Summary:
Add the `--leader_path` option to specify the directory path of the leader for a follower RocksDB instance. This PR also adds a `count` command to the repl shell. While not specific to followers, it is useful for testing purposes.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/12682
Reviewed By: jowlyzhang
Differential Revision: D57642296
Pulled By: anand1976
fbshipit-source-id: 53767d496ecadc363ff92cd958b8e15a7bf3b151
Summary:
Mixed code from `MultiGetCommand` and `GetEntityCommand` to introduce `MultiGetEntityCommand`. Some minor fixes for the related subcommands are included.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/12593
Reviewed By: jaykorean
Differential Revision: D56687147
Pulled By: ajkr
fbshipit-source-id: 2ad7b7ba8e05e990b43f2d1eb4990f746ce5f1ea
Summary:
# Summary
Following up jowlyzhang 's comment in https://github.com/facebook/rocksdb/issues/12283 .
- Remove `ARG_TTL` from help which is not relevant to `multi_get` command
- Treat NotFound status as non-error case for both `Get` and `MultiGet` and updated the unit test, `ldb_test.py`
- Print key along with value in `multi_get` command
Pull Request resolved: https://github.com/facebook/rocksdb/pull/12332
Test Plan:
**Unit Test**
```
$>python3 tools/ldb_test.py
...
Ran 25 tests in 17.447s
OK
```
**Manual Run**
```
$> ./ldb --db=/data/users/jewoongh/rocksdb_test/T173992396/rocksdb_crashtest_blackbox --hex multi_get 0x0000000000000009000000000000012B00000000000000D8 0x0000000000000009000000000000002678787878BEEF
0x0000000000000009000000000000012B00000000000000D8 ==> 0x47000000434241404F4E4D4C4B4A494857565554535251505F5E5D5C5B5A595867666564636261606F6E6D6C6B6A696877767574737271707F7E7D7C7B7A797807060504030201000F0E0D0C0B0A090817161514131211101F1E1D1C1B1A1918
Key not found: 0x0000000000000009000000000000002678787878BEEF
```
```
$> ./ldb --db=/data/users/jewoongh/rocksdb_test/T173992396/rocksdb_crashtest_blackbox --hex get 0x00000000000000090000000000
Key not found
```
Reviewed By: jowlyzhang
Differential Revision: D53450164
Pulled By: jaykorean
fbshipit-source-id: 9ccec78ad3695e65b1ed0c147c7cbac502a1bd48
Summary:
In preparing some seqno_to_time_mapping improvements, I found that some of the wrap-up work for creating column families was unnecessarily repeated in the case of DB::Open with create_missing_column_families. This change fixes that (`CreateColumnFamily()` -> `CreateColumnFamilyImpl()` in `DBImpl::Open()`), motivated by avoiding repeated calls to `RegisterRecordSeqnoTimeWorker()` but with the side benefit of avoiding repeated calls to `WriteOptionsFile()` for each CF.
Also in this change:
* Add a `Status::UpdateIfOk()` function for combining statuses in a common pattern
* Rename `max_time_duration` -> `min_preserve_seconds` (include units as much as possible)
* Improved comments in several places
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11920
Test Plan: tests added / updated
Reviewed By: jaykorean
Differential Revision: D49919147
Pulled By: pdillinger
fbshipit-source-id: 3d0318c1d070c842c5331da0a5b415caedc104f1
Summary:
We haven't been actively mantaining RocksDB LITE recently and the size must have been gone up significantly. We are removing the support.
Most of changes were done through following comments:
unifdef -m -UROCKSDB_LITE `git grep -l ROCKSDB_LITE | egrep '[.](cc|h)'`
by Peter Dillinger. Others changes were manually applied to build scripts, CircleCI manifests, ROCKSDB_LITE is used in an expression and file db_stress_test_base.cc.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11147
Test Plan: See CI
Reviewed By: pdillinger
Differential Revision: D42796341
fbshipit-source-id: 4920e15fc2060c2cd2221330a6d0e5e65d4b7fe2
Summary:
Some lines of .h and .cc files are not properly fomatted. Clear them up with clang format.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10868
Test Plan: Watch existing CI to pass
Reviewed By: ajkr
Differential Revision: D40683485
fbshipit-source-id: 491fbb78b2cdcb948164f306829909ad816d5d0b
Summary:
If the DB path is specified, the user would expect ldb loads the
options from the path, but it's not:
```
$ ldb list_live_files_metadata --db=`pwd`
```
Default `try_load_options` to true in that case. The user can still
disable that by:
```
$ ldb list_live_files_metadata --db=`pwd` --try_load_options=false
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9937
Test Plan:
`ldb list_live_files_metadata --db=`pwd`` is able to work for
a db generated with different options.num_levels.
