> 1. These operations think they can use ordinary heap_update operations > to change pg_index entries when they don't have exclusive lock on the > parent table. The lack of ex-lock means that another backend could be > currently loading up its list of index OIDs for the table --- and since > it scans pg_index with SnapshotNow to do that, the heap_update could > result in the other backend failing to see this index *at all*. That's > okay if it causes the other backend to not use the index for scanning... > but not okay if it causes the other backend to fail to make index > entries it is supposed to make. > > I think this could possibly be fixed by using nontransactional > update-in-place when we're trying to change indisvalid and/or > indisready, but I've not really thought through the details.
Only solution there is to fix SnapshotNow, as we discussed last Christmas. I'll dig out my patch for that, which IIRC I was nervous of committing at last minute into 9.2.
