Summary:
This patch update the Iterator API to introduce new functions that allow users to keep the Slices returned by key() valid as long as the Iterator is not deleted
ReadOptions::pin_data : If true keep loaded blocks in memory as long as the iterator is not deleted
Iterator::IsKeyPinned() : If true, this mean that the Slice returned by key() is valid as long as the iterator is not deleted
Also add a new option BlockBasedTableOptions::use_delta_encoding to allow users to disable delta_encoding if needed.
Benchmark results (using https://phabricator.fb.com/P20083553)
```
// $ du -h /home/tec/local/normal.4K.Snappy/db10077
// 6.1G /home/tec/local/normal.4K.Snappy/db10077
// $ du -h /home/tec/local/zero.8K.LZ4/db10077
// 6.4G /home/tec/local/zero.8K.LZ4/db10077
// Benchmarks for shard db10077
// _build/opt/rocks/benchmark/rocks_copy_benchmark \
// --normal_db_path="/home/tec/local/normal.4K.Snappy/db10077" \
// --zero_db_path="/home/tec/local/zero.8K.LZ4/db10077"
// First run
// ============================================================================
// rocks/benchmark/RocksCopyBenchmark.cpp relative time/iter iters/s
// ============================================================================
// BM_StringCopy 1.73s 576.97m
// BM_StringPiece 103.74% 1.67s 598.55m
// ============================================================================
// Match rate : 1000000 / 1000000
// Second run
// ============================================================================
// rocks/benchmark/RocksCopyBenchmark.cpp relative time/iter iters/s
// ============================================================================
// BM_StringCopy 611.99ms 1.63
// BM_StringPiece 203.76% 300.35ms 3.33
// ============================================================================
// Match rate : 1000000 / 1000000
```
Test Plan: Unit tests
Reviewers: sdong, igor, anthony, yhchiang, rven
Reviewed By: rven
Subscribers: dhruba, lovro, adsharma
Differential Revision: https://reviews.facebook.net/D48999
Summary: With recent commit 33e0c93826, db iterator skips perf context counter internal_key_skipped_count when blindly issuing internal Next(). Now increment the counter by one when issuing this Next()
Test Plan: Run all existing tests
Reviewers: rven, yhchiang, IslamAbdelRahman, kradhakrishnan, igor, anthony
Reviewed By: anthony
Subscribers: yoshinorim, leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D51465
Summary: Now DBIter::Next() always compares with current key with itself first, which is unnecessary if the last key is not a merge key. I made the change and didn't see db_iter_test fails. Want to hear whether people have any idea what I miss.
Test Plan: Run all unit tests
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D48279
Summary: Use IterKey to store prefix_start_ so that it doesn't get freed
Test Plan: PrefixTest.PrefixValid
Reviewers: anthony, IslamAbdelRahman
Reviewed By: IslamAbdelRahman
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D50289
Summary:
MyRocks testing found an issue that while iterating over keys
that are outside the prefix, sometimes wrong results were seen for keys
outside the prefix. We now tighten the range of keys seen with a new
read option called prefix_seen_at_start. This remembers the starting
prefix and then compares it on a Next for equality of prefix. If they
are from a different prefix, it sets valid to false.
Test Plan: PrefixTest.PrefixValid
Reviewers: IslamAbdelRahman, sdong, yhchiang, anthony
Reviewed By: anthony
Subscribers: spetrunia, hermanlee4, yoshinorim, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D50211
Summary:
Separate a new class InternalIterator from class Iterator, when the look-up is done internally, which also means they operate on key with sequence ID and type.
This change will enable potential future optimizations but for now InternalIterator's functions are still the same as Iterator's.
At the same time, separate the cleanup function to a separate class and let both of InternalIterator and Iterator inherit from it.
Test Plan: Run all existing tests.
Reviewers: igor, yhchiang, anthony, kradhakrishnan, IslamAbdelRahman, rven
Reviewed By: rven
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D48549
Summary:
This patch fixes#7460559. It introduces SingleDelete as a new database
operation. This operation can be used to delete keys that were never
overwritten (no put following another put of the same key). If an overwritten
key is single deleted the behavior is undefined. Single deletion of a
non-existent key has no effect but multiple consecutive single deletions are
not allowed (see limitations).
