The partial decoding feature allows you to decode the value of an ASN.1 type and obtain only a part of the value back from the decode function. This feature is meant to provide the following benefits:
direct access to the returned values (you don’t need to navigate through the normal data structures)
less memory used by the data returned from the decode function, since only a part of the decoded type is returned
Some other, incidental benefits might also be realized, including:
faster decoding
less code generated
The extent of these incidental benefits will depend upon your particular schema and the values you are targeting. There might be some element values which partial decoding will skip over more quickly than a decoder would decode them. Or, there might be types in your schema which will never be encountered in your partial decoding scenario, making it unnecessary to generate any code for those types.
Partial decoding is only supported for PER (aligned or unaligned).