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 14:50:44 |
Message-ID: | 5.1.0.14.0.20030424004359.058a7c18@mail.rhyme.com.au |
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Lists: | pgsql-hackers |
At 10:36 AM 23/04/2003 -0400, Tom Lane wrote:
> > Cast(8 as bit(10)) => '0001000000'
> > Cast(8 as bit(4)) => '0001'
>
>That part we could do, I think, if you are willing to abandon the
>assumption that the result of casting int to bit(n) and then to bit(m)
>should agree with the result of casting int directly to bit(m).
I'm not sure I follow the implication; in fact I would hope that:
Cast(B'0001' as bit(10))
would yield '0001000000'.
> > B'1' # Cast(1 as bit(32)) => '00000000000000000000000000000000'
>
>Eh? What is the # operator supposed to be doing here?
It's the XOR operator. Current implementation has:
Cast(B'1' as bit(32)) XOR Cast(1 as bit(32))
giving
10000000000000000000000000000001
Another thing I have forgotten to mention is that there are no
text<->varbit conversions.
>Perhaps these
>operators should only exist for varbit, or should demand inputs already
>the same length for bit.
That seems like a good idea. I'd prefer to make these changes for varbit only.
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