SupportSQLiteDatabase

abstract void beginTransaction()

Begins a transaction in EXCLUSIVE mode.

Transactions can be nested. When the outer transaction is ended all of the work done in that transaction and all of the nested transactions will be committed or rolled back. The changes will be rolled back if any transaction is ended without being marked as clean (by calling setTransactionSuccessful). Otherwise they will be committed.

Here is the standard idiom for transactions:

db.beginTransaction()
try {
    ...
    db.setTransactionSuccessful()
} finally {
    db.endTransaction()
}

abstract void beginTransactionNonExclusive()

Begins a transaction in IMMEDIATE mode. Transactions can be nested. When the outer transaction is ended all of the work done in that transaction and all of the nested transactions will be committed or rolled back. The changes will be rolled back if any transaction is ended without being marked as clean (by calling setTransactionSuccessful). Otherwise they will be committed.

Here is the standard idiom for transactions:

db.beginTransactionNonExclusive()
try {
    ...
    db.setTransactionSuccessful()
} finally {
    db.endTransaction()
}

default void beginTransactionReadOnly()

Begins a transaction in DEFERRED mode, with the android-specific constraint that the transaction is read-only. The database may not be modified inside a read-only transaction otherwise a android.database.sqlite.SQLiteDatabaseLockedException might be thrown.

Read-only transactions may run concurrently with other read-only transactions, and if they database is in WAL mode, they may also run concurrently with IMMEDIATE or EXCLUSIVE transactions.

Transactions can be nested. However, the behavior of the transaction is not altered by nested transactions. A nested transaction may be any of the three transaction types but if the outermost type is read-only then nested transactions remain read-only, regardless of how they are started.

Here is the standard idiom for read-only transactions:

db.beginTransactionReadOnly();
try {
  ...
} finally {
  db.endTransaction();
}

If the implementation does not support read-only transactions then the default implementation delegates to beginTransaction.

abstract void beginTransactionWithListener(
    @NonNull SQLiteTransactionListener transactionListener
)

Begins a transaction in EXCLUSIVE mode.

Transactions can be nested. When the outer transaction is ended all of the work done in that transaction and all of the nested transactions will be committed or rolled back. The changes will be rolled back if any transaction is ended without being marked as clean (by calling setTransactionSuccessful). Otherwise they will be committed.

Here is the standard idiom for transactions:

db.beginTransactionWithListener(listener)
try {
    ...
    db.setTransactionSuccessful()
} finally {
    db.endTransaction()
}

abstract void beginTransactionWithListenerNonExclusive(
    @NonNull SQLiteTransactionListener transactionListener
)

Begins a transaction in IMMEDIATE mode. Transactions can be nested. When the outer transaction is ended all of the work done in that transaction and all of the nested transactions will be committed or rolled back. The changes will be rolled back if any transaction is ended without being marked as clean (by calling setTransactionSuccessful). Otherwise they will be committed.

Here is the standard idiom for transactions:

db.beginTransactionWithListenerNonExclusive(listener)
try {
    ...
    db.setTransactionSuccessful()
} finally {
    db.endTransaction()
}

default void beginTransactionWithListenerReadOnly(
    @NonNull SQLiteTransactionListener transactionListener
)

Begins a transaction in read-only mode with a {@link SQLiteTransactionListener} listener. The database may not be modified inside a read-only transaction otherwise a android.database.sqlite.SQLiteDatabaseLockedException might be thrown.

Transactions can be nested. However, the behavior of the transaction is not altered by nested transactions. A nested transaction may be any of the three transaction types but if the outermost type is read-only then nested transactions remain read-only, regardless of how they are started.

Here is the standard idiom for read-only transactions:

db.beginTransactionWightListenerReadOnly(listener);
try {
  ...
} finally {
  db.endTransaction();
}

If the implementation does not support read-only transactions then the default implementation delegates to beginTransactionWithListener.

abstract @NonNull SupportSQLiteStatement compileStatement(@NonNull String sql)

Compiles the given SQL statement.

abstract int delete(@NonNull String table, String whereClause, Object[] whereArgs)

Convenience method for deleting rows in the database.

abstract void disableWriteAheadLogging()

This method disables the features enabled by enableWriteAheadLogging.

abstract boolean enableWriteAheadLogging()

This method enables parallel execution of queries from multiple threads on the same database. It does this by opening multiple connections to the database and using a different database connection for each query. The database journal mode is also changed to enable writes to proceed concurrently with reads.

