com.apple.foundationdb

Interface ReadTransaction

All Superinterfaces:

ReadTransactionContext

All Known Subinterfaces:

Transaction

public interface ReadTransaction
extends ReadTransactionContext

A read-only subset of a FoundationDB Transaction. This is the interface that Transaction's snapshot presents.

Note: Client must call Transaction.commit() and wait on the result on all transactions, even ones that only read. This is done automatically when using the retry loops from Database.run(Function). This is explained more in the intro to Transaction.

See Also:

Transaction

Field Summary

Fields

Modifier and Type	Field and Description
static int	ROW_LIMIT_UNLIMITED When passed to a getRange() call that takes a limit parameter, indicates that the query should return unlimited rows.

Method Summary

Modifier and Type	Method and Description
java.util.concurrent.CompletableFuture<byte[]>	get(byte[] key) Gets a value from the database.
java.util.concurrent.CompletableFuture<byte[]>	getKey(KeySelector selector) Returns the key referenced by the specified KeySelector.
AsyncIterable<KeyValue>	getRange(byte[] begin, byte[] end) Gets an ordered range of keys and values from the database.
AsyncIterable<KeyValue>	getRange(byte[] begin, byte[] end, int limit) Gets an ordered range of keys and values from the database.
AsyncIterable<KeyValue>	getRange(byte[] begin, byte[] end, int limit, boolean reverse) Gets an ordered range of keys and values from the database.
AsyncIterable<KeyValue>	getRange(byte[] begin, byte[] end, int limit, boolean reverse, StreamingMode mode) Gets an ordered range of keys and values from the database.
AsyncIterable<KeyValue>	getRange(KeySelector begin, KeySelector end) Gets an ordered range of keys and values from the database.
AsyncIterable<KeyValue>	getRange(KeySelector begin, KeySelector end, int limit) Gets an ordered range of keys and values from the database.
AsyncIterable<KeyValue>	getRange(KeySelector begin, KeySelector end, int limit, boolean reverse) Gets an ordered range of keys and values from the database.
AsyncIterable<KeyValue>	getRange(KeySelector begin, KeySelector end, int limit, boolean reverse, StreamingMode mode) Gets an ordered range of keys and values from the database.
AsyncIterable<KeyValue>	getRange(Range range) Gets an ordered range of keys and values from the database.
AsyncIterable<KeyValue>	getRange(Range range, int limit) Gets an ordered range of keys and values from the database.
AsyncIterable<KeyValue>	getRange(Range range, int limit, boolean reverse) Gets an ordered range of keys and values from the database.
AsyncIterable<KeyValue>	getRange(Range range, int limit, boolean reverse, StreamingMode mode) Gets an ordered range of keys and values from the database.
java.util.concurrent.CompletableFuture<java.lang.Long>	getReadVersion() Gets the version at which the reads for this Transaction will access the database.
TransactionOptions	options() Returns a set of options that can be set on a Transaction

Methods inherited from interface com.apple.foundationdb.ReadTransactionContext

getExecutor, read, readAsync

Field Detail

ROW_LIMIT_UNLIMITED

static final int ROW_LIMIT_UNLIMITED

When passed to a getRange() call that takes a limit parameter, indicates that the query should return unlimited rows.

See Also:

Constant Field Values

Method Detail

getReadVersion

java.util.concurrent.CompletableFuture<java.lang.Long> getReadVersion()

Gets the version at which the reads for this Transaction will access the database.

Returns:

the version for database reads

get

java.util.concurrent.CompletableFuture<byte[]> get(byte[] key)

Gets a value from the database. The call will return null if the key is not present in the database.

Parameters:

key - the key whose value to fetch from the database

Returns:

a CompletableFuture which will be set to the value corresponding to the key or to null if the key does not exist.

getKey

java.util.concurrent.CompletableFuture<byte[]> getKey(KeySelector selector)

Returns the key referenced by the specified KeySelector. By default, the key is cached for the duration of the transaction, providing a potential performance benefit. However, the value of the key is also retrieved, using network bandwidth. Invoking setReadYourWritesDisable will avoid both the caching and the increased network bandwidth.

