The STORAGE option is designed to hold a map of options
used for customizing storage for given keyspace.
The option is kept in a system_schema.scylla_keyspaces table.
The option is only available if the whole cluster is aware
of it - guarded by a cluster feature.
Example of the table contents:
```
cassandra@cqlsh> select * from system_schema.scylla_keyspaces;
keyspace_name | storage_options | storage_type
---------------+------------------------------------------------+--------------
ksx | {'bucket': '/tmp/xx', 'endpoint': 'localhost'} | S3
```
Alternator is a coordinator-side service and so should not access
the replica module. In this series all but one of uses of the replica
module are replaced with data_dictionary.
One case remains - accessing the replication map which is not
available (and should not be available) via the data dictionary.
The data_dictionary module is expanded with missing accessors.
Closes#9945
* github.com:scylladb/scylla:
alternator: switch to data_dictionary for table listing purposes
data_dictionary: add get_tables()
data_dictionary: introduce keyspace::is_internal()
Unlike replica::database::get_column_families() which is replaces,
it returns a vector of tables rather than a map. Map-like access
is provided by get_table(), so it's redundant to build a new
map container to expose the same functionality.
Instead of the replica module's is_internal_keyspace(), provide
it as part of data_dictionary. By making it a member of the keyspace
class, it is also more future proof in that it doesn't depend on
a static list of names.
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.
Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.
The changes we applied mechanically with a script, except to
licenses/README.md.
Closes#9937
Mirroring replica::database::get_keyspaces(), for Thrift's use.
We return a vector instead of a hash map. Random access is already
available via database::find_keyspace(). The name is available
via the keyspace metadata, and in fact Thrift ignore the map
name and uses the metadata name. Using a simpler type reduces
include dependencies for this heavily used module.
The function is plumbed to replica::database::get_keyspaces() so
it returns the same data.
Move replica-oriented classes to the replica namespace. The main
classes moved are ::database, ::keyspace, and ::table, but a few
ancillary classes are also moved. There are certainly classes that
should be moved but aren't (like distributed_loader) but we have
to start somewhere.
References are adjusted treewide. In many cases, it is obvious that
a call site should not access the replica (but the data_dictionary
instead), but that is left for separate work.
scylla-gdb.py is adjusted to look for both the new and old names.
Add metadata-only counterparts to ::database, ::keyspace, and ::table.
Apart from being metadata-only objects suitable for the coordinator,
the new types are also type-erased and so they can be mocked without
being linked to ::database and friends.
We use a single abstract class to mediate between data_dictionary
objects and the objects they represent (data_dictionary::impl).
This makes the data_dictionary objects very lightweight - they
only contain a pointer to the impl object (of which only one
needs to be instantiated), and a reference to the object that
is represented. This allows these objects to be easily passed
by value.
The abstraction is leaky: in one place it is outright breached
with data_dictionary::database::real_database() that returns
a ::database reference. This is used so that we can perform the
transition incrementally. Another place is that one of the
methods returns a secondary_index_manager, which in turn grants
access to the real objects. This will be addressed later, probably
by type erasing as well.
This patch only contains the interface, and no implementation. It
is somewhat messy since it mimics the years-old evolution of the
real objects, but maybe it will be easier to improve it now.
The new module will contain all schema related metadata, detached from
actual data access (provided by the database class). User types is the
first contents to be moved to the new module.
