Summary:
As title. The goal is to shorten the execution time of several tests
when they are combined together in a single TEST_F.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7105

Test Plan:
make db_wal_test
./db_wal_test

Reviewed By: ltamasi

Differential Revision: D22442705

Pulled By: riversand963

fbshipit-source-id: 0ad49b8f21fa86dcd5a4d3c9a06af313735ac217

Summary:
as title.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7107

Test Plan: make ldb && ./ldb

Reviewed By: pdillinger

Differential Revision: D22451399

Pulled By: riversand963

fbshipit-source-id: 797645e06473bb9cf139c533877e5161281515e8

Summary:
Although PR https://github.com/facebook/rocksdb/issues/7032 fixes the construction of the `SstFileDumper` in `GetFileDbIdentities` by setting a proper `Env` of the `Options` passed in the constructor, the file path was not corrected accordingly. This actually disables backup engine to use db session ids in the file names since the `db_session_id` is always empty.

Now it is fixed by setting the correct path in the construction of `SstFileDumper`. Furthermore, to preserve the Direct IO property that backup engine already has, parameter `EnvOptions` is added to `GetFileDbIdentities` and `SstFileDumper`.

The `BackupUsingDirectIO` test is updated accordingly.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7104

Test Plan: backupable_db_test and some manual tests.

Reviewed By: ajkr

Differential Revision: D22443245

Pulled By: gg814

fbshipit-source-id: 056a9bb8b82947c5e73d7c3fbb62bfe23af5e562

Update Flush policy in PartitionedIndexBuilder on switching from user-key to internal-key mode (#7096)

Summary:
When format_version is high enough to support user-key and
there are index entries for same user key that spans multiple data
blocks then it changes from user-key mode to internal-key mode. But the
flush policy is not reset to point to Block Builder of internal-keys.
After this switch, no entries are added to user key index partition
result, thus it never triggers flushing the block.

Fix: 1. After adding the entry in sub_builder_index_, if there is a switch
from user-key to internal-key, then flush policy is updated to point to
Block Builder of internal-keys index partition.
2. Set sub_builder_index_->seperator_is_key_plus_seq_ = true if
seperator_is_key_plus_seq_  is set to true so that subsequent partitions
can also use internal key mode.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7096

Test Plan: make check -j64

Reviewed By: ajkr

Differential Revision: D22416598

Pulled By: akankshamahajan15

fbshipit-source-id: 01fc2dc07ea1b32f8fb803995ebe6e9a3fbe67ac

Summary:
WITH_TESTS=OFF and WITH_BENCHMARK_TOOLS=ON

there has errors:
 /bin/ld: cannot find -ltestharness

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7040

Reviewed By: riversand963

Differential Revision: D22447637

Pulled By: ajkr

fbshipit-source-id: f63058376deb4a2e6722d63541c40caa617c331a

Summary:
Delicious copy-pasta from https://github.com/facebook/rocksdb/issues/7039

Also fixing DestroyDir to allow files to go missing while it is operating. This seems to fix failures I got with test plan reproducer.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7103

Test Plan:
make blackbox_crash_test_with_atomic_flush for a while with
checkpoint_one_in=100

Reviewed By: siying

Differential Revision: D22435315

Pulled By: pdillinger

fbshipit-source-id: 0ec0538402493887aeda43ecc03f32979cb84ced

Summary:
The fix in PR https://github.com/facebook/rocksdb/issues/7082 is not really successful because there is still a small chance that the test will fail.

In addtion to flushing, we close the DB and then reopen before corrupting a table file in the DB. Specifically, we corrupt a table file before backup takes place as follows.
* Open DB
* Fill DB
* Flush DB (optional, no flushing here also works)
* Close DB
* Reopen DB
* Corrupt a table file in the DB

This should make the test reliable.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7102

Test Plan:
`while ./backupable_db_test --gtest_filter=*TableFileCorruptedBeforeBackup*; do true; done`
(kept running for an hour or so :)

