Revision cadc1adffa447f02eb65bd848cf26c13142a74bb authored by sdong on 13 June 2014, 22:54:19 UTC, committed by sdong on 16 June 2014, 23:10:52 UTC
Summary:
We added multiple fields to FileMetaData recently and are planning to add more.
This refactoring separate the minimum information for accessing the file. This object is copyable (FileMetaData is not copyable since the ref counter). I hope this refactoring can enable further improvements:

(1) use it to design a more efficient data structure to speed up read queries.
(2) in the future, when we add information of storage level, we can easily do the encoding, instead of enlarge this structure, which might expand memory work set for file meta data.

The definition is same as current EncodedFileMetaData used in two level iterator, so now the logic in two level iterator is easier to understand.

Test Plan: make all check

Reviewers: haobo, igor, ljin

Reviewed By: ljin

Subscribers: leveldb, dhruba, yhchiang

Differential Revision: https://reviews.facebook.net/D18933
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Raw File
ROCKSDB_LITE.md
# RocksDBLite

RocksDBLite is a project focused on mobile use cases, which don't need a lot of fancy things we've built for server workloads and they are very sensitive to binary size. For that reason, we added a compile flag ROCKSDB_LITE that comments out a lot of the nonessential code and keeps the binary lean.

Some examples of the features disabled by ROCKSDB_LITE:
* compiled-in support for LDB tool
* No backupable DB
* No support for replication (which we provide in form of TrasactionalIterator)
* No advanced monitoring tools
* No special-purpose memtables that are highly optimized for specific use cases

When adding a new big feature to RocksDB, please add ROCKSDB_LITE compile guard if:
* Nobody from mobile really needs your feature,
* Your feature is adding a lot of weight to the binary.

Don't add ROCKSDB_LITE compile guard if:
* It would introduce a lot of code complexity. Compile guards make code harder to read. It's a trade-off.
* Your feature is not adding a lot of weight.

If unsure, ask. :)
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