Commit Graph

2664 Commits

Author SHA1 Message Date
Leonidas Galanis
72202962f9 fix db_sst_test flakiness
Summary:
db_sst_test had been flaky occasionally in the following way: reached_max_space_on_compaction can in very rare cases be 0. This happens when the limit on maximum allowable space set using SetMaxAllowedSpaceUsage is hit during flush for all test db sizes (1,2,4,8 and 10MB).The fix clears the error returned when the the space limit is reached during flush. This ensures that the compaction call back will always be called. The runtime is increased slightly because the 1MB loop writes more data and hits the limit during multiple flushes until compaction is scheduled.
Closes https://github.com/facebook/rocksdb/pull/1861

Differential Revision: D4557396

Pulled By: lgalanis

fbshipit-source-id: ff778d1
2017-03-07 11:24:13 -08:00
Reid Horuff
58b12dfe37 Set logs as getting flushed before releasing lock, race condition fix
Summary:
Relating to #1903:

In MaybeFlushColumnFamilies() we want to modify the 'getting_flushed' flag before releasing the db mutex when SwitchMemtable() is called.

The following 2 actions need to be atomic in MaybeFlushColumnFamilies()
- getting_flushed is false on oldest log
- we determine that all CFs can be flushed to successfully release oldest log
- we set getting_flushed = true on the oldest log.
-------
- getting_flushed is false on oldest log
- we determine that all CFs can NOT be flushed to successfully release oldest log
- we set unable_to_flush_oldest_log_ = true on the oldest log.

#### In the 2pc case:

T1 enters function but is unable to flush all CFs to release log
T1 sets unable_to_flush_oldest_log_ = true
T1 begins flushing all CFs possible

T2 enters function but is unable to flush all CFs to release log
T2 sees unable_to_flush_oldes_log_ has been set so exits

T3 enters function and will be able to flush all CFs to release oldest log
T3 sets getting_flushed = true on oldes
Closes https://github.com/facebook/rocksdb/pull/1909

Differential Revision: D4646235

Pulled By: reidHoruff

fbshipit-source-id: c8d0447
2017-03-06 15:09:11 -08:00
Maysam Yabandeh
534581a356 Fix a bug in tests in options operator=
Summary:
Note: Using the default operator= is an unsafe approach for Options since it destructs shared_ptr in
the same order of their creation, in contrast to destructors which
destructs them in the opposite order of creation. One particular problme is
that the cache destructor might invoke callback functions that use Option
members such as statistics. To work around this problem, we manually call
destructor of table_facotry which eventually clears the block cache.
Closes https://github.com/facebook/rocksdb/pull/1950

Differential Revision: D4655473

Pulled By: maysamyabandeh

fbshipit-source-id: 6c4bbff
2017-03-05 18:09:09 -08:00
Andrew Kryczka
4561275c2d fix rate limiter test flakiness
Summary:
fix when elapsed time spans non-integral number of intervals since the rate limiter may still be drained during a partial interval.
Closes https://github.com/facebook/rocksdb/pull/1948

Differential Revision: D4651304

Pulled By: ajkr

fbshipit-source-id: b1f9e70
2017-03-03 11:09:11 -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
Aaron Gao
6fb9013441 sanitize readahead when direct read enabled
Summary:
no readahead:
readseq      :       8.438 micros/op 118510 ops/sec;   13.1 MB/s
sanitize to 10MB:
readseq      :       6.051 micros/op 165248 ops/sec;   18.3 MB/s
Closes https://github.com/facebook/rocksdb/pull/1945

Differential Revision: D4645811

Pulled By: lightmark

fbshipit-source-id: 5d63770
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
Siying Dong
d5b607a43f Make db_wal_test slightly faster
Summary:
Avoid to run db_wal_test in all the DB test options, and some small changes.
Closes https://github.com/facebook/rocksdb/pull/1921

