From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mark Dilger <markdilger@yahoo.com>
Cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Sent: Tuesday, May 29, 2012 3:42 PM
Subject: Re: [HACKERS] Performance patch for Win32
Mark Dilger <
markdilger@yahoo.com> writes:
> I am hesitant to write a function like AllocateDirWithFilePattern
> if the pattern is simply ignored on non-Windows. In my patch,
> the pattern underspecified the files, and the ad-hoc matching code
> applied to all the returned files tightened that up. But a person
> could just as well overspecify the pattern and then they would get
> different behavior on Windows vs. non-Windows, with fewer
> files returned by FindNextFile() than would have matched the
> ad-hoc pattern.
Well, if you're imagining that we wouldn't need to test carefully on
both Windows and non-Windows, I think that's a pipe dream. As an
example, your proposal of AllocateDirWithFilePrefix would only work
consistently across platforms if the prefix didn't contain anything
that Windows thought was a pattern metacharacter. (This might never
come up, but I'm not too sure what the metacharacters are on Windows.)
Having said that, I have nothing particularly against the idea of
specifying a prefix rather than an arbitrary pattern. I'm just
saying it'll still need testing. Also, I wonder how many of the
potential stat-equivalent operations we'll be unable to optimize
away with the more restricted definition. Using a tighter pattern
on Windows seems basically free (modulo testing) if we accept that
it's Windows-only.
regards, tom lane
