Tom Lane napsal(a):
I concur that I don't want to see this patch adding more than the absolute unavoidable minimum of overhead for data that meets the "current" layout definition. I'm disturbed by the proposal to stick overhead into tuple header access, for example.
OK. I agree that it is overhead. However the patch contains also Tuple and Page API cleanup which is general thing. All function should use HeapTuple access not HeapTupleHeader. I used function in the patch because I added multi version access, but they can be macro.
The main change of page API is to add two function PageGetHeapTuple and PageGetIndexTuple. I also add function like PageItemIsDead and so on. These change are not only related to upgrade.
I accepting your complains about Tuples, but I think we should have multi page version access method. The main advantage is that indexes are ready for reading without any problem. It helps mostly in TOAST chunk data access and it is necessary for retoasting. OK it will works until somebody change btree ondisk format, but now it helps.
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