Archive of Ranking Table

[wergstatt]

The goal of this issue is to build a parsimonious archive, that updates only values that have changed since the the last retrieval of information.

The basic idea is to dumb the whole table into the according landing zone table and transfer only those to the current table that differ from the current entry. As soon as a current entry would be replaced, a new entry is appended to the archive table containing a start and end timestamp.

• [x] Create LZ, CT and ARCH table.
• [x] Introduce hashes to check for equality of each item. Note: Journals are uniquely identified by their link.
• [x] Build transfer pipeline.

[wergstatt]

As noted in #2 postgreSQL allows triggers after a copy from statement, which should be compatible with the current design of the archive.