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Date: Mon, 12 Jun 2006 21:58:13 -0500
From: "Aaron Bono" <postgresql@aranya.com>
To: "Tom Lane" <tgl@sss.pgh.pa.us>
Subject: Re: COPY to table with array columns (Longish)
Cc: phillips@weatherbeeta.com.au, pgsql-sql@postgresql.org
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I agree with Tom.  Personally I cannot think of a time I would use an array
column over a child table.  Maybe someone can enlighten me on when an array
column would be a good choice.

What language are you using to do the export if I may ask?

-Aaron

On 6/12/06, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> "Phillip Smith" <phillips@weatherbeeta.com.au> writes:
> > The whole sys file is variable length records like this - they range =
> > from 1
> > to over 17,000 fields per record.
>
> 17000?  I think you really need to rethink your schema.  While you could
> theoretically drop 17000 elements into a PG array column, you wouldn't
> like the performance --- it'd be almost unsearchable for instance.
>
> I'd think about two tables, one with a single row for each SYS record
> from the original, and one with one row for each detail item (the
> invoice numbers in this case).  With suitable indexes and a foreign key
> constraint, this will perform a lot better than an array-based
> translation.
>
> And no, in neither case will you be able to import that file without
> massaging it first.
>
>                         regards, tom lane
>

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I agree with Tom.&nbsp; Personally I cannot think of a time I would use an array column over a child table.&nbsp; Maybe someone can enlighten me on when an array column would be a good choice.<br><br>What language are you using to do the export if I may ask?
<br><br>-Aaron<br><br><div><span class="gmail_quote">On 6/12/06, <b class="gmail_sendername">Tom Lane</b> &lt;<a href="mailto:tgl@sss.pgh.pa.us">tgl@sss.pgh.pa.us</a>&gt; wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
&quot;Phillip Smith&quot; &lt;<a href="mailto:phillips@weatherbeeta.com.au">phillips@weatherbeeta.com.au</a>&gt; writes:<br>&gt; The whole sys file is variable length records like this - they range =<br>&gt; from 1<br>&gt; to over 17,000 fields per record.
<br><br>17000?&nbsp;&nbsp;I think you really need to rethink your schema.&nbsp;&nbsp;While you could<br>theoretically drop 17000 elements into a PG array column, you wouldn't<br>like the performance --- it'd be almost unsearchable for instance.
<br><br>I'd think about two tables, one with a single row for each SYS record<br>from the original, and one with one row for each detail item (the<br>invoice numbers in this case).&nbsp;&nbsp;With suitable indexes and a foreign key
<br>constraint, this will perform a lot better than an array-based<br>translation.<br><br>And no, in neither case will you be able to import that file without<br>massaging it first.<br><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;regards, tom lane
<br></blockquote></div><br>

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