Reviewed By: ajkr
Differential Revision: D36106708
Pulled By: jay-zhuang
fbshipit-source-id: 2732fdc027a4d172436b2c9b6a9787b56b10c710
Summary:
The goal of this change is to allow changes to the "current" (in
FileSystem) file temperatures to feed back into DB metadata, so that
they can inform decisions and stats reporting. In part because of
modular code factoring, it doesn't seem easy to do this automagically,
where opening an SST file and observing current Temperature different
from expected would trigger a change in metadata and DB manifest write
(essentially giving the deep read path access to the write path). It is also
difficult to do this while the DB is open because of the limitations of
LogAndApply.
This change allows updating file temperature metadata on a closed DB
using an experimental utility function UpdateManifestForFilesState()
or `ldb update_manifest --update_temperatures`. This should suffice for
"migration" scenarios where outside tooling has placed or re-arranged DB
files into a (different) tiered configuration without going through
RocksDB itself (currently, only compaction can change temperature
metadata).
Some details:
* Refactored and added unit test for `ldb unsafe_remove_sst_file` because
of shared functionality
* Pulled in autovector.h changes from https://github.com/facebook/rocksdb/issues/9546 to fix SuperVersionContext
move constructor (related to an older draft of this change)
Possible follow-up work:
* Support updating manifest with file checksums, such as when a
new checksum function is used and want existing DB metadata updated
for it.
* It's possible that for some repair scenarios, lighter weight than
full repair, we might want to support UpdateManifestForFilesState() to
modify critical file details like size or checksum using same
algorithm. But let's make sure these are differentiated from modifying
file details in ways that don't suspect corruption (or require extreme
trust).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9683
Test Plan: unit tests added
Reviewed By: jay-zhuang
Differential Revision: D34798828
Pulled By: pdillinger
fbshipit-source-id: cfd83e8fb10761d8c9e7f9c020d68c9106a95554
Summary:
Opening DB as seconeary instance has been supported in ldb but it is not mentioned in --help. Mention it there. The part of the help message after the modification:
```
commands MUST specify --db=<full_path_to_db_directory> when necessary
commands can optionally specify
--env_uri=<uri_of_environment> or --fs_uri=<uri_of_filesystem> if necessary
--secondary_path=<secondary_path> to open DB as secondary instance. Operations not supported in secondary instance will fail.
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9582
Test Plan: Build and run ldb --help
Reviewed By: riversand963
Differential Revision: D34286427
fbshipit-source-id: e56c5290d0548098ab6acc6dde2167f5a64f34f3
Summary:
Add an argument to ldb to dump live file names, column families, and levels, `list_live_files_metadata`. The output shows all active SST file names, sorted first by column family and then by level. For each level the SST files are sorted alphabetically.
Typically, the output looks like this:
```
./ldb --db=/tmp/test_db list_live_files_metadata
Live SST Files:
===== Column Family: default =====
---------- level 0 ----------
/tmp/test_db/000069.sst
---------- level 1 ----------
/tmp/test_db/000064.sst
/tmp/test_db/000065.sst
/tmp/test_db/000066.sst
/tmp/test_db/000071.sst
---------- level 2 ----------
/tmp/test_db/000038.sst
/tmp/test_db/000039.sst
/tmp/test_db/000052.sst
/tmp/test_db/000067.sst
/tmp/test_db/000070.sst
------------------------------
```
Second, a flag was added `--sort_by_filename`, to change the layout of the output. When this flag is added to the command, the output shows all active SST files sorted by name, in front of which the LSM level and the column family are mentioned. With the same example, the following command would return:
```
./ldb --db=/tmp/test_db list_live_files_metadata --sort_by_filename
Live SST Files:
/tmp/test_db/000038.sst : level 2, column family 'default'
/tmp/test_db/000039.sst : level 2, column family 'default'
/tmp/test_db/000052.sst : level 2, column family 'default'
/tmp/test_db/000064.sst : level 1, column family 'default'
/tmp/test_db/000065.sst : level 1, column family 'default'
/tmp/test_db/000066.sst : level 1, column family 'default'
/tmp/test_db/000067.sst : level 2, column family 'default'
/tmp/test_db/000069.sst : level 0, column family 'default'
/tmp/test_db/000070.sst : level 2, column family 'default'
/tmp/test_db/000071.sst : level 1, column family 'default'
------------------------------
```
Thus, the user can either request to show the files by levels, or sorted by filenames.
