Re: Phantom Command ID

Heikki Linnakangas <heikki@enterprisedb.com> writes:
> We could also limit the size of the hash table, which takes up most of 
> the memory, and only keep the latest phantom cids there. Presumably, if 
> current command id is 1000, you're not likely to set cmax to 500 on any 
> tuple in that transaction anymore.

The downside of that though is that if you did generate any such, you'd
assign a fresh (duplicate) phantom cid --- so you're bloating the array
in exchange for reducing the hash size.

It is quite easy to have current command counter much greater than the
CID of a still-live command: consider for example an UPDATE that is
firing triggers as it goes, and each trigger executes some queries.
        regards, tom lane