Ühel kenal päeval, E, 2006-06-26 kell 11:31, kirjutas Bruce Momjian: > Hannu Krosing wrote: > > > > pass 3: clean heap based on ctid from pass 1 > > > > > > > > If yo do it this way, you dont need to invent new data structures to > > > > pass extra info about CITC internals to passes 2 and 3 > > > > > > > > On more thing - when should free space map be notified about free space > > > > in pages with CITC chains ? > > > > > > Uh, well, I am thinking we only free CITC space when we are going to use > > > it for an UPDATE, rather than free things while doing an operation. It > > > is good to keep the cleanup overhead out of the main path as much as > > > possible. > > > > So vacuum should only remove dead CITC chains and leave the ones with > > live tuples to CITC internal use ? > > Yes, it has to. What else would it do? Add index entries?
No, clean out the dead part. But this would probably add the page to FSM - do we want that. Also, this cleaning should probably be done at pass1, so we dont have to carry the ctids of tuples which have no index entries around to passes 2 and 3 . This has the downside of possibly writing the heap page twice, so maybe we dont want it. > > That would also suggest that pages having live CITC chains and less than > > N% of free space should mot be reported to FSM. > > Parts of the CITC that are not visible can be used for free space by > vacuum, but the visible part is left alone. > -- ---------------- Hannu Krosing Database Architect Skype Technologies OÜ Akadeemia tee 21 F, Tallinn, 12618, Estonia Skype me: callto:hkrosing Get Skype for free: http://www.skype.com ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