Reviewed By: pdillinger

Differential Revision: D22432417

Pulled By: gg814

fbshipit-source-id: d407eee93ff428bb662f80cde1659fbf0149d0cd

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7092

Reviewed By: riversand963

Differential Revision: D22412323

Pulled By: ajkr

fbshipit-source-id: 3fc1c63bb19a8cd2c0ae620800c28f199a7f494b

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7080

Reviewed By: riversand963

Differential Revision: D22412352

Pulled By: ajkr

fbshipit-source-id: 1d7f4c1621040a0130245139b52c3f4d3deac865

Summary:
Currently, `EventListener` in listner.h only have callback functions for file read and write. One may favor extended callback functions for more file I/O operations like flush, sync and close. This PR tries to add those interface and have them called when appropriate throughout the code base.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7055

Test Plan:
Write an experimental listener with those new callback functions with log output in them; run experiments and check logs to see those functions are actually called.
Default test suits `make check` should also be included.

Reviewed By: riversand963

Differential Revision: D22380624

Pulled By: roghnin

fbshipit-source-id: 4121491d45c2c2aae8c255e7998090559a241c6a

Summary:
Replace `BlockIter::comparator_` and `IndexBlockIter::user_comparator_wrapper_` with a concrete `UserComparatorWrapper` and `InternalKeyComparator`. The motivation for this change was the inconvenience of not knowing the concrete type of `BlockIter::comparator_`, which prevented calling specialized internal key comparison functions to optimize comparison of keys with global seqno applied.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/6944

Test Plan:
benchmark setup -- single file DBs, in-memory, no compression. "normal_db"
created by regular flush; "ingestion_db" created by ingesting a file. Both
DBs have same contents.

```
$ TEST_TMPDIR=/dev/shm/normal_db/ ./db_bench -benchmarks=fillrandom,compact -write_buffer_size=10485760000 -disable_auto_compactions=true -compression_type=none -num=1000000
$ ./ldb write_extern_sst ./tmp.sst --db=/dev/shm/ingestion_db/dbbench/ --compression_type=no --hex --create_if_missing < <(./sst_dump --command=scan --output_hex --file=/dev/shm/normal_db/dbbench/000007.sst | awk 'began {print "0x" substr($1, 2, length($1) - 2), "==>", "0x" $5} ; /^Sst file format: block-based/ {began=1}')
$ ./ldb ingest_extern_sst ./tmp.sst --db=/dev/shm/ingestion_db/dbbench/
```

benchmark run command:

```
$ TEST_TMPDIR=/dev/shm/$DB/ ./db_bench -benchmarks=seekrandom -seek_nexts=$SEEK_NEXT -use_existing_db=true -cache_index_and_filter_blocks=false -num=1000000 -cache_size=0 -threads=1 -reads=200000000 -mmap_read=1 -verify_checksum=false
```

results: perf improved marginally for ingestion_db and did not change significantly for normal_db:

SEEK_NEXT | DB | code | ops/sec | % change
-- | -- | -- | -- | --
0 | normal_db | master | 350880 |  
0 | normal_db | PR6944 | 351040 | 0.0
0 | ingestion_db | master | 343255 |  
0 | ingestion_db | PR6944 | 349424 | 1.8
10 | normal_db | master | 218711 |  
10 | normal_db | PR6944 | 217892 | -0.4
10 | ingestion_db | master | 220334 |  
10 | ingestion_db | PR6944 | 226437 | 2.8

Reviewed By: pdillinger

Differential Revision: D21924676

Pulled By: ajkr

fbshipit-source-id: ea4288a2eefa8112eb6c651a671c1de18c12e538

Summary:
On some platforms like MacOS, a second 'make check' can lead to
/bin/rm: Argument list too long

This is fixed by replacing with a 'find'. Also, using '-f' for more rm calls
to avoid prompt.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7095

Test Plan: 'make check' on Linux and MacOS

Reviewed By: riversand963

Differential Revision: D22415808

Pulled By: pdillinger

fbshipit-source-id: 0fd1ebae13739c9d81f9e813e99b062715604d6b

Summary:
by tracking and linking against runtime dependent libraries in
Makefile

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7098

Test Plan: look for fix in CircleCI

Reviewed By: riversand963

Differential Revision: D22420860

Pulled By: pdillinger

fbshipit-source-id: d211d709214bf5306db68e43b7a2f18169281022

Summary:
Fix a Facebook internal build

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7093

Test Plan:
buck build mode/opt :c_test :c_test_bin (was compilation
failure, now "not found")
buck build mode/dev :c_test :c_test_bin (still passes)

