Summary:
The first key is used to defer reading the data block until this file gets to the top of merging iterator's heap. For short range scans, most files never make it to the top of the heap, so this change can reduce read amplification by a lot sometimes.
Consider the following workload. There are a few data streams (we'll be calling them "logs"), each stream consisting of a sequence of blobs (we'll be calling them "records"). Each record is identified by log ID and a sequence number within the log. RocksDB key is concatenation of log ID and sequence number (big endian). Reads are mostly relatively short range scans, each within a single log. Writes are mostly sequential for each log, but writes to different logs are randomly interleaved. Compactions are disabled; instead, when we accumulate a few tens of sst files, we create a new column family and start writing to it.
So, a typical sst file consists of a few ranges of blocks, each range corresponding to one log ID (we use FlushBlockPolicy to cut blocks at log boundaries). A typical read would go like this. First, iterator Seek() reads one block from each sst file. Then a series of Next()s move through one sst file (since writes to each log are mostly sequential) until the subiterator reaches the end of this log in this sst file; then Next() switches to the next sst file and reads sequentially from that, and so on. Often a range scan will only return records from a small number of blocks in small number of sst files; in this case, the cost of initial Seek() reading one block from each file may be bigger than the cost of reading the actually useful blocks.
Neither iterate_upper_bound nor bloom filters can prevent reading one block from each file in Seek(). But this PR can: if the index contains first key from each block, we don't have to read the block until this block actually makes it to the top of merging iterator's heap, so for short range scans we won't read any blocks from most of the sst files.
This PR does the deferred block loading inside value() call. This is not ideal: there's no good way to report an IO error from inside value(). As discussed with siying offline, it would probably be better to change InternalIterator's interface to explicitly fetch deferred value and get status. I'll do it in a separate PR.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5289
Differential Revision: D15256423
Pulled By: al13n321
fbshipit-source-id: 750e4c39ce88e8d41662f701cf6275d9388ba46a
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:
`Block::restart_index_`, `Block::restarts_`, and `Block::current_` are defined as uint32_t but `BlockBasedTableOptions::block_size` is defined as a size_t so user might see corruption as in https://github.com/facebook/rocksdb/issues/5486.
This PR adds a check in `BlockBasedTableFactory::SanitizeOptions` to disallow such configurations.
yiwu-arbug
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5492
Differential Revision: D15914047
Pulled By: miasantreble
fbshipit-source-id: c943f153d967e15aee7f2795730ab8259e2be201
Summary:
Currently the read-ahead logic for user reads and compaction reads go through different code paths where compaction reads create new table readers and use `ReadaheadRandomAccessFile`. This change is to unify read-ahead logic to use read-ahead in BlockBasedTableReader::InitDataBlock(). As a result of the change `ReadAheadRandomAccessFile` class and `new_table_reader_for_compaction_inputs` option will no longer be used.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5431
Test Plan:
make check
Here is the benchmarking - https://gist.github.com/vjnadimpalli/083cf423f7b6aa12dcdb14c858bc18a5
Differential Revision: D15772533
Pulled By: vjnadimpalli
fbshipit-source-id: b71dca710590471ede6fb37553388654e2e479b9
Summary:
The patch brings the semantics of per-block-type read performance
context counters in sync with the generic block_read_count by only
incrementing the counter if the block was actually read from the file.
It also fixes index_block_read_count, which fell victim to the
refactoring in PR https://github.com/facebook/rocksdb/issues/5298.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5484
Test Plan: Extended the unit tests.
Differential Revision: D15887431
Pulled By: ltamasi
fbshipit-source-id: a3889759d0ac5759d56625d692cd828d1b9207a6
Summary:
PR https://github.com/facebook/rocksdb/issues/5298 subtly changed how read options are applied to the index block
during a Get, MultiGet, or iteration. Earlier, only the read_tier option
applied to the index block read; since PR https://github.com/facebook/rocksdb/issues/5298, fill_cache and
verify_checksums also have an effect. This patch restores the earlier
behavior to prevent surprise memory increases for clients due to the
index block not being cached.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5481
Test Plan: make check
Differential Revision: D15883082
Pulled By: ltamasi
fbshipit-source-id: 9a065ec3a6db5a365cf6dd5e95190a20c5756356
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:
BlockCacheLookupContext only contains the caller for now.