This PR includes a simple Python unit test that makes sure the file name and level printed out by this new feature matches the one found with an existing feature, `dump_live_file`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8446
Reviewed By: akankshamahajan15
Differential Revision: D29320080
Pulled By: bjlemaire
fbshipit-source-id: 01fb7b5637c59010d74c80730a28d815994e7009
Summary:
This PR adds support for custom file systems to ldb and sst_dump by adding command line options for specifying --fs_uri and --backup_fs uri (for ldb backup/restore commands). fs_uri is already supported in db_bench and db_stress, and there is already support in ldb and db stress for specifying customized envs.
The PR also fixes what looks like a bug in the ldb backup/restore commands. As it is right now, backups can only be made from and to the same environment/file system which does not seem to be the intended behavior. This PR makes it possible to do/restore backups between different envs/file systems.
Example:
`./ldb backup --fs_uri=zenfs://dev:nvme2n1 --backup_fs_uri=posix:// --backup_dir=/tmp/my_rocksdb_backup --db=rocksdbtest/dbbench
`
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8010
Reviewed By: jay-zhuang
Differential Revision: D26904654
Pulled By: ajkr
fbshipit-source-id: 9b695ed8b944fcc6b27c4daaa9f52e87ee2c1fb4
Summary:
So that we can more easily get aggregate live table data such
as total filter, index, and data sizes.
Also adds ldb support for getting properties
Also fixed some missing/inaccurate related comments in db.h
For example:
$ ./ldb --db=testdb get_property rocksdb.aggregated-table-properties
rocksdb.aggregated-table-properties.data_size: 102871
rocksdb.aggregated-table-properties.filter_size: 0
rocksdb.aggregated-table-properties.index_partitions: 0
rocksdb.aggregated-table-properties.index_size: 2232
rocksdb.aggregated-table-properties.num_data_blocks: 100
rocksdb.aggregated-table-properties.num_deletions: 0
rocksdb.aggregated-table-properties.num_entries: 15000
rocksdb.aggregated-table-properties.num_merge_operands: 0
rocksdb.aggregated-table-properties.num_range_deletions: 0
rocksdb.aggregated-table-properties.raw_key_size: 288890
rocksdb.aggregated-table-properties.raw_value_size: 198890
rocksdb.aggregated-table-properties.top_level_index_size: 0
$ ./ldb --db=testdb get_property rocksdb.aggregated-table-properties-at-level1
rocksdb.aggregated-table-properties-at-level1.data_size: 80909
rocksdb.aggregated-table-properties-at-level1.filter_size: 0
rocksdb.aggregated-table-properties-at-level1.index_partitions: 0
rocksdb.aggregated-table-properties-at-level1.index_size: 1787
rocksdb.aggregated-table-properties-at-level1.num_data_blocks: 81
rocksdb.aggregated-table-properties-at-level1.num_deletions: 0
rocksdb.aggregated-table-properties-at-level1.num_entries: 12466
rocksdb.aggregated-table-properties-at-level1.num_merge_operands: 0
rocksdb.aggregated-table-properties-at-level1.num_range_deletions: 0
rocksdb.aggregated-table-properties-at-level1.raw_key_size: 238210
rocksdb.aggregated-table-properties-at-level1.raw_value_size: 163414
rocksdb.aggregated-table-properties-at-level1.top_level_index_size: 0
$
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7779
Test Plan: Added a test to ldb_test.py
Reviewed By: jay-zhuang
Differential Revision: D25653103
Pulled By: pdillinger
fbshipit-source-id: 2905469a08a64dd6b5510cbd7be2e64d3234d6d3
Summary:
This is adapted from https://github.com/facebook/rocksdb/issues/6678 but takes a different approach, avoiding opening a read-write DB and avoiding the `DeleteFile()` API.
First, this PR refactors how options variables are initialized in `ldb` so it can be reused in a subcommand that doesn't open a DB:
- Separated remaining option initialization logic out of `OpenDB()`. The new `PrepareOptions()` function initializes the full options state.
- Fixed an old TODO about applying the subcommand CF option overrides to the proper `ColumnFamilyOptions` object.
Second, this PR adds the `ldb unsafe_remove_sst_file` subcommand. It uses the `VersionSet`-level APIs to remove the file with the specified number.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7335
Test Plan: played with interactive python and this file removal command. Verified openability/correct results in case of multiple column families, multiple levels, etc.
