That's done by picking the ideal level for the input, such
that LCS won't have to either promote or demote data, because
the output level is not the best candidate for having the
size of the output data.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
ideal level is calculated as:
ceil(log base10 of ((input_size + max_fragment_size - 1) / max_fragment_size))
such that 20 fragments will be placed at level 2, as level 1
capacity is 10 fragments only.
The goal of extracting it is that the formula will be useful for
major in addition to reshape.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Bucket awareness in cleanup was introduced in a69d98c3d0.
STCS and TWCS already support it, and now LCS will receive it.
The goal of bucket awareness is to reduce writeamp in cleanup,
therefore reducing operation time. Additionally, garbage collection
becomes more efficient as shadowed data can now be potentially
compacted with the data that shadows it, assuming they're on
the same level.
The implementation for LCS is simple. Will reuse the procedure
for STCS for returning jobs in level 0. And one job will be
returned for each non-empty level > 0. What allows us to do it
is our incremental selection approach used in compaction,
that sets a limit on memory usage and disk space requirement.
Fixes#10097.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <20220331173417.211257-1-raphaelsc@scylladb.com>
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.
Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.
The changes we applied mechanically with a script, except to
licenses/README.md.
Closes#9937
Last method in compaction_strategy using table. From now on,
compaction strategy no longer works directly with table.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
From now on, get_major_compaction_job() will use table_state instead of
a plain reference to table.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
From now on, get_sstables_for_compaction() will use table_state.
With table_state, we avoid layer violations like strategy using
manager and also makes testing easier.
Compaction unit tests were temporarily disabled to avoid a giant
commit which is hard to parse.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
This warning can catch a virtual function that thinks it
overrides another, but doesn't, because the two functions
have different signatures. This isn't very likely since most
of our virtual functions override pure virtuals, but it's
still worth having.
Enable the warning and fix numerous violations.
Closes#9347
Since compaction is layered on top of sstables, let's move all compaction code
into a new top-level directory.
This change will give me extra motivation to remove all layer violations, like
sstable calling compaction-specific code, and compaction entanglement with
other components like table and storage service.
Next steps:
- remove all layer violations
- move compaction code in sstables namespace into a new one for compaction.
- move compaction unit tests into its own file
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <20210707194058.87060-1-raphaelsc@scylladb.com>