Reviewed By: ajkr

Differential Revision: D22412528

Pulled By: pdillinger

fbshipit-source-id: 8e55c43dbf95386597e4cc690c41d9cbdcee03aa

Summary:
Primarily, this change adds a way to work around a bug limiting the effective output (and therefore debugability) of the Linux builds using parallel make. We would get
make[1]: write error: stdout
probably due to a kernel bug, apparently affecting both available ubuntu 16 machine images (maybe not affecting docker images, less horsepower). https://bugs.launchpad.net/ubuntu/+source/linux-signed/+bug/1814393

Now in the CircleCI config, make output on Ubuntu is piped through a custom 'cat' that ignores EAGAIN errors, which seems to fix the problem.

Significant other changes:
* Add another linux build that combines
  * LIB_MODE=shared, to ensure this works with compile and unit test execution
  * Alternative rocksdb namespace, to ensure this works (not rely on Travis)
  * ASSERT_STATUS_CHECKED=1, but with building all unit tests and running those expected to pass with it
* Run release build with and without gflags. (Was running only without, ignore large swaths of code in a normal release build! Two regressions in this build, only with gflags, in the last week not caught by CI!)
* Use gflags with unity and LITE build, as typical case.

Debugability improvements:
* Use V=1 to show commands being executed (thanks to EAGAIN work-around)
* Print kernel version and compiler versions as part of V=1 output from Makefile

Cosmetic other changes:
* Put more commands on one line, for less clutter in CircleCI output pages
* Remove redundant "all" in "make all check" and put make command options before targets
* Change some recursive "make clean" into dependency on "clean," toward minimizing unnecessary overhead (detect platform, build version, etc.) of extra recursive makes

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7078

Reviewed By: siying

Differential Revision: D22391647

Pulled By: pdillinger

fbshipit-source-id: d446fccf5a8c568b37dc8748621c8a5c546fe135

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7086

Test Plan: `make check`

Reviewed By: zhichao-cao

Differential Revision: D22395420

Pulled By: ltamasi

fbshipit-source-id: 088a20097bd6b73b0c433cd79725779f97ec04f2

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7072

Reviewed By: ajkr

Differential Revision: D22391641

Pulled By: pdillinger

fbshipit-source-id: 0ef355576454514263ab684eb1a5c06787f3242a

Summary:
Closes https://github.com/facebook/rocksdb/issues/5852
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7047

Reviewed By: cheng-chang

Differential Revision: D22335162

Pulled By: pdillinger

fbshipit-source-id: 75f3c524deccea7ebc0ad288da41f1ea81406c1c

Summary:
(a) use STRESS_LIBRARY for db_stress and make sure
STRESS_LIBRARY has other stress test dependencies (as in buck build)

(b) fix rpath option to be accepted on MacOS. It still doesn't fully work
for me e.g. to run a LIB_MODE=shared unit test binary from another
directory, as it does on Linux, but the option is now accepted, and running
unit tests from current directory works for me.

Also adding LIB_MODE=shared to Travis. (Later TBD where best to fit in
in CircleCI.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7066

Test Plan: manual

Reviewed By: cheng-chang

Differential Revision: D22364068

Pulled By: pdillinger

fbshipit-source-id: 6fa98a222f89f808ee786474de1100d92c1adec3

Summary:
Adds the function `RocksDB#rocksdbVersion()` for retrieving the RocksDB version.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7083

Reviewed By: cheng-chang

Differential Revision: D22391628

Pulled By: pdillinger

fbshipit-source-id: e1cabcf28aa81f5ee8dcdce5c9eca6b3155a279e

Summary:
If the corruption of a table file is done before flushing, then db manifest may record the checksum for the corrupted table, which results in "matching checksums" when backup engine tries to verfiy the checksum, and causes a flaky test.

