Commit Graph

1063 Commits

Author SHA1 Message Date
Siying Dong
67d7623794 Expose the stalling information through DB::GetProperty()
Summary:
Add two DB properties: rocksdb.actual_delayed_write_rate and rocksdb.is_write_stooped, for people to know whether current writes are being throttled.
Closes https://github.com/facebook/rocksdb/pull/2043

Differential Revision: D4782975

Pulled By: siying

fbshipit-source-id: 6b2f5cf
2017-03-29 11:54:20 -07:00
Maysam Yabandeh
e7731d119a Configure index partition size
Summary:
Allow the users to specify the target index partition size.

With this patch an index partition is cut before its estimated in-memory size goes above the configured value for metadata_block_size. The filter partitions are still cut right after an index partition is cut.
Closes https://github.com/facebook/rocksdb/pull/2041

Differential Revision: D4780216

Pulled By: maysamyabandeh

fbshipit-source-id: 95a0831
2017-03-28 12:09:12 -07:00
Shu Zhang
8dee8cad9e Enable fifo compaction benchmark to db_bench
Summary:
Added fifo benchmark to db_bench.
One thing i am not sure is that i am using CompactRange() instead of CompactFiles(). (may cause performance skew because CompactionRange() is not happening in current thread?)  For CompactFiles(), for some reason FIFO compaction doesn't work as expected. More insight is welcomed. I guess FIFO compaction doesn't work with file names? igorcanadi

test cmd:
./db_bench --compaction_style=2 --benchmarks=fillseqdeterministic --disable_auto_compactions --num_levels=1 --fifo_compaction_max_table_files_size_mb=10

---------------------- DB 0 LSM ---------------------
Level[0]: /000014.sst(size: 4211014 bytes)
fillseqdeterministic :       4.731 micros/op 211381 ops/sec;   23.4 MB/s
Closes https://github.com/facebook/rocksdb/pull/1734

Differential Revision: D4774964

Pulled By: siying

fbshipit-source-id: 9d08df6
2017-03-24 17:09:15 -07:00
Warren Falk
41ccae6d26 Add C API functions (and tests) for WriteBatchWithIndex
Summary:
I've added functions to the C API to support WriteBatchWithIndex as requested in #1833.

I've also added unit tests to c_test

I've implemented the WriteBatchWithIndex variation of every function available for regular WriteBatch.  And added additional functions unique to WriteBatchWithIndex.

For now, the following is omitted:
  1. The ability to create WriteBatchWithIndex's custom batch-only iterator as I'm not sure what its purpose is.  It should be possible to add later if anyone wants it.
  2. The ability to create the batch with a fallback comparator, since it appears to be unnecessary.  I believe the column family comparator will be used for this, meaning those using a custom comparator can just use the column family variations.
Closes https://github.com/facebook/rocksdb/pull/1985

Differential Revision: D4760039

Pulled By: siying

fbshipit-source-id: 393227e
2017-03-23 15:54:13 -07:00
Siying Dong
9ef3627fd3 Allow checkpointing without flushing
Summary:
Add a parameter to Checkpoint::CreateCheckpoint() so that flush can be skipped if total log file size is within a threshold.
Closes https://github.com/facebook/rocksdb/pull/1993

Differential Revision: D4719842

Pulled By: siying

fbshipit-source-id: 4f9d9e1
2017-03-21 18:09:13 -07:00
Siying Dong
17866ecc3a Allow Users to change customized ldb tools' header in help printing
Summary: Closes https://github.com/facebook/rocksdb/pull/2018

Differential Revision: D4748448

Pulled By: siying

fbshipit-source-id: a54c2f9
2017-03-21 17:39:12 -07:00
Maysam Yabandeh
21d8c31796 remove LIKELY from public headers
Summary:
Fixes #2008
Closes https://github.com/facebook/rocksdb/pull/2009

Differential Revision: D4739885

Pulled By: maysamyabandeh

fbshipit-source-id: 36fba5d
2017-03-20 12:54:14 -07:00
Siying Dong
dbae438a0e Replace "DEPRECATED" comment to "not supported"
Summary:
"DEPRECATED" is ambiguous. Make it clear that those options not supported won't take effect.
Closes https://github.com/facebook/rocksdb/pull/1995

