Summary:
This is a new API added to db.h to allow for fetching all merge operands associated with a Key. The main motivation for this API is to support use cases where doing a full online merge is not necessary as it is performance sensitive. Example use-cases:
1. Update subset of columns and read subset of columns -
Imagine a SQL Table, a row is encoded as a K/V pair (as it is done in MyRocks). If there are many columns and users only updated one of them, we can use merge operator to reduce write amplification. While users only read one or two columns in the read query, this feature can avoid a full merging of the whole row, and save some CPU.
2. Updating very few attributes in a value which is a JSON-like document -
Updating one attribute can be done efficiently using merge operator, while reading back one attribute can be done more efficiently if we don't need to do a full merge.
----------------------------------------------------------------------------------------------------
API :
Status GetMergeOperands(
const ReadOptions& options, ColumnFamilyHandle* column_family,
const Slice& key, PinnableSlice* merge_operands,
GetMergeOperandsOptions* get_merge_operands_options,
int* number_of_operands)
Example usage :
int size = 100;
int number_of_operands = 0;
std::vector<PinnableSlice> values(size);
GetMergeOperandsOptions merge_operands_info;
db_->GetMergeOperands(ReadOptions(), db_->DefaultColumnFamily(), "k1", values.data(), merge_operands_info, &number_of_operands);
Description :
Returns all the merge operands corresponding to the key. If the number of merge operands in DB is greater than merge_operands_options.expected_max_number_of_operands no merge operands are returned and status is Incomplete. Merge operands returned are in the order of insertion.
merge_operands-> Points to an array of at-least merge_operands_options.expected_max_number_of_operands and the caller is responsible for allocating it. If the status returned is Incomplete then number_of_operands will contain the total number of merge operands found in DB for key.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5604
Test Plan:
Added unit test and perf test in db_bench that can be run using the command:
./db_bench -benchmarks=getmergeoperands --merge_operator=sortlist
Differential Revision: D16657366
Pulled By: vjnadimpalli
fbshipit-source-id: 0faadd752351745224ee12d4ae9ef3cb529951bf
Summary:
This PR updated the python script to plot graphs for stats output from block cache analyzer.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5673
Test Plan: Manually run the script to generate graphs.
Differential Revision: D16657145
Pulled By: HaoyuHuang
fbshipit-source-id: fd510b5fd4307835f9a986fac545734dbe003d28
Summary:
This PR implements cache eviction using reinforcement learning. It includes two implementations:
1. An implementation of Thompson Sampling for the Bernoulli Bandit [1].
2. An implementation of LinUCB with disjoint linear models [2].
The idea is that a cache uses multiple eviction policies, e.g., MRU, LRU, and LFU. The cache learns which eviction policy is the best and uses it upon a cache miss.
Thompson Sampling is contextless and does not include any features.
LinUCB includes features such as level, block type, caller, column family id to decide which eviction policy to use.
[1] Daniel J. Russo, Benjamin Van Roy, Abbas Kazerouni, Ian Osband, and Zheng Wen. 2018. A Tutorial on Thompson Sampling. Found. Trends Mach. Learn. 11, 1 (July 2018), 1-96. DOI: https://doi.org/10.1561/2200000070
[2] Lihong Li, Wei Chu, John Langford, and Robert E. Schapire. 2010. A contextual-bandit approach to personalized news article recommendation. In Proceedings of the 19th international conference on World wide web (WWW '10). ACM, New York, NY, USA, 661-670. DOI=http://dx.doi.org/10.1145/1772690.1772758
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5610
Differential Revision: D16435067
Pulled By: HaoyuHuang
fbshipit-source-id: 6549239ae14115c01cb1e70548af9e46d8dc21bb
Summary:
The ObjectRegistry class replaces the Registrar and NewCustomObjects. Objects are registered with the registry by Type (the class must implement the static const char *Type() method).
This change is necessary for a few reasons:
- By having a class (rather than static template instances), the class can be passed between compilation units, meaning that objects could be registered and shared from a dynamic library with an executable.
- By having a class with instances, different units could have different objects registered. This could be useful if, for example, one Option allowed for a dynamic library and one did not.
