Summary: The method Version::GetOverlappingInputs used a sequential search to map a kay-range to a set of files. But the files are arranged in ascending order of key, so a biary search is more effective. This patch implements Version::GetOverlappingInputsBinarySearch that finds one file that corresponds to the specified key range and then iterates backwards and forwards to find all overlapping files. This patch is critical for making compactions efficient, especially when there are thousands of files in a single level. I measured that 1000 iterations of TEST_MaxNextLevelOverlappingBytes takes 16000 microseconds without this patch. With this patch, the same method takes about 4600 microseconds. Test Plan: Almost all unit tests in db_test uses this method to lookup keys. Reviewers: heyongqiang Reviewed By: heyongqiang CC: MarkCallaghan, emayanke, sheki Differential Revision: https://reviews.facebook.net/D6465
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
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