sdong
13dc9c7f56
Use a different approach to make sure BlockBasedTableReader can use hash index on older files
Summary:
A recent commit e37dd216f9
makes sure hash index can be used when reading existing files. This patch uses another way to achieve the approach:
(1) Currently, always writing kBinarySearch to files, despite of BlockBasedTableOptions.IndexType setting.
(2) When reading a file, read out the field, and make sure it is kBinarySearch, while always use index type by users.
The reason for doing it is, to reserve kHashSearch property on disk to future. If now we write out binary index for both of kHashSearch and kBinarySearch. We have to use a new flag in the future for hash index on disk, otherwise compatibility would break. Also, we want the real index type and type shown in properties block to be consistent.
Test Plan: make all check
Reviewers: haobo, kailiu
Reviewed By: kailiu
CC: igor, ljin, yhchiang, xjin, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D18009
Conflicts:
table/block_based_table_reader.cc
rocksdb: A persistent key-value store for flash storage Authors: * The Facebook Database Engineering Team * Build 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 an 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. The core of this code has been derived from open-source leveldb. The code under this directory implements a system for maintaining a persistent key/value store. See doc/index.html and github wiki (https://github.com/facebook/rocksdb/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. Guide to header files: include/rocksdb/db.h Main interface to the DB: Start here include/rocksdb/options.h Control over the behavior of an entire database, and also control over the behavior of individual reads and writes. include/rocksdb/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/rocksdb/iterator.h Interface for iterating over data. You can get an iterator from a DB object. include/rocksdb/write_batch.h Interface for atomically applying multiple updates to a database. include/rocksdb/slice.h A simple module for maintaining a pointer and a length into some other byte array. include/rocksdb/status.h Status is returned from many of the public interfaces and is used to report success and various kinds of errors. include/rocksdb/env.h Abstraction of the OS environment. A posix implementation of this interface is in util/env_posix.cc include/rocksdb/table_builder.h Lower-level modules that most clients probably won't use directly include/rocksdb/cache.h An API for the block cache. include/rocksdb/compaction_filter.h An API for a application filter invoked on every compaction. include/rocksdb/filter_policy.h An API for configuring a bloom filter. include/rocksdb/memtablerep.h An API for implementing a memtable. include/rocksdb/statistics.h An API to retrieve various database statistics. include/rocksdb/transaction_log.h An API to retrieve transaction logs from a database. Design discussions are conducted in https://www.facebook.com/groups/rocksdb.dev/
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