>From the explanation of Tom Lane, it seems we could get around the problem in this way: avoid using "nextval" etc. on the sequence to be dropped in the same transaction. The details can be like this. Support we want to drop a sequence sA and would like to get the next available sA sequence value before we want to drop it. (This is the situation where Dmitry and I found this bug.) We would do 1. exec statement "SELECT last_value from sA" to get the last value of this sequence. 2. increment this last value 3. drop the sequence sA.
We have seen that this fixed the problem. I am not sure we can absolutely guarantee that the last value we get this way would be the same as calling "nextval", since another request might change the sequence we want to drop (depending on transaction mode?). However we can live with it since dropping sequence does not happen often at all. But my question is: will this completely get around the problem of server corrupt? In particular, if in a transaction, the "nextval" is called on a sequence different from the sequence we are trying to drop, would there be a problem? My tests showed NO problem in this situation. Also the analysis from Tom Lane seems confirming this. But I am still not sure on this. Thanks, Heng Sun ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