Differential Revision: D4724241

Pulled By: siying

fbshipit-source-id: 1e812b8
2017-03-16 13:54:11 -07:00
Islam AbdelRahman
995618a821 Support SstFileManager::SetDeleteRateBytesPerSecond()
Summary:
Update DeleteScheduler component to support changing delete rate in runtime by introducing
SstFileManager::SetDeleteRateBytesPerSecond()
Closes https://github.com/facebook/rocksdb/pull/1994

Differential Revision: D4719906

Pulled By: IslamAbdelRahman

fbshipit-source-id: e6b8d9e
2017-03-16 12:09:15 -07:00
slyrz
5fa927aa97 Add Xpress and ZSTD CompressionType values to C header
Summary:
This PR copies the missing CompressionType values
```cpp
enum CompressionType : unsigned char {
  ...
  kXpressCompression = 0x6,
  kZSTD = 0x7,
  ...
};
```
into the C header.
Closes https://github.com/facebook/rocksdb/pull/1989

Differential Revision: D4706265

Pulled By: siying

fbshipit-source-id: e65e62a
2017-03-14 12:09:21 -07:00
Maysam Yabandeh
11526252cc Pinnableslice (2nd attempt)
Summary:
PinnableSlice

    Summary:
    Currently the point lookup values are copied to a string provided by the
    user. This incures an extra memcpy cost. This patch allows doing point lookup
    via a PinnableSlice which pins the source memory location (instead of
    copying their content) and releases them after the content is consumed
    by the user. The old API of Get(string) is translated to the new API
    underneath.

    Here is the summary for improvements:

    value 100 byte: 1.8% regular, 1.2% merge values
    value 1k byte: 11.5% regular, 7.5% merge values
    value 10k byte: 26% regular, 29.9% merge values
    The improvement for merge could be more if we extend this approach to
    pin the merge output and delay the full merge operation until the user
    actually needs it. We have put that for future work.

    PS:
    Sometimes we observe a small decrease in performance when switching from
    t5452014 to this patch but with the old Get(string) API. The d
Closes https://github.com/facebook/rocksdb/pull/1756

Differential Revision: D4391738

Pulled By: maysamyabandeh

fbshipit-source-id: 6f3edd3
2017-03-13 11:54:10 -07:00
Sagar Vemuri
1ffbdfd9a7 Add a new SstFileWriter constructor without explicit comparator
Summary:
The comparator param in SstFileWriter constructor is redundant as it already exists as a field in options. So the current SstFileWriter constructor should be deprecated in favor of a new one which does not take a comparator.
Note that the jni/java apis have not been touched yet.
Closes https://github.com/facebook/rocksdb/pull/1978

Differential Revision: D4685629

Pulled By: sagar0

fbshipit-source-id: 372ce96
2017-03-13 11:39:13 -07:00
Andrew Kryczka
fe1835617a release 5.3
Summary: Closes https://github.com/facebook/rocksdb/pull/1971

Differential Revision: D4683851

Pulled By: ajkr

fbshipit-source-id: 967116e
2017-03-09 12:39:10 -08:00
Andrew Kryczka
5b11124e39 add max to histogram stats
Summary:
Domas enlightened me about p100 (i.e., max) stats. Let's add them to our histograms.
Closes https://github.com/facebook/rocksdb/pull/1968

Differential Revision: D4678716

Pulled By: ajkr

fbshipit-source-id: 65e7118
2017-03-08 22:24:15 -08:00
Maysam Yabandeh
54b434110e Builders for partition filter
Summary:
This is the second split of this pull request: https://github.com/facebook/rocksdb/pull/1891 which includes only the builder part. The testing will be included in the third split, where the reader is also included.
Closes https://github.com/facebook/rocksdb/pull/1952

Differential Revision: D4660272

Pulled By: maysamyabandeh

fbshipit-source-id: 36b3cf0
2017-03-07 13:54:12 -08:00
Sagar Vemuri
97edc72d39 Add a memtable-only iterator
Summary:
This PR is to support a way to iterate over all the keys that are just in memtables.
Closes https://github.com/facebook/rocksdb/pull/1953

Differential Revision: D4663500

Pulled By: sagar0

fbshipit-source-id: 144e177
2017-03-07 11:54:10 -08:00
Andrew Kryczka
7c80a6d7d1 Statistic for how often rate limiter is drained
Summary:
This is the metric I plan to use for adaptive rate limiting. The statistics are updated only if the rate limiter is drained by flush or compaction. I believe (but am not certain) that this is the normal case.

