Re: forcing returned values to be binary

From: Dave Cramer <pg(at)fastcrypt(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: forcing returned values to be binary
Date: 2005-11-15 18:01:20
Message-ID: 62C2F43E-4209-4C7B-B998-EB91E50A1732@fastcrypt.com
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I've talked to Ken Geis via email. He suggests that there is
considerable overhead to be saved if we go to binary; especially in
date, and timestamp fields

One thing though if the date is 64 bit instead of float, what does
the binary output look like? Are they different ?

If so this would seem to complicate things quite a bit.

Dave
On 14-Nov-05, at 12:12 AM, Tom Lane wrote:

> Dave Cramer <pg(at)fastcrypt(dot)com> writes:
>> I was thinking that it may be necessary to issue a describe before
>> the execute, but I'm thinking now that the driver can only handle
>> specific types, so anything outside of what it knows about would be
>> an error anyway.
>
>> I gather it's not possible to mix the return format? For example all
>> known types would be binary, others would be text ? At this point I'm
>> not even sure it would help.
>
> You can ask for mixed return formats; see the description of the Bind
> message. The sticky spot is that you can't really do that without
> first
> having gotten the list of output columns (via Describe Statement).
> Without that, you don't even know how many output columns there are,
> let alone which ones have datatypes you understand.
>
> I'm not sure that this is a fatal objection, at least not for
> prepared-in-advance statements. You can put a Describe Statement into
> the same network packet exchange as the original Parse message, so
> there isn't any reason that you can't know the column types. It is
> problematic if you want to Parse/Bind/Execute in just one round trip.
>
> regards, tom lane
>
> ---------------------------(end of
> broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
> choose an index scan if your joining column's datatypes do not
> match
>

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