* Add compression controls (#417)
* Add compression controls
Add configuration options to allow for a compression algorithm of `none` to disable compression altogether. Also an option to change the point in the LSM tree when compression is applied.
* Handle configurable defaults consistently
Move them into leveled.hrl. This forces double-definitions to be resolved.
There are some other constants in leveled_bookie that are relevant outside of leveled_bookie. These are all now in the non-configurable startup defaults section.
* Clarify referred-to default is OTP not leveled
* Update leveled_bookie.erl
Handle xref issue with eunit include
* Use backwards compatible term_to_binary
So that where we have hashed term_to_binary output in OTP25 or earlier, that has will be matched in OTP 26.
* Test reliability
If all keys are put in order, the max_slots may not be used, as the driver at L0 is penciller cache size, and merge to new files (managed by the parameter) only occurs when there are overlapping files the level below
* Mas i370 patch d (#383)
* Refactor penciller memory
In high-volume tests on large key-count clusters, so significant variation in the P0031 time has been seen:
TimeBucket PatchA
a.0ms_to_1ms 18554
b.1ms_to_2ms 51778
c.2ms_to_3ms 696
d.3ms_to_5ms 220
e.5ms_to_8ms 59
f.8ms_to_13ms 40
g.13ms_to_21ms 364
h.21ms_to_34ms 277
i.34ms_to_55ms 34
j.55ms_to_89ms 17
k.89ms_to_144ms 21
l.144ms_to_233ms 31
m.233ms_to_377ms 45
n.377ms_to_610ms 52
o.610ms_to_987ms 59
p.987ms_to_1597ms 55
q.1597ms_to_2684ms 54
r.2684ms_to_4281ms 29
s.4281ms_to_6965ms 7
t.6295ms_to_11246ms 1
It is unclear why this varies so much. The time to add to the cache appears to be minimal (but perhaps there is an issue with timing points in the code), whereas the time to add to the index is much more significant and variable. There is also variable time when the memory is rolled (although the actual activity here appears to be minimal.
The refactoring here is two-fold:
- tidy and simplify by keeping LoopState managed within handle_call, and add more helpful dialyzer specs;
- change the update to the index to be a simple extension of a list, rather than any conversion.
This alternative version of the pmem index in unit test is orders of magnitude faster to add - and is the same order of magnitude to check. Anticipation is that it may be more efficient in terms of memory changes.
* Compress SST index
Reduces the size of the leveled_sst index with two changes:
1 - Where there is a common prefix of tuple elements (e.g. Bucket) across the whole leveled_sst file - only the non-common part is indexed, and a function is used to compare.
2 - There is less "indexing" of the index i.e. only 1 in 16 keys are passed into the gb_trees part instead of 1 in 4
* Immediate hibernate
Reasons for delay in hibernate were not clear.
Straight after creation the process will not be in receipt of messages (must wait for the manifest to be updated), so better to hibernate now. This also means the log PC023 provides more accurate information.
* Refactor BIC
This patch avoids the following:
- repeated replacement of the same element in the BIC (via get_kvrange), by checking presence via GET before sing SET
- Stops re-reading of all elements to discover high modified date
Also there appears to have been a bug where a missing HMD for the file is required to add to the cache. However, now the cache may be erased without erasing the HMD. This means that the cache can never be rebuilt
* Use correct size in test results
erts_debug:flat_size/1 returns size in words (i.e. 8 bytes on 64-bit CPU) not bytes
* Don't change summary record
As it is persisted as part of the file write, any change to the summary record cannot be rolled back
* Clerk to prompt L0 write
Simplifies the logic if the clerk request work for the penciller prompts L0 writes as well as Manifest changes.
The advantage now is that if the penciller memory is full, and PUT load stops, the clerk should still be able to prompt persistence. the penciller can therefore make use of dead time this way
* Add push on journal compact
If there has been a backlog, followed by a quiet period - there may be a large ledger cache left unpushed. Journal compaction events are about once per hour, so the performance overhead of a false push should be minimal, with the advantage of clearing any backlog before load starts again.
This is only relevant to riak users with very off/full batch type workloads.
* Extend tests
To more consistently trigger all overload scenarios
* Fix range keys smaller than prefix
Can't make end key an empty binary in this case, as it may be bigger than any keys within the range, but will appear to be smaller.
Unit tests and ct tests added to expose the potential issue
* Tidy-up
- Remove penciller logs which are no longer called
- Get pclerk to only wait MIN_TIMEOUT after doing work, in case there is a backlog
- Remove update_levelzero_cache function as it is unique to handle_call of push_mem, and simple enough to be inline
- Alight testutil slow offer with standard slow offer used
* Tidy-up
Remove pre-otp20 references.