Differential Revision: D4622054

Pulled By: siying

fbshipit-source-id: 890fd64
2017-02-28 17:39:10 -08:00
Siying Dong
ba4c77bd6b Divide external_sst_file_test
Summary:
Separate the platform dependent tests from external_sst_file_test. Only those tests need to run on platforms like OSX
Closes https://github.com/facebook/rocksdb/pull/1923

Differential Revision: D4622461

Pulled By: siying

fbshipit-source-id: d2d6f04
2017-02-28 14:24:11 -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
Peter (Stig) Edwards
2ca2059f66 Get unique_ptr to use delete[] for char[] in DumpMallocStats
Summary:
Avoid mismatched free() / delete / delete [] in DumpMallocStats
Closes https://github.com/facebook/rocksdb/pull/1927

Differential Revision: D4622045

Pulled By: siying

fbshipit-source-id: 1131b30
2017-02-27 17:39:12 -08:00
Siying Dong
8ad0fcdf99 Separate small subset tests in DBTest
Summary:
Separate a smal subset of tests in DBTest to DBBasicTest. Tests in DBTest don't have to run in CI tests on platforms like OSX, as long as they are covered by Linux.
Closes https://github.com/facebook/rocksdb/pull/1924

Differential Revision: D4616702

Pulled By: siying

fbshipit-source-id: 13e6549
2017-02-27 12:24:11 -08:00
Siying Dong
3b8ba703cb Fix flaky DBTestUniversalCompaction.UniversalCompactionTrivialMoveTest2
Summary:
A previous fix to DBTestUniversalCompaction.UniversalCompactionTrivialMoveTest2 didn't address the right problem. The problem is L0->L0 compaction is not trivial move in the scenario, not parallel compactions. Fix this.
Closes https://github.com/facebook/rocksdb/pull/1911

Differential Revision: D4608955

Pulled By: siying

fbshipit-source-id: 7a712cb
2017-02-23 18:39:13 -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
Siying Dong
1ba2804b7f Remove XFunc tests
Summary:
Xfunc is hardly used. Remove it to keep the code simple.
Closes https://github.com/facebook/rocksdb/pull/1905

Differential Revision: D4603220

Pulled By: siying

fbshipit-source-id: 731f96d
2017-02-23 12:09:11 -08:00
Aaron Gao
1ef5f50e84 detect logical sector size
Summary:
querying logical sector size from the device instead of hardcoding it for linux platform.
Closes https://github.com/facebook/rocksdb/pull/1875

Differential Revision: D4591946

Pulled By: ajkr

fbshipit-source-id: 4e9805c
2017-02-23 11:25:36 -08:00
Aaron Gao
0824934423 truncate patch
Summary:
omit the override for the previous commit
Closes https://github.com/facebook/rocksdb/pull/1898

Differential Revision: D4598743

Pulled By: lightmark

fbshipit-source-id: f98a378
2017-02-22 10:39:11 -08:00
Aaron Gao
286a36db7f posix writablefile truncate
Summary:
we occasionally missing this call so the file size will be wrong
Closes https://github.com/facebook/rocksdb/pull/1894

Differential Revision: D4598446

Pulled By: lightmark

fbshipit-source-id: 42b6ef5
2017-02-22 10:09:14 -08:00
Mike Kolupaev
18eeb7b90e Fix interference between max_total_wal_size and db_write_buffer_size checks
Summary:
This is a trivial fix for OOMs we've seen a few days ago in logdevice.