The Statistics object is passed in RateLimiter::Request() to avoid requiring changes to client code, which would've been necessary if we passed it in the RateLimiter constructor.
Closes https://github.com/facebook/rocksdb/pull/1946

Differential Revision: D4646489

Pulled By: ajkr

fbshipit-source-id: d8e0161
2017-03-02 17:54:15 -08:00
Andrew Kryczka
0ad5af42d0 Clarify VerifyBackup behavior
Summary:
It's non-obvious to users that using the same backup engine for creating/verifying provides better results than using separate backup engines, so add a comment in header.
Closes https://github.com/facebook/rocksdb/pull/1942

Differential Revision: D4637865

Pulled By: ajkr

fbshipit-source-id: e6efe24
2017-03-02 17:24:11 -08:00
Islam AbdelRahman
f89b3893c0 Remove skip_table_builder_flush and default it to true
Summary:
This option is needed to be enabled for Direct IO
and I cannot think of a reason where we need to disable it

remove it and default it to true
Closes https://github.com/facebook/rocksdb/pull/1944

Differential Revision: D4641088

Pulled By: IslamAbdelRahman

fbshipit-source-id: d7085b9
2017-03-02 16:54:10 -08:00
Aaron Gao
e877afa08b Remove bulk loading and auto_roll_logger in rocksdb_lite
Summary:
shrink lite size
Closes https://github.com/facebook/rocksdb/pull/1929

Differential Revision: D4622059

Pulled By: siying

fbshipit-source-id: 050b796
2017-02-28 11:09:11 -08:00
Islam AbdelRahman
08864df212 Move advanced column family options to advanced_options.h
Summary:
For the sake of making our options simpler, we should keep options.h as simple as possible and move more advanced/less common options to advaned_options.h

I started with ColumnFamilyOptions and also did some re-ordering

I have moved all ColumnFamilyOptions to advanced_options.h and only left these options in options.h

```
const Comparator* comparator = BytewiseComparator();
std::shared_ptr<MergeOperator> merge_operator = nullptr;
const CompactionFilter* compaction_filter = nullptr;
std::shared_ptr<CompactionFilterFactory> compaction_filter_factory = nullptr;
size_t write_buffer_size = 64 << 20;
CompressionType compression;
int level0_file_num_compaction_trigger = 4;
bool disable_auto_compactions = false;
```
Please feel free to comment on specific options if you think they should be advanced or should not be
Closes https://github.com/facebook/rocksdb/pull/1847

Differential Revision: D4519996

Pulled By: IslamAbdelRahman

fbshipit-source-id: abebd9a
2017-02-27 17:54:14 -08:00
Siying Dong
8efb5ffa2a [rocksdb][PR] Remove option min_partial_merge_operands and verify_checksums_in_comp…
Summary:
…action

 The two options, min_partial_merge_operands and verify_checksums_in_compaction, are not seldom used. Remove them to reduce the total number of options. Also remove them from Java and C interface.
Closes https://github.com/facebook/rocksdb/pull/1902

Differential Revision: D4601219

Pulled By: siying

fbshipit-source-id: aad4cb2
2017-02-23 15:09:12 -08:00
Giuseppe Ottaviano
4d7c06cedf Make WriteBatchWithIndex moveble
Summary:
`WriteBatchWithIndex` has an incorrect implicitly-generated move constructor (it will copy the pointer causing a double-free on destruction). Just switch to `unique_ptr` so we get correct move semantics for free.
Closes https://github.com/facebook/rocksdb/pull/1899

Differential Revision: D4598896

Pulled By: ajkr

fbshipit-source-id: 2373d47
2017-02-22 17:54:11 -08:00
Islam AbdelRahman
1560b2f5f0 Temporarly return deprecated functions to fix MongoRocks build
Summary:
MongoRocks is still using some deprecated functions, return them temporarily
Closes https://github.com/facebook/rocksdb/pull/1892

Differential Revision: D4592451

Pulled By: IslamAbdelRahman

fbshipit-source-id: 5e6be3e
2017-02-21 12:54:11 -08:00
Yi Wu
381fd32247 Remove timeout_hint_us from WriteOptions
Summary:
The option has been deprecated for two years and has no effect. Removing.
Closes https://github.com/facebook/rocksdb/pull/1866

Differential Revision: D4555203

Pulled By: yiwu-arbug

fbshipit-source-id: c48f627
2017-02-17 15:24:17 -08:00
Marcin Dlugajczyk
a618a16f44 New subcode for IOError to detect the ESTALE errno
Summary:
I'd like to propose a patch to expose a new IOError type with subcode kStaleFile to allow to detect when ESTALE error is returned. This allows the rocksdb consumers to handle this error separately from other IOErrors.

