Simon Riggs wrote: > On Sat, 2007-09-08 at 23:13 -0400, Bruce Momjian wrote: > > In summary, I feel we have the HOT mechanics down well, but the open > > issue is _when_ to activate each operation. > > That has been the only open issue for months. The interplay of behaviour > is where HOT succeeds and fails. Some behaviours sound like they will be > good, but aren't.
Looking at the patch, it seems defragmentation is checked every time a heap page is pinned in heapam.c by calling heap_page_prune_defrag(). If page free space < 1.2 * average_tuple_size the page is defragmented. It would seem defragmentation is checked as much as possible. Seems pruning is also as aggressive as possible. I think an open question is whether defragmentation should happen _only_ when we are trying to add something to the page and it doesn't fit. Another open question is whether pruning should happen only when the chain gets to a certain length. The larger question is how are we going to get these answers? -- Bruce Momjian <[EMAIL PROTECTED]> http://momjian.us EnterpriseDB http://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---------------------------(end of broadcast)--------------------------- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate
