Python Data Mappings
How Python types map to server types
By default, the Client
maps the supported Python types to Aerospike server types. When an unsupported type is encountered by the module, it uses cPickle to serialize and deserialize the data, storing it in the server as a blob with ‘Python encoding’ (AS_BYTES_PYTHON).
The functions set_serializer()
and set_deserializer()
allow for user-defined functions to handle serialization, instead. The user provided function will be run instead of
cPickle. The serialized data is stored in the server with generic encoding (AS_BYTES_BLOB). This type allows the storage of binary data readable by Aerospike Clients in other languages. The serialization config parameter of aerospike.client()
registers an instance-level pair of functions that handle serialization.
Unless a user specified serializer has been provided, all other types will be stored as Python specific bytes. Python specific bytes may not be readable by Aerospike Clients for other languages.
Warning
Aerospike is introducing a new boolean data type in server version 5.6.
In order to support cross client compatibility and rolling upgrades, Python client version 6.x
comes with a new client config, send_bool_as
.
It configures how the client writes Python booleans and allows for opting into using the new boolean type.
It is important to consider how other clients connected to the Aerospike database write booleans in order to maintain cross client compatibility.
For example, if there is a client that reads and writes booleans as integers, then another Python client working with the same data should do the same thing.
send_bool_as
can be set so the client writes Python booleans as AS_BYTES_PYTHON
, integers, or the new server boolean type.
All versions before 6.x
wrote Python booleans as AS_BYTES_PYTHON
.
The following table shows which Python types map directly to Aerospike server types.
Python Type |
Server type |
---|---|
depends on send_bool_as |
|
|
|
Note
KeyOrderedDict is a special case. Like dict
, KeyOrderedDict
maps to the Aerospike map data type. However, the map will be sorted in key order before being sent to the server (see Map Order).
It is possible to nest these datatypes. For example a list may contain a dictionary, or a dictionary may contain a list as a value.
Unless a user specified serializer has been provided, all other types will be stored as Python specific bytes. Python specific bytes may not be readable by Aerospike Clients for other languages.