We will trace block accesses at five places:
1. BlockBasedTable::GetFilter.
2. BlockBasedTable::GetUncompressedDict.
3. BlockBasedTable::MaybeReadAndLoadToCache. (To trace access on data, index, and range deletion block.)
4. BlockBasedTable::Get. (To trace the referenced key and whether the referenced key exists in a fetched data block.)
5. BlockBasedTable::MultiGet. (To trace the referenced key and whether the referenced key exists in a fetched data block.)
We create the context at:
1. BlockBasedTable::Get. (kUserGet)
2. BlockBasedTable::MultiGet. (kUserMGet)
3. BlockBasedTable::NewIterator. (either kUserIterator, kCompaction, or external SST ingestion calls this function.)
4. BlockBasedTable::Open. (kPrefetch)
5. Index/Filter::CacheDependencies. (kPrefetch)
6. BlockBasedTable::ApproximateOffsetOf. (kCompaction or kUserApproximateSize).
I loaded 1 million key-value pairs into the database and ran the readrandom benchmark with a single thread. I gave the block cache 10 GB to make sure all reads hit the block cache after warmup. The throughput is comparable.
Throughput of this PR: 231334 ops/s.
Throughput of the master branch: 238428 ops/s.
Experiment setup:
RocksDB: version 6.2
Date: Mon Jun 10 10:42:51 2019
CPU: 24 * Intel Core Processor (Skylake)
CPUCache: 16384 KB
Keys: 20 bytes each
Values: 100 bytes each (100 bytes after compression)
Entries: 1000000
Prefix: 20 bytes
Keys per prefix: 0
RawSize: 114.4 MB (estimated)
FileSize: 114.4 MB (estimated)
Write rate: 0 bytes/second
Read rate: 0 ops/second
Compression: NoCompression
Compression sampling rate: 0
Memtablerep: skip_list
Perf Level: 1
Load command: ./db_bench --benchmarks="fillseq" --key_size=20 --prefix_size=20 --keys_per_prefix=0 --value_size=100 --statistics --cache_index_and_filter_blocks --cache_size=10737418240 --disable_auto_compactions=1 --disable_wal=1 --compression_type=none --min_level_to_compress=-1 --compression_ratio=1 --num=1000000
Run command: ./db_bench --benchmarks="readrandom,stats" --use_existing_db --threads=1 --duration=120 --key_size=20 --prefix_size=20 --keys_per_prefix=0 --value_size=100 --statistics --cache_index_and_filter_blocks --cache_size=10737418240 --disable_auto_compactions=1 --disable_wal=1 --compression_type=none --min_level_to_compress=-1 --compression_ratio=1 --num=1000000 --duration=120
TODOs:
1. Create a caller for external SST file ingestion and differentiate the callers for iterator.
2. Integrate tracer to trace block cache accesses.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5421
Differential Revision: D15704258
Pulled By: HaoyuHuang
fbshipit-source-id: 4aa8a55f8cb1576ffb367bfa3186a91d8f06d93a
Summary:
Instead of creating a new DataBlockIterator for every key in a MultiGet batch, reuse it if the next key is in the same block. This results in a small 1-2% cpu improvement.
TEST_TMPDIR=/dev/shm/multiget numactl -C 10 ./db_bench.tmp -use_existing_db=true -benchmarks="readseq,multireadrandom" -write_buffer_size=4194304 -target_file_size_base=4194304 -max_bytes_for_level_base=16777216 -num=12000000 -reads=12000000 -duration=90 -threads=1 -compression_type=none -cache_size=4194304000 -batch_size=32 -disable_auto_compactions=true -bloom_bits=10 -cache_index_and_filter_blocks=true -pin_l0_filter_and_index_blocks_in_cache=true -multiread_batched=true -multiread_stride=4
Without the change -
multireadrandom : 3.066 micros/op 326122 ops/sec; (29375968 of 29375968 found)
With the change -
multireadrandom : 3.003 micros/op 332945 ops/sec; (29983968 of 29983968 found)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5314
Differential Revision: D15742108
Pulled By: anand1976
fbshipit-source-id: 220fb0b8eea9a0d602ddeb371528f7af7936d771
Summary:
PR #5111 reduced the number of key comparisons when iterating with
upper/lower bounds; however, this caused a regression for MyRocks.
