Re: postgres external table

2010/1/18 Tom Lane <tgl@sss.pgh.pa.us>:
> Greg Smith <greg@2ndquadrant.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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Another case, Tom, could be when the file is updated from a non-DB
application and you need to synchronize
the data with other DB applications ...

--
Vincenzo Romano
NotOrAnd Information Technologies
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