I've also added a missing string representation for the kDeadlock subcode, I believe calling ToString() on Status object with that subcode would result in an out of band access in the msgs array,

Please let me know if you have any questions or would like me to make any changes to this pull request.
Closes https://github.com/facebook/rocksdb/pull/1748

Differential Revision: D4387675

Pulled By: IslamAbdelRahman

fbshipit-source-id: 67feb13
2017-02-17 10:54:13 -08:00
Islam AbdelRahman
7ab0051835 Remove deprecated DB::AddFile and DB::CompactRange
Summary:
Remove functions that we deprecated long time ago in db.h
Closes https://github.com/facebook/rocksdb/pull/1878

Differential Revision: D4576521

Pulled By: IslamAbdelRahman

fbshipit-source-id: dfddad1
2017-02-17 10:54:13 -08:00
Aaron Gao
db2b4eb50e avoid direct io in rocksdb_lite
Summary:
fix lite bugs
disable direct io in lite mode
Closes https://github.com/facebook/rocksdb/pull/1870

Differential Revision: D4559866

Pulled By: yiwu-arbug

fbshipit-source-id: 3761c51
2017-02-16 10:39:13 -08:00
Xiaofei Du
7106a994fe Use monotonic time points in write_controller.cc and rate_limiter.cc
Summary:
NowMicros() provides non-monotonic time. When wall clock is
synchronized or changed, the non-monotonicity time points will affect write rate
controllers. This patch changes write_controller.cc and rate_limiter.cc to use
monotonic time points.
Closes https://github.com/facebook/rocksdb/pull/1865

Differential Revision: D4561732

Pulled By: siying

fbshipit-source-id: 95ece62
2017-02-14 18:24:24 -08:00
Sagar Vemuri
eb912a927e Remove disableDataSync option
Summary:
Remove disableDataSync, and another similarly named disable_data_sync options.
This is being done to simplify options, and also because the performance gains of this feature can be achieved by other methods.
Closes https://github.com/facebook/rocksdb/pull/1859

Differential Revision: D4541292

Pulled By: sagar0

fbshipit-source-id: 5b3a6ca
2017-02-13 11:09:13 -08:00
Siying Dong
9afa20cf2f Increase build version and HISTORY.md for releasing 5.2
Summary:
Also clean up HISTORY.md a little bit.
Closes https://github.com/facebook/rocksdb/pull/1854

Differential Revision: D4539556

Pulled By: siying

fbshipit-source-id: 567391e
2017-02-10 12:09:15 -08:00
Maysam Yabandeh
ac2a77a746 Announce the experimetnal two-level index feature in HISTORY.md
Summary:
Announce the experimetnal two-level index feature in HISTORY.md. Also updated the default for index_per_partition to 1024.
Closes https://github.com/facebook/rocksdb/pull/1855

Differential Revision: D4530102

Pulled By: maysamyabandeh

fbshipit-source-id: b0fc6ff
2017-02-08 14:24:10 -08:00
Andrew Kryczka
186c7eedb0 Remove incorrect statistics warning
Summary:
statistics are always concurrently updated regardless of whether a single instance or multiple instances are used. remove the warning since it's unnecessarily preventing people from sharing stats objects across rocksdb instances.

replace #1819 which was having some problem with our internal tools.
Closes https://github.com/facebook/rocksdb/pull/1826

Differential Revision: D4495970

Pulled By: ajkr

fbshipit-source-id: 6601f61
2017-02-07 11:39:12 -08:00
Maysam Yabandeh
69d5262c81 Two-level Indexes
Summary:
Partition Index blocks and use a Partition-index as a 2nd level index.

