Tomas Vondra wrote: > My idea was to keep the per-database stats, but allow some sort of > "random" access - updating / deleting the records in place, adding > records etc. The simplest way I could think of was adding a simple > "index" - a mapping of OID to position in the stat file. > > I.e. a simple array of (oid, offset) pairs, stored in oid.stat.index or > something like that. This would make it quite simple to access existing > record > > 1: get position from the index > 2: read sizeof(Entry) from the file > 3: if it's update, just overwrite the bytes, for delete set isdeleted > flag (needs to be added to all entries) > > or reading all the records (just read the whole file as today).
Sounds reasonable. However, I think the index should be a real index, i.e. have a tree structure that can be walked down, not just a plain array. If you have a 400 MB stat file, then you must have about 4 million tables, and you will not want to scan such a large array every time you want to find an entry. -- 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