In contrast to the conventional Delete() operation, the deletion entry is
removed along with the value when the two are lined up in a compaction. Note:
The semantics are similar to @igor's prototype that allowed to have this
behavior on the granularity of a column family (
https://reviews.facebook.net/D42093 ). This new patch, however, is more
aggressive when it comes to removing tombstones: It removes the SingleDelete
together with the value whenever there is no snapshot between them while the
older patch only did this when the sequence number of the deletion was older
than the earliest snapshot.
Most of the complex additions are in the Compaction Iterator, all other changes
should be relatively straightforward. The patch also includes basic support for
single deletions in db_stress and db_bench.
Limitations:
- Not compatible with cuckoo hash tables
- Single deletions cannot be used in combination with merges and normal
deletions on the same key (other keys are not affected by this)
- Consecutive single deletions are currently not allowed (and older version of
this patch supported this so it could be resurrected if needed)
Test Plan: make all check
Reviewers: yhchiang, sdong, rven, anthony, yoshinorim, igor
Reviewed By: igor
Subscribers: maykov, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D43179
Summary:
There are currently no statistics on seeks, only on gets. This adds the following counters:
rocksdb.number.db.seek
rocksdb.number.db.next
rocksdb.number.db.prev
(number of calls)
rocksdb.db.iterate.bytes.read
(number of bytes read from key + value using seek/next/prev)
rocksdb.number.keys.seek.found
rocksdb.number.keys.next.found
rocksdb.number.keys.prev.found
(number of calls where seek/next/prev found a value)
Test Plan:
./db_bench -statistics -benchmarks fillrandom,seekrandom -seek_nexts 5
./db_bench -statistics -benchmarks fillrandom,seekrandom -seek_nexts 5 -reverse_iterator
Reviewers: yhchiang, rven, kradhakrishnan, IslamAbdelRahman, MarkCallaghan, sdong, igor
Reviewed By: sdong
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D46605
Summary:
In some cases, equality comparisons can be done more efficiently than three-way
comparisons. There are quite a few places in the code where we only care about
equality. This patch adds an Equal() method that defaults to using the
Compare() method.
Test Plan: make clean all check
Reviewers: rven, anthony, yhchiang, igor, sdong
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D46233
Summary:
When DBIter changes iterating direction from forward to backward, it might see some much larger keys with higher sequence ID. With this commit, these rows will be actively filtered out. It should fix existing disabled tests in db_iter_test.
This may not be a perfect fix, but it introduces least impact on existing codes, in order to be safe.
Test Plan:
Enable existing tests and make sure they pass. Add a new test DBIterWithMergeIterTest.InnerMergeIteratorDataRace8.
Also run all existing tests.
Reviewers: yhchiang, rven, anthony, IslamAbdelRahman, kradhakrishnan, igor
Reviewed By: igor
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D45567
Summary: There is a check to fail the iterator if prefix extractor is specified but upper bound is out of the prefix for the seek key. Relax this constraint to allow users to set upper bound to the next prefix of the current one.
Test Plan: make commit-prereq
Reviewers: igor, anthony, kradhakrishnan, yhchiang, rven
Reviewed By: rven
Subscribers: tnovak, leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D44949
Summary:
While working on single delete support for db_bench, I realized that
db_bench/db_stress contain a bunch of duplicate code related to
copmression and found some typos. This patch removes duplicate code,
typos and a redundant #ifndef in internal_stats.cc.
Test Plan: make db_stress && make db_bench && ./db_bench --benchmarks=compress,uncompress
Reviewers: yhchiang, sdong, rven, anthony, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D43965
Summary:
When seeking to the last occurrence of a key with sequence number 0, db_iter
ends up in an endless loop because it seeks to type kValueTypeForSeek
which is larger than kTypeDeletion/kTypeValue. Added test case that triggers
the behavior.
Test Plan: make clean all check
Reviewers: igor, rven, anthony, yhchiang, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D43653
Summary:
While doing forward iterating, if current key is merge, internal iterator position is placed to the next key. If Prev() is called now, needs to do extra Prev() to recover the location.
This is second attempt of fixing after reverting ec70fea4c4. This time shrink the fix to only merge key is the current key and avoid the reseeking logic for max_iterating skipping
Test Plan: enable the two disabled tests and make sure they pass
Reviewers: rven, IslamAbdelRahman, kradhakrishnan, tnovak, yhchiang
Reviewed By: yhchiang
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D43557
Summary:
This diff reverts the following two previous diffs related to
DBIter::FindPrevUserKey(), which makes db_stress unstable.
