7632fdb5cb
Summary: The compaction process takes some files from LevelK and merges it into LevelK+1. The number of files it picks from LevelK was capped such a way that the total amount of data picked does not exceed the maxfilesize of that level. This essentially meant that only one file from LevelK is picked for a single compaction. For bulkloads, we would like to take many many file from LevelK and compact them using a single compaction run. This patch introduces a option called the 'source_compaction_factor' (similar to expanded_compaction_factor). It is a multiplier that is multiplied by the maxfilesize of that level to arrive at the limit that is used to throttle the number of source files from LevelK. For bulk loads, set source_compaction_factor to a very high number so that multiple files from the same level are picked for compaction in a single compaction. The default value of source_compaction_factor is 1, so that we can keep backward compatibilty with existing compaction semantics. Test Plan: make clean check Reviewers: emayanke, sheki Reviewed By: emayanke CC: leveldb Differential Revision: https://reviews.facebook.net/D6867
leveldb: A key-value store
Authors: Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com)
The code under this directory implements a system for maintaining a
persistent key/value store.
See doc/index.html for more explanation.
See doc/impl.html for a brief overview of the implementation.
The public interface is in include/*.h. 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.
Guide to header files:
include/db.h
Main interface to the DB: Start here
include/options.h
Control over the behavior of an entire database, and also
control over the behavior of individual reads and writes.
include/comparator.h
Abstraction for user-specified comparison function. If you want
just bytewise comparison of keys, you can use the default comparator,
but clients can write their own comparator implementations if they
want custom ordering (e.g. to handle different character
encodings, etc.)
include/iterator.h
Interface for iterating over data. You can get an iterator
from a DB object.
include/write_batch.h
Interface for atomically applying multiple updates to a database.
include/slice.h
A simple module for maintaining a pointer and a length into some
other byte array.
include/status.h
Status is returned from many of the public interfaces and is used
to report success and various kinds of errors.
include/env.h
Abstraction of the OS environment. A posix implementation of
this interface is in util/env_posix.cc
include/table.h
include/table_builder.h
Lower-level modules that most clients probably won't use directly