Remove the existing PLPGSQL function that implements drop_chunks, replacing it with a direct call to the C function, which also implements the old PLPGSQL checks in C. Refactor out much of the code shared between the C implementations of show_chunks and drop_chunks.
Timescale provides an efficient and easy to use api to drop individual
chunks from timescale database through drop_chunks. This PR builds on
that functionality and through a new show_chunks function gives the
opportunity to see the chunks that would be dropped if drop_chunks was run.
Additionally, it adds a newer_than option to drop_chunks (also supported
by show_chunks) that allows to see/drop chunks in an interval or newer
than a point in time.
This commit includes:
- Implementation of show_chunks in C
- Additional helper functions to work with chunks
- New version of drop_chunks in sql that uses show_chunks. This
also adds a newer_than option to drop_chunks
- More enhanced tests of drop_chunks and new tests for show_chunks
Among other reasons, show_chunks was implemented in C in order
to be able to have both older_than and newer_than arguments be null. This
was not possible in SQL because the arguments had to have polymorphic types
and whether they are used in function body or not, PL/pgSQL requires these
arguments to typecheck.
