rocksdb/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
* No Transactions

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. :)
RocksDBLite Summary: Introducing RocksDBLite! Removes all the non-essential features and reduces the binary size. This effort should help our adoption on mobile. Binary size when compiling for IOS (`TARGET_OS=IOS m static_lib`) is down to 9MB from 15MB (without stripping) Test Plan: compiles :) Reviewers: dhruba, haobo, ljin, sdong, yhchiang Reviewed By: yhchiang CC: leveldb Differential Revision: https://reviews.facebook.net/D17835 2014-04-15 22:39:26 +02:00			`# 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`
Optimistic Transactions Summary: Optimistic transactions supporting begin/commit/rollback semantics. Currently relies on checking the memtable to determine if there are any collisions at commit time. Not yet implemented would be a way of enuring the memtable has some minimum amount of history so that we won't fail to commit when the memtable is empty. You should probably start with transaction.h to get an overview of what is currently supported. Test Plan: Added a new test, but still need to look into stress testing. Reviewers: yhchiang, igor, rven, sdong Reviewed By: sdong Subscribers: adamretter, MarkCallaghan, leveldb, dhruba Differential Revision: https://reviews.facebook.net/D33435 2015-05-29 23:36:35 +02:00			`* No Transactions`
RocksDBLite Summary: Introducing RocksDBLite! Removes all the non-essential features and reduces the binary size. This effort should help our adoption on mobile. Binary size when compiling for IOS (`TARGET_OS=IOS m static_lib`) is down to 9MB from 15MB (without stripping) Test Plan: compiles :) Reviewers: dhruba, haobo, ljin, sdong, yhchiang Reviewed By: yhchiang CC: leveldb Differential Revision: https://reviews.facebook.net/D17835 2014-04-15 22:39:26 +02:00
			`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. :)`