Reviewed By: pdillinger
Differential Revision: D23454575
Pulled By: ajkr
fbshipit-source-id: 039b7a8cbfc42fd123dcb25821eef51d61148afe
Summary:
**Summary**
Remove the extraneous newline when using ldb tool. For example, the subcommand list_column_families will print an empty line to stderr even if there are no errors.
**Test plan**
Passed make check; manually tested a few ldb subcommands.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6897
Reviewed By: pdillinger
Differential Revision: D21819352
Pulled By: gg814
fbshipit-source-id: 5a16a6431bb96684fe97647f4d3ac5bf0ec7fc90
Summary:
When using ldb, users cannot turn on force consistency check in most commands, while they cannot use checksonsistnecy with --try_load_options. The change fixes both by:
1. checkconsistency now calls OpenDB() so that it gets all the options loading and sanitized options logic
2. use options.check_consistency_checks = true by default, and add a --disable_consistency_checks to turn it off.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6802
Test Plan: Add a new unit test. Some manual tests with corrupted DBs.
Reviewed By: pdillinger
Differential Revision: D21388051
fbshipit-source-id: 8d122732d391b426e3982a1c3232a8e3763ffad0
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 PR allows for the creation of custom env when using sst_dump. If
the user does not set options.env or set options.env to nullptr, then sst_dump
will automatically try to create a custom env depending on the path to the sst
file or db directory. In order to use this feature, the user must call
ObjectRegistry::Register() beforehand.
Test Plan (on devserver):
```
$make all && make check
```
All tests must pass to ensure this change does not break anything.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5845
Differential Revision: D17678038
Pulled By: riversand963
fbshipit-source-id: 58ecb4b3f75246d52b07c4c924a63ee61c1ee626
Summary:
Add a command in ldb so that users can print out tombstones in SST files.
In order to test the code, change the interface of LDBCommandRunner::RunCommand() so that it doesn't return from the program, but return the status code.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5615
Test Plan: Add a new unit test
Differential Revision: D16550326
fbshipit-source-id: 88ddfe6984bdcbb3a528abdd115089df09eba52e
Summary:
`create_column_family` cmd already exists but was somehow missed in the help message.
also add `drop_column_family` cmd which can drop a cf without opening db.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5503
Test Plan: Updated existing ldb_test.py to test deleting a column family.
Differential Revision: D16018414
Pulled By: lightmark
fbshipit-source-id: 1fc33680b742104fea86b10efc8499f79e722301
Summary:
We add two subcommands `write_extern_sst` and `ingest_extern_sst` to ldb. This PR avoids changing existing code because we hope to cherry-pick to earlier releases to support compatibility check for external SST file ingestion.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4205
Differential Revision: D9112711
Pulled By: riversand963
fbshipit-source-id: 7cae88380d4de86da8440230e87eca66755648e4
Summary:
This reverts the previous commit 1d7048c598, which broke the build.
Did a `git revert 1d7048c`.
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:
Added a flag, `ignore_unknown_options`, to skip unknown options when loading an options file (using `LoadLatestOptions`/`LoadOptionsFromFile`) or while verifying options (using `CheckOptionsCompatibility`). This will help in downgrading the db to an older version.
Also added `--ignore_unknown_options` flag to ldb
**Example Use case:**
In MyRocks, if copying from newer version to older version, it is often impossible to start because of new RocksDB options that don't exist in older version, even though data format is compatible.
MyRocks uses these load and verify functions in [ha_rocksdb.cc::check_rocksdb_options_compatibility](e004fd9f41/storage/rocksdb/ha_rocksdb.cc (L3348-L3401)).
**Test Plan:**
Updated the unit tests.
`make check`
ldb:
$ ./ldb --db=/tmp/test_db --create_if_missing put a1 b1
OK
Now edit /tmp/test_db/<OPTIONS-file> and add an unknown option.
Try loading the options now, and it fails:
$ ./ldb --db=/tmp/test_db --try_load_options get a1
Failed: Invalid argument: Unrecognized option DBOptions:: abcd
Passes with the new --ignore_unknown_options flag
$ ./ldb --db=/tmp/test_db --try_load_options --ignore_unknown_options get a1
b1
Closes https://github.com/facebook/rocksdb/pull/2423
Differential Revision: D5212091
Pulled By: sagar0
fbshipit-source-id: 2ec17636feb47dc0351b53a77e5f15ef7cbf2ca7
Summary:
tools/check_format_compatible.sh will check a newer version of RocksDB can open option files generated by older version releases. In order to achieve that, a new parameter "--try_load_options" is added to ldb. With this parameter set, if option file exists, we load the option file and use it to open the DB. With this opiton set, we can validate option loading logic.
