Summary:
The patch makes sure that the functionality required for the new integrated
BlobDB implementation (most importantly, the classes related to reading and
writing blob files) is also built in LITE mode by removing the corresponding
`#ifndef`s.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7272

Test Plan: Ran `make check` in both regular and LITE mode.

Reviewed By: zhichao-cao

Differential Revision: D23173280

Pulled By: ltamasi

fbshipit-source-id: 1596bd1a76409a8a6d83d8f1dbfe08bfdea7ffe6

Summary:
`WalAddition`, `WalDeletion` are defined in `wal_version.h` and used in `VersionEdit`.
`WalAddition` is used to represent events of creating a new WAL (no size, just log number), or closing a WAL (with size).
`WalDeletion` is used to represent events of deleting or archiving a WAL, it means the WAL is no longer alive (won't be replayed during recovery).

`WalSet` is the set of alive WALs kept in `VersionSet`.

1. Why use `WalDeletion` instead of relying on `MinLogNumber` to identify outdated WALs

On recovery, we can compute `MinLogNumber()` based on the log numbers kept in MANIFEST, any log with number < MinLogNumber can be ignored. So it seems that we don't need to persist `WalDeletion` to MANIFEST, since we can ignore the WALs based on MinLogNumber.

But the `MinLogNumber()` is actually a lower bound, it does not exactly mean that logs starting from MinLogNumber must exist. This is because in a corner case, when a column family is empty and never flushed, its log number is set to the largest log number, but not persisted in MANIFEST. So let's say there are 2 column families, when creating the DB, the first WAL has log number 1, so it's persisted to MANIFEST for both column families. Then CF 0 is empty and never flushed, CF 1 is updated and flushed, so a new WAL with log number 2 is created and persisted to MANIFEST for CF 1. But CF 0's log number in MANIFEST is still 1. So on recovery, MinLogNumber is 1, but since log 1 only contains data for CF 1, and CF 1 is flushed, log 1 might have already been deleted from disk.

We can make `MinLogNumber()` be the exactly minimum log number that must exist, by persisting the most recent log number for empty column families that are not flushed. But if there are N such column families, then every time a new WAL is created, we need to add N records to MANIFEST.

In current design, a record is persisted to MANIFEST only when WAL is created, closed, or deleted/archived, so the number of WAL related records are bounded to 3x number of WALs.

2. Why keep `WalSet` in `VersionSet` instead of applying the `VersionEdit`s to `VersionStorageInfo`

`VersionEdit`s are originally designed to track the addition and deletion of SST files. The SST files are related to column families, each column family has a list of `Version`s, and each `Version` keeps the set of active SST files in `VersionStorageInfo`.

But WALs are a concept of DB, they are not bounded to specific column families. So logically it does not make sense to store WALs in a column family's `Version`s.
Also, `Version`'s purpose is to keep reference to SST / blob files, so that they are not deleted until there is no version referencing them. But a WAL is deleted regardless of version references.
So we keep the WALs in `VersionSet`  for the purpose of writing out the DB state's snapshot when creating new MANIFESTs.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7164

Test Plan:
make version_edit_test && ./version_edit_test
make wal_edit_test && ./wal_edit_test

Reviewed By: ltamasi

Differential Revision: D22677936

Pulled By: cheng-chang

fbshipit-source-id: 5a3b6890140e572ffd79eb37e6e4c3c32361a859

Summary:
In db_options.c, we should avoid including header files in the `db` directory to avoid introducing unnecessary dependency. The reason why `version_edit.h` has been included in `db_options.cc` is because we need two constants, `kUnknownChecksum` and `kUnknownChecksumFuncName`. We can put these two constants as `constexpr` in the public header `file_checksum.h`.

Test plan (devserver):
make check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6952

Reviewed By: zhichao-cao

Differential Revision: D21925341

Pulled By: riversand963

fbshipit-source-id: 2902f3b74c97f0cf16c58ad24c095c787c3a40e2

Summary:
This reverts commit e10553f2.

