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Delayed Writes: fix L0 calc bug #311

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Dec 25, 2022
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Delayed Writes: fix L0 calc bug #311

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4 changes: 2 additions & 2 deletions db/column_family.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1013,15 +1013,15 @@ ColumnFamilyData::CalculateWriteDelayDividerAndMaybeUpdateWriteStallCause(

// L0 files
double l0_divider = 1;
const auto extra_l0_ssts = vstorage->NumLevelFiles(0) -
const auto extra_l0_ssts = vstorage->l0_delay_trigger_count() -
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it means that you used the incorrect value to calc the write delay , right?

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i think that l0_delay_trigger_count() is used generically which works for universal compaction as well. it worked just as well before but i noticed that l0_delay_trigger_count() is used to count the L0 files before and after that point in the code..

mutable_cf_options.level0_slowdown_writes_trigger;
if (extra_l0_ssts > 0) {
const auto num_L0_steps = mutable_cf_options.level0_stop_writes_trigger -
mutable_cf_options.level0_slowdown_writes_trigger;
assert(num_L0_steps > 0);
// since extra_l0_ssts == num_L0_steps then we're in a stop condition.
assert(extra_l0_ssts < num_L0_steps);
l0_divider = 1 / (1 - (extra_l0_ssts / num_L0_steps));
l0_divider = 1 / (1 - (static_cast<double>(extra_l0_ssts) / num_L0_steps));
}

if (l0_divider > biggest_divider) {
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