Fix the issue by adding `Flush()` before trying to corrupt a table file in *db*.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7082

Test Plan:
`buck test`
Without the fix, failed 5 of 100 tests.
Suspected whether the pseudo randomness causes the issue: doubling `keys_iteration` resulted in 2 of 100 tests failed; deterministically corrupting tables file also caused 2 of 100 tests to fail.
With the fix, passed 200 of 200 tests.

Reviewed By: pdillinger

Differential Revision: D22375421

Pulled By: gg814

fbshipit-source-id: 7304618e7520684b6087e42d0b58329c5ad18329

Summary:
The issue is introduced by https://github.com/facebook/rocksdb/issues/7067

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7077

Test Plan: `make release`

Reviewed By: pdillinger

Differential Revision: D22370835

Pulled By: jay-zhuang

fbshipit-source-id: 44326bae07809c4518371b6a7d1f47124e24a4f3

Summary:
This is to fix special logic to run tests inside FB.
Buck test is broken after moving to cpp_unittest(). Move c_test back to the previous approach.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7076

Test Plan: Watch the Sandcastle run

Reviewed By: ajkr

Differential Revision: D22370096

fbshipit-source-id: 4a464d0903f2c76ae2de3a8ad373ffc9bedec64c

Summary:
Replace `reinterpret_cast` with `static_cast_with_check` for `DBImpl` and `ColumnFamilyHandleImpl`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7067

Reviewed By: siying

Differential Revision: D22361587

Pulled By: jay-zhuang

fbshipit-source-id: dfe9e8f3af39c3d27cc372c55ab9ad905eb0a5a1

Summary:
When table file checksums are enabled and stored in the DB manifest by using the RocksDB default crc32c checksum function, BackupEngine will calculate the crc32c checksum of the file to be copied and compare the calculated result with the one stored in the DB manifest before copying the file to the backup directory.

After copying to the backup directory, BackupEngine will verify the checksum of the copied file with the one calculated before copying. This helps detect some rare corruption events such as bit-flips during the copying process.

No verification with checksums in DB manifest will be performed if the table file checksum function is not the RocksDB default crc32c checksum function.

In addition, If `share_table_files` and `share_files_with_checksum` are true, BackupEngine will compare the checksums computed before and after copying of the table files.

Corresponding tests are added.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7015

Test Plan: Passed make check

Reviewed By: pdillinger

Differential Revision: D22165732

Pulled By: gg814

fbshipit-source-id: ee0e8cc397c455eba64545c29380b9d9853588ec

Summary:
Even though local bisection gave me a clear signal (and still does) that reverting https://github.com/facebook/rocksdb/issues/7049 would fix the failures in MultiThreadedDBTest, https://github.com/facebook/rocksdb/issues/7022 seems to be the root cause. Reverting https://github.com/facebook/rocksdb/issues/7022 and keeping https://github.com/facebook/rocksdb/issues/7049 seems to fix the issue in local reproducer also. (Had these landed in opposite order, bisection would have found the root cause.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7071

Reviewed By: akankshamahajan15

Differential Revision: D22362857

Pulled By: pdillinger

fbshipit-source-id: ed63df3d74e9d4ce1604de8fe43b216166c7a3f0

Summary:
This reverts commit 4f1534bd.

This commit caused failures and deadlocks in
MultiThreadedDBTest.MultiThreaded/69 and others.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7070

Reviewed By: riversand963

Differential Revision: D22358778

Pulled By: pdillinger

fbshipit-source-id: faf8f2cb469a7063a113921c8e9c64a9f7610dac

Summary:
After https://github.com/facebook/rocksdb/pull/7036, we still see extra DBTest that can timeout when running 10 or 20 in parallel. Expand skip-fsync mode in whole DBTest. Still preserve other tests from doing this mode to be conservative.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7049

Test Plan: Run all existing files.