When write-ahead logging is not enabled (the default), it is not possible for reads and writes to occur on the database at the same time. Before modifying the database, the writer implicitly acquires an exclusive lock on the database which prevents readers from accessing the database until the write is completed.

In contrast, when write-ahead logging is enabled (by calling this method), write operations occur in a separate log file which allows reads to proceed concurrently. While a write is in progress, readers on other threads will perceive the state of the database as it was before the write began. When the write completes, readers on other threads will then perceive the new state of the database.

It is a good idea to enable write-ahead logging whenever a database will be concurrently accessed and modified by multiple threads at the same time. However, write-ahead logging uses significantly more memory than ordinary journaling because there are multiple connections to the same database. So if a database will only be used by a single thread, or if optimizing concurrency is not very important, then write-ahead logging should be disabled.

After calling this method, execution of queries in parallel is enabled as long as the database remains open. To disable execution of queries in parallel, either call disableWriteAheadLogging or close the database and reopen it.

The maximum number of connections used to execute queries in parallel is dependent upon the device memory and possibly other properties.

If a query is part of a transaction, then it is executed on the same database handle the transaction was begun.

Writers should use beginTransactionNonExclusive or beginTransactionWithListenerNonExclusive to start a transaction. Non-exclusive mode allows database file to be in readable by other threads executing queries.

If the database has any attached databases, then execution of queries in parallel is NOT possible. Likewise, write-ahead logging is not supported for read-only databases or memory databases. In such cases, enableWriteAheadLogging returns false.

The best way to enable write-ahead logging is to pass the android.database.sqlite.SQLiteDatabase.ENABLE_WRITE_AHEAD_LOGGING flag to android.database.sqlite.SQLiteDatabase.openDatabase. This is more efficient than calling

SQLiteDatabase db = SQLiteDatabase.openDatabase("db_filename", cursorFactory, SQLiteDatabase.CREATE_IF_NECESSARY | SQLiteDatabase.ENABLE_WRITE_AHEAD_LOGGING, myDatabaseErrorHandler) db.enableWriteAheadLogging()

Another way to enable write-ahead logging is to call enableWriteAheadLogging after opening the database.

SQLiteDatabase db = SQLiteDatabase.openDatabase("db_filename", cursorFactory, SQLiteDatabase.CREATE_IF_NECESSARY, myDatabaseErrorHandler) db.enableWriteAheadLogging()

See also SQLite Write-Ahead Logging for more details about how write-ahead logging works.

abstract void endTransaction()

End a transaction. See beginTransaction for notes about how to use this and when transactions are committed and rolled back.

default void execPerConnectionSQL(@NonNull String sql, Object[] bindArgs)

Execute the given SQL statement on all connections to this database.

This statement will be immediately executed on all existing connections, and will be automatically executed on all future connections.

Some example usages are changes like PRAGMA trusted_schema=OFF or functions like SELECT icu_load_collation(). If you execute these statements using execSQL then they will only apply to a single database connection; using this method will ensure that they are uniformly applied to all current and future connections.

An implementation of SupportSQLiteDatabase might not support this operation. Use isExecPerConnectionSQLSupported to check if this operation is supported before calling this method.

abstract void execSQL(@NonNull String sql)

Execute a single SQL statement that does not return any data.

When using enableWriteAheadLogging, journal_mode is automatically managed by this class. So, do not set journal_mode using "PRAGMA journal_mode" statement if your app is using enableWriteAheadLogging

abstract void execSQL(@NonNull String sql, @NonNull Object[] bindArgs)

Execute a single SQL statement that does not return any data.

When using enableWriteAheadLogging, journal_mode is automatically managed by this class. So, do not set journal_mode using "PRAGMA journal_mode" statement if your app is using enableWriteAheadLogging