Andres Freund wrote: > On 2014-08-19 17:42:06 -0400, Alvaro Herrera wrote: > > MauMau wrote: > > > > > With that said, copying to a temporary file like <dest>.tmp and > > > renaming it to <dest> sounds worthwhile even as a basic copy > > > utility. I want to avoid copying to a temporary file with a fixed > > > name like _copy.tmp, because some advanced utility may want to run > > > multiple instances of pg_copy to copy several files into the same > > > directory simultaneously. However, I'm afraid multiple <dest>.tmp > > > files might continue to occupy disk space after canceling copy or > > > power failure in some use cases, where the copy of the same file > > > won't be retried. That's also the reason why I chose to not use a > > > temporary file like cp/copy. > > > > Is there a way to create a link to a file which only exists as an open > > file descriptor? If there was, you could create a temp file, open an > > fd, then delete the file. That would remove the issue with files being > > leaked due to failures of various kinds. > > Isn't this a solution looking for a problem? We're using tempfiles in > dozens of other places and I really don't see why this is the place to > stop doing so. Just copy to <dest>.tmp and move it into place. If things > crash during that, the command will be repeated shortly afterwards again > *anyway*. Let's not get into platform specific games here.
The issue is what happens if there's a crash while the temp file is in the middle of being filled. I agree there are bigger problems to solve in this area though. Yes, I agree that a fixed name such as _copy.tmp is a really bad choice for several reasons. -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
