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From: Jeroen Vermeulen <jtv@xs4all.nl>
To: Whit Armstrong <armstrong.whit@gmail.com>
Cc: pgsql-interfaces@postgresql.org
Subject: Re: simple example of copying data from a c/c++ array into postgres
Date: Thu, 11 Dec 2008 23:20:55 +0700
Message-ID: <49413DE7.8040703@xs4all.nl> (raw)
In-Reply-To: <8ec76080812090936g596abf91jdd8a184c3f56c32@mail.gmail.com>
References: <8ec76080812090708g93000f9l7e7f3e2162587331@mail.gmail.com>
	<493EA271.8010209@xs4all.nl>
	<8ec76080812090936g596abf91jdd8a184c3f56c32@mail.gmail.com>

Whit Armstrong wrote:

> can copy be used to append data to a table?

Yes.  The only thing it will not do for you is update existing rows.


> The only reason I'm hesitant to use the copy command is because I
> would have to render every row of my data to a string, and 64bit
> doubles could mean long strings, formating issues, etc.
> 
> roughly what I was thinking was (this is pseudocode):
> 
> PGtuple myTuple = createTuple();
> myTuple.push_back(toPGDate(myDate));
> myTuple.push_back(toPGDouble(myDouble));
> etc...
> 
> PGinsert_tuple(conn, myDestinationTable, myTuple);
> 
> are there facilities to do something like that, or am I really reaching here?

In libpqxx I mostly provide self-made text conversions, but you can also 
use the standard library to "print" most values into text buffers.  Just 
be sure to use the C locale where you do this, or you might end up with 
strange bugs depending on local notations!


Jeroen

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