OptionalafterKeyset position: the last rowid emitted for DumpCursor.table.
Null means nothing emitted yet and is not 0: rowid 0 is a real row (Drupal's anonymous user).
Optionalemittedrows emitted from this table so far, so limitPerTable survives a resume
OptionaloffsetOFFSET position, used only for a WITHOUT ROWID table
OptionalshapeFingerprint of the dump shape this cursor belongs to.
Options arrive separately on every call, so resuming ?all=1 with defaults would splice two
dumps; dumpChunk throws on a mismatch.
Optionaltablethe table being emitted, by name
Where a resumable export has got to.
Plain JSON, since it travels to the client between invocations. The table is named, not indexed: an index into a list rebuilt from
sqlite_mastershifts when a table is created or dropped mid-export and would resume into the wrong table.