Re: [HACKERS] Re: [GENERAL] Update of bitmask type
От | Adriaan Joubert |
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Тема | Re: [HACKERS] Re: [GENERAL] Update of bitmask type |
Дата | |
Msg-id | 37E9E490.1CD9623B@albourne.com обсуждение исходный текст |
Ответ на | Re: [HACKERS] Re: [GENERAL] Update of bitmask type (The Hermit Hacker <scrappy@hub.org>) |
Список | pgsql-hackers |
> > I don't have time right now to type up a short summary, but can do > that later if you like. But the data entry for an SQL92 bit type looks > like > > B'10111' > X'17' > > The underlying data type is BIT(n), a fixed-length type where n is the > exact number of bits. BIT VARYING (n) allows a variable number of bits > (duh!) up to n bits. We can support these SQL92 constructs in the > parser, folding them into an internal type as we do for character > strings currently. > > It could be implemented just like the character types, having a header > on the internal representation which holds the length. It can't re-use > the character type support functions as-is, since they currently > consider a zero byte in the string as end-of-string. OK, I'll have a go at this as I get a chance. If somebody has the SQL standard on line and could send me the appropriate sections I would appreciate it. As I know very little about the postgres internals I would also appreciate a short roadmap as to what needs to be done where, i.e. does the parser need to be changed, and where the files are /new files hsould go that I need to update. If this is somewhere in the docs please point me to it. What I've found upto now is backend/utils/adt/varlena.c backend/utils/adt/varchar.c which I will use as starting point? I found the file src/backend/lib/bit.c (Bruce's according to the log message). Has that got anything to do with bit arrays? Cheers, Adriaan
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