12 Commits (5d7cf311ca46b4f808d24443d0678d583bdca76c)

Author	SHA1	Message	Date
Changyu Bi	f291eefb02	Cache fragmented range tombstone list for mutable memtables (#10547) ... Summary: Each read from memtable used to read and fragment all the range tombstones into a `FragmentedRangeTombstoneList`. https://github.com/facebook/rocksdb/issues/10380 improved the inefficient here by caching a `FragmentedRangeTombstoneList` with each immutable memtable. This PR extends the caching to mutable memtables. The fragmented range tombstone can be constructed in either read (This PR) or write path (https://github.com/facebook/rocksdb/issues/10584). With both implementation, each `DeleteRange()` will invalidate the cache, and the difference is where the cache is re-constructed.`CoreLocalArray` is used to store the cache with each memtable so that multi-threaded reads can be efficient. More specifically, each core will have a shared_ptr to a shared_ptr pointing to the current cache. Each read thread will only update the reference count in its core-local shared_ptr, and this is only needed when reading from mutable memtables. The choice between write path and read path is not an easy one: they are both improvement compared to no caching in the current implementation, but they favor different operations and could cause regression in the other operation (read vs write). The write path caching in (https://github.com/facebook/rocksdb/issues/10584) leads to a cleaner implementation, but I chose the read path caching here to avoid significant regression in write performance when there is a considerable amount of range tombstones in a single memtable (the number from the benchmark below suggests >1000 with concurrent writers). Note that even though the fragmented range tombstone list is only constructed in `DeleteRange()` operations, it could block other writes from proceeding, and hence affects overall write performance. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10547 Test Plan: - TestGet() in stress test is updated in https://github.com/facebook/rocksdb/issues/10553 to compare Get() result against expected state: `./db_stress_branch --readpercent=57 --prefixpercent=4 --writepercent=25 -delpercent=5 --iterpercent=5 --delrangepercent=4` - Perf benchmark: tested read and write performance where a memtable has 0, 1, 10, 100 and 1000 range tombstones. ``` ./db_bench --benchmarks=fillrandom,readrandom --writes_per_range_tombstone=200 --max_write_buffer_number=100 --min_write_buffer_number_to_merge=100 --writes=200000 --reads=100000 --disable_auto_compactions --max_num_range_tombstones=1000 ``` Write perf regressed since the cost of constructing fragmented range tombstone list is shifted from every read to a single write. 6cbe5d8e172dc5f1ef65c9d0a6eedbd9987b2c72 is included in the last column as a reference to see performance impact on multi-thread reads if `CoreLocalArray` is not used. micros/op averaged over 5 runs: first 4 columns are for fillrandom, last 4 columns are for readrandom. | |fillrandom main | write path caching | read path caching |memtable V3 (https://github.com/facebook/rocksdb/issues/10308) | readrandom main | write path caching | read path caching |memtable V3 | |--- |--- |--- |--- |--- | --- | --- | --- | --- | | 0 |6.35 |6.15 |5.82 |6.12 |2.24 |2.26 |2.03 |2.07 | | 1 |5.99 |5.88 |5.77 |6.28 |2.65 |2.27 |2.24 |2.5 | | 10 |6.15 |6.02 |5.92 |5.95 |5.15 |2.61 |2.31 |2.53 | | 100 |5.95 |5.78 |5.88 |6.23 |28.31 |2.34 |2.45 |2.94 | | 100 25 threads |52.01 |45.85 |46.18 |47.52 |35.97 |3.34 |3.34 |3.56 | | 1000 |6.0 |7.07 |5.98 |6.08 |333.18 |2.86 |2.7 |3.6 | | 1000 25 threads |52.6 |148.86 |79.06 |45.52 |473.49 |3.66 |3.48 |4.38 | - Benchmark performance of`readwhilewriting` from https://github.com/facebook/rocksdb/issues/10552, 100 range tombstones are written: `./db_bench --benchmarks=readwhilewriting --writes_per_range_tombstone=500 --max_write_buffer_number=100 --min_write_buffer_number_to_merge=100 --writes=100000 --reads=500000 --disable_auto_compactions --max_num_range_tombstones=10000 --finish_after_writes` readrandom micros/op: | |main |write path caching |read path caching |memtable V3 | |---|---|---|---|---| | single thread |48.28 |1.55 |1.52 |1.96 | | 25 threads |64.3 |2.55 |2.67 |2.64 | Reviewed By: ajkr Differential Revision: D38895410 Pulled By: cbi42 fbshipit-source-id: 930bfc309dd1b2f4e8e9042f5126785bba577559	2 years ago