The two-level index can be used by setting
BlockBasedTableOptions::kTwoLevelIndexSearch as the index type and
configuring BlockBasedTableOptions::index_per_partition

t15539501
Closes https://github.com/facebook/rocksdb/pull/1814

Differential Revision: D4473535

Pulled By: maysamyabandeh

fbshipit-source-id: bffb87e
2017-02-06 16:39:12 -08:00
Dmitri Smirnov
0a4cdde50a Windows thread
Summary:
introduce new methods into a public threadpool interface,
- allow submission of std::functions as they allow greater flexibility.
- add Joining methods to the implementation to join scheduled and submitted jobs with
  an option to cancel jobs that did not start executing.
- Remove ugly `#ifdefs` between pthread and std implementation, make it uniform.
- introduce pimpl for a drop in replacement of the implementation
- Introduce rocksdb::port::Thread typedef which is a replacement for std::thread.  On Posix Thread defaults as before std::thread.
- Implement WindowsThread that allocates memory in a more controllable manner than windows std::thread with a replaceable implementation.
- should be no functionality changes.
Closes https://github.com/facebook/rocksdb/pull/1823

Differential Revision: D4492902

Pulled By: siying

fbshipit-source-id: c74cb11
2017-02-06 14:54:18 -08:00
Vitaliy Liptchinsky
1aaa898cf1 Adding GetApproximateMemTableStats method
Summary:
Added method that returns approx num of entries as well as size for memtables.
Closes https://github.com/facebook/rocksdb/pull/1841

Differential Revision: D4511990

Pulled By: VitaliyLi

fbshipit-source-id: 9a4576e
2017-02-06 14:54:16 -08:00
Siying Dong
4a3e7d320c Change the default of delayed slowdown value to 16MB/s
Summary:
Change the default of delayed slowdown value to 16MB/s and further increase the L0 stop condition to 36 files.
Closes https://github.com/facebook/rocksdb/pull/1821

Differential Revision: D4489229

Pulled By: siying

fbshipit-source-id: 1003981
2017-02-01 20:39:17 -08:00
Islam AbdelRahman
8b369ae5bd Cleaner default options using C++11 in-class init
Summary:
C++11 in-class initialization is cleaner and makes it the default more explicit to our users and more visible.
Use it for ColumnFamilyOptions and DBOptions
Closes https://github.com/facebook/rocksdb/pull/1822

Differential Revision: D4490473

Pulled By: IslamAbdelRahman

fbshipit-source-id: c493a87
2017-01-31 18:09:15 -08:00
oranagra
b96372dead improving the C wrapper
Summary:
- rocksdb_property_int (so that we don't have to parse strings)
- and rocksdb_set_options (to allow controlling options via strings)
- a few other missing options exposed
- a documentation comment fix
Closes https://github.com/facebook/rocksdb/pull/1793

Differential Revision: D4456569

Pulled By: yiwu-arbug

fbshipit-source-id: 9f1fac1
2017-01-27 17:39:16 -08:00
Siying Dong
2d75cd40d3 NewLRUCache() to pick number of shard bits based on capacity if not given
Summary:
If the users use the NewLRUCache() without passing in the number of shard bits, instead of using hard-coded 6, we'll determine it based on capacity.
Closes https://github.com/facebook/rocksdb/pull/1584

Differential Revision: D4242517

Pulled By: siying

fbshipit-source-id: 86b0f18
2017-01-27 06:39:12 -08:00
Andrew Kryczka
17c1180603 Generalize Env registration framework
Summary:
The Env registration framework supports registering client Envs and selecting which one to instantiate according to a text field. This enabled things like adding the -env_uri argument to db_bench, so the same binary could be reused with different Envs just by changing CLI config.

Now this problem has come up again in a non-Env context, as I want to instantiate a client Statistics implementation from db_bench, which is configured entirely via text parameters. Also, in the future we may wish to use it for deserializing client objects when loading OPTIONS file.

This diff generalizes the Env registration logic to work with arbitrary types.

- Generalized registration and instantiation code by templating them
- The entire implementation is in a header file as that's Google style guide's recommendation for template definitions
- Pattern match with std::regex_match rather than checking prefix, which was the previous behavior
- Rename functions/files to be non-Env-specific
Closes https://github.com/facebook/rocksdb/pull/1776

Differential Revision: D4421933

Pulled By: ajkr

fbshipit-source-id: 34647d1
2017-01-25 16:09:14 -08:00
Hyeonseok Oh
f2b4939da4 fixed typo
Summary:
I fixed exisit -> exist
Closes https://github.com/facebook/rocksdb/pull/1799

Differential Revision: D4451466

Pulled By: yiwu-arbug

fbshipit-source-id: b447c3a
2017-01-23 12:54:13 -08:00
Jay Lee
537da370da c: allow set savepoint to writebatch
Summary:
Allow set SavePoint to WriteBatch in C ABI.
Closes https://github.com/facebook/rocksdb/pull/1698

