| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Greg Smith <greg(at)2ndquadrant(dot)com> |
| Cc: | Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>, Amy Smith <vah123(at)gmail(dot)com>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: postgres external table |
| Date: | 2010-01-18 14:57:02 |
| Message-ID: | 5335.1263826622@sss.pgh.pa.us |
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| Lists: | pgsql-general |
Greg Smith <greg(at)2ndquadrant(dot)com> writes:
> Craig Ringer wrote:
>> For those non-Oracle users among us, what's an external table?
> External tables let you map a text file directly to a table without
> explicitly loading it. In PostgreSQL, if you have data in a CSV file,
> usually you'd import it with COPY before you'd use it. If external
> tables were available, you'd just say there's an external table as a CSV
> file and you could start running queries against it.
I'm finding it hard to visualize a use-case for that. We must postulate
that the table is so big that you don't want to import it, and yet you
don't feel a need to have any index on it. Which among other things
implies that every query will seqscan the whole table. Where's the
savings?
regards, tom lane
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