RocksDB get into the following state:
(1) Write throughput is too high for flushes to keep up. Compactions are out of the picture - automatic compactions are disabled, and for manual compactions we don't care that much if they fall behind. We write to many CFs, with only a few L0 sst files in each, so compactions are not needed most of the time.
(2) total_log_size_ is consistently greater than GetMaxTotalWalSize(). It doesn't get smaller since flushes are falling ever further behind.
(3) Total size of memtables is way above db_write_buffer_size and keeps growing. But the write_buffer_manager_->ShouldFlush() is not checked because (2) prevents it (for no good reason, afaict; this is what this commit fixes).
(4) Every call to WriteImpl() hits the MaybeFlushColumnFamilies() path. This keeps flushing the memtables one by one in order of increasing log file number.
(5) No write stalling trigger is hit. We rely on max_write_buffer_number
Closes https://github.com/facebook/rocksdb/pull/1893

Differential Revision: D4593590

Pulled By: yiwu-arbug

fbshipit-source-id: af79c5f
2017-02-21 16:09:10 -08:00
Aaron Gao
2a0f3d0de1 level compaction expansion
Summary:
reimplement the compaction expansion on lower level.

Considering such a case:
input level file: 1[B E] 2[F G] 3[H I] 4 [J M]
output level file: 5[A C] 6[D K] 7[L O]

If we initially pick file 2, now we will compact file 2 and 6. But we can safely compact 2, 3 and 6 without expanding the output level.

The previous code is messy and wrong.

In this diff, I first determine the input range [a, b], and output range [c, d],
then we get the range [e,f] = [min(a, c), max(b, d] and put all eligible clean-cut files within [e, f] into this compaction.

**Note: clean-cut means the files don't have the same user key on the boundaries of some files that are not chosen in this compaction**.
Closes https://github.com/facebook/rocksdb/pull/1760

Differential Revision: D4395564

Pulled By: lightmark

fbshipit-source-id: 2dc2c5c
2017-02-21 10:24:17 -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
Islam AbdelRahman
fce7a6e196 Fail IngestExternalFile when bg_error_ exists
Summary:
Fail IngestExternalFile() when bg_error_ exists
Closes https://github.com/facebook/rocksdb/pull/1881

Differential Revision: D4580621

Pulled By: IslamAbdelRahman

fbshipit-source-id: 1194913
2017-02-17 13:39:17 -08:00
Shu Zhang
756c5924e6 Allow adding external v1 sst file with no global seqno support
Summary:
This is a follow up fix for https://github.com/facebook/rocksdb/pull/1783. After it, we should be able to ingest external v1 sst files with no global seqno field.
Closes https://github.com/facebook/rocksdb/pull/1874

Differential Revision: D4576194

Pulled By: IslamAbdelRahman

fbshipit-source-id: 5b34a3e
2017-02-16 17:09:12 -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
Andrew Kryczka
43e9f01c20 Fix repair_test on ROCKSDB_LITE
Summary:
RepairDB isn't included in rocksdb lite, so don't test it.
Closes https://github.com/facebook/rocksdb/pull/1873

Differential Revision: D4565094

Pulled By: ajkr

fbshipit-source-id: 8cc0898
2017-02-15 11:24:12 -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
Yi Wu
c2247dc1c7 Make DBImpl::has_unpersisted_data_ atomic
Summary:
Seems to me `has_unpersisted_data_` is read from read thread and write
from write thread concurrently without synchronization. Making it an
atomic.

I update the logic not because seeing any problem with it, but it just
feel confusing.
Closes https://github.com/facebook/rocksdb/pull/1869

Differential Revision: D4555837

Pulled By: yiwu-arbug

fbshipit-source-id: eff2ab8
2017-02-13 18:54:13 -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
Dmitri Smirnov
a5adda0642 Fix repair issues
Summary:
Record the first parsed sequence number as the minimum
  so we can find the true minimum otherwise everything is larger than zero.
  Fix the comparator name comparision.
Closes https://github.com/facebook/rocksdb/pull/1858

Differential Revision: D4544365

Pulled By: ajkr

fbshipit-source-id: 439cbc2
2017-02-10 10:54:12 -08:00
Andrew Kryczka
b48e4778be Consolidate file cutting logic in compaction loop
Summary:
It was really annoying to have two places (top and bottom of compaction loop) where we cut output files. I had bugs in both DeleteRange and dictionary compression due to updating only one of the two. This diff consolidates the file-cutting logic to the bottom of the compaction loop.