Pass make asan_check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6569

Reviewed By: riversand963

Differential Revision: D20574319

Pulled By: zhichao-cao

fbshipit-source-id: ce36981a21596f5f2e14da6a59a2bb3619509a8b

Summary:
Each time RocksDB switches to a new MANIFEST file from old one, it calls WriteCurrentStateToManifest() which writes a 'snapshot' of the current in-memory state of versions to the beginning of the new manifest as a bunch of version edits. We can distinguish these version edits from other version edits written during normal operations with a custom, safe-to-ignore tag.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6530

Test Plan: added test to version_edit_test, pass make asan_check

Reviewed By: riversand963

Differential Revision: D20524516

Pulled By: zhichao-cao

fbshipit-source-id: f1de102f5499bfa88dae3caa2f32c7f42cf904db

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/6519

Test Plan:
```
make all
make check
```

Differential Revision: D20400691

Pulled By: ltamasi

fbshipit-source-id: 20ef911cf1c2c92c7f71ef0b493f9be64f2eef94

Summary:
It's never too soon to refactor something. The patch splits the recently
introduced (`VersionEdit` related) `BlobFileState` into two classes
`BlobFileAddition` and `BlobFileGarbage`. The idea is that once blob files
are closed, they are immutable, and the only thing that changes is the
amount of garbage in them. In the new design, `BlobFileAddition` contains
the immutable attributes (currently, the count and total size of all blobs, checksum
method, and checksum value), while `BlobFileGarbage` contains the mutable
GC-related information elements (count and total size of garbage blobs). This is a
better fit for the GC logic and is more consistent with how SST files are handled.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6502

Test Plan: `make check`

Differential Revision: D20348352

Pulled By: ltamasi

fbshipit-source-id: ff93f0121e80ab15e0e0a6525ba0d6af16a0e008

Summary:
BlobDB currently does not keep track of blob files: no records are written to
the manifest when a blob file is added or removed, and upon opening a database,
the list of blob files is populated simply based on the contents of the blob directory.
This means that lost blob files cannot be detected at the moment. We plan to solve
this issue by making blob files a part of `Version`; as a first step, this patch makes
it possible to store information about blob files in `VersionEdit`. Currently, this information
includes blob file number, total number and size of all blobs, and total number and size
of garbage blobs. However, the format is extensible: new fields can be added in
both a forward compatible and a forward incompatible manner if needed (similarly
to `kNewFile4`).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6416

Test Plan: `make check`

Differential Revision: D19894234

Pulled By: ltamasi

fbshipit-source-id: f9753e1f2aedf6dadb70c09b345207cb9c58c329

Summary:
When dynamically linking two binaries together, different builds of RocksDB from two sources might cause errors. To provide a tool for user to solve the problem, the RocksDB namespace is changed to a flag which can be overridden in build time.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6433

Test Plan: Build release, all and jtest. Try to build with ROCKSDB_NAMESPACE with another flag.

Differential Revision: D19977691

fbshipit-source-id: aa7f2d0972e1c31d75339ac48478f34f6cfcfb3e

Summary:
In the current code base, RocksDB generate the checksum for each block and verify the checksum at usage. Current PR enable SST file checksum. After a SST file is generated by Flush or Compaction, RocksDB generate the SST file checksum and store the checksum value and checksum method name in the vs_info and MANIFEST as part for the FileMetadata.

Added the enable_sst_file_checksum to Options to enable or disable file checksum. Added sst_file_checksum to Options such that user can plugin their own SST file checksum calculate method via overriding the SstFileChecksum class. The checksum information inlcuding uint32_t checksum value and a checksum name (string).  A new tool is added to LDB such that user can dump out a list of file checksum information from MANIFEST. If user enables the file checksum but does not provide the sst_file_checksum instance, RocksDB will use the default crc32checksum implemented in table/sst_file_checksum_crc32c.h
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6216

Test Plan: Added the testing case in table_test and ldb_cmd_test to verify checksum is correct in different level. Pass make asan_check.

