cc87075d63
Summary:
There is a hardcoded constraint in our statistics collection that prevents reading properties from more than 20 SST files. This means our statistics will be very inaccurate for databases with > 20 files since additional files are just ignored. The purpose of constraining the number of files used is to bound the I/O performed during statistics collection, since these statistics need to be recomputed every time the database reopened.
However, this constraint doesn't take into account the case where option "max_open_files" is -1. In that case, all the file metadata has already been read, so MaybeInitializeFileMetaData() won't incur any I/O cost. so this diff gets rid of the 20-file constraint in case max_open_files == -1.
Test Plan:
write into unit test db/db_properties_test.cc - "ValidateSampleNumber".
We generate 20 files with 2 rows and 10 files with 1 row.
If max_open_files !=-1, the `rocksdb.estimate-num-keys` should be (10*1 + 10*2)/20 * 30 = 45. Otherwise, it should be the ground truth, 50.
{F1089153}
Reviewers: andrewkr
Reviewed By: andrewkr
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D56253
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| arcanist_util | ||
| build_tools | ||
| coverage | ||
| db | ||
| doc | ||
| examples | ||
| hdfs | ||
| include/rocksdb | ||
| java | ||
| memtable | ||
| port | ||
| table | ||
| third-party | ||
| tools | ||
| util | ||
| utilities | ||
| .arcconfig | ||
| .clang-format | ||
| .gitignore | ||
| .travis.yml | ||
| appveyor.yml | ||
| AUTHORS | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| DEFAULT_OPTIONS_HISTORY.md | ||
| DUMP_FORMAT.md | ||
| HISTORY.md | ||
| INSTALL.md | ||
| LICENSE | ||
| Makefile | ||
| PATENTS | ||
| README.md | ||
| ROCKSDB_LITE.md | ||
| src.mk | ||
| thirdparty.inc | ||
| USERS.md | ||
| Vagrantfile | ||
| WINDOWS_PORT.md | ||
RocksDB: A Persistent Key-Value Store for Flash and RAM Storage
RocksDB is developed and maintained by Facebook Database Engineering Team. It is built on earlier work on LevelDB by Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com)
This code is a library that forms the core building block for a fast key value server, especially suited for storing data on flash drives. It has a Log-Structured-Merge-Database (LSM) design with flexible tradeoffs between Write-Amplification-Factor (WAF), Read-Amplification-Factor (RAF) and Space-Amplification-Factor (SAF). It has multi-threaded compactions, making it specially suitable for storing multiple terabytes of data in a single database.
Start with example usage here: https://github.com/facebook/rocksdb/tree/master/examples
See the github wiki for more explanation.
The public interface is in include/. Callers should not include or
rely on the details of any other header files in this package. Those
internal APIs may be changed without warning.
Design discussions are conducted in https://www.facebook.com/groups/rocksdb.dev/