Reinstate the check that the starting pid is still active, this was added to tidy up shutdown.
Resolve failure to run on otp20 due to `-if` sttaement
* Tidy up
Using null rather then {null, Key} is potentially clearer as it is not a concern what they Key is in this case, and removes a comparison step from the leveled_codec:endkey_passed/2 function.
There were issues with coverage in eunit tests as the leveled_pclerk shut down. This prompted a general tidy of leveled_pclerk (remove passing of LoopState into internal functions, and add dialyzer specs.
* Remove R16 relic
* Further testing another issue
The StartKey must always be less than or equal to the prefix when the first N characters are stripped, but this is not true of the EndKey (for the query) which does not have to be between the FirstKey and the LastKey.
If the EndKey query does not match it must be greater than the Prefix (as otherwise it would not have been greater than the FirstKey - so set to null.
* Fix unit test
Unit test had a typo - and result interpretation had a misunderstanding.
* Code and spec tidy
Also look to the cover the situation when the FirstKey is the same as the Prefix with tests.
This is, in theory, not an issue as it is the EndKey for each sublist which is indexed in leveled_tree. However, guard against it mapping to null here, just in case there are dangers lurking (note that tests will still pass without `M > N` guard in place.
* Hibernate on BIC complete
There are three situations when the BIC becomes complete:
- In a file created as part of a merge the BIS is learned in the merge
- After startup, files below L1 learn the block cache through reads that happen to read the block, eventually the while cache will be read, unless...
- Either before/after the cache is complete, it can get whiped by a timeout after a get_sqn request (e.g. as prompted by a journal compaction) ... it will then be re-filled of the back of get/get-range requests.
In all these situations we want to hibernate after the BIC is fill - to reflect the fact that the LoopState should now be relatively stable, so it is a good point to GC and rationalise location of data.
Previously on the the first base was covered. Now all three are covered through the bic_complete message.
* Test all index keys have same term
This works functionally, but is not optimised (the term is replicated in the index)
* Summaries with same index term
If the summary index all have the same index term - only the object keys need to be indexes
* Simplify case statements
We either match the pattern of <<Prefix:N, Suffix>> or the answer should be null
* OK for M == N
If M = N for the first key, it will have a suffix of <<>>. This will match (as expected) a query Start Key of the sam size, and be smaller than any query Start Key that has the same prefix.
If the query Start Key does not match the prefix - it will be null - as it must be smaller than the Prefix (as other wise the query Start Key would be bigger than the Last Key).
The constraint of M > N was introduced before the *_prefix_filter functions were checking the prefix, to avoid issues. Now the prefix is being checked, then M == N is ok.
* Simplify
Correct the test to use a binary field in the range.
To avoid further issue, only apply filter when everything is a binary() type.
* Add test for head_only mode
When leveled is used as a tictacaae key store (in parallel mode), the keys will be head_only entries. Double check they are handled as expected like object keys
* Revert previous change - must support typed buckets
Add assertion to confirm worthwhile optimisation
* Add support for configurable cache multiple (#375)
* Mas i370 patch e (#385)
Improvement to monitoring for efficiency and improved readability of logs and stats.
As part of this, where possible, tried to avoid updating loop state on READ messages in leveled processes (as was the case when tracking stats within each process).
No performance benefits found with change, but improved stats has helped discover other potential gains.
* Don't use fetch_cache below the page_cache level
* Don't time fetches due to SQN checks
SQN checks are all background processes
* Hibernate on SQN check
SQN check in the penciller is used for journal (all object) folds, but mainly for journal compaction. Use this to trigger hibernation where SST files stay quiet after the compaction check.
* Add catch for hibernate timeout
* Scale cache_size with level
Based on volume testing. Relatively speaking, far higher value to be gained from caches at higher levels (lower numbered levels). The cache at lower levels are proportionally much less efficient. so cache more at higher levels, where there is value, and less at lower levels where there is more cost relative to value.
* OTP 24 fix to cherry-pick
* Make minimal change to previous setup
Making significant change appears to not have had the expected positive improvement - so a more minimal change is proposed.
The assumption is that the cache only really gets used for double reads in the write path (e.g. where the application reads before a write) - and so a large cache make minimal difference, but no cache still has a downside.
* Introduce new types
* Mas i370 d30 sstmemory (#374)
* Don't time fetches due to SQN checks
SQN checks are all background processes
* Hibernate on SQN check
SQN check in the penciller is used for journal (all object) folds, but mainly for journal compaction. Use this to trigger hibernation where SST files stay quiet after the compaction check.