Keep in mind that my goal with input_status is to be consistent with the past behavior, even though I'm not sure it's ideal.
Closes https://github.com/facebook/rocksdb/pull/1832

Differential Revision: D4503038

Pulled By: ajkr

fbshipit-source-id: 7da5213
2017-02-08 16:24:17 -08:00
Maysam Yabandeh
c4a37dcb44 Print the missed last layer in cfstats
Summary:
Printing compaction stats used to operate on two variable:
number_levels_: for printing the layer
num_levels_to_check: for updating the compaction score

After this commit: 361010d447 these two are mixed up and as a result the last layer might not be printed out: https://fb.facebook.com/groups/rocksdb.internal/permalink/1315716625143616/

number_levels_ was used to decide which layers to print: 672300f47f/db/internal_stats.cc (L753) but after the patch it is based on the return value of DumpCFMapStats 361010d447/db/internal_stats.cc (L929) which returns num_levels_to_check: 361010d447/db/internal_stats.cc (L917)
Closes https://github.com/facebook/rocksdb/pull/1853

Differential Revision: D4529280

Pulled By: maysamyabandeh

fbshipit-source-id: 3fd9448
2017-02-08 10:39:15 -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
036d668b19 Fix wrong result in data race case related to Get()
Summary:
In theory, Get() can get a wrong result, if it races in a special with with flush. The bug can be reproduced in DBTest2.GetRaceFlush. Fix this bug by getting snapshot after referencing the super version.
Closes https://github.com/facebook/rocksdb/pull/1816

Differential Revision: D4475958

Pulled By: siying

fbshipit-source-id: bd9e67a
2017-02-03 11:39:15 -08:00
Islam AbdelRahman
574b543f80 Rename merger.h -> merging_iterator.h
Summary:
merger.h was always a confusing name for me, simply give the file a better name
Closes https://github.com/facebook/rocksdb/pull/1836

Differential Revision: D4505357

Pulled By: IslamAbdelRahman

fbshipit-source-id: 07b28d8
2017-02-02 16:54:19 -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
04c4ec41d1 Change corruption_test to use 4 bits.
Summary:
In the patch which LRU cache was made use dynamic shard bits, I changed to 2 shard bits to make the test happy. Look like it is occasionally still unhappy. Change it to 4 shard bits.
Closes https://github.com/facebook/rocksdb/pull/1815

Differential Revision: D4475849

Pulled By: siying

fbshipit-source-id: 575ff00
2017-01-27 11:24:16 -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
Siying Dong
f25f1ec60b Add test DBTest2.GetRaceFlush which can expose a data race bug
Summary:
A current data race issue in Get() and Flush() can cause a Get() to return wrong results when a flush happened in the middle. Disable the test for now.
Closes https://github.com/facebook/rocksdb/pull/1813

Differential Revision: D4472310

Pulled By: siying

fbshipit-source-id: 5755ebd
2017-01-26 16:39:14 -08:00
sdong
5dad9d6d28 Avoid logs_ operation out of DB mutex
Summary:
logs_.back() is called out of DB mutex, which can cause data race. We move the access into the DB mutex protection area.
Closes https://github.com/facebook/rocksdb/pull/1774

Reviewed By: AsyncDBConnMarkedDownDBException

Differential Revision: D4417472

Pulled By: AsyncDBConnMarkedDownDBException

fbshipit-source-id: 2da1f1e
2017-01-25 15:54:13 -08:00
Islam AbdelRahman
a7b13919bf Fix CompactFiles() bug when used with CompactionFilter using SuperVersion
Summary:
GetAndRefSuperVersion() should not be called again in the same thread before ReturnAndCleanupSuperVersion() is called.

