The cursor means something like declare c cursor for select * from t;
The holdable cursor means declare c cursor WITH HOLD for select * from t;
Holdable cursor is good at transaction, user can still access it after the transaction is commit. But it is bad at it have to save all the record to tuple store before we fetch 1 row.
what I want is:
1. The cursor is still be able to fetch after the transaction is committed.
2. the cursor will not fetch the data when fetch statement is issue (just like non-holdable cursor).
I called this as with X cursor..
I check the current implementation and think it would be possible with the following methods:
1. allocate the memory in a {LongerMemoryContext}, like EState to prevent they are
2. allocate a more bigger resource owner to prevent the LockReleaseAll during CommitTransaction.
3. add the "with X" option to cursor so that Precommit_portals will not drop it during CommitTransaction.
Before I implement it, could you give some suggestions?
Thanks!