A boolean type would save a lot of space. We wouldn't need to retain the column db, only the index db in LMDB. To get the value for that column for a particular rowid, just check one of the values (either true or false) in the ix:db for that column. If the rowid isn't in one, it must be in the other.
This method would save at least 5 bytes per row per column, plus whatever LMDB overhead for the actual db column.
A boolean type would save a lot of space. We wouldn't need to retain the column db, only the index db in LMDB. To get the value for that column for a particular rowid, just check one of the values (either true or false) in the ix:db for that column. If the rowid isn't in one, it must be in the other.
This method would save at least 5 bytes per row per column, plus whatever LMDB overhead for the actual db column.