API

The API is split into two modules: the multicorn module and the utils module:

  • The multicorn module contains the whole API needed for implementing a Foreign Data Wrapper.
  • The utils module contains logging and error reporting functions, which are ultimately implemented as calls to the PostgreSQL API.

Implementing an FDW

Implementing an FDW is as simple as implementing the ~multicorn.ForeignDataWrapper class.

Required API

py:currentmodule: multicorn.ForeignDataWrapper

This subset of the API allows your ForeignDataWrapper to be used for read-only queries.

You have to implement the following methods:

  • __init__
  • execute

Note

In the documentation, FDWs implementing this API will be marked with:

api_compat:

Write API

To implement full write capabilites, the following property must be implemented:

autoattribute: multicorn.ForeignDataWrapper.rowid_column

In addition to that, you should implement each DML operation as you see fit:

  • insert
  • update
  • delete

Note

In the documentation, FDWs implementing this API will be marked with:

api_compat:

Transactional API

Transactional Capabilities can be implemented with the following methods:

automethod: multicorn.ForeignDataWrapper.begin
automethod: multicorn.ForeignDataWrapper.pre_commit
automethod: multicorn.ForeignDataWrapper.rollback
automethod: multicorn.ForeignDataWrapper.sub_begin
automethod: multicorn.ForeignDataWrapper.sub_commit
automethod: multicorn.ForeignDataWrapper.sub_rollback

Note

In the documentation, FDWs implementing this API will be marked with:

api_compat:

Full API

autoclass: multicorn.ForeignDataWrapper
autoclass: multicorn.SortKey
autoclass: multicorn.Qual
autoclass: multicorn.ColumnDefinition
autoclass: multicorn.TableDefinition