Parameters:

selector - the relative key location to resolve

Returns:

a CompletableFuture which will be set to an absolute database key

See Also:

KeySelector

getRange

AsyncIterable<KeyValue> getRange(KeySelector begin,
                                 KeySelector end)

Gets an ordered range of keys and values from the database. The begin and end keys are specified by KeySelectors, with the begin KeySelector inclusive and the end KeySelector exclusive.

Parameters:

begin - the beginning of the range (inclusive)

end - the end of the range (exclusive)

Returns:

a handle to access the results of the asynchronous call

See Also:

KeySelector, AsyncIterator

getRange

AsyncIterable<KeyValue> getRange(KeySelector begin,
                                 KeySelector end,
                                 int limit)

Gets an ordered range of keys and values from the database. The begin and end keys are specified by KeySelectors, with the begin KeySelector inclusive and the end KeySelector exclusive.

Parameters:

begin - the beginning of the range (inclusive)

end - the end of the range (exclusive)

limit - the maximum number of results to return. Limits results to the first keys in the range. Pass ROW_LIMIT_UNLIMITED if this query should not limit the number of results.

Returns:

a handle to access the results of the asynchronous call

See Also:

KeySelector, AsyncIterator

getRange

AsyncIterable<KeyValue> getRange(KeySelector begin,
                                 KeySelector end,
                                 int limit,
                                 boolean reverse)

Gets an ordered range of keys and values from the database. The begin and end keys are specified by KeySelectors, with the begin KeySelector inclusive and the end KeySelector exclusive.

Parameters:

begin - the beginning of the range (inclusive)

end - the end of the range (exclusive)

limit - the maximum number of results to return. Limits results to the first keys in the range. Pass ROW_LIMIT_UNLIMITED if this query should not limit the number of results. If reverse is true rows will be limited starting at the end of the range.

reverse - return results starting at the end of the range in reverse order

Returns:

a handle to access the results of the asynchronous call

See Also:

KeySelector, AsyncIterator

getRange

AsyncIterable<KeyValue> getRange(KeySelector begin,
                                 KeySelector end,
                                 int limit,
                                 boolean reverse,
                                 StreamingMode mode)

Gets an ordered range of keys and values from the database. The begin and end keys are specified by KeySelectors, with the begin KeySelector inclusive and the end KeySelector exclusive.

Parameters:

begin - the beginning of the range (inclusive)

end - the end of the range (exclusive)

limit - the maximum number of results to return. Limits results to the first keys in the range. Pass ROW_LIMIT_UNLIMITED if this query should not limit the number of results. If reverse is true rows will be limited starting at the end of the range.

reverse - return results starting at the end of the range in reverse order

mode - provide a hint about how the results are to be used. This can provide speed improvements or efficiency gains based on the caller's knowledge of the upcoming access pattern.

Returns:

a handle to access the results of the asynchronous call

See Also:

KeySelector, AsyncIterator

getRange

AsyncIterable<KeyValue> getRange(byte[] begin,
                                 byte[] end)

Gets an ordered range of keys and values from the database. The begin and end keys are specified by byte[] arrays, with the begin key inclusive and the end key exclusive.

Parameters:

begin - the beginning of the range (inclusive)

end - the end of the range (exclusive)

Returns:

a handle to access the results of the asynchronous call

See Also:

KeySelector, AsyncIterator

getRange

AsyncIterable<KeyValue> getRange(byte[] begin,
                                 byte[] end,
                                 int limit)

Gets an ordered range of keys and values from the database. The begin and end keys are specified by byte[] arrays, with the begin key inclusive and the end key exclusive.

Parameters:

begin - the beginning of the range (inclusive)

end - the end of the range (exclusive)

limit - the maximum number of results to return. Limits results to the first keys in the range. Pass ROW_LIMIT_UNLIMITED if this query should not limit the number of results.

Returns:

a handle to access the results of the asynchronous call

See Also:

KeySelector, AsyncIterator

getRange

AsyncIterable<KeyValue> getRange(byte[] begin,
                                 byte[] end,
                                 int limit,
                                 boolean reverse)

Gets an ordered range of keys and values from the database. The begin and end keys are specified by byte[] arrays, with the begin key inclusive and the end key exclusive.