We should bake a better fix for this.
* "Fix a comparison in DBIter::FindPrevUserKey()"
ec70fea4c4.
* "Fixed endless loop in DBIter::FindPrevUserKey()"
acee2b08a2.
Test Plan: db_stress
Reviewers: anthony, igor, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D41301
Summary:
When seek target is a merge key (`kTypeMerge`), `DBIter::FindNextUserEntry()`
advances the underlying iterator _past_ the current key (`saved_key_`); see
`MergeValuesNewToOld()`. However, `FindPrevUserKey()` assumes that `iter_`
points to an entry with the same user key as `saved_key_`. As a result,
`it->Seek(key) && it->Prev()` can cause the iterator to be positioned at the
_next_, instead of the previous, entry (new test, written by @lovro, reproduces
the bug).
This diff changes `FindPrevUserKey()` to also skip keys that are _greater_ than
`saved_key_`.
Test Plan: db_test
Reviewers: igor, sdong
Reviewed By: sdong
Subscribers: leveldb, dhruba, lovro
Differential Revision: https://reviews.facebook.net/D40791
Summary: #7124486: RocksDB's Iterator.SeekToLast should seek to the last key before iterate_upper_bound if presents
Test Plan: ./db_iter_test run successfully with the new testcase
Reviewers: rven, yhchiang, igor, anthony, kradhakrishnan, sdong
Reviewed By: sdong
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D40425
Summary:
We have addded new stats and perf_context for measuring the merge and filter operation time consumption.
We have bounded all the merge operations within the GUARD statment and collected the total time for these operations in the DB.
Test Plan: WIP
Reviewers: rven, yhchiang, kradhakrishnan, igor, sdong
Reviewed By: sdong
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D34377
Summary:
When using latest clang (3.6 or 3.7/trunck) rocksdb is failing with many errors. Almost all of them are missing override errors. This diff adds missing override keyword. No manual changes.
Prerequisites: bear and clang 3.5 build with extra tools
```lang=bash
% USE_CLANG=1 bear make all # generate a compilation database http://clang.llvm.org/docs/JSONCompilationDatabase.html
% clang-modernize -p . -include . -add-override
% make format
```
Test Plan:
Make sure all tests are passing.
```lang=bash
% #Use default fb code clang.
% make check
```
Verify less error and no missing override errors.
```lang=bash
% # Have trunk clang present in path.
% ROCKSDB_NO_FBCODE=1 CC=clang CXX=clang++ make
```
Reviewers: igor, kradhakrishnan, rven, meyering, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D34077
Summary:
This diff contains trivial fixes for 6 scan-build warnings:
**db/c_test.c**
`db` variable is never read. Removed assignment.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-9b77d2.html#EndPath
**db/db_iter.cc**
`skipping` local variable is assigned to false. Then in the next switch block the only "non return" case assign `skipping` to true, the rest cases don't use it and all do return.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-13fca7.html#EndPath
**db/log_reader.cc**
In `bool Reader::SkipToInitialBlock()` `offset_in_block` local variable is assigned to 0 `if (offset_in_block > kBlockSize - 6)` and then never used. Removed the assignment and renamed it to `initial_offset_in_block` to avoid confusion.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-a618dd.html#EndPath
In `bool Reader::ReadRecord(Slice* record, std::string* scratch)` local variable `in_fragmented_record` in switch case `kFullType` block is assigned to false and then does `return` without use. In the other switch case `kFirstType` block the same `in_fragmented_record` is assigned to false, but later assigned to true without prior use. Removed assignment for both cases.
scan-build reprots:
http://home.fburl.com/~sugak/latest20/report-bb86b0.html#EndPathhttp://home.fburl.com/~sugak/latest20/report-a975be.html#EndPath
**table/plain_table_key_coding.cc**
Local variable `user_key_size` is assigned when declared. But then in both places where it is used assigned to `static_cast<uint32_t>(key.size() - 8)`. Changed to initialize the variable to the proper value in declaration.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-9e6b86.html#EndPath
**tools/db_stress.cc**
Missing `break` in switch case block. This seems to be a bug. Added missing `break`.
Test Plan:
Make sure all tests are passing and scan-build does not report 'Dead assignment' and 'Dead initialization' bugs.
```lang=bash
% make check
% make analyze
```
Reviewers: meyering, igor, kradhakrishnan, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D33795
Summary: Replace exception by setting valid_ = false in DBIter::MergeValuesNewToOld().