Reverting to the previous behavior in BlockBasedTableIterator as a hotfix.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5428
Differential Revision: D15721038
Pulled By: ltamasi
fbshipit-source-id: 5450106442f1763bccd17f6cfd648697f2ae8b6c
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:
The patch cleans up the handling of cache hit/miss/insertion related
performance counters, get context counters, and statistics by
eliminating some code duplication and factoring out the affected logic
into separate methods. In addition, it makes the semantics of cache hit
metrics more consistent by changing the code so that accessing a
partition of partitioned indexes/filters through a pinned reference no
longer counts as a cache hit.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5408
Differential Revision: D15610883
Pulled By: ltamasi
fbshipit-source-id: ee749c18965077aca971d8f8bee8b24ed8fa76f1
Summary:
It's useful to be able to (optionally) associate key-value pairs with user-provided timestamps. This PR is an early effort towards this goal and continues the work of facebook#4942. A suite of new unit tests exist in DBBasicTestWithTimestampWithParam. Support for timestamp requires the user to provide timestamp as a slice in `ReadOptions` and `WriteOptions`. All timestamps of the same database must share the same length, format, etc. The format of the timestamp is the same throughout the same database, and the user is responsible for providing a comparator function (Comparator) to order the <key, timestamp> tuples. Once created, the format and length of the timestamp cannot change (at least for now).
Test plan (on devserver):
```
$COMPILE_WITH_ASAN=1 make -j32 all
$./db_basic_test --gtest_filter=Timestamp/DBBasicTestWithTimestampWithParam.PutAndGet/*
$make check
```
All tests must pass.
We also run the following db_bench tests to verify whether there is regression on Get/Put while timestamp is not enabled.
```
$TEST_TMPDIR=/dev/shm ./db_bench -benchmarks=fillseq,readrandom -num=1000000
$TEST_TMPDIR=/dev/shm ./db_bench -benchmarks=fillrandom -num=1000000
```
Repeat for 6 times for both versions.
Results are as follows:
```
| | readrandom | fillrandom |
| master | 16.77 MB/s | 47.05 MB/s |
| PR5079 | 16.44 MB/s | 47.03 MB/s |
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5079
Differential Revision: D15132946
Pulled By: riversand963
fbshipit-source-id: 833a0d657eac21182f0f206c910a6438154c742c
Summary:
The commit makes GetEntryFromCache become a member function. It also makes all its callers become member functions.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5394
Differential Revision: D15579222
Pulled By: HaoyuHuang
fbshipit-source-id: 07509c42ee9022dcded54950012bd3bd562aa1ae
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:
Many methods are passing around pointers to non-const objects when in fact
they do not/should not modify said objects. The patch makes the semantics
clearer and also helps from a thread safety point-of-view by changing some
pointers to pointers-to-const and marking some instance methods as const.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5383
Differential Revision: D15562770
Pulled By: ltamasi
fbshipit-source-id: 89361dadbb8b25bbe54d17e8da28fee24a2419af
Summary:
Currently, when the block cache is used for index blocks as well, it is
not really the index block that is stored in the cache but an
IndexReader object. Since this object is not pure data (it has, for
instance, pointers that might dangle), it's not really sharable. To
avoid the issues around this, the current code uses a dummy unique cache
key for each TableReader to store the IndexReader, and erases the
IndexReader entry when the TableReader is closed. Instead of doing this,
the new code moves the IndexReader out of the cache altogether. In
particular, instead of the TableReader owning, or caching/pinning the
IndexReader based on the customer's settings, the TableReader
unconditionally owns the IndexReader, which in turn owns/caches/pins
the index block (which is itself sharable and thus can be safely put in
the cache without any hacks).
Note: the change has two side effects:
1) Partitions of partitioned indexes no longer affect the read
amplification statistics.
2) Eviction statistics for index blocks are temporarily broken. We plan to fix
this in a separate phase.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5298
Differential Revision: D15303203
Pulled By: ltamasi
fbshipit-source-id: 935a69ba59d87d5e44f42e2310619b790c366e47
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:
Previously if iterator upper/lower bound presents, `DBIter` will check the bound for every key. This patch turns the check into per-file or per-data block check when applicable, by checking against either file largest/smallest key or block index key.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5111
Differential Revision: D15330061
Pulled By: siying
fbshipit-source-id: 8a653fe3cd50d94d81eb2d13b087326c58ee2024
Summary:
Performing unordered writes in rocksdb when unordered_write option is set to true. When enabled the writes to memtable are done without joining any write thread. This offers much higher write throughput since the upcoming writes would not have to wait for the slowest memtable write to finish. The tradeoff is that the writes visible to a snapshot might change over time. If the application cannot tolerate that, it should implement its own mechanisms to work around that. Using TransactionDB with WRITE_PREPARED write policy is one way to achieve that. Doing so increases the max throughput by 2.2x without however compromising the snapshot guarantees.