If we have a compaction filter that is using DB::Get, This will happen
```
CompactFiles() {
  GetAndRefSuperVersion() // -- first call
    ..
    CompactionFilter() {
      GetAndRefSuperVersion() // -- second call
      ReturnAndCleanupSuperVersion()
    }
    ..
  ReturnAndCleanupSuperVersion()
}
```

We solve this issue in the same way Iterator is solving it, but using GetReferencedSuperVersion()

This was discovered in https://github.com/facebook/mysql-5.6/issues/427 by alxyang
Closes https://github.com/facebook/rocksdb/pull/1803

Differential Revision: D4460155

Pulled By: IslamAbdelRahman

fbshipit-source-id: 5e54322
2017-01-25 14:09:13 -08:00
Andrew Kryczka
616a1464ea Fix DeleteRange including sentinels in output files
Summary:
when writing RangeDelAggregator::AddToBuilder, I forgot that there are sentinel tombstones in the middle of the interval map since gaps between real tombstones are represented with sentinels.

blame: #1614
Closes https://github.com/facebook/rocksdb/pull/1804

Differential Revision: D4460426

Pulled By: ajkr

fbshipit-source-id: 69444b5
2017-01-25 11:09:12 -08:00
Islam AbdelRahman
03ca2ac8a9 Remove function from DBImpl that are not used anywhere
Summary:
GetAndRefSuperVersionUnlocked
ReturnAndCleanupSuperVersionUnlocked
GetColumnFamilyHandleUnlocked

Are dead code that are not used any where
Closes https://github.com/facebook/rocksdb/pull/1802

Differential Revision: D4459948

Pulled By: IslamAbdelRahman

fbshipit-source-id: 30fa89d
2017-01-24 19:24:13 -08:00
Andrew Kryczka
b0029bc7fa Test merge op covered by range deletion in memtable
Summary:
It's a test case for #1797. Also got rid of kTypeDeletion in the conditional since we treat it the same as kTypeRangeDeletion.
Closes https://github.com/facebook/rocksdb/pull/1800

Differential Revision: D4451300

Pulled By: ajkr

fbshipit-source-id: b39dda1
2017-01-24 13:39:11 -08:00
Andrew Kryczka
d438e1ec17 Test range deletion block outlives table reader
Summary:
This test ensures RangeDelAggregator can still access blocks even if it outlives the table readers that created them (detailed description in comments).

I plan to optimize away the extra cache lookup we currently do in BlockBasedTable::NewRangeTombstoneIterator(), as it is ~5% CPU in my random read benchmark in a database with 1k tombstones. This test will help make sure nothing breaks in the process.
Closes https://github.com/facebook/rocksdb/pull/1739

Differential Revision: D4375954

Pulled By: ajkr

fbshipit-source-id: aef9357
2017-01-24 13:24:14 -08:00
Andrew Kryczka
9da4d542fe Range deletions unsupported in tailing iterator
Summary:
change the iterator status to NotSupported as soon as a range tombstone
is encountered by a ForwardIterator.
Closes https://github.com/facebook/rocksdb/pull/1593

Differential Revision: D4246294

Pulled By: ajkr

fbshipit-source-id: aef9f49
2017-01-23 13:39:12 -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
yinqiwen
973f1b78fd memtable: delete merge value for range deleteion
Summary: Closes https://github.com/facebook/rocksdb/pull/1797

Differential Revision: D4448004

Pulled By: ajkr

fbshipit-source-id: 3ffc27c
2017-01-23 12:24:14 -08:00
Vitaliy Liptchinsky
753ff84a3d Fix get approx size
Summary:
Fixing GetApproximateSize bug for the case of computing stats for mem tables only.
Closes https://github.com/facebook/rocksdb/pull/1795

Differential Revision: D4445507

Pulled By: IslamAbdelRahman

fbshipit-source-id: 3905846
2017-01-20 15:54:12 -08:00