It turns out recent changes broke tne SQLite index support (from adding
support for MS SQL partial/filtered indexes), so fix it by using the
pgsql-index structure rather than the specific sqlite-idx one.
In passing, improve detection of PRIMARY KEY indexes, which was still
lacking. This work showed that the introspection done by pgloader was
wrong, it's way more crazy that we though, so adjust the code to loop
over PRAGMA calls for each object we inspect.
While adding PRAGMA calls, add support for foreign keys too, we have the
code infrastructure that makes it easy now.
Add the workers and concurrency settings to the LOAD commands for
database sources so that users can tweak them now, and add mentions of
them in the documentation too.
From the documentation string of the copy-from method as found in
src/sources/common/methods.lisp:
We allow WORKER-COUNT simultaneous workers to be active at the same time
in the context of this COPY object. A single unit of work consist of
several kinds of workers:
- a reader getting raw data from the COPY source with `map-rows',
- N transformers preparing raw data for PostgreSQL COPY protocol,
- N writers sending the data down to PostgreSQL.
The N here is setup to the CONCURRENCY parameter: with a CONCURRENCY of
2, we start (+ 1 2 2) = 5 concurrent tasks, with a CONCURRENCY of 4 we
start (+ 1 4 4) = 9 concurrent tasks, of which only WORKER-COUNT may be
active simultaneously.
Those options should find their way in the remaining sources, that's for
a follow-up patch tho.
Filter the list of tables we migrate directly from the SQLite query,
avoiding to return useless data. To do that, use the LIKE pattern
matching supported by SQLite, where the REGEX operator is only available
when extra features are loaded apparently.
See #310 where filtering out the view still caused errors in the
loading.