When combined with some other PRs (being able to load shared libraries, a Configurable interface to configure objects to/from string), this code will allow objects in external shared libraries to be added to a RocksDB image at run-time, rather than requiring every new extension to be built into the main library and called explicitly by every program.
Test plan (on riversand963's devserver)
```
$COMPILE_WITH_ASAN=1 make -j32 all && sleep 1 && make check
```
All tests pass.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5293
Differential Revision: D16363396
Pulled By: riversand963
fbshipit-source-id: fbe4acb615bfc11103eef40a0b288845791c0180
Summary:
Right now, ldb cannot scan a DB with merge operands with default ldb. There is no hard to give a general merge operator so that it can at least print out something
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5607
Test Plan: Run ldb against a DB with merge operands and see the outputs.
Differential Revision: D16442634
fbshipit-source-id: c66c414ec07f219cfc6e6ec2cc14c783ee95df54
Summary:
- Compute correlation between a few features and predictions, e.g., number of accesses since the last access vs number of accesses till the next access on a block.
- Output human readable trace file so python can consume it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5596
Test Plan: make clean && USE_CLANG=1 make check -j32
Differential Revision: D16373200
Pulled By: HaoyuHuang
fbshipit-source-id: c848d26bc2e9210461f317d7dbee42d55be5a0cc
Summary:
Atomic flush test started to fail after https://github.com/facebook/rocksdb/issues/5099. Then https://github.com/facebook/rocksdb/issues/5278 provided a fix after
which the same error occurred much less frequently. However it still occur
occasionally. Not sure what the root cause is. This PR disables the feature of
snapshot list refresh, and we should keep an eye on the failure in the future.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5581
Differential Revision: D16295985
Pulled By: riversand963
fbshipit-source-id: c9e62e65133c52c21b07097de359632ca62571e4
Summary:
ldb idump now only works for default column family. Extend it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5594
Test Plan: Compile and run the tool against a multiple CF DB.
Differential Revision: D16380684
fbshipit-source-id: bfb8af36fdad1806837c90aaaab492d71528aceb
Summary:
This PR traces the referenced key for Get for all types of blocks. This is useful when evaluating hybrid row-block caches.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5548
Test Plan: make clean && USE_CLANG=1 make check -j32
Differential Revision: D16157979
Pulled By: HaoyuHuang
fbshipit-source-id: f6327411c9deb74e35e22a35f66cdbae09ab9d87
Summary:
Currently, when the block cache is used for the filter block, it is not
really the block itself that is stored in the cache but a FilterBlockReader
object. Since this object is not pure data (it has, for instance, pointers that
might dangle, including in one case a back pointer to the TableReader), it's not
really sharable. To avoid the issues around this, the current code erases the
cache entries when the TableReader is closed (which, BTW, is not sufficient
since a concurrent TableReader might have picked up the object in the meantime).
Instead of doing this, the patch moves the FilterBlockReader out of the cache
altogether, and decouples the filter reader object from the filter block.
In particular, instead of the TableReader owning, or caching/pinning the
FilterBlockReader (based on the customer's settings), with the change the
TableReader unconditionally owns the FilterBlockReader, which in turn
owns/caches/pins the filter block. This change also enables us to reuse the code
paths historically used for data blocks for filters as well.
Note:
Eviction statistics for filter blocks are temporarily broken. We plan to fix this in a
separate phase.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5504
Test Plan: make asan_check
Differential Revision: D16036974
Pulled By: ltamasi
fbshipit-source-id: 770f543c5fb4ed126fd1e04bfd3809cf4ff9c091
Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/5563
Test Plan: Manually run the script on files generated by block_cache_trace_analyzer.
Differential Revision: D16214400
Pulled By: HaoyuHuang
fbshipit-source-id: 94485eed995e9b2b63e197c5dfeb80129fa7897f
Summary:
This PR adds a ghost cache for admission control. Specifically, it admits an entry on its second access.
It also adds a hybrid row-block cache that caches the referenced key-value pairs of a Get/MultiGet request instead of its blocks.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5534
Test Plan: make clean && COMPILE_WITH_ASAN=1 make check -j32
Differential Revision: D16101124
Pulled By: HaoyuHuang
fbshipit-source-id: b99edda6418a888e94eb40f71ece45d375e234b1
Summary:
When atomic flush stress test fails, we print internal keys within the range with mismatched key/values for all column families.
