Ottavio Campana <ottavio@xxxxxxxxxxxxx> writes: > Postgresql doc says "a cursor that encapsulates the query, and then read > the query result a few rows at a time." So, when I open a cursor, is all > the query executed No, just enough to give you the rows you ask for. Otherwise the query state is held open until the next FETCH. Exception: if you declare a cursor WITH HOLD then it's executed to completion before the transaction commits, because the resources involved in an open query (eg locks) can't be kept across transactions. Also, depending on how complex the query is, the system might have to do most of the work before it can deliver even the first row. ORDER BY implemented by an explicit sort step is like that, for example. regards, tom lane
