codespell reports that "statics" could be the misspelling of
"statistics". but "static" here means the static column(s). so
replace "static" with more specific wording.
Refs #589
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#17216
Currently, the compactor requires a valid stream and thus abandoning a
partition in the middle was not possible. This causes some complications
for the compacting reader, which implements methods such as
`next_partition()` which is possibly called in the middle of a
partition. In this case the compacting reader attempts to close the
partition properly by inserting a synthetic partition-end fragment into
the stream. This is not enough however as it doesn't close any range
tombstone changes that might be active. Instead of piling on more
complexity, add an API to the compactor which allows abandoning the
current partition.
The mutation compactor has a validator which it uses to validate the
stream of mutation fragments that passes through it. This validator is
supposed to validate the stream as it enters the compactor, as opposed
to its compacted form (output). This was true for most fragment kinds
except range tombstones, as purged range tombstones were not visible to
the validator for the most part.
This mistake was introduced by e2c9cdb576, which itself was a flawed
attempt at fixing an error seen because purged tombstones were not
terminated by the compactor.
This patch corrects this mistake by fixing the above problem properly:
on page-cut, if the validator has an active tombstone, a closing
tombstone is generated for it, to avoid the false-positive error. With
this, range tombstones can be validated again as they come in.
Commit 8c4b5e4283 introduced an optimization which only
calculates max purgeable timestamp when a tombstone satisfy the
grace period.
Commit 'repair: Get rid of the gc_grace_seconds' inverted the order,
probably under the assumption that getting grace period can be
more expensive than calculating max purgeable, as repair-mode GC
will look up into history data in order to calculate gc_before.
This caused a significant regression on tombstone heavy compactions,
where most of tombstones are still newer than grace period.
A compaction which used to take 5s, now takes 35s. 7x slower.
The reason is simple, now calculation of max purgeable happens
for every single tombstone (once for each key), even the ones that
cannot be GC'ed yet. And each calculation has to iterate through
(i.e. check the bloom filter of) every single sstable that doesn't
participate in compaction.
Flame graph makes it very clear that bloom filter is a heavy path
without the optimization:
45.64% 45.64% sstable_compact sstable_compaction_test_g
[.] utils::filter::bloom_filter::is_present
With its resurrection, the problem is gone.
This scenario can easily happen, e.g. after a deletion burst, and
tombstones becoming only GC'able after they reach upper tiers in
the LSM tree.
Before this patch, a compaction can be estimated to have this # of
filter checks:
(# of keys containing *any* tombstone) * (# of uncompacting sstable
runs[1])
[1] It's # of *runs*, as each key tend to overlap with only one
fragment of each run.
After this patch, the estimation becomes:
(# of keys containing a GC'able tombstone) * (# of uncompacting
runs).
With repair mode for tombstone GC, the assumption, that retrieval
of gc_before is more expensive than calculating max purgeable,
is kept. We can revisit it later. But the default mode, which
is the "timeout" (i.e. gc_grace_seconds) one, we still benefit
from the optimization of deferring the calculation until
needed.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Closes#13908
Allowing the validation level to be customized by whoever creates the
compaction state. Add a default value (the previous hardcoded level) to
avoid the churn of updating all call sites.
e2c9cdb576 moved the validation of the
range tombstone change to the place where it is actually consumed, so we
don't attempt to pass purged or discarded range tombstones to the
validator. In doing so however, the validate pass was moved after the
consume call, which moves the range tombstone change, the validator
having been passed a moved-from range tombstone. Fix this by moving he
validation to before the consume call.
Refs: #12575
The purpose of `_stop` is to remember whether the consumption of the
last partition was interrupted or it was consumed fully. In the former
case, the compactor allows retreiving the compaction state for the given
partition, so that its compaction can be resumed at a later point in
time.
Currently, `_stop` is set to `stop_iteration::yes` whenever the return
value of any of the `consume()` methods is also `stop_iteration::yes`.
Meaning, if the consuming of the partition is interrupted, this is
remembered in `_stop`.
However, a partition whose consumption was interrupted is not always
continued later. Sometimes consumption of a partitions is interrputed
because the partition is not interesting and the downstream consumer
wants to stop it. In these cases the compactor should not return an
engagned optional from `detach_state()`, because there is not state to
detach, the state should be thrown away. This was incorrectly handled so
far and is fixed in this patch, but overwriting `_stop` in
`consume_partition_end()` with whatever the downstream consumer returns.
Meaning if they want to skip the partition, then `_stop` is reset to
`stop_partition::no` and `detach_state()` will return a disengaged
optional as it should in this case.
Fixes: #12629Closes#13365
Move mutation-related files to a new mutation/ directory. The names
are kept in the global namespace to reduce churn; the names are
unambiguous in any case.
mutation_reader remains in the readers/ module.
mutation_partition_v2.cc was missing from CMakeLists.txt; it's added in this
patch.
This is a step forward towards librarization or modularization of the
source base.
Closes#12788