The patch is prepared based on an original by siying
Existing unit tests are extended to include unordered_write option.
Benchmark Results:
```
TEST_TMPDIR=/dev/shm/ ./db_bench_unordered --benchmarks=fillrandom --threads=32 --num=10000000 -max_write_buffer_number=16 --max_background_jobs=64 --batch_size=8 --writes=3000000 -level0_file_num_compaction_trigger=99999 --level0_slowdown_writes_trigger=99999 --level0_stop_writes_trigger=99999 -enable_pipelined_write=false -disable_auto_compactions --unordered_write=1
```
With WAL
- Vanilla RocksDB: 78.6 MB/s
- WRITER_PREPARED with unordered_write: 177.8 MB/s (2.2x)
- unordered_write: 368.9 MB/s (4.7x with relaxed snapshot guarantees)
Without WAL
- Vanilla RocksDB: 111.3 MB/s
- WRITER_PREPARED with unordered_write: 259.3 MB/s MB/s (2.3x)
- unordered_write: 645.6 MB/s (5.8x with relaxed snapshot guarantees)
- WRITER_PREPARED with unordered_write disable concurrency control: 185.3 MB/s MB/s (2.35x)
Limitations:
- The feature is not yet extended to `max_successive_merges` > 0. The feature is also incompatible with `enable_pipelined_write` = true as well as with `allow_concurrent_memtable_write` = false.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5218
Differential Revision: D15219029
Pulled By: maysamyabandeh
fbshipit-source-id: 38f2abc4af8780148c6128acdba2b3227bc81759
Summary:
https://github.com/facebook/rocksdb/pull/5256 broke it: `block_iter_.user_key()` may not be valid even if `block_iter_points_to_real_block_` is true. E.g. if there was an IO error or Status::Incomplete.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5291
Differential Revision: D15273324
Pulled By: al13n321
fbshipit-source-id: 442e5b09f9884a58f92a6ac1ca93af719c219886
Summary:
CachableEntry is used in a variety of contexts: it may refer to a cached
object (i.e. an object in the block cache), an owned object, or an
unowned object; also, in some cases (most notably with iterators), the
responsibility of managing the pointed-to object gets handed off to
another object. Each of the above scenarios have different implications
for the lifecycle of the referenced object. For the most part, the patch
does not change the lifecycle of managed objects; however, it makes
these relationships explicit, and it also enables us to eliminate some
hacks and accident-prone code around releasing cache handles and
deleting/cleaning up objects. (The only places where the patch changes
how an objects are managed are the partitions of partitioned indexes and
filters.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5252
Differential Revision: D15101358
Pulled By: ltamasi
fbshipit-source-id: 9eb59e9ae5a7230e3345789762d0ba1f189485be
Summary:
When reseek happens in merging iterator, reseeking a child iterator can be avoided if:
(1) the iterator represents imutable data
(2) reseek() to a larger key than the current key
(3) the current key of the child iterator is larger than the seek key
because it is guaranteed that the result will fall into the same position.
This optimization will be useful for use cases where users keep seeking to keys nearby in ascending order.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5286
Differential Revision: D15283635
Pulled By: siying
fbshipit-source-id: 35f79ffd5ce3609146faa8cd55f2bfd733502f83
Summary:
Right now there is a potential race condition where two threads are created to iterate through the DB (https://gist.github.com/miasantreble/88f5798a397ee7cb8e7baff9db2d9e85). The problem is that in `BlockBasedTable::NewIndexIterator`, if both threads failed to find index_reader from block cache, they will call `CreateIndexReader->UpdateIndexType()` which creates a race to update `index_type` in the shared rep_ object. By checking the code, we realize the index type is always populated by `PrefetchIndexAndFilterBlocks` during the table `Open` call, so there is no need to update index type every time during iterator creation. This PR attempts to fix the race condition by removing the unnecessary call to `UpdateIndexType`
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5288
Differential Revision: D15252509
Pulled By: miasantreble
fbshipit-source-id: 6e3258652121d5c76d267f7ac457e15c5e84756e
Summary:
Part of compaction cpu goes to processing snapshot list, the larger the list the bigger the overhead. Although the lifetime of most of the snapshots is much shorter than the lifetime of compactions, the compaction conservatively operates on the list of snapshots that it initially obtained. This patch allows the snapshot list to be updated via a callback if the compaction is taking long. This should let the compaction to continue more efficiently with much smaller snapshot list.