Reviewed By: pdillinger

Differential Revision: D22301700

fbshipit-source-id: f9a9e3b3b26ce640665a47cb8bff33ba0c89b565

Summary:
GetFileDbIdentities requires either db_id non-null or db_session_id non-null.
Passing nullptr for db_id or db_session_id in CopyOrCreateFile indicates the caller does not want to obtain the value for db_id or db_session_id.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7063

Test Plan:
USE_CLANG=1 make analyze
backupable_db_test

Reviewed By: pdillinger

Differential Revision: D22338497

Pulled By: gg814

fbshipit-source-id: 2aa2dcc14d156b0f99b07d6cf3c731ee088272cd

Update Flush policy in PartitionedIndexBuilder on switching from user-key to internal-key mode (#7022)

Summary:
When format_version is high enough to support user-key and there are index entries for same user key that spans multiple data blocks then it changes from user-key mode to internal-key mode. But the flush policy is not reset to point to Block Builder of internal-keys. After this switch, no entries are added to user key index partition result, thus it never triggers flushing the block.

Fix: After adding the entry in sub_builder_index_, if there is a switch from user-key to internal-key, then flush policy is updated to point to Block Builder of internal-keys index partition.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7022

Test Plan:
1. make check -j64
           2. Added one unit test case

Reviewed By: ajkr

Differential Revision: D22197734

Pulled By: akankshamahajan15

fbshipit-source-id: d87e9e46bccab8e896ee6979d6b79c51f73d479e

Summary:
This check is flaky because compaction could run between the `Flush()` and the `TestGetTickerCount()`, which would increase the `BLOCK_CACHE_INDEX_MISS` count beyond what the test expects. Verified by adding a `sleep(1)` between those two lines and observing the counter is too high every time. The solution is just to remove this check as it doesn't have any use anyways. The latter check of index miss is sufficient to conclude the newest L0 file (i.e., the one generated by intra-L0) does not have its index block pinned in cache. It'd be nice to simultaneously check the L0 files generated by flush do have their index blocks pinned in cache, but that's not what the line deleted in this PR was checking..
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7065

Reviewed By: pdillinger

Differential Revision: D22340327

Pulled By: ajkr

fbshipit-source-id: e076b2c7228b7fa763dd0c0cb13828e176c1abee

Summary:
Random memtable layouts could cause random failure,
reproducible with command below running for a while. Test now using
deterministic behavior.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7064

Test Plan: while ./db_test --gtest_filter=*SizesMemTable*; do true; done

Reviewed By: siying

Differential Revision: D22339442

Pulled By: pdillinger

fbshipit-source-id: 8e74e5a9b5e88f7030854045a22c12cf561d5de6

Summary:
Follow-up to https://github.com/facebook/rocksdb/issues/6660. Release build had linker error. fbcode+clang+shared build was erroring on unused parameter '-nostdinc'.

Fixes https://github.com/facebook/rocksdb/issues/7061

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7062

Test Plan: make release, USE_CLANG=1 LIB_MODE=shared make check, etc.

Reviewed By: siying

Differential Revision: D22335663

Pulled By: pdillinger

fbshipit-source-id: 261cd959ca1f6c273dc763a70020a535ba8e81de

Summary:
Change the linking of tests/tools to be against a library rather than a list of objects.  This change substantially reduces the size of the objects produced.

peterd clean repo size: 264M
Before this change, with make all: 40G
After this change, with make all: 28G
With make LIB_MODE=shared all: 7.0G

The list of TESTS was changed from being hard-coded to generated from the test sources variable.  Note that there are some test sources that are not built as tests (though the set of tests is identical to the previous version).

Added OBJ_DIR option to Makefile to allow objects to be placed in an alternative location.  By default, OBJ_DIR is the same as before ("./").

This change is a precursor to being able to build/run the tests/tools linked against static libraries.  Additionally, it should be possible to clean up and merge some of the rules for building tests and the like if so desired.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6660

Reviewed By: riversand963

Differential Revision: D22244463

Pulled By: pdillinger

fbshipit-source-id: db9c6341d81ed62c2270374f4ede02fb9604c754

Generalize BackupEngine naming option for share_files_with_checksum SSTs and revert BackupEngine::VerifyBackup to check only file sizes by default (#7032)

Summary:
`bool BackupableDBOptions::new_naming_for_backup_files` is updated to `BackupTableNameOption BackupableDBOptions::share_files_with_checksum_naming`, where `BackupTableNameOption` is an `enum` type with two enumerators `kChecksumAndFileSize` and `kChecksumAndFileSize`. This opens up possibilities of extenting the current naming scheme for backup table files. By default, `BackupTableNameOption BackupableDBOptions::share_files_with_checksum_naming` is set to `kChecksumAndDbSessionId`.

