Re: bit strings - anyone working on them?

From: Philip Warner <pjw(at)rhyme(dot)com(dot)au>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Christopher Kings-Lynne" <chriskl(at)familyhealth(dot)com(dot)au>, "PostgreSQL Hackers" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: bit strings - anyone working on them?
Date: 2003-04-23 16:38:34
Message-ID: 5.1.0.14.0.20030424022221.044b4e38@mail.rhyme.com.au
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At 12:02 PM 23/04/2003 -0400, Tom Lane wrote:
>and instead
>add a separate function that maps an integer to an LSB-first bitstring?

This would work, but it's not going to be very friendly without automatic
cast support. Does the spec mention LSB and/or numeric conversions? Also, I
just noticed that B'0' is not equal to B'00', which also seems unfortunate.

Perhaps we could also add an LSB-last function, and output some kind of
warning when using numeric casts to the effect that the application should
use the LSB-last function because the casts will start using LSB-first in a
future version.

Alternatively, we could consider creating a new type that works as one
would expect:

- Automatic casting (sizes and numeric)
- Automatic padding
- numeric & text conversion
- extract_bits using LSB as position 1.

and one of:
- LSB on right
- pad on left
or
- LSB on left
- pad on right

Another option: can we use some aspect of the type definition to specify
the LSB position to store in attyypmod?

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