> Is there any documentation or README explaining this whole 64-bit XID > mechanism? > There is none, unfortunately. I would come back to this later.
> Could you tell me what happens if new tuple with XID larger than xid_base > + 0xFFFFFFFF is inserted into the page? Such new tuple is not allowed to be > inserted into that page? Or xid_base and xids of all existing tuples in the > page are increased? Also what happens if one of those xids (of existing > tuples) cannot be changed because the tuple still can be seen by > very-long-running transaction? > All this mechanism is around heap_insert/heap_update by calling heap_page_prepare_for_xid() and if it fails (due to tuple still visible) error is raised. Also If xid_base shift is not viable, it will try to remove old tuples. -- Best regards, Maxim Orlov.
