Re: Bugs in CREATE/DROP INDEX CONCURRENTLY

Kevin Grittner wrote:
> Hmm. The comment is probably better now, but I've been re-checking
> the code, and I think my actual code change is completely wrong.
> Give me a bit to sort this out.

I'm having trouble seeing a way to make this work without rearranging
the code for concurrent drop to get to a state where it has set
indisvalid = false, made that visible to all processes, and ensured
that all scans of the index are complete -- while indisready is still
true. That is the point where TransferPredicateLocksToHeapRelation()
could be safely called. Then we would need to set indisready = false,
make that visible to all processes, and ensure that all access to the
index is complete. I can't see where it works to set both flags at
the same time. I want to sleep on it to see if I can come up with any
other way, but right now that's the only way I'm seeing to make DROP
INDEX CONCURRENTLY compatible with SERIALIZABLE transactions. :-(

-Kevin