Revert `BackupEngine::VerifyBackup` to only check file sizes by default.

Also fix the construction of the `SstFileDumper` in `GetFileDbIdentities` by setting a proper `Env` of the `Options` passed in the constructor.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7032

Test Plan: make check

Reviewed By: ajkr

Differential Revision: D22237763

Pulled By: gg814

fbshipit-source-id: 466902a4e731babd64e30f0e82ca1aa82962e52e

Summary:
As title.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7057

Test Plan: ./tools/check_format_compatible.sh

Reviewed By: pdillinger

Differential Revision: D22319831

Pulled By: riversand963

fbshipit-source-id: 82653a525a5296ef65a6a7a439cdd6bff88f498e

Summary:
With mmap enabled on an uncompressed file, we were previously always doing a heap allocation to obtain the scratch buffer for `RandomAccessFileReader::Read()`. However, that allocation was unnecessary as the underlying file reader returned a pointer into its mapped memory, not the provided scratch buffer. This PR makes passes the `BlockFetcher`'s inline buffer as the scratch buffer if the data block is small enough (less than `kDefaultStackBufferSize` bytes, currently 5000). Ideally we would not pass a scratch buffer at all for an mmap read; however, the `RandomAccessFile::Read()` API guarantees such a buffer is provided, and non-standard implementations may be relying on it even when `Options::allow_mmap_reads == true`. In that case, this PR still works but introduces an extra copy from the inline buffer to a heap buffer.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7043

Reviewed By: cheng-chang

Differential Revision: D22320606

Pulled By: ajkr

fbshipit-source-id: ad964dd23df34e07d979c6032c2dfe5454c98b52

Summary:
The earlier `VersionBuilder` code only cleaned up blob files that were
marked as entirely consisting of garbage using `VersionEdits` with
`BlobFileGarbage`. This covers the cases when table files go through
regular compaction, where we iterate through the KVs and thus have an
opportunity to calculate the amount of garbage (that is, most cases).
However, it does not help when table files are simply dropped (e.g. deletion
compactions or the `DeleteFile` API). To deal with such cases, the patch
adds logic that cleans up all blob files at the head of the list until the first
one with linked SSTs is found. (As an example, let's assume we have blob files
with numbers 1..10, and the first one with any linked SSTs is number 8.
This means that SSTs in the `Version` only rely on blob files with numbers >= 8,
and thus 1..7 are no longer needed.)

The code change itself is pretty small; however, changing the logic like this
necessitated changes to some tests that have been added recently (namely
to the ones that use blob files in isolation, i.e. without any table files referring
to them). Some of these cases were fixed by bypassing `VersionBuilder` altogether
in order to keep the tests simple (which actually makes them more proper unit tests
as well), while the `VersionBuilder` unit tests were fixed by adding dummy table
files to the test cases as needed.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7001

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D22119474

Pulled By: ltamasi

fbshipit-source-id: c6547141355667d4291d9661d6518eb741e7b54a

Summary:
as title.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7059

Test Plan: ./tools/check_format_compatible.sh

Reviewed By: siying

Differential Revision: D22320774

Pulled By: riversand963

fbshipit-source-id: 124d13b08703d077a7aab3678e1eb639fcbcceca

Summary:
There are errors like `Transaction put: Operation timed out: Timeout waiting to lock key
terminate called without an active exception`, based on experiment on devserver, increasing timeouts can resolve the issue.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7056

Test Plan: watch stress test with txn.

Reviewed By: anand1976

Differential Revision: D22317265

Pulled By: cheng-chang

fbshipit-source-id: 2dc3352def5e78d2c39a18d7262a3a65ca98bbba