Bruce Momjian wrote: > Heikki Linnakangas wrote: > > Here's an updated version of the phantom command ids patch. > > > > I found one more subtle safety issue. The array and hash table for > > phantom command ids is dynamically grown when HeapTupleHeaderSetCmax is > > called. Unfortunately, since HeapTupleHeaderSetCmax is used inside a > > critical sections, running out of memory while trying to grow them would > > cause a PANIC. That's why I moved the SetXmax/SetCmax calls outside > > critical sections in heapam.c. I believe that's safe; if a backend > > aborts after setting the xmax/cmax, no-one is going to care about the > > xid of an aborted transaction in there. > > > > Per Tom's suggestion, I replaced the function cache code in fmgr.c and > > similar code in plperl.c, pltcl.c, plpgsql/pl_comp.c and plpython.c to > > use xmin+tid instead of xmin+cmin for the up-to-dateness check. I don't > > have any tcl, perl or python test cases handy to test them, but the > > change is small and essentially same for all of the above. Is there any > > regression tests for the PL languages? > > > > I made cmin and cmax system attributes aliases for the same physical > > commandid field. I support the idea of a complete overhaul of those > > system attributes, but let's do that in a separate patch. > > > > To measure the overhead, I ran a plpgsql test case that updates a single > > row 10000 times in a loop, generating a new phantom command id in each > > iteration. The test took ~5% longer with the patch, so I think that's > > acceptable. I couldn't measure a difference with pgbench (as expected). > > > > I think the patch is ready. Please remove the PHANTOMCID_DEBUG define > > and ifdef blocks before applying. > > Heikki, I found something odd in your patch. You had an extra > parentheses at the end of the line in the orginal and new version of the > patch (attached). I removed it before applying, but I just wanted to > confirm this was OK.
Huh, you already applied it? -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
