Re: [Oledb-dev] Re: double precision error with pg linux server, but not with windows pg server

From: Shachar Shemesh <shachar(at)shemesh(dot)biz>
To: Andrew Dunstan <andrew(at)dunslane(dot)net>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, oledb-devel(at)pgfoundry(dot)org, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [Oledb-dev] Re: double precision error with pg linux server, but not with windows pg server
Date: 2007-05-20 04:25:55
Message-ID: 464FCDD3.9080608@shemesh.biz
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Andrew Dunstan wrote:
> Why the heck do the OLE DB specs care about the internals of the
> client-server prototocol? It is documented fairly clearly that text is
> the only portable way to transfer data.
>
Is it?
> Perhaps we need to expand this sentence in the docs: "Keep in mind that
> binary representations for complex data types may change across server
> versions;"
>
Where is that in the docs. It does not appear in the page discussing
PQLIB and binary data transfers
(http://www.postgresql.org/docs/8.2/interactive/libpq-exec.html).

Even the original sentence does not describe the problem we're seeing
here. It does not mention cross platform incompatibility.
> The COPY docs are probably more correct: "The BINARY key word causes all
> data to be stored/read as binary format rather than as text. It is
> somewhat faster than the normal text mode, but a binary-format file is
> less portable across machine architectures and PostgreSQL versions."
>
Again, to me this sentence spells "you have a problem, we're not going
to help you out, deal with it". This is especially true if what Tom said
was true, that the text format does not maintain total precision. You
are essentially telling the user "you cannot move your data reliably
even between servers of the same version".

Shachar

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