Test Plan:
Not sure if I am right at this, but it seems we currently don't have a good
way to test that code path as it requires dynamically set merge_operator = nullptr
at the time while Merge() is calling.
Reviewers: igor, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D29811
Summary: It turns out that -Wshadow has different rules for gcc than clang. Previous commit fixed clang. This commits fixes the rest of the warnings for gcc.
Test Plan: compiles
Reviewers: ljin, yhchiang, rven, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D28131
Summary: Apply InfoLogLevel to the logs in db/db_iter.cc
Test Plan: make
Reviewers: igor, ljin, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D27861
Summary:
I found it is almost impossible to get rid of this function in a single
batch. I will take a step by step approach
Test Plan: make release
Reviewers: sdong, yhchiang, igor
Reviewed By: igor
Subscribers: leveldb
Differential Revision: https://reviews.facebook.net/D22995
This eliminates the need to remember to call PERF_TIMER_STOP when a section has
been timed. This allows more useful design with the perf timers and enables
possible return value optimizations. Simplistic example:
class Foo {
public:
Foo(int v) : m_v(v);
private:
int m_v;
}
Foo makeFrobbedFoo(int *errno)
{
*errno = 0;
return Foo();
}
Foo bar(int *errno)
{
PERF_TIMER_GUARD(some_timer);
return makeFrobbedFoo(errno);
}
int main(int argc, char[] argv)
{
Foo f;
int errno;
f = bar(&errno);
if (errno)
return -1;
return 0;
}
After bar() is called, perf_context.some_timer would be incremented as if
Stop(&perf_context.some_timer) was called at the end, and the compiler is still
able to produce optimizations on the return value from makeFrobbedFoo() through
to main().
Summary: as title
Test Plan: make release
Reviewers: sdong, yhchiang
Reviewed By: yhchiang
Subscribers: leveldb
Differential Revision: https://reviews.facebook.net/D21717
Summary: Fix old issue with DBTest.Randomized with BlockBasedTableWithWholeKeyHashIndex + added printing in DBTest.Randomized.
Test Plan: make all check
Reviewers: zagfox, igor, ljin, yhchiang, sdong
Reviewed By: sdong
Subscribers: leveldb
Differential Revision: https://reviews.facebook.net/D21003
Summary:
Make StatisticsImpl being able to forward stats to provided statistics
implementation. The main purpose is to allow us to collect internal
stats in the future even when user supplies custom statistics
implementation. It avoids intrumenting 2 sets of stats collection code.
One immediate use case is tuning advisor, which needs to collect some
internal stats, users may not be interested.
Test Plan:
ran db_bench and see stats show up at the end of run
Will run make all check since some tests rely on statistics
Reviewers: yhchiang, sdong, igor
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D20145
Summary: Implement Prev() with merge operator for DBIterator. Request from mongoDB. Task 4673663.
Test Plan: make all check
Reviewers: sdong
Reviewed By: sdong
Subscribers: leveldb
Differential Revision: https://reviews.facebook.net/D19743
Summary:
In this patch, try to allocate the whole iterator tree starting from DBIter from an arena
1. ArenaWrappedDBIter is created when serves as the entry point of an iterator tree, with an arena in it.
2. Add an option to create iterator from arena for following iterators: DBIter, MergingIterator, MemtableIterator, all mem table's iterators, all table reader's iterators and two level iterator.
3. MergeIteratorBuilder is created to incrementally build the tree of internal iterators. It is passed to mem table list and version set and add iterators to it.
Limitations:
(1) Only DB::NewIterator() without tailing uses the arena. Other cases, including readonly DB and compactions are still from malloc
(2) Two level iterator itself is allocated in arena, but not iterators inside it.
Test Plan: make all check
Reviewers: ljin, haobo
Reviewed By: haobo
Subscribers: leveldb, dhruba, yhchiang, igor
Differential Revision: https://reviews.facebook.net/D18513
Summary:
Forward iterator puts everything together in a flat structure instead of
a hierarchy of nested iterators. this should simplify the code and
provide better performance. It also enables more optimization since all
information are accessiable in one place.