Test plan (on devserver)
Manually hack the code to randomly insert wrong data. Run the test.
```
$make clean && COMPILE_WITH_TSAN=1 make -j32 db_stress
$./db_stress -test_atomic_flush=true -ops_per_thread=10000
```
Check that proper error messages are printed, as follows:
```
2019/07/08-17:40:14 Starting verification
Verification failed
Latest Sequence Number: 190903
[default] 000000000000050B => 56290000525350515E5F5C5D5A5B5859
[3] 0000000000000533 => EE100000EAEBE8E9E6E7E4E5E2E3E0E1FEFFFCFDFAFBF8F9
Internal keys in CF 'default', [000000000000050B, 0000000000000533] (max 8)
key 000000000000050B seq 139920 type 1
key 0000000000000533 seq 0 type 1
Internal keys in CF '3', [000000000000050B, 0000000000000533] (max 8)
key 0000000000000533 seq 0 type 1
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5549
Differential Revision: D16158709
Pulled By: riversand963
fbshipit-source-id: f07fa87763f87b3bd908da03c956709c6456bcab
Summary:
Right now ldb can open running DB through read-only DB. However, it might leave info logs files to the read-only DB directory. Add an option to open the DB as secondary to avoid it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5537
Test Plan:
Run
./ldb scan --max_keys=10 --db=/tmp/rocksdbtest-2491/dbbench --secondary_path=/tmp --no_value --hex
and
./ldb get 0x00000000000000103030303030303030 --hex --db=/tmp/rocksdbtest-2491/dbbench --secondary_path=/tmp
against a normal db_bench run and observe the output changes. Also observe that no new info logs files are created under /tmp/rocksdbtest-2491/dbbench.
Run without --secondary_path and observe that new info logs created under /tmp/rocksdbtest-2491/dbbench.
Differential Revision: D16113886
fbshipit-source-id: 4e09dec47c2528f6ca08a9e7a7894ba2d9daebbb
Summary:
Print out some more information when db_tress fails with verification failures to help debugging problems.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5543
Test Plan:
Manually ingest some failures and observe the outputs are like this:
Verification failed
[default] 0000000000199A5A => 7C3D000078797A7B74757677707172736C6D6E6F68696A6B
[6] 000000000019C8BD => 65380000616063626D6C6F6E69686B6A
internal keys in default CF [0000000000199A5A, 000000000019C8BD] (max 8)
key 0000000000199A5A seq 179246 type 1
key 000000000019C8BD seq 163970 type 1
Lastest Sequence Number: 292234
Differential Revision: D16153717
fbshipit-source-id: b33fa50a828c190cbf8249a37955432044f92daf
Summary:
Sometimes it is helpful to fetch the whole history of stats after benchmark runs. Add such an option
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5532
Test Plan: Run the benchmark manually and observe the output is as expected.
Differential Revision: D16097764
fbshipit-source-id: 10b5b735a22a18be198b8f348be11f11f8806904
Summary:
Formatting fixes in db_bench_tool that were accidentally omitted
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5525
Test Plan: Unit tests
Differential Revision: D16078516
Pulled By: elipoz
fbshipit-source-id: bf8df0e3f08092a91794ebf285396d9b8a335bb9
Summary:
This PR creates cache_simulator.h file. It contains a CacheSimulator that runs against a block cache trace record. We can add alternative cache simulators derived from CacheSimulator later. For example, this PR adds a PrioritizedCacheSimulator that inserts filter/index/uncompressed dictionary blocks with high priority.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5517
Test Plan: make clean && COMPILE_WITH_ASAN=1 make check -j32
Differential Revision: D16043689
Pulled By: HaoyuHuang
fbshipit-source-id: 65f28ed52b866ffb0e6eceffd7f9ca7c45bb680d
Summary:
`create_column_family` cmd already exists but was somehow missed in the help message.
also add `drop_column_family` cmd which can drop a cf without opening db.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5503
Test Plan: Updated existing ldb_test.py to test deleting a column family.
Differential Revision: D16018414
Pulled By: lightmark
fbshipit-source-id: 1fc33680b742104fea86b10efc8499f79e722301
Summary:
This PR adds a feature in block cache trace analysis tool to write statistics into csv files.