For simplicity, to avoid the feature is disabled in two cases: i) When more than one sub-compaction are sharing the same snapshot list, ii) when Range Delete is used in which the range delete aggregator has its own copy of snapshot list.
This fixes the reverted https://github.com/facebook/rocksdb/pull/5099 issue with range deletes.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5278
Differential Revision: D15203291
Pulled By: maysamyabandeh
fbshipit-source-id: fa645611e606aa222c7ce53176dc5bb6f259c258
Summary:
This PR fixes three memory issues found by ASAN
* in db_stress, the key vector for MultiGet is created using `emplace_back` which could potentially invalidates references to the underlying storage (vector<string>) due to auto resizing. Fix by calling reserve in advance.
* Similar issue in construction of GetContext autovector in version_set.cc
* In multiget_context.h use T[] specialization for unique_ptr that holds a char array
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5279
Differential Revision: D15202893
Pulled By: miasantreble
fbshipit-source-id: 14cc2cda0ed64d29f2a1e264a6bfdaa4294ee75d
Summary:
Right now, when Seek() is called again, RocksDB always does a binary search against the files and index blocks, even if they end up with the same file/block. Improve it as following:
1. in LevelIterator, reseek first try to check the boundary of the current file. If it falls into the same file, skip the binary search to find the file
2. in block based table iterator, reseek skip to reseek the iterator block if the seek key is larger than the current key and lower than the index key (boundary of the current block and the next block).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5256
Differential Revision: D15105072
Pulled By: siying
fbshipit-source-id: 39634bdb4a881082451fa39cecd7ecf12160bf80
Summary:
Our daily stress tests are failing after this feature. Reverting temporarily until we figure the reason for test failures.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5269
Differential Revision: D15151285
Pulled By: maysamyabandeh
fbshipit-source-id: e4002b99690a97df30d4b4b58bf0f61e9591bc6e
Summary:
At least one of the meta-block loading functions (`ReadRangeDelBlock`)
uses the same block reading function (`NewDataBlockIterator`) as data
block reads, which means it uses the dictionary handle. However, the
dictionary handle was uninitialized while reading meta-blocks, causing
readers to receive an error. This situation was only noticed when
`cache_index_and_filter_blocks=true`.
This PR initializes the handle to null while reading meta-blocks to
prevent the error. It also adds support to `db_stress` /
`db_crashtest.py` for `cache_index_and_filter_blocks`.
Fixes#5263.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5267
Differential Revision: D15149264
Pulled By: maysamyabandeh
fbshipit-source-id: 991d38a306c62db5976778bfb050fa3cd4a0671b
Summary:
Improve the iterators performance when the user explicitly sets the readahead size via `ReadOptions.readahead_size`.
1. Stop creating new table readers when the user explicitly sets readahead size.
2. Make use of an internal buffer based on `FilePrefetchBuffer` instead of using `ReadaheadRandomAccessFileReader`, to handle the user readahead requests (for both buffered and direct io cases).
3. Add `readahead_size` to db_bench.
**Benchmarks:**
https://gist.github.com/sagar0/53693edc320a18abeaeca94ca32f5737
For 1 MB readahead, Buffered IO performance improves by 28% and Direct IO performance improves by 50%.
For 512KB readahead, Buffered IO performance improves by 30% and Direct IO performance improves by 67%.
**Test Plan:**
Updated `DBIteratorTest.ReadAhead` test to make sure that:
- no new table readers are created for iterators on setting ReadOptions.readahead_size
- At least "readahead" number of bytes are actually getting read on each iterator read.
TODO later:
- Use similar logic for compactions as well.
