Room | Android Developers

The Room persistence library provides an abstraction layer over SQLite to allow for more robust database access while harnessing the full power of SQLite. See the reference docs for more information.

Declaring dependencies

To add a dependency on Room, you must add the Google Maven repository to your project. Read Google's Maven repository for more information.

Dependencies for Room include testing Room migrations and Room RxJava

Add the dependencies for the artifacts you need in the build.gradle file for your app or module:

dependencies {
    def room_version = "2.1.0-alpha04"

    implementation "androidx.room:room-runtime:$room_version"
    annotationProcessor "androidx.room:room-compiler:$room_version" // For Kotlin use kapt instead of annotationProcessor

    // optional - RxJava support for Room
    implementation "androidx.room:room-rxjava2:$room_version"

    // optional - Guava support for Room, including Optional and ListenableFuture
    implementation "androidx.room:room-guava:$room_version"

    // optional - Coroutines support for Room
    implementation "androidx.room:room-coroutines:$room_version"

    // Test helpers
    testImplementation "androidx.room:room-testing:$room_version"
}

For more information about dependencies, see Add Build Dependencies.

Version 2.1.0-alpha04

January 25, 2019

New Features

DAO methods annotated with @Query containing INSERT, UPDATE or DELETE statements can now return async types Single, Mayble, Completable and ListenableFuture. Additionally they can also be suspend functions. b/120227284

API / Behavior Changes

Room will now throw an error if a non-abstract DAO method annotated with @Transaction returns an async type such as Single, Mayble, Completable, LiveData or ListenableFuture. Since transactions are thread confined it is currently impossible for Room to begin and end a transaction around a function that may peform queries in different threads. b/120109336
OnConflictStrategy.FAIL and OnConflictStrategy.ROLLBACK have been @Deprecated since they do not behave as intended with Android's current SQLite bindings. b/117266738

Bug Fixes

Fixed a bug where Room wouldn't correctly use the TypeConverter of a return type if the DAO method was a suspend function. b/122988159
Fixed a bug where Room would incorrectly identify inherited suspend functions as non-suspending. b/122902595
Fixed a bug where Room would generate incorrect code when an @Embedded field was in a parent class and used in multiple child classes. b/121099048
Fixed an issue where the database would deadlock when invoking DAO suspend functions between a beginTransaction() and endTransaction(). b/120854786

Version 2.1.0-alpha03

December 4, 2018

API Changes

The FTS tokenizer in @Fts3/@Fts4 now takes a String instead of an Enum. This allows custom tokenizers to be used by Room. Built-in tokenizers are still defined in FtsOptions as string constants. b/119234881

New Features

Couroutines: DAO methods can now be suspend functions. To support suspend functions in Room a new artifact has been released, room-coroutines. b/69474692
DAO methods annotated with @Insert, @Delete or @Update now support ListenableFuture as return type. b/119418331

Bug Fixes

Fixed a bug where Room would incorrectly attempt to find a constructor with columns in the ignoredColumns property of @Entity. b/119830714
Fixed a bug where Room would not mark DAO method parameters as final in their generated implementation. b/118015483
Fixed a bug where Room's processor would crash when reporting an error on a query with special symbols. b/119520136
Fixed a bug where Room would decline other various Collection implementations as arguments of an IN expression. b/119884035
Fixed a bug where LiveData returned from Room would get garbage collected when observed forever causing it to no longer emit new data. b/74477406
Updated RoomDatabase's close lock to reduce lock contention. b/117900450

Version 2.1.0-alpha02

October 30, 2018

New Features

Added support for referencing a @DatabaseView in a @Relation. b/117680932

Bug Fixes

Fixed a bug where Room would perform disk I/O in the main thread when subscribing and disposing from an Rx return type. b/117201279
Fixed a bug where Room would fail to find an appropriate type converter for a field in a Kotlin entity class. b/111404868
Fixed a bug where Room would generate incorrect code for a DAO interface implementation containing a Kotlin default method that has no arguments. b/117527454
Updated Room's SQLite grammar parser, fixing a performance issue that would cause long build times. b/117401230

Version 2.1.0-alpha01

October 8, 2018

New Features

FTS: Room now supports entities with a mapping FTS3 or FTS4 table. Classes annotated with @Entity can now be additionally annotated with @Fts3 or @Fts4 to declare a class with a mapping full-text search table. FTS options for further customization are available via the annotation’s methods. b/62356416
Views: Room now supports declaring a class as a stored query, also known as a view using the @DatabaseView annotation. b/67033276
Auto Value: Room now supports declaring AutoValue annotated classes as entities and POJOs. The Room annotations @PrimaryKey, @ColumnInfo, @Embedded and @Relation can now be declared in an auto value annotated class’ abstract methods. Note that these annotation must also be accompanied by @CopyAnnotations for Room to properly understand them. b/62408420
Additional Rx Return Types Support: DAO methods annotated with @Insert, @Delete or @Update now support Rx return types Completable, Single<T> and Maybe<T>. b/63317956
Immutable Types with @Relation: Room previously required @Relation annotated fields to be settable but now they can be constructor parameters.
enableMultiInstanceInvalidation: Is a new API in RoomDatabase.Builder to enable invalidation across multiple instances of RoomDatabase using the same database file. This multi-instance invalidation mechanism also works across multiple processes. b/62334005
fallbackToDestructiveMigrationOnDowngrade: Is a new API in RoomDatabase.Builder to automatically re-create the database if a downgrade happens. b/110416954
ignoredColumns: Is a new API in the @Entity annotation that can be used to list ignored fields by name. Useful for ignoring inherited fields on an entity. b/63522075

