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LCS: reshape: tolerate more sstables in level 0 with relaxed mode

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Relaxed mode, used during initialization, of reshape only tolerates min_threshold
(default: 4) L0 sstables. However, relaxed mode should tolerate more sstables in
level 0, otherwise boot will have to reshape level 0 every time it crosses the
min threshold. So let's make LCS reshape tolerate a max of max_threshold and 32.
This change is beneficial because once table is populated, LCS regular compaction
can decide to merge those sstables in level 0 into level 1 instead, therefore
reducing WA.

Refs #8297.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <20210318131442.17935-1-raphaelsc@scylladb.com>
(cherry picked from commit e53cedabb1)
This commit is contained in:
Raphael S. Carvalho
2021-03-18 10:14:42 -03:00
committed by Avi Kivity
parent 03f2eb529f
commit ee48ed2864
1 changed files with 1 additions and 1 deletions
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sstables/leveled_compaction_strategy.cc
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@@ -178,7 +178,7 @@ leveled_compaction_strategy::get_reshaping_job(std::vector<shared_sstable> input
unsigned max_filled_level = 0;
size_t offstrategy_threshold = std::max(schema->min_compaction_threshold(), 4);
size_t offstrategy_threshold = (mode == reshape_mode::strict) ? std::max(schema->min_compaction_threshold(), 4) : std::max(schema->max_compaction_threshold(), 32);
size_t max_sstables = std::max(schema->max_compaction_threshold(), int(offstrategy_threshold));
auto tolerance = [mode] (unsigned level) -> unsigned {
if (mode == reshape_mode::strict) {