2015-07-15 15:53 GMT+02:00 Zhaomo Yang <zhy...@cs.ucsd.edu>: > > there is other question - what is effect of ALTER TABLE of global temp > table on > > instances of this table in active sessions? > > As I said, we need to first agree on the behaviors of the existing > commands. I can think of two options now for ALTER TABLE: 1) only allow > ALTER TABLE when there is no other active sessions (this is how Oracle > deals with it.) 2) handle it as if session copies inherit from the global > copy and ALTER TABLE executes on the global copy. >
There are two possible kinds of GLOBAL TEMP tables - session related and transation related. Transaction related tables has very short life - and @1 needs outage, @2 requires stronger locks and can slow and less effective - because a) some changes can be invisible in other transactions (depends on isolation levels), b) the structure can be changed, but function code not (without dependency on isolation levels) - so it can be non consistent, c) why to change table if this table will be dropped in next milisecond. For this case the behave like PL functions can be very practical ~ third option for ALTER TABLE Regards Pavel > Thanks, > Zhaomo >