1. The analysis tool supports grouping the number of accesses per second by various labels, e.g., block, column family, block type, or a combination of them.
2. It also computes reuse distance and reuse interval.
Reuse distance: The cumulated size of unique blocks read between two consecutive accesses on the same block.
Reuse interval: The time between two consecutive accesses on the same block.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5490
Differential Revision: D15901322
Pulled By: HaoyuHuang
fbshipit-source-id: b5454fea408a32757a80be63de6fe1c8149ca70e
Summary:
This PR adds more callers for table readers. These information are only used for block cache analysis so that we can know which caller accesses a block.
1. It renames the BlockCacheLookupCaller to TableReaderCaller as passing the caller from upstream requires changes to table_reader.h and TableReaderCaller is a more appropriate name.
2. It adds more table reader callers in table/table_reader_caller.h, e.g., kCompactionRefill, kExternalSSTIngestion, and kBuildTable.
This PR is long as it requires modification of interfaces in table_reader.h, e.g., NewIterator.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5454
Test Plan: make clean && COMPILE_WITH_ASAN=1 make check -j32.
Differential Revision: D15819451
Pulled By: HaoyuHuang
fbshipit-source-id: b6caa704c8fb96ddd15b9a934b7e7ea87f88092d
Summary:
sprintf is unsafe and has buffer overrun risk. Replace it with the safer version snprintf where buffer size is supplied to avoid overrun.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5475
Differential Revision: D15879481
Pulled By: sagar0
fbshipit-source-id: 7ae1958ffc9727fa50261dfbb98ddd74e70a72d8
Summary:
This PR adds a BlockCacheTraceSimulator that reports the miss ratios given different cache configurations. A cache configuration contains "cache_name,num_shard_bits,cache_capacities". For example, "lru, 1, 1K, 2K, 4M, 4G".
When we replay the trace, we also perform lookups and inserts on the simulated caches.
In the end, it reports the miss ratio for each tuple <cache_name, num_shard_bits, cache_capacity> in a output file.
This PR also adds a main source block_cache_trace_analyzer so that we can run the analyzer in command line.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5449
Test Plan:
Added tests for block_cache_trace_analyzer.
COMPILE_WITH_ASAN=1 make check -j32.
Differential Revision: D15797073
Pulled By: HaoyuHuang
fbshipit-source-id: aef0c5c2e7938f3e8b6a10d4a6a50e6928ecf408
Summary:
This PR continues the work in https://github.com/facebook/rocksdb/pull/4748 and https://github.com/facebook/rocksdb/pull/4535 by adding a new DBOption `persist_stats_to_disk` which instructs RocksDB to persist stats history to RocksDB itself. When statistics is enabled, and both options `stats_persist_period_sec` and `persist_stats_to_disk` are set, RocksDB will periodically write stats to a built-in column family in the following form: key -> (timestamp in microseconds)#(stats name), value -> stats value. The existing API `GetStatsHistory` will detect the current value of `persist_stats_to_disk` and either read from in-memory data structure or from the hidden column family on disk.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5046
Differential Revision: D15863138
Pulled By: miasantreble
fbshipit-source-id: bb82abdb3f2ca581aa42531734ac799f113e931b
Summary:
This PR integrates the block cache tracing into db_bench. It adds three command line arguments.
-block_cache_trace_file (Block cache trace file path.) type: string default: ""
-block_cache_trace_max_trace_file_size_in_bytes (The maximum block cache
trace file size in bytes. Block cache accesses will not be logged if the
trace file size exceeds this threshold. Default is 64 GB.) type: int64
default: 68719476736
-block_cache_trace_sampling_frequency (Block cache trace sampling
frequency, termed s. It uses spatial downsampling and samples accesses to
one out of s blocks.) type: int32 default: 1
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5459
Differential Revision: D15832031
Pulled By: HaoyuHuang
fbshipit-source-id: 0ecf2f2686557251fe741a2769b21170777efa3d
Summary:
This PR integrates the block cache tracer into block based table reader. The tracer will write the block cache accesses using the trace_writer. The tracer is null in this PR so that nothing will be logged.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5441
Differential Revision: D15772029
Pulled By: HaoyuHuang
fbshipit-source-id: a64adb92642cd23222e0ba8b10d86bf522b42f9b
Summary:
This PR integrates the block cache tracer class into db_impl.cc.