Baptiste Lemaire	e817bc9628	Added memtable garbage statistics (#8411) ... Summary: **Summary**: 2 new statistics counters are added to RocksDB: `MEMTABLE_PAYLOAD_BYTES_AT_FLUSH` and `MEMTABLE_GARBAGE_BYTES_AT_FLUSH`. The former tracks how many raw bytes of useful data are present on the memtable at flush time, whereas the latter is tracks how many of these raw bytes are considered garbage, meaning that they ended up not being imported on the SSTables resulting from the flush operations. **Unit test**: run `make db_flush_test -j$(nproc); ./db_flush_test` to run the unit test. This executable includes 3 tests, that test support and correct stat calculations for workloads with inserts, deletes, and DeleteRanges. The parameters are set such that the workloads are performed on a single memtable, and a single SSTable is created as a result of the flush operation. The flush operation is manually called in the test file. The tests verify that the values of these 2 statistics counters introduced in this PR can be exactly predicted, showing that we have a full understanding of the underlying operations. **Performance testing**: `./db_bench -statistics -benchmarks=fillrandom -num=10000000` repeated 10 times. Timing done using "date" function in a bash script. _Results_: Original Rocksdb fork: mean 66.6 sec, std 1.18 sec. This feature branch: mean 67.4 sec, std 1.35 sec. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8411 Reviewed By: akankshamahajan15 Differential Revision: D29150629 Pulled By: bjlemaire fbshipit-source-id: 7b3c2e86d50c6aa34fa50fd134282eacb543a5b1	4 years ago
sdong	2f1984dd45	Compare memtable insert and flush count (#8288) ... Summary: When a memtable is flushed, it will validate number of entries it reads, and compare the number with how many entries inserted into memtable. This serves as one sanity c\ heck against memory corruption. This change will also allow more counters to be added in the future for better validation. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8288 Test Plan: Pass all existing tests Reviewed By: ajkr Differential Revision: D28369194 fbshipit-source-id: 7ff870380c41eab7f99eee508550dcdce32838ad	4 years ago
sdong	fdf882ded2	Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) ... Summary: When dynamically linking two binaries together, different builds of RocksDB from two sources might cause errors. To provide a tool for user to solve the problem, the RocksDB namespace is changed to a flag which can be overridden in build time. Pull Request resolved: https://github.com/facebook/rocksdb/pull/6433 Test Plan: Build release, all and jtest. Try to build with ROCKSDB_NAMESPACE with another flag. Differential Revision: D19977691 fbshipit-source-id: aa7f2d0972e1c31d75339ac48478f34f6cfcfb3e	5 years ago
Jeffrey Xiao	eae9f040eb	Initialized pinned_pos_ and pinned_seq_pos_ in FragmentedRangeTombstoneIterator (#5720) ... Summary: These uninitialized member variables can cause a key to not be pinned when it should be, causing erroneous behavior. For example ingesting a file with range deletion tombstones will yield an "external file have corrupted keys" on a Mac. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5720 Differential Revision: D17217673 fbshipit-source-id: cd7df7ce3ad9cf69c841c4d3dc6fd144eff9e212	5 years ago
