From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
---|---|
To: | Boszormenyi Zoltan <zb(at)cybertec(dot)at> |
Cc: | PGSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Inconsistent ::bit(N) and get_bit()? |
Date: | 2010-08-11 15:48:26 |
Message-ID: | AANLkTi=Dmc_uCn8jAcj0v4cAArXGhp-VsQsbHe2Lfnyb@mail.gmail.com |
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2010/8/11 Boszormenyi Zoltan <zb(at)cybertec(dot)at>:
> Shouldn't it at least be documented in more depth? Say, get_bit(, N)
> provides the Nth bit (0-based) counting from the leftmost bit?
> I would certainly appreciate a warning spelled out about this
> so if you convert a number to bitstring of length N and you want the
> Mth bit (according to any programming language) then you need to use
> get_bit(..., N-1-M).
The fact that bit-strings subscript from the left rather than from the
right seems pretty odd to me, but it is documented. I wouldn't object
to adding a note to somewhere around here, if we can think of a
suitable way to word it:
http://www.postgresql.org/docs/9.0/static/functions-bitstring.html
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company
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