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Add the option to co-locate tablets of different tables. For example, a base table and its CDC table, or a local index. main changes and ideas: * "table group" - a set of one or more tables that should be co-located. (Example: base table and CDC table). A group consists of one base table and zero or more children tables. * new column `base_table` in `system.tablets`: when creating a new table, it can be set to point to a base table, which the new table's tablets will be co-located with. when it's set, the tablet map information should be retrieved from the base table map. the child map doesn't contain per-tablet information. * co-located tables always have the same tablet count and the same tablet replicas. each tablet operation - migration, resize, repair - is applied on all tablets in a synchronized manner by the topology coordinator. * resize decision for a group is made by combining the per-table hints and comparing the average tablet size (over all tablets in the group) with the target tablet size. * the tablets load balancer works with the base table as a representative of the group. it represents a single migration unit with some `group_size` that is taken into account. * view tablets are co-located with base tablets when the partition keys match. Fixes https://github.com/scylladb/scylladb/issues/17043 backport is not needed. this is preliminary work for support of MVs and CDC with tablets. Closes scylladb/scylladb#22906 * github.com:scylladb/scylladb: tablets: validate no clustering row mutations on co-located tables raft_group0_client: extend validate_change to mixed_change type docs: topology-over-raft: document co-located tables tablet-mon.py: visual indication for co-located tablets tablet-mon.py: handle co-located tablets test/boost/view_schema_test.cc: fix race in wait_until_built boost/tablets_test: test load balancing and resize of co-located tablets test/tablets: test tablets colocation tablets: co-locate view tablets with base when the partition keys match test/pylib/tablets: common get_tablet_count api test_mv_tablets: use get_tablet_replicas from common tablets api test/pylib/tablets: fix test api to read tablet replicas from base table tablets: allocator: create co-located tables in a single operation alternator: prepare all new tables in a single announcement migration_manager: add notification for creating multiple tables tablets: read_tablet_transition_stage: read from base table storage service: allow repair request only on base tables tablets: keyspace_rf_change: apply on base table storage service: generate tablet migration updates on base tables tablets: replace all_tables method tablets: split when all co-located tablets are ready tablets: load balancer: sizing plan for table groups tablets: load balancer: handle co-located tablets tablets: allocate co-located tablets tablets: handle migration of co-located tablets storage service: add repair colocated tablets rpc tablets: save and read tablet metadata of co-located tables tablets: represent co-located tables in tablet metadata tablets: add base_table column to system.tablets docs: update system.tablets schema
Scylla unit tests using C++ and the Boost test framework
The source files in this directory are Scylla unit tests written in C++ using the Boost.Test framework. These unit tests come in three flavors:
-
Some simple tests that check stand-alone C++ functions or classes use Boost's
BOOST_AUTO_TEST_CASE. -
Some tests require Seastar features, and need to be declared with Seastar's extensions to Boost.Test, namely
SEASTAR_TEST_CASE. -
Even more elaborate tests require not just a functioning Seastar environment but also a complete (or partial) Scylla environment. Those tests use the
do_with_cql_env()ordo_with_cql_env_thread()function to set up a mostly-functioning environment behaving like a single-node Scylla, in which the test can run.
While we have many tests of the third flavor, writing new tests of this type should be reserved to white box tests - tests where it is necessary to inspect or control Scylla internals that do not have user-facing APIs such as CQL. In contrast, black-box tests - tests that can be written only using user-facing APIs, should be written in one of newer test frameworks that we offer - such as test/cqlpy or test/alternator (in Python, using the CQL or DynamoDB APIs respectively) or test/cql (using textual CQL commands), or - if more than one Scylla node is needed for a test - using the test/topology* framework.
Running tests
Because these are C++ tests, they need to be compiled before running.
To compile a single test executable row_cache_test, use a command like
ninja build/dev/test/boost/row_cache_test
You can also use ninja dev-test to build all C++ tests, or use
ninja deb-build to build the C++ tests and also the full Scylla executable
(however, note that full Scylla executable isn't needed to run Boost tests).
Replace "dev" by "debug" or "release" in the examples above and below to use the "debug" build mode (which, importantly, compiles the test with ASAN and UBSAN enabling on and helps catch difficult-to-catch use-after-free bugs) or the "release" build mode (optimized for run speed).
To run an entire test file row_cache_test, including all its test
functions, use a command like:
build/dev/test/boost/row_cache_test -- -c1 -m1G
to run a single test function test_reproduce_18045() from the longer test
file, use a command like:
build/dev/test/boost/row_cache_test -t test_reproduce_18045 -- -c1 -m1G
In these command lines, the parameters before the -- are passed to
Boost.Test, while the parameters after the -- are passed to the test code,
and in particular to Seastar. In this example Seastar is asked to run on one
CPU (-c1) and use 1G of memory (-m1G) instead of hogging the entire
machine. The Boost.Test option -t test_reproduce_18045 asks it to run just
this one test function instead of all the test functions in the executable.
Unfortunately, interrupting a running test with control-C while doesn't
work. This is a known bug (#5696). Kill a test with SIGKILL (-9) if you
need to kill it while it's running.
Boost tests can also be run using test.py - which is a script that provides a uniform way to run all tests in scylladb.git - C++ tests, Python tests, etc.
Execution with pytest
To run all tests with pytest execute
pytest test/boost
To execute all tests in one file, provide the path to the source filename as a parameter
pytest test/boost/aggregate_fcts_test.cc
Since it's a normal path, autocompletion works in the terminal out of the box.
To execute only one test function, provide the path to the source file and function name
pytest --mode dev test/boost/aggregate_fcts_test.cc::test_aggregate_avg
To provide a specific mode, use the next parameter --mode dev,
if parameter isn't provided pytest tries to use ninja mode_list to find out the compiled modes.
Parallel execution is controlled by pytest-xdist and the parameter -n auto.
This command starts tests with the number of workers equal to CPU cores.
The useful command to discover the tests in the file or directory is
pytest --collect-only -q --mode dev test/boost/aggregate_fcts_test.cc
That will return all test functions in the file.
To execute only one function from the test, you can invoke the output from the previous command.
However, suffix for mode should be skipped.
For example,
output shows in the terminal something like this test/boost/aggregate_fcts_test.cc::test_aggregate_avg.dev.
So to execute this specific test function, please use the next command
pytest --mode dev test/boost/aggregate_fcts_test.cc::test_aggregate_avg
Writing tests
Because of the large build time and build size of each separate test executable, it is recommended to put test functions into relatively large source files. But not too large - to keep compilation time of a single source file (during development) at reasonable levels.
When adding new source files in test/boost, don't forget to list the new source file in configure.py and also in CMakeLists.txt. The former is needed by our CI, but the latter is preferred by some developers.