Abhishek Madan	abf931afa6	Add compaction logic to RangeDelAggregatorV2 (#4758) ... Summary: RangeDelAggregatorV2 now supports ShouldDelete calls on snapshot stripes and creation of range tombstone compaction iterators. RangeDelAggregator is no longer used on any non-test code path, and will be removed in a future commit. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4758 Differential Revision: D13439254 Pulled By: abhimadan fbshipit-source-id: fe105bcf8e3d4a2df37a622d5510843cd71b0401	6 years ago
Abhishek Madan	cad248f5c6	Prepare FragmentedRangeTombstoneIterator for use in compaction (#4740) ... Summary: To support the flush/compaction use cases of RangeDelAggregator in v2, FragmentedRangeTombstoneIterator now supports dropping tombstones that cannot be read in the compaction output file. Furthermore, FragmentedRangeTombstoneIterator supports the "snapshot striping" use case by allowing an iterator to be split by a list of snapshots. RangeDelAggregatorV2 will use these changes in a follow-up change. In the process of making these changes, other miscellaneous cleanups were also done in these files. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4740 Differential Revision: D13287382 Pulled By: abhimadan fbshipit-source-id: f5aeb03e1b3058049b80c02a558ee48f723fa48c	6 years ago
Abhishek Madan	8fe1e06ca0	Clean up FragmentedRangeTombstoneList (#4692) ... Summary: Removed `one_time_use` flag, which removed the need for some tests, and changed all `NewRangeTombstoneIterator` methods to return `FragmentedRangeTombstoneIterators`. These changes also led to removing `RangeDelAggregatorV2::AddUnfragmentedTombstones` and one of the `MemTableListVersion::AddRangeTombstoneIterators` methods. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4692 Differential Revision: D13106570 Pulled By: abhimadan fbshipit-source-id: cbab5432d7fc2d9cdfd8d9d40361a1bffaa8f845	6 years ago
Abhishek Madan	457f77b9ff	Introduce RangeDelAggregatorV2 (#4649) ... Summary: The old RangeDelAggregator did expensive pre-processing work to create a collapsed, binary-searchable representation of range tombstones. With FragmentedRangeTombstoneIterator, much of this work is now unnecessary. RangeDelAggregatorV2 takes advantage of this by seeking in each iterator to find a covering tombstone in ShouldDelete, while doing minimal work in AddTombstones. The old RangeDelAggregator is still used during flush/compaction for now, though RangeDelAggregatorV2 will support those uses in a future PR. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4649 Differential Revision: D13146964 Pulled By: abhimadan fbshipit-source-id: be29a4c020fc440500c137216fcc1cf529571eb3	6 years ago
Abhishek Madan	6bee36a786	Modify FragmentedRangeTombstoneList member layout (#4632) ... Summary: Rather than storing a `vector<RangeTombstone>`, we now store a `vector<RangeTombstoneStack>` and a `vector<SequenceNumber>`. A `RangeTombstoneStack` contains the start and end keys of a range tombstone fragment, and indices into the seqnum vector to indicate which sequence numbers the fragment is located at. The diagram below illustrates an example: ``` tombstones_: [a, b) [c, e) [h, k) | \ / \ / | | \ / \ / | v v v v tombstone_seqs_: [ 5 3 10 7 2 8 6 ] ``` This format allows binary searching the tombstone list to use less key comparisons, which helps in cases where there are many overlapping tombstones. Also, this format makes it easier to add DBIter-like semantics to `FragmentedRangeTombstoneIterator` in the future. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4632 Differential Revision: D13053103 Pulled By: abhimadan fbshipit-source-id: e8220cc712fcf5be4d602913bb23ace8ea5f8ef0	6 years ago