API / Behavior Changes

mCallback and mDatabase in RoomDatabase are now @Deprecated and will be removed in the next major version of Room. b/76109329

Bug Fixes

Fixed two issues where Room wouldn’t properly recover from a corrupted database or a bad migration during initialization. b/111504749 and b/111519144
Room will now properly use Kotlin’s primary constructor in data classes avoiding the need to declare the fields as vars. b/105769985

Version 2.0.0-beta01

July 2, 2018

API / Behavior Changes

Added RoomDatabase.Builder.setQueryExecutor() to allow customization of where queries are run
Added RxJava2 Observable support
Generated DAO and Database implementations are now final

Bug Fixes

Specify class/field name in "cannot find getter for field" error b/73334503
Fixed RoomOpenHelper backwards compatibility with older versions of Room b/110197391

Pre-AndroidX Dependencies

For the pre-AndroidX versions of Room, include these dependencies:

dependencies {
    def room_version = "1.1.1"

    implementation "android.arch.persistence.room:runtime:$room_version"
    annotationProcessor "android.arch.persistence.room:compiler:$room_version" // For Kotlin use kapt instead of annotationProcessor

    // optional - RxJava support for Room
    implementation "android.arch.persistence.room:rxjava2:$room_version"

    // optional - Guava support for Room, including Optional and ListenableFuture
    implementation "android.arch.persistence.room:guava:$room_version"

    // Test helpers
    testImplementation "android.arch.persistence.room:testing:$room_version"
}

Version 1.1.1

June 19, 2018

Room 1.1.1 is identical to Room 1.1.1-rc1.

Version 1.1.1-rc1

May 16, 2018 We highly recommend using Room 1.1.1-rc1 instead of 1.1.0 if you are using migrations.

Fixed a bug where Room would not handle post migration initialization properly b/79362399

Version 1.1.0-beta3

April 19, 2018

Bug Fixes

Fix compilation error when a Kotlin POJO references a relation entity that was defined in Java b/78199923

Version 1.1.0-beta2

April 5, 2018

Bug Fixes

Fixed a critical bug in Room's Rx Single and Maybe implementations where it would recycle the query ahead of time, causing problems if you add more than 1 observer to the returned Single or Maybe instancces. b/76031240
[RoomDatabase.clearAllTables][ref-clearAllTables] will not VACUUM the database if it is called inside a transaction. b/77235565

Version 1.1.0-beta1

March 21, 2018

API Changes

Based on API Review feedback, @RawQuery does not accept passing a String as the query parameter anymore. You need to use [SupportSQLiteQuery][ref-SupportSQLiteQuery]. (see [SimpleSQLiteQuery][ref-SimpleSQLiteQuery] to easily create an instance of [SupportSQLiteQuery][ref-SupportSQLiteQuery] with argument support).
RoomDatabase.Builder's [fallbackToDestructiveMigrationFrom][ref-fallbackToDestructiveMigrationFrom] method now accepts vararg int instead of vararg Integer.

Bug Fixes

[RoomDatabase.clearAllTables][ref-clearAllTables] now tries to return space back to the operating system by setting a WAL checkpoint and VACUUMing the database.
[@RawQuery][ref-RawQuery] now accepts any Pojo for the observedEntities property as long as the Pojo references to one or more entities via its Embedded fields or Relations. b/74041772
Paging: Room’s DataSource implementation now correctly handles multi-table dependencies (such as relations, and joins). Previously these would fail to trigger new results, or could fail to compile. b/74128314

Version 1.1.0-alpha1

January 22, 2018

New Features

RawQuery: This new API allows @Dao methods to receive the SQL as a query parameter b/62103290, b/71458963
fallBackToDestructiveMigrationsFrom: This new API in RoomDatabase.Builder allows for finer grained control over from which starting schema versions destructive migrations are allowed (as compared to fallbackToDestructiveMigration) b/64989640
Room now only supports newer Paging APIs (alpha-4+), dropping support for the deprecated LivePagedListProvider. To use the new Room alpha, you’ll need to use paging alpha-4 or higher, and switch from LivePagedListProvider to LivePagedListBuilder if you haven’t already.

Bug Fixes

Improved support for Kotlin Kapt types. b/69164099
Order of fields do not invalidate schema anymore. b/64290754