-There are special database functions required by a (little-used) API call, the migrations and diff replication. The former two are provided as *either* pure SQL functions or a compiled shared library. It is recommended that you start with the pure SQL versions, as described below, and only install the compiled shared library if you are running a production server making a lot of `/changes` API calls or need the diff replication functionality.
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-If you aren't sure which you need, install the SQL version below.