Differential Revision: D19171461

Pulled By: zhichao-cao

fbshipit-source-id: b2e53479eefc5bb0437189eaa1941670e5ba8b87

Summary:
This is a bunch of small improvements to `VersionEdit`. Namely, the patch

* Makes the names and order of variables, methods, and code chunks related
  to the various information elements more consistent, and adds missing
  getters for the sake of completeness.
* Initializes previously uninitialized stack variables.
* Marks all getters const to improve const correctness.
* Adds in-class initializers and removes the default ctor that would
  create an object with uninitialized built-in fields and call `Clear`
  afterwards.
* Adds a new type alias for new files and changes the existing `typedef`
  for deleted files into a type alias as well.
* Makes the helper method `DecodeNewFile4From` private.
* Switches from long-winded iterator syntax to range based loops in a
  couple of places.
* Fixes a couple of assignments where an integer 0 was assigned to
  boolean members.
* Fixes a getter which used to return a `const std::string` instead of
the intended `const std::string&`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6383

Test Plan: make check

Differential Revision: D19780537

Pulled By: ltamasi

fbshipit-source-id: b0b4f09fee0ec0e7c7b7a6d76bfe5346e91824d0

Summary:
options.periodic_compaction_seconds isn't supported when options.max_open_files != -1. It's because that the information of file creation time is stored in table properties and are not guaranteed to be loaded unless options.max_open_files = -1. Relax this constraint by storing the information in manifest.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6090

Test Plan: Pass all existing tests; Modify an existing test to force the manifest value to take 0 to simulate backward compatibility case; manually open the DB generated with the change by release 4.2.

Differential Revision: D18702268

fbshipit-source-id: 13e0bd94f546498a04f3dc5fc0d9dff5125ec9eb

Summary:
Previously, options.ttl cannot be set with options.max_open_files = -1, because it makes use of creation_time field in table properties, which is not available unless max_open_files = -1. With this commit, the information will be stored in manifest and when it is available, will be used instead.

Note that, this change will break forward compatibility for release 5.1 and older.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6060

Test Plan: Extend existing test case to options.max_open_files != -1, and simulate backward compatility in one test case by forcing the value to be 0.

Differential Revision: D18631623

fbshipit-source-id: 30c232a8672de5432ce9608bb2488ecc19138830

Summary:
This is groundwork for adding garbage collection support to BlobDB. The
patch adds logic that keeps track of the oldest blob file referred to by
each SST file. The oldest blob file is identified during flush/
compaction (similarly to how the range of keys covered by the SST is
identified), and persisted in the manifest as a custom field of the new
file edit record. Blob indexes with TTL are ignored for the purposes of
identifying the oldest blob file (since such blob files are cleaned up by the
TTL logic in BlobDB).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5903

Test Plan:
Added new unit tests; also ran db_bench in BlobDB mode, inspected the
manifest using ldb, and confirmed (by scanning the SST files using
sst_dump) that the value of the oldest blob file number field matches
the contents of the file for each SST.

Differential Revision: D17859997

Pulled By: ltamasi

fbshipit-source-id: 21662c137c6259a6af70446faaf3a9912c550e90

Summary:
Each DB has a globally unique ID. A DB can be physically copied around, or backed-up and restored, and the users should be identify the same DB. This unique ID right now is stored as plain text in file IDENTITY under the DB directory. This approach introduces at least two problems: (1) the file is not checksumed; (2) the source of truth of a DB is the manifest file, which can be copied separately from IDENTITY file, causing the DB ID to be wrong.
The goal of this PR is solve this problem by moving the  DB ID to manifest. To begin with we will write to both identity file and manifest. Write to Manifest is controlled via the flag write_dbid_to_manifest in Options and default is false.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5725

Test Plan: Added unit tests.