- This ties in nicely with #4052 and paves the way for removing ReadaheadRandomAcessFile later.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5246
Differential Revision: D15107946
Pulled By: sagar0
fbshipit-source-id: 2c1149729ca7d779e4e8b7710ba6f4e8cbfd3bea
Summary:
Part of compaction cpu goes to processing snapshot list, the larger the list the bigger the overhead. Although the lifetime of most of the snapshots is much shorter than the lifetime of compactions, the compaction conservatively operates on the list of snapshots that it initially obtained. This patch allows the snapshot list to be updated via a callback if the compaction is taking long. This should let the compaction to continue more efficiently with much smaller snapshot list.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5099
Differential Revision: D15086710
Pulled By: maysamyabandeh
fbshipit-source-id: 7649f56c3b6b2fb334962048150142a3bf9c1a12
Summary:
Introduce BlockBasedTableOptions::index_shortening to give users control on which key shortening techniques to be used in building index blocks. Before this patch, both separators and successor keys where shortened in indexes. With this patch, the default is set to kShortenSeparators to only shorten the separators. Since each index block has many separators and only one successor (last key), the change should not have negative impact on index block size. However it should prevent many unnecessary block loads where due to approximation introduced by shorted successor, seek would land us to the previous block and then fix it by moving to the next one.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5174
Differential Revision: D14884185
Pulled By: al13n321
fbshipit-source-id: 1b08bc8c03edcf09b6b8c16e9a7eea08ad4dd534
Summary:
Cleanup a couple of stray includes left by #5011.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5219
Differential Revision: D15007244
Pulled By: anand1976
fbshipit-source-id: 15ca1d4f977b5b60e99df3bfb8fc3db217d19bdd
Summary:
We found an issue in Periodic Compactions (introduced in #5166) where files were not being picked up for compactions as all the SST files created with older versions of RocksDB have `file_creation_time` as 0. (Note that `file_creation_time` is a new table property introduced in #5166).
To address this, Periodic compactions now fall back to looking at the `creation_time` table property or the file's modification time (as given by the Env) when `file_creation_time` table property is found to be 0.
Here how the file's modification time (and, in turn, the file age) is computed now:
1. Use `file_creation_time` table property if it is > 0.
1. If not, then use `creation_time` table property if it is > 0.
1. If not, then use file's mtime stat metadata given by the underlying Env.
Don't consider the file at all for compaction if the modification time cannot be correctly determined based on the above conditions.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5184
Differential Revision: D14907795
Pulled By: sagar0
fbshipit-source-id: 4bb2f3631f9a3e04470c674a1d13544584e1e56c
Summary:
In long scans, virtual function calls of Next(), Valid(), key() and value() are not trivial. By introducing NextAndGetResult(), Some of the Next(), Valid() and key() calls are consolidated into one virtual function call to reduce CPU.
Also did some inline tricks and add some "final" randomly in some functions. Even without the "final" annotation, most Next() calls are inlined with -O3, but sometimes with a final it is inlined by O2 too. It doesn't hurt to add those final annotations.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5197
Differential Revision: D14945977
Pulled By: siying
fbshipit-source-id: 7003969f9a5f1d5717f0bda503b91d19ba75ed88
Summary:
#4905 removed the implementation of `NewEmptyIterator` but kept its
declaration in the public header. This breaks some systems that depend on
RocksDB if the systems use `NewEmptyIterator`. Therefore, add it back to fix. cc maysamyabandeh please remind me if I miss anything here. Thanks
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5203
Differential Revision: D14968382
Pulled By: riversand963
fbshipit-source-id: 5fb86e99c8cfaf9f7a9473cdb1355d7558ff6e01
Summary:
This is second attempt for #5101. Original commit message:
`BlockBasedTableIterator` avoid reading next block on `Next()` if it detects the iterator will be out of bound, by checking against index key. The optimization was added in #2239, and by the time it only check the bound per block. It seems later change make it a per-key check, which introduce unnecessary key comparisons.
This patch come with two fixes:
Fix 1: To optimize checking for bounds, we need comparing the bounds with index key as well. However BlockBasedTableIterator doesn't know whether its index iterator is internally using user keys or internal keys. The patch fixes that by extending InternalIterator with a user_key() function that is overridden by In IndexBlockIter.
Fix 2: In #5101 we return `IsOutOfBound()=true` when block index key is out of bound. But the index key can be larger than smallest key of the next file on the level. That file can be within upper bound and should not be filtered out.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5142
Differential Revision: D14907113
Pulled By: siying
fbshipit-source-id: ac95775c5b4e7b700f76ab43e39f45402c98fbfb
