very specialised query  (Matthew Wakeling, )
 Re: Very specialised query  (Matthew Wakeling, )
  Re: Very specialised query  (Віталій Тимчишин, )
   Re: Very specialised query  (Matthew Wakeling, )
    Re: Very specialised query  (Matthew Wakeling, )
     Re: Very specialised query  (Matthew Wakeling, )
      Re: Very specialised query  (Craig Ringer, )
 Re: Very specialised query  ("Marc Mamin", )
  Re: Very specialised query  (Matthew Wakeling, )

On Wed, 1 Apr 2009, Matthew Wakeling wrote:
> So, I have written a plpgsql function to calculate overlaps. It works
> reasonably quickly where there aren't that many overlaps. However, it seems
> to go very slowly when there are a large number of rows to return.

In plpgsql, what happens about memory allocation? It's just, I'm
generating and throwing away an awful lot of arrays. When do they get
unallocated?

Also, if I assign a variable (or an element of an array) to be the
contents of another variable (which may be a primitive, array, or row),
does it copy the contents or do it by reference?

Matthew

--
 For those of you who are into writing programs that are as obscure and
 complicated as possible, there are opportunities for... real fun here
                                        -- Computer Science Lecturer


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