Support for TTL-based data removal when using tablets.
The essence of this commit is a separate code path for finding token
ranges owned by the current shard for the cases when tablets are used
and not vnodes. At the same time, the vnodes-case is not touched not to
cause any regressions.
The TTL-caused data removal is normally performed by the primary
replica (both when using vnodes and tablets). For the tablets case,
the already-existing method tablet_map::get_primary_replica(tablet_id)
is used to know if a shard execuring the TTL-related data removal is
the primary replica for each tablet.
A new method tablet_map::get_secondary_replica(tablet_id) has been
added. It is needed by the data invalidation procedure to remove data
when the primary replica node is down - the data is then removed by the
secondary replica node. The mechanism is the same as in the vnodes case.
Since alternator now supports TTL, the test
`test_ttl_enable_error_with_tablets` has been removed.
Also, tests in the test_ttl.py have been made to run twice, once with
vnodes and once with tablets. When run with tablets, the due to lack of
support for LWT with tablets (#18068), tests use
'system:write_isolation' of 'unsafe_rmw'. This approach allows early
regression testing with tablets and is meant only as a tentative
solution.
Fixesscylladb/scylladb#16567Closesscylladb/scylladb#23662
In commit c24bc3b we decided that creating a new table in Alternator
will by default use vnodes - not tablets - because of all the missing
features in our tablets implementation that are important for
Alternator, namely - LWT, CDC and Alternator TTL.
We never documented this, or the fact that we support a tag
`experimental:initial_tablets` which allows to override this decision
and create an Alternator table using tablets. We also never documented
what exactly doesn't work when Alternator uses tablet.
This patch adds the missing documentation in docs/alternator/new-apis.md
(which is a good place for describing the `experimental:initial_tablets`
tag). The patch also adds a new test file, test_tablets.py, which
includes tests for all the statements made in the document regarding
how `experimental:initial_tablets` works and what works or doesn't
work when tablets are enabled.
Two existing tests - for TTL and Streams non-support with tablets -
are moved to the new test file.
When the tablets feature will finally be completed, both the document
and the tests will need to be modified (some of the tests should be
outright deleted). But it seems this will not happen for at least
several months, and that is too long to wait without accurate
documentation.
Fixes#21629
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Closesscylladb/scylladb#22462