Closes https://github.com/facebook/rocksdb/pull/2178
Differential Revision: D4914989
Pulled By: siying
fbshipit-source-id: db114f7724fcb41e5e9483116d84d7c4b8389ca4
Summary:
move the argument description to the right section, make it clearer that the '=' sign is required, and use it in one subcommand where it seemed forgotten before.
Closes https://github.com/facebook/rocksdb/pull/1840
Differential Revision: D4515096
Pulled By: ajkr
fbshipit-source-id: 7b5b1c1
Summary:
Add a subcommand to ldb with which we can delete a range of keys.
Closes https://github.com/facebook/rocksdb/pull/1521
Differential Revision: D4186338
Pulled By: ajkr
fbshipit-source-id: b8e9861
Summary:
Use 16384 as e.g .value for ldb the --compression_max_dict_bytes option.
I think 14 was copy and pasted from the options in the lines above.
Closes https://github.com/facebook/rocksdb/pull/1483
Differential Revision: D4154393
Pulled By: siying
fbshipit-source-id: ef53a69
Summary:
- Added a new subcommand, 'ldb restore', that restores from backup
- Made backup_env_uri optional (also for 'ldb backup') because it can use db_env when backup_env isn't provided
Test Plan:
verify backup and restore commands work:
$ ./ldb backup --db=/data/users/andrewkr/rocksdb/db_bench-out/ --num_threads 1 --backup_dir=/data/users/andrewkr/rocksdb/db_bench-out/backup/
$ ./ldb restore --db=/data/users/andrewkr/rocksdb/db_bench-out/restore/ --num_threads 1 --backup_dir=/data/users/andrewkr/rocksdb/db_bench-out/backup/
Reviewers: sdong, wanning
Reviewed By: wanning
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D60849
Summary: add backup support for ldb tool, and use it to run load test for backup on two HDFS envs
Test Plan: first generate some db, then compile against load test in fbcode, run load_test --db=<db path> backup --backup_env_uri=<URI of backup env> --backup_dir=<backup directory> --num_threads=<number of thread>
Reviewers: andrewkr
Reviewed By: andrewkr
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D60633
Summary:
The implementation remains where it is. Only the
header is exported. This is so that a customized
ldb tool can print help along with its own
extra commands
Test Plan: make ldb
Reviewers: sdong, IslamAbdelRahman
Reviewed By: IslamAbdelRahman
Subscribers: andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D57255
Summary:
This is needed so that rocksdb users can add more
commands to the included ldb tool by adding more custom
commands.
Test Plan: make -j ldb
Reviewers: sdong, IslamAbdelRahman
Reviewed By: IslamAbdelRahman
Subscribers: andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D57243
Summary: This will make it easier for admins and devs to use RepairDB.
Test Plan:
Tried deleting the manifest and verified it recovers:
$ ldb --create_if_missing --db=/tmp/test_db put ok ok
$ rm -f /tmp/test_db/MANIFEST-000001
$ ./ldb --db=/tmp/test_db repair
$ ldb --db=/tmp/test_db get ok
ok
Reviewers: yhchiang, sdong, IslamAbdelRahman
Reviewed By: IslamAbdelRahman
Subscribers: leveldb, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D55359
Summary:
Add an option --column_family option, so that users can query or update specific column family.
Also add an create column family parameter to make unit test easier.
Still need to add unit tests.
Test Plan: Will add a test case in ldb python test.
Reviewers: yhchiang, rven, andrewkr, IslamAbdelRahman, kradhakrishnan, anthony
Reviewed By: anthony
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D53265
Summary:
Based on https://github.com/facebook/rocksdb/issues/843
It looks that when the data is hot we spend significant amount of time moving data out of RocksDB blocks. This patch reduce moving memory when possible
Original performance
```
$ time ./ldb --db=/home/tec/local/ellina_test/testdb scan > /dev/null
real 0m16.736s
user 0m11.993s
sys 0m4.725s
```
Performance after reducing memcpy
```
$ time ./ldb --db=/home/tec/local/ellina_test/testdb scan > /dev/null
real 0m11.590s
user 0m6.983s
sys 0m4.595s
```
Test Plan:
dump the output of the scan into 2 files and verifying the are exactly the same
make check
Reviewers: sdong, yhchiang, anthony, rven, igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D51093
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