Re: BUG #18711: Attempting a connection with a database name longer than 63 characters now fails
От | Nathan Bossart |
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Тема | Re: BUG #18711: Attempting a connection with a database name longer than 63 characters now fails |
Дата | |
Msg-id | Zz4BxVqAZnWHFXFB@nathan обсуждение исходный текст |
Ответ на | Re: BUG #18711: Attempting a connection with a database name longer than 63 characters now fails (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: BUG #18711: Attempting a connection with a database name longer than 63 characters now fails
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Список | pgsql-bugs |
On Tue, Nov 19, 2024 at 11:23:13PM -0500, Tom Lane wrote: > Nathan Bossart <nathandbossart@gmail.com> writes: >> I'm admittedly not an expert in the multi-byte code, but since there are >> encodings like LATIN1 that use a byte per character, don't we need to do >> multiple lookups any time the NAMEDATALEN-1'th byte is non-ASCII? > > I don't think so, but maybe I'm missing something. An important > property of backend-legal encodings is that all bytes of a multibyte > character have their high bits set. Thus if the NAMEDATALEN-2'th > byte does not have that, it is not part of a multibyte character. > That's also the reason we can stop if we reach a high-bit-clear > byte while backing up to earlier bytes. That's good to know. If we can assume that 1) all bytes of a multibyte character have the high bit set and 2) all multibyte characters actually require multiple bytes, then there are just a handful of cases that require multiple lookups, and we can restrict even those to some extent, too. -- nathan
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