On 10 Jun 1998, Jukka Neppius wrote: > I don't even have source for current dpkg:) I only made simple (~300 > lines) test program to read 'available'. It finds every tag (Package, > Installed-Size, ...) for every package and qsorts packages. After > sort most operations should be fast. It should have enough error > checking. It probably could be used in dpkg or in dselect with few > small modifications (data structure). I could mail it to anyone who > wants to test it.
Hmm, well sorting and finding tags is not really comparable to the parsing that is required by at least apt, take a look at http://www.debian.org/~jgg/deity/cache.html That is the in-memory (and cached on disk) structure that the packages files are broken into. The cache generator in APT uses a few faulty assumptions so isn't terribly fast, I have a design for one that should be a few magnitudes faster but I don't think I'll implement it soon. > Of course reading many small *.list files is very slow. New format > is only possibility to speed it. File size becomes large (=slow), so > some kind of compressed/binary format is needed. (I failed to find > Jason Gunthorpe's proposal for new format.) Strangely so did I. I wonder where it went. Since I don't expire my sent-mail I've pulled it out and put it at http://www.debian.org/~jgg/mail.txt Think of it as some thoughts on the subject and why we should not use a generic dbm. You should read and understand the apt cache document before reading this - it is the same idea. With a mmap'd data structure like I explore, multiple dpkg startup time would be very close to instant on a wide class of machines. > Also 'Depends' lines in available could cause a problem. When > removing a package, it is necessary to scan all installed packages to > find dependencies (at least i believe so:). This is rather slow. > Simplifying 'Depends' line format would help ('|' is unnecessary > because 'Provides' could be used instead.) This is very fast with APT's format, it actually does alot of such 'reverse' lookups. Jason -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