* Add catch for hibernate timeout
* Scale cache_size with level
Based on volume testing. Relatively speaking, far higher value to be gained from caches at higher levels (lower numbered levels). The cache at lower levels are proportionally much less efficient. so cache more at higher levels, where there is value, and less at lower levels where there is more cost relative to value.
* Make minimal change to previous setup
Making significant change appears to not have had the expected positive improvement - so a more minimal change is proposed.
The assumption is that the cache only really gets used for double reads in the write path (e.g. where the application reads before a write) - and so a large cache make minimal difference, but no cache still has a downside.
* Introduce new types
* More memory management
Clear blockindex_cache on timeout, and manually GC on pclerk after work.
* Add further garbage collection prompt
After fetching level zero, significant change in references in the penciller memory, so prompt a garbage_collect() at this point.
SQN check in the penciller is used for journal (all object) folds, but mainly for journal compaction. Use this to trigger hibernation where SST files stay quiet after the compaction check.
Initial test included for running with recallc, and also transition from retain to recalc.
Moves all logic for startup fold into leveled_bookie - avoid the Inker requiring any direct knowledge about implementation of the Penciller.
Change the penciller check so that it returns current/replaced/missing not just true/false.
Reduce unnecessary penciller checks for non-standard keys that will always be retained - and remove redunandt code.
Expand tests of retain and recover to make sure that compaction on delete is well covered.
Also move the SQN number laong during initial loads - to stop aggressive loop to find starting SQN every file.
this was previously not na issue as leveled_codec:segment_hash/1 would handle anyhting that could be hashed. This now has to be a tuple, and one with a first element - so corrupted tuples are failing.
Add a guard chekcing for a corrupted tuple, but we only need this when doing journal compaction.
Change user_defined keys to be `retain` as a tag strategy
the skip/retain/recalc handlign was confusing. This removes the switcheroo between leveled_codec and leveled_iclerk when mkaing the decision.
Also now the building of the accumulator is handled efficiently (not using ++ on the list).
Tried to rmeove as much of ?HEAD tag handling from leveled_head - as we want leveled_head to be only concerned with the head manipulation for object tags (?STD, ?RIAK and user-defined).
To allow for extraction of metadata, and building of head responses - it should eb possible to dynamically and user-defined tags, and functions to treat them.
If no function is defined, revert to the behaviour of the ?STD tag.
More obvious how to extend the code as it is all in one module.
Also add a new field to the standard object metadata tuple that may hold in the future other object metadata base don user-defined functions.
Adds support with test for tuplebuckets in Riak keys.
This exposed that there was no filter using the seglist on the in-mmemory keys. This means that if there is no filter applied in the fold_function, many false positives may emerge.
This is probably not a big performance benefit (and indeed for performance it may be better to apply during the leveled_pmem:merge_trees).
Some thought still required as to what is more likely to contribute to future bugs: an extra location using the hash matching found in leveled_sst, or the extra results in the query.
To support max_keys and the last modified date range.
This applies the last modified date check on all ledger folds. This is hard to avoid, but ultimately a very low cost.
The limit on the number of heads to fold, is the limit based on passing to the accumulator - not on the limit being added to the accumulator. So if the FoldFun perfoms a filter (e.g. for the preflist), then those filtered results will still count towards the maximum.
There needs to be someway at the end of signalling from the fold if the outcome was or was not 'constrained' by max_keys - as the fold cannot simply tel by lenght checking the outcome.
Note this is used rather than length checking the buffer and throwing a 'stop_fold' message when the limit is reached. The choice is made for simplicity, and ease of testing. The throw mechanism is necessary if there is a need to stop parallel folds across the the cluster - but in this case the node_worker_pool will be used.
There were some bad specs in '|' OR'd specs. These were being falsely ignored in dialyzer until https://github.com/erlang/otp/pull/1722.
Running on OTP21 exposed these incomplete specs.
the concept of the segment hash belongs to the leveled_tictac module, not the codec.
Previously the alignment of tictac and store was accidental, this change makes it explicit.
Originally had disabled the ability to lookup individual values when running in head_only mode. This is a saving of about 11% at PUT time (about 3 microseconds per PUT) on a macbook.
Not sure this saving is sufficient enought to justify the extra work if this is used as an AAE Keystore with Bitcask and LWW (when we need to lookup the current value before adjusting).
So reverted to re-adding support for HEAD requests with these keys.
Initial commit to add head_only mode to leveled. This allows leveled to receive batches of object changes, but where those objects exist only in the Penciller's Ledger (once they have been persisted within the Ledger).
The aim is to reduce significantly the cost of compaction. Also, the objects ar enot directly accessible (they can only be accessed through folds). Again this makes life easier during merging in the LSM trees (as no bloom filters have to be created).