Differential Revision: D4378556

Pulled By: yiwu-arbug

fbshipit-source-id: afca746
2017-01-20 13:24:13 -08:00
Vitaliy Liptchinsky
e840213d6e Change DB::GetApproximateSizes for more flexibility needed for MyRocks
Summary:
Added an option to GetApproximateSizes to exclude file stats, as MyRocks has those counted exactly and we need only stats from memtables.
Closes https://github.com/facebook/rocksdb/pull/1787

Differential Revision: D4441111

Pulled By: IslamAbdelRahman

fbshipit-source-id: c11f4c3
2017-01-20 09:39:11 -08:00
Aaron Gao
3e6899d116 change UseDirectIO() to use_direct_io()
Summary:
also change variable name `direct_io_` to `use_direct_io_` in WritableFile to make it consistent with read path.
Closes https://github.com/facebook/rocksdb/pull/1770

Differential Revision: D4416435

Pulled By: lightmark

fbshipit-source-id: 4143c53
2017-01-13 12:09:15 -08:00
Aaron Gao
dc2584eea0 direct reads refactor
Summary:
direct IO reads refactoring
remove unnecessary classes and unified interfaces
tested with db_bench

need more change for options and ON/OFF for different files.
Since disabled is default, it should be fine now
Closes https://github.com/facebook/rocksdb/pull/1636

Differential Revision: D4307189

Pulled By: lightmark

fbshipit-source-id: 6991e22
2017-01-11 16:54:12 -08:00
Mike Kolupaev
d18dd2c41f Abort compactions more reliably when closing DB
Summary:
DB shutdown aborts running compactions by setting an atomic shutting_down=true that CompactionJob periodically checks. Without this PR it checks it before processing every _output_ value. If compaction filter filters everything out, the compaction is uninterruptible. This PR adds checks for shutting_down on every _input_ value (in CompactionIterator and MergeHelper).

There's also some minor code cleanup along the way.
Closes https://github.com/facebook/rocksdb/pull/1639

Differential Revision: D4306571

Pulled By: yiwu-arbug

fbshipit-source-id: f050890
2017-01-11 15:09:21 -08:00
Andrew Kryczka
fe395fb63d Allow incrementing refcount on cache handles
Summary:
Previously the only way to increment a handle's refcount was to invoke Lookup(), which (1) did hash table lookup to get cache handle, (2) incremented that handle's refcount. For a future DeleteRange optimization, I added a function, Ref(), for when the caller already has a cache handle and only needs to do (2).
Closes https://github.com/facebook/rocksdb/pull/1761

Differential Revision: D4397114

Pulled By: ajkr

fbshipit-source-id: 9addbe5
2017-01-10 16:54:20 -08:00
Maysam Yabandeh
d0ba8ec8f9 Revert "PinnableSlice"
Summary:
This reverts commit 54d94e9c2c.

The pull request was landed by mistake.
Closes https://github.com/facebook/rocksdb/pull/1755

Differential Revision: D4391678

Pulled By: maysamyabandeh

fbshipit-source-id: 36d5149
2017-01-08 14:24:12 -08:00
Maysam Yabandeh
54d94e9c2c PinnableSlice
Summary:
Currently the point lookup values are copied to a string provided by the user.
This incures an extra memcpy cost. This patch allows doing point lookup
via a PinnableSlice which pins the source memory location (instead of
copying their content) and releases them after the content is consumed
by the user. The old API of Get(string) is translated to the new API
underneath.

 Here is the summary for improvements:
 1. value 100 byte: 1.8%  regular, 1.2% merge values
 2. value 1k   byte: 11.5% regular, 7.5% merge values
 3. value 10k byte: 26% regular,    29.9% merge values

 The improvement for merge could be more if we extend this approach to
 pin the merge output and delay the full merge operation until the user
 actually needs it. We have put that for future work.

PS:
Sometimes we observe a small decrease in performance when switching from
t5452014 to this patch but with the old Get(string) API. The difference
is a little and could be noise. More importantly it is safely
cancelled
Closes https://github.com/facebook/rocksdb/pull/1732

Differential Revision: D4374613

Pulled By: maysamyabandeh

fbshipit-source-id: a077f1a
2017-01-08 13:54:13 -08:00