Abhishek Madan	7528130e38	Cache fragmented range tombstones in BlockBasedTableReader (#4493) ... Summary: This allows tombstone fragmenting to only be performed when the table is opened, and cached for subsequent accesses. On the same DB used in #4449, running `readrandom` results in the following: ``` readrandom : 0.983 micros/op 1017076 ops/sec; 78.3 MB/s (63103 of 100000 found) ``` Now that Get performance in the presence of range tombstones is reasonable, I also compared the performance between a DB with range tombstones, "expanded" range tombstones (several point tombstones that cover the same keys the equivalent range tombstone would cover, a common workaround for DeleteRange), and no range tombstones. The created DBs had 5 million keys each, and DeleteRange was called at regular intervals (depending on the total number of range tombstones being written) after 4.5 million Puts. The table below summarizes the results of a `readwhilewriting` benchmark (in order to provide somewhat more realistic results): ``` Tombstones? | avg micros/op | stddev micros/op | avg ops/s | stddev ops/s ----------------- | ------------- | ---------------- | ------------ | ------------ None | 0.6186 | 0.04637 | 1,625,252.90 | 124,679.41 500 Expanded | 0.6019 | 0.03628 | 1,666,670.40 | 101,142.65 500 Unexpanded | 0.6435 | 0.03994 | 1,559,979.40 | 104,090.52 1k Expanded | 0.6034 | 0.04349 | 1,665,128.10 | 125,144.57 1k Unexpanded | 0.6261 | 0.03093 | 1,600,457.50 | 79,024.94 5k Expanded | 0.6163 | 0.05926 | 1,636,668.80 | 154,888.85 5k Unexpanded | 0.6402 | 0.04002 | 1,567,804.70 | 100,965.55 10k Expanded | 0.6036 | 0.05105 | 1,667,237.70 | 142,830.36 10k Unexpanded | 0.6128 | 0.02598 | 1,634,633.40 | 72,161.82 25k Expanded | 0.6198 | 0.04542 | 1,620,980.50 | 116,662.93 25k Unexpanded | 0.5478 | 0.0362 | 1,833,059.10 | 121,233.81 50k Expanded | 0.5104 | 0.04347 | 1,973,107.90 | 184,073.49 50k Unexpanded | 0.4528 | 0.03387 | 2,219,034.50 | 170,984.32 ``` After a large enough quantity of range tombstones are written, range tombstone Gets can become faster than reading from an equivalent DB with several point tombstones. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4493 Differential Revision: D10842844 Pulled By: abhimadan fbshipit-source-id: a7d44534f8120e6aabb65779d26c6b9df954c509	6 years ago
Abhishek Madan	8c78348c77	Use only "local" range tombstones during Get (#4449) ... Summary: Previously, range tombstones were accumulated from every level, which was necessary if a range tombstone in a higher level covered a key in a lower level. However, RangeDelAggregator::AddTombstones's complexity is based on the number of tombstones that are currently stored in it, which is wasteful in the Get case, where we only need to know the highest sequence number of range tombstones that cover the key from higher levels, and compute the highest covering sequence number at the current level. This change introduces this optimization, and removes the use of RangeDelAggregator from the Get path. In the benchmark results, the following command was used to initialize the database: ``` ./db_bench -db=/dev/shm/5k-rts -use_existing_db=false -benchmarks=filluniquerandom -write_buffer_size=1048576 -compression_type=lz4 -target_file_size_base=1048576 -max_bytes_for_level_base=4194304 -value_size=112 -key_size=16 -block_size=4096 -level_compaction_dynamic_level_bytes=true -num=5000000 -max_background_jobs=12 -benchmark_write_rate_limit=20971520 -range_tombstone_width=100 -writes_per_range_tombstone=100 -max_num_range_tombstones=50000 -bloom_bits=8 ``` ...and the following command was used to measure read throughput: ``` ./db_bench -db=/dev/shm/5k-rts/ -use_existing_db=true -benchmarks=readrandom -disable_auto_compactions=true -num=5000000 -reads=100000 -threads=32 ``` The filluniquerandom command was only run once, and the resulting database was used to measure read performance before and after the PR. Both binaries were compiled with `DEBUG_LEVEL=0`. Readrandom results before PR: ``` readrandom : 4.544 micros/op 220090 ops/sec; 16.9 MB/s (63103 of 100000 found) ``` Readrandom results after PR: ``` readrandom : 11.147 micros/op 89707 ops/sec; 6.9 MB/s (63103 of 100000 found) ``` So it's actually slower right now, but this PR paves the way for future optimizations (see #4493). ---- Pull Request resolved: https://github.com/facebook/rocksdb/pull/4449 Differential Revision: D10370575 Pulled By: abhimadan fbshipit-source-id: 9a2e152be1ef36969055c0e9eb4beb0d96c11f4d	6 years ago