Parameters:

begin - the beginning of the range (inclusive)

end - the end of the range (exclusive)

limit - the maximum number of results to return. Limits results to the first keys in the range. Pass ROW_LIMIT_UNLIMITED if this query should not limit the number of results. If reverse is true rows will be limited starting at the end of the range.

reverse - return results starting at the end of the range in reverse order

Returns:

a handle to access the results of the asynchronous call

See Also:

KeySelector, AsyncIterator

getRange

AsyncIterable<KeyValue> getRange(byte[] begin,
                                 byte[] end,
                                 int limit,
                                 boolean reverse,
                                 StreamingMode mode)

Gets an ordered range of keys and values from the database. The begin and end keys are specified by byte[] arrays, with the begin key inclusive and the end key exclusive.

Parameters:

begin - the beginning of the range (inclusive)

end - the end of the range (exclusive)

limit - the maximum number of results to return. Limits results to the first keys in the range. Pass ROW_LIMIT_UNLIMITED if this query should not limit the number of results. If reverse is true rows will be limited starting at the end of the range.

reverse - return results starting at the end of the range in reverse order

mode - provide a hint about how the results are to be used. This can provide speed improvements or efficiency gains based on the caller's knowledge of the upcoming access pattern.

Returns:

a handle to access the results of the asynchronous call

See Also:

KeySelector, AsyncIterator

getRange

AsyncIterable<KeyValue> getRange(Range range)

Gets an ordered range of keys and values from the database. The begin and end keys are specified by byte[] arrays, with the begin key inclusive and the end key exclusive. Ranges are returned from calls to Tuple.range() and Range.startsWith(byte[]).

Note: users of older version of the API should replace old calls to getRangeStartsWith( k ) with getRange(Range.startsWith( k ))

Parameters:

range - the range of keys to return

Returns:

a handle to access the results of the asynchronous call

See Also:

KeySelector, AsyncIterator

getRange

AsyncIterable<KeyValue> getRange(Range range,
                                 int limit)

Gets an ordered range of keys and values from the database. The begin and end keys are specified by byte[] arrays, with the begin key inclusive and the end key exclusive. Ranges are returned from calls to Tuple.range() and Range.startsWith(byte[]).

Note: users of older version of the API should replace old calls to getRangeStartsWith( k ) with getRange(Range.startsWith( k ))

Parameters:

range - the range of keys to return

limit - the maximum number of results to return. Limits results to the first keys in the range. Pass ROW_LIMIT_UNLIMITED if this query should not limit the number of results.

Returns:

a handle to access the results of the asynchronous call

See Also:

KeySelector, AsyncIterator

getRange

AsyncIterable<KeyValue> getRange(Range range,
                                 int limit,
                                 boolean reverse)

Gets an ordered range of keys and values from the database. The begin and end keys are specified by byte[] arrays, with the begin key inclusive and the end key exclusive. Ranges are returned from calls to Tuple.range() and Range.startsWith(byte[]).

Note: users of older version of the API should replace old calls to getRangeStartsWith( k ) with getRange(Range.startsWith( k ))

Parameters:

range - the range of keys to return

limit - the maximum number of results to return. Limits results to the first keys in the range. Pass ROW_LIMIT_UNLIMITED if this query should not limit the number of results. If reverse is true rows will be limited starting at the end of the range.

reverse - return results starting at the end of the range in reverse order

Returns:

a handle to access the results of the asynchronous call

See Also:

KeySelector, AsyncIterator

getRange

AsyncIterable<KeyValue> getRange(Range range,
                                 int limit,
                                 boolean reverse,
                                 StreamingMode mode)

Gets an ordered range of keys and values from the database. The begin and end keys are specified by byte[] arrays, with the begin key inclusive and the end key exclusive. Ranges are returned from calls to Tuple.range() and Range.startsWith(byte[]).

Note: users of older version of the API should replace old calls to getRangeStartsWith( k ) with getRange(Range.startsWith( k ))

Parameters:

range - the range of keys to return

limit - the maximum number of results to return. Limits results to the first keys in the range. Pass ROW_LIMIT_UNLIMITED if this query should not limit the number of results. If reverse is true rows will be limited starting at the end of the range.

reverse - return results starting at the end of the range in reverse order

mode - provide a hint about how the results are to be used. This can provide speed improvements or efficiency gains based on the caller's knowledge of the upcoming access pattern.

Returns:

a handle to access the results of the asynchronous call

See Also:

KeySelector, AsyncIterator

options

TransactionOptions options()

Returns a set of options that can be set on a Transaction

Returns:

a set of transaction-specific options affecting this Transaction