Multinode-related APIs now raise errors when called any PostgreSQL
version below 11, as these versions do not have the required features
to support multinode or have different behavior.
Raising errors at runtime on affected APIs is preferred over excluding
these functions altogether. Having a different user-facing SQL API
would severly complicate the upgrade process for the extension.
A new CMake check has been added to disable multinode features on
unsupported PostgreSQL versions. It also generates a macro in
`config.h` that can be used in code to check for multinode support.
This change ensures that chunk replicas are created on remote
(datanode) servers whenever a chunk is created in a local distributed
hypertable.
Remote chunks are created using the `create_chunk()` function, which
has been slightly refactored to allow specifying an explicit chunk
table name. The one making the remote call also records the resulting
remote chunk IDs in its `chunk_server` mappings table.
Since remote command invokation without super-user permissions
requires password authentication, the test configuration files have
been updated to require password authentication for a cluster test
user that is used in tests.
A frontend node will now maintain mappings from a local chunk to the
corresponding remote chunks in a `chunk_server` table.
The frontend creates local chunks as foreign tables and adds entries
to `chunk_server` for each chunk it creates on remote data node.
Currently, the creation of remote chunks is not implemented, so a
dummy chunk_id for the remote chunk will be added instead for testing
purposes.
This adds an internal API function to create a chunk using explicit
constraints (dimension slices). A function to export a chunk in a
format consistent with the chunk creation function is also added.
The chunk export/create functions are needed for distributed
hypertables so that an access node can create chunks on data nodes
according to its own (global) partitioning configuration.
