space_object:get()

object space_object¶

space_object:get(key)¶

Search for a tuple in the given space.

Parameters:	space_object (space_object) – an object reference key (scalar/table) – value to be matched against the index key, which may be multi-part.
Return:	the tuple whose index key matches key, or nil.
Rtype:	tuple

Possible errors:

• space_object does not exist.
• ER_TRANSACTION_CONFLICT if a transaction conflict is detected in the MVCC transaction mode.

Complexity factors: Index size, Index type, Number of indexes accessed, WAL settings.

The box.space...select function returns a set of tuples as a Lua table; the box.space...get function returns at most a single tuple. And it is possible to get the first tuple in a space by appending [1]. Therefore box.space.tester:get{1} has the same effect as box.space.tester:select{1}[1], if exactly one tuple is found.

Example:

box.space.tester:get{1}

Using field names instead of field numbers: get() can use field names described by the optional space_object:format() clause. This is true because the object returned by get() can be used with most of the features described in the Submodule box.tuple description, including tuple_object[field-name].

For example, we can format the tester space with a field named x and use the name x in the index definition:

box.space.tester:format({{name='x',type='scalar'}})
box.space.tester:create_index('I',{parts={'x'}})

Then, if get or select retrieves a single tuple, we can reference the field ‘x’ in the tuple by its name:

box.space.tester:get{1}['x']
box.space.tester:select{1}[1]['x']