Init evaluation shows about 6% improvement
Test Plan: db_test and db_bench
Reviewers: dhruba, igor, tnovak, sdong, haobo
Reviewed By: haobo
Subscribers: sdong, leveldb
Differential Revision: https://reviews.facebook.net/D18795
Summary: as title
Test Plan: Still compile
Reviewers: haobo, igor, yhchiang
Reviewed By: igor
CC: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D18603
Summary:
replace the super version acquisision in tailing itrator with thread
local
Test Plan: will post results
Reviewers: igor, haobo, sdong, yhchiang, dhruba
Reviewed By: igor
CC: leveldb
Differential Revision: https://reviews.facebook.net/D17757
Summary: This will allow us to disable them completely for iOS or for better performance
Test Plan: will run make all check
Reviewers: igor, haobo, dhruba
Reviewed By: haobo
CC: leveldb
Differential Revision: https://reviews.facebook.net/D17511
Summary:
Move PlainTableIterator's copied key from std::string local buffer to avoid paying the extra costs in std::string related to sharing. Reuse the same buffer class in DbIter. Move the class to dbformat.h.
This patch improves iterator performance significantly. Running this benchmark:
./table_reader_bench --num_keys2=17 --iterator --plain_table --time_unit=nanosecond
The average latency is improved to about 750 nanoseconds from 1100 nanoseconds.
Test Plan:
Add a unit test.
make all check
Reviewers: haobo, ljin
Reviewed By: haobo
CC: igor, yhchiang, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D17547
Summary: DBIter now uses a std::string for saved_key. Based on some profiling, it could be more expensive than we though. Optimize it with the same technique as LookupKey -- if it is short, we copy it to a static allocated char. Otherwise, dynamically allocate memory for it.
Test Plan: make all check
Reviewers: haobo, ljin
Reviewed By: haobo
CC: dhruba, igor, yhchiang, leveldb
Differential Revision: https://reviews.facebook.net/D17289
Summary:
* PartialMerge api now takes a list of operands instead of two operands.
* Add min_pertial_merge_operands to Options, indicating the minimum
number of operands to trigger partial merge.
* This diff is based on Schalk's previous diff (D14601), but it also
includes necessary changes such as updating the pure C api for
partial merge.
Test Plan:
* make check all
* develop tests for cases where partial merge takes more than two
operands.
TODOs (from Schalk):
* Add test with min_partial_merge_operands > 2.
* Perform benchmarks to measure the performance improvements (can probably
use results of task #2837810.)
* Add description of problem to doc/index.html.
* Change wiki pages to reflect the interface changes.
Reviewers: haobo, igor, vamsi
Reviewed By: haobo
CC: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D16815
Summary: Prev() now can hang when there is a key with more than max_skipped number of appearance internally but all of them are newer than the sequence ID to seek. Add unit tests to confirm the bug and fix it.
Test Plan: make all check
Reviewers: igor, haobo
Reviewed By: igor
CC: ljin, yhchiang, leveldb
Differential Revision: https://reviews.facebook.net/D16899
Summary: In PlainTable, use one single byte to represent 8 bytes of internal bytes, if seqID = 0 and it is value type (which should be common for bottom most files). It is to save 7 bytes for uncompressed cases.
Test Plan: make all check
Reviewers: haobo, dhruba, kailiu
Reviewed By: haobo
CC: igor, leveldb
Differential Revision: https://reviews.facebook.net/D15489
Summary:
I have added three new value types:
* kTypeColumnFamilyDeletion
* kTypeColumnFamilyValue
* kTypeColumnFamilyMerge
which include column family Varint32 before the data (value, deletion and merge). These values are used only in WAL (not in memtables yet).
This endeavour required changing some WriteBatch internals.
Test Plan: Added a unittest
Reviewers: dhruba, haobo, sdong, kailiu
CC: leveldb
Differential Revision: https://reviews.facebook.net/D15045
Summary:
I went through all remaining shared_ptrs and removed the ones that I found not-necessary. Only GenerateCachePrefix() is called fairly often, so don't expect much perf wins.
The ones that are left are accessed infrequently and I think we're fine with keeping them.
Test Plan: make asan_check
Reviewers: dhruba, haobo
Reviewed By: dhruba
CC: leveldb
Differential Revision: https://reviews.facebook.net/D14427
Summary: liveness of the statistics object is already ensured by the shared pointer in DB options. There's no reason to pass again shared pointer among internal functions. Raw pointer is sufficient and efficient.
Test Plan: make check
Reviewers: dhruba, MarkCallaghan, igor
Reviewed By: dhruba
CC: leveldb, reconnect.grayhat
Differential Revision: https://reviews.facebook.net/D14289
Peter Mattis