Differential Revision: D16963840

Pulled By: vjnadimpalli

fbshipit-source-id: 8a86a4c8c82c716003c40fd6b9d2d758030d92e9

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:
Move arena, allocator, and memory tools under util to a separate memory/ directory.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5382

Differential Revision: D15564655

Pulled By: siying

fbshipit-source-id: 9cd6b5d0d3d52b39606e19221fa154596e5852a5

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:
We want to reserve some right that some extra information added manifest
in the future can be forward compatible by previous versions. Now we create a
place holder for that. A bit in tag is added to indicate that a field can be
safely ignored.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4960

Differential Revision: D14000484

Pulled By: siying

fbshipit-source-id: cbf5bad3f9d5ec798f789806f244d1c20d3b66d6

Summary:
Hi, Lintian, the Debian package checker complains about spelling error (spelling-error-in-binary).

See https://salsa.debian.org/mariadb-team/mariadb-10.3/-/jobs/98380
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4827

Differential Revision: D13566362

Pulled By: riversand963

fbshipit-source-id: cd4e9212133c73b0591030de6cdedaa47575968d

Summary:
If one column family is dropped, we should simply skip it and continue to flush
other active ones.
Currently we use Status::ShutdownInProgress to notify caller of column families
being dropped. In the future, we should consider using a different Status code.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4708

Differential Revision: D13378954

Pulled By: riversand963

fbshipit-source-id: 42f248cdf2d32d4c0f677cd39012694b8f1328ca

Summary:
During recovery, RocksDB is able to handle version edits that belong to group commits.
This PR is a subset of [PR 3752](https://github.com/facebook/rocksdb/pull/3752)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/3945

Differential Revision: D8529122

Pulled By: riversand963

fbshipit-source-id: 57cb0f9cc55ecca684a837742d6626dc9c07f37e

Summary:
Given that index value is a BlockHandle, which is basically an <offset, size> pair we can apply delta encoding on the values. The first value at each index restart interval encoded the full BlockHandle but the rest encode only the size. Refer to IndexBlockIter::DecodeCurrentValue for the detail of the encoding. This reduces the index size which helps using the  block cache more efficiently. The feature is enabled with using format_version 4.

The feature comes with a bit of cpu overhead which should be paid back by the higher cache hits due to smaller index block size.
Results with sysbench read-only using 4k blocks and using 16 index restart interval:
Format 2:
19585   rocksdb read-only range=100
Format 3:
19569   rocksdb read-only range=100
Format 4:
19352   rocksdb read-only range=100
Pull Request resolved: https://github.com/facebook/rocksdb/pull/3983

Differential Revision: D8361343

Pulled By: maysamyabandeh

fbshipit-source-id: f882ee082322acac32b0072e2bdbb0b5f854e651

Summary:
RocksDB used to store global_seqno in external SST files written by
SstFileWriter. During file ingestion, RocksDB uses `pwrite` to update the
`global_seqno`. Since random write is not supported in some non-POSIX compliant
file systems, external SST file ingestion is not supported on these file
systems. To address this limitation, we no longer update `global_seqno` during
file ingestion. Later RocksDB uses the MANIFEST and other information in table
properties to deduce global seqno for externally-ingested SST files.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4172

Differential Revision: D8961465

Pulled By: riversand963

fbshipit-source-id: 4382ec85270a96be5bc0cf33758ca2b167b05071

Summary:
Explicitly specify the underlying type of enums help developers understand the physical storage.
Closes https://github.com/facebook/rocksdb/pull/3892

Differential Revision: D8107027

Pulled By: riversand963

fbshipit-source-id: a00efecbba46df4a3c8eed0994a2d4972ad1a1d3

Summary:
This patch record min log number to keep to the manifest while flushing SST files to ignore them and any WAL older than them during recovery. This is to avoid scenarios when we have a gap between the WAL files are fed to the recovery procedure. The gap could happen by for example out-of-order WAL deletion. Such gap could cause problems in 2PC recovery where the prepared and commit entry are placed into two separate WAL and gap in the WALs could result into not processing the WAL with the commit entry and hence breaking the 2PC recovery logic.

