Re: Support for REINDEX CONCURRENTLY

On 2013-08-27 15:34:22 +0900, Michael Paquier wrote:
> I have been working a little bit more on this patch for the next
> commit fest. Compared to the previous version, I have removed the part
> of the code where process running REINDEX CONCURRENTLY was waiting for
> transactions holding a snapshot older than the snapshot xmin of
> process running REINDEX CONCURRENTLY at the validation and swap phase.
> At the validation phase, there was a risk that the newly-validated
> index might not contain deleted tuples before the snapshot used for
> validation was taken. I tried to break the code in this area by
> playing with multiple sessions but couldn't. Feel free to try the code
> and break it if you can!

Hm. Do you have any justifications for removing those waits besides "I
couldn't break it"? The logic for the concurrent indexing is pretty
intricate and we've got it wrong a couple of times without noticing bugs
for a long while, so I am really uncomfortable with statements like this.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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