db_impl.cc contains a member variable of AtomicBlockCacheTraceWriter class and passes its reference to the block_based_table_reader.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5433
Differential Revision: D15728016
Pulled By: HaoyuHuang
fbshipit-source-id: 23d5659e8c82d556833dcc1a5558aac8c1f7db71
Summary:
The tsan crash tests are failing with a data race compliant with pipelined write option. Temporarily disable it until its concurrency issue are fixed.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5445
Differential Revision: D15783824
Pulled By: maysamyabandeh
fbshipit-source-id: 413a0c3230b86f524fc7eeea2cf8e8375406e65b
Summary:
This PR contains the first commit for block cache trace analyzer. It reads a block cache trace file and prints statistics of the traces.
We will extend this class to provide more functionalities.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5425
Differential Revision: D15709580
Pulled By: HaoyuHuang
fbshipit-source-id: 2f43bd2311f460ab569880819d95eeae217c20bb
Summary:
When using `PRIu64` type of printf specifier, current code base does the following:
```
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <inttypes.h>
```
However, this can be simplified to
```
#include <cinttypes>
```
as long as flag `-std=c++11` is used.
This should solve issues like https://github.com/facebook/rocksdb/issues/5159
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5402
Differential Revision: D15701195
Pulled By: miasantreble
fbshipit-source-id: 6dac0a05f52aadb55e9728038599d3d2e4b59d03
Summary:
util/ means for lower level libraries. trace_replay is highly integrated to DB and sometimes call DB. Move it out to a separate directory.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5376
Differential Revision: D15550938
Pulled By: siying
fbshipit-source-id: f46dce5ceffdc05a73f26379c7bb1b79ebe6c207
Summary:
Many logging related source files are under util/. It will be more structured if they are together.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5387
Differential Revision: D15579036
Pulled By: siying
fbshipit-source-id: 3850134ed50b8c0bb40a0c8ae1f184fa4081303f
Summary:
1. Fix a bug in WAL replay in which write batches with old sequence numbers are mistakenly inserted into memtables.
2. Add support for benchmarking secondary instance to db_bench_tool.
With changes made in this PR, we can start benchmarking secondary instance
using two processes. It is also possible to vary the frequency at which the
secondary instance tries to catch up with the primary. The info log of the
secondary can be found in a directory whose path can be specified with
'-secondary_path'.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5170
Differential Revision: D15564608
Pulled By: riversand963
fbshipit-source-id: ce97688ed3d33f69d3a0b9266ebbbbf887aa0ec8
Summary:
When the --reopen option is non-zero, the DB is reopened after every ops_per_thread/(reopen+1) ops, with the check being done after every op. With MultiGet, we might do multiple ops in one iteration, which broke the logic that checked when to synchronize among the threads and reopen the DB. This PR fixes that logic.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5374
Differential Revision: D15559780
Pulled By: anand1976
fbshipit-source-id: ee6563a68045df7f367eca3cbc2500d3e26359ef
Summary:
There are too many types of files under util/. Some test related files don't belong to there or just are just loosely related. Mo
ve them to a new directory test_util/, so that util/ is cleaner.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5377
Differential Revision: D15551366
Pulled By: siying
fbshipit-source-id: 0f5c8653832354ef8caa31749c0143815d719e2c
Summary:
util/ means for lower level libraries, so it's a good idea to move the files which requires knowledge to DB out. Create a file/ and move some files there.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5375
Differential Revision: D15550935
Pulled By: siying
fbshipit-source-id: 61a9715dcde5386eebfb43e93f847bba1ae0d3f2
Summary:
This enables the user to set TransactionDBOptions::skip_concurrency_control so the standard `DB::Write(const WriteOptions& opts, WriteBatch* updates)` would skip the concurrency control. This would give higher throughput to the users who know their use case doesn't need concurrency control.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5330
Differential Revision: D15525932
Pulled By: maysamyabandeh
fbshipit-source-id: 68421ac1ba34f549a4a8de9ce4c2dccf6fb4b06b
Vijay Nadimpalli