Before the commit, for 2PC case, we determined which log number to keep in FindObsoleteFiles(). We looked at the earliest logs with outstanding prepare entries, or prepare entries whose respective commit or abort are in memtable. With the commit, the same calculation is done while we apply the SST flush. Just before installing the flush file, we precompute the earliest log file to keep after the flush finishes using the same logic (but skipping the memtables just flushed), record this information to the manifest entry for this new flushed SST file. This pre-computed value is also remembered in memory, and will later be used to determine whether a log file can be deleted. This value is unlikely to change until next flush because the commit entry will stay in memtable. (In WritePrepared, we could have removed the older log files as soon as all prepared entries are committed. It's not yet done anyway. Even if we do it, the only thing we loss with this new approach is earlier log deletion between two flushes, which does not guarantee to happen anyway because the obsolete file clean-up function is only executed after flush or compaction)

This min log number to keep is stored in the manifest using the safely-ignore customized field of AddFile entry, in order to guarantee that the DB generated using newer release can be opened by previous releases no older than 4.2.
Closes https://github.com/facebook/rocksdb/pull/3765

Differential Revision: D7747618

Pulled By: siying

fbshipit-source-id: d00c92105b4f83852e9754a1b70d6b64cb590729

Summary:
This reverts commit 73f21a7b.

It breaks compatibility. When created a DB using a build with this new change, opening the DB and reading the data will fail with this error:

"Corruption: Can't access /000000.sst: IO error: while stat a file for size: /tmp/xxxx/000000.sst: No such file or directory"

This is because the dummy AddFile4 entry generated by the new code will be treated as a real entry by an older build. The older build will think there is a real file with number 0, but there isn't such a file.
Closes https://github.com/facebook/rocksdb/pull/3762

Differential Revision: D7730035

Pulled By: siying

fbshipit-source-id: f2051859eff20ef1837575ecb1e1bb96b3751e77

Summary:
This patch record the deleted WAL numbers in the manifest to ignore them and any WAL older than them during recovery. This is to avoid scenarios when we have a gap between the WAL files are fed to the recovery procedure. The gap could happen by for example out-of-order WAL deletion. Such gap could cause problems in 2PC recovery where the prepared and commit entry are placed into two separate WAL and gap in the WALs could result into not processing the WAL with the commit entry and hence breaking the 2PC recovery logic.
Closes https://github.com/facebook/rocksdb/pull/3488

Differential Revision: D6967893

Pulled By: maysamyabandeh

fbshipit-source-id: 13119feb155a08ab6d4909f437c7a750480dc8a1

Summary:
Submitting on behalf of another employee.
Closes https://github.com/facebook/rocksdb/pull/3557

Differential Revision: D7146025

Pulled By: ajkr

fbshipit-source-id: 495ca5db5beec3789e671e26f78170957704e77e

Reviewed By: igorsugak

fbshipit-source-id: 4a93675cc1931089ddd574cacdb15d228b1e5f37

Reviewed By: everiq, igorsugak

Differential Revision: D7046710

fbshipit-source-id: 8e10b1f1e2aecebbfb229c742e214db887e5a461

Summary:
This reverts the previous commit 1d7048c5, which broke the build.

Did a `git revert 1d7048c5`.
Closes https://github.com/facebook/rocksdb/pull/2627

Differential Revision: D5476473

Pulled By: sagar0

fbshipit-source-id: 4756ff5c0dfc88c17eceb00e02c36176de728d06

Summary: This uses `clang-tidy` to comment out unused parameters (in functions, methods and lambdas) in fbcode. Cases that the tool failed to handle are fixed manually.

Reviewed By: igorsugak

Differential Revision: D5454343

fbshipit-source-id: 5dee339b4334e25e963891b519a5aa81fbf627b2

Summary: Closes https://github.com/facebook/rocksdb/pull/2589

Differential Revision: D5431502

Pulled By: siying

fbshipit-source-id: 8ebf8c87883daa9daa54b2303d11ce01ab1f6f75

Summary: Closes https://github.com/facebook/rocksdb/pull/2226

Differential Revision: D4967547

Pulled By: siying

fbshipit-source-id: dd3b58ae1e7a106ab6bb6f37ab5c88575b125ab4

Summary:
This is an effort to club all string related utility functions into one common place, in string_util, so that it is easier for everyone to know what string processing functions are available. Right now they seem to be spread out across multiple modules, like logging and options_helper.

Check the sub-commits for easier reviewing.
Closes https://github.com/facebook/rocksdb/pull/2094

Differential Revision: D4837730

Pulled By: sagar0

fbshipit-source-id: 344278a

Summary:
I was investigating performance issues in the SstFileWriter and found all of the following:

- The SstFileWriter::Add() function created a local InternalKey every time it was called generating a allocation and free each time.  Changed to have an InternalKey member variable that can be reset with the new InternalKey::Set() function.
- In SstFileWriter::Add() the smallest_key and largest_key values were assigned the result of a ToString() call, but it is simpler to just assign them directly from the user's key.
- The Slice class had no move constructor so each time one was returned from a function a new one had to be allocated, the old data copied to the new, and the old one was freed.  I added the move constructor which also required a copy constructor and assignment operator.
- The BlockBuilder::CurrentSizeEstimate() function calculates the current estimate size, but was being called 2 or 3 times for each key added.  I changed the class to maintain a running estimate (equal to the original calculation) so that the function can return an already calculated value.
- The code in BlockBuilder::Add() that calculated the shared bytes between the last key and the new key duplicated what Slice::difference_offset does, so I replaced it with the standard function.
- BlockBuilder::Add() had code to copy just the changed portion into the last key value (and asserted that it now matched the new key).  It is more efficient just to copy the whole new key over.
- Moved this same code up into the 'if (use_delta_encoding_)' since the last key value is only needed when delta encoding is on.
- FlushBlockBySizePolicy::BlockAlmostFull calculated a standard deviation value each time it was called, but this information would only change if block_size of block_size_deviation changed, so I created a member variable to hold the value to avoid the calculation each time.
- Each PutVarint??() function has a buffer and calls std::string::append().  Two or three calls in a row could share a buffer and a single call to std::string::append().

Some of these will be helpful outside of the SstFileWriter.  I'm not 100% the addition of the move constructor is appropriate as I wonder why this wasn't done before - maybe because of compiler compatibility?  I tried it on gcc 4.8 and 4.9.

Test Plan: The changes should not affect the results so the existing tests should all still work and no new tests were added.  The value of the changes was seen by manually testing the SstFileWriter class through MyRocks and adding timing code to identify problem areas.

Reviewers: sdong, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D59607

Summary: With this commit, we add a new format in manifest when adding a new file. Now path ID and need-compaction hint are first two customized fields.

Test Plan: Add a test case in version_edit_test to verify the encoding and decoding logic. Add a unit test in db_test to verify need compaction is persistent after DB restarting.

Reviewers: kradhakrishnan, anthony, IslamAbdelRahman, yhchiang, rven, igor

Reviewed By: igor

Subscribers: javigon, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D48123

Summary:
Added a new flag --json to the ldb manifest_dump command
that prints out the version edits as JSON objects for easier
reading and parsing of information.

Test Plan:
**Sample usage: **
```
./ldb manifest_dump --json --path=path/to/manifest/file
```

**Sample output:**
```
{"EditNumber": 0, "Comparator": "leveldb.BytewiseComparator", "ColumnFamily": 0}
{"EditNumber": 1, "LogNumber": 0, "ColumnFamily": 0}
{"EditNumber": 2, "LogNumber": 4, "PrevLogNumber": 0, "NextFileNumber": 7, "LastSeq": 35356, "AddedFiles": [{"Level": 0, "FileNumber": 5, "FileSize": 1949284, "SmallestIKey": "'", "LargestIKey": "'"}], "ColumnFamily": 0}
...
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...
```

Reviewers: sdong, anthony, yhchiang, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D41727