Commit 968177da04 has changed the schema
of cdc_topology_description and cdc_description tables in the
system_distributed keyspace.
Unfortunately this was a backwards-incompatible change: these tables
would always be created, irrespective of whether or not "experimental"
was enabled. They just wouldn't be populated with experimental=off.
If the user now tries to upgrade Scylla from a version before this change
to a version after this change, it will work as long as CDC is protected
b the experimental flag and the flag is off.
However, if we drop the flag, or if the user turns experimental on,
weird things will happen, such as nodes refusing to start because they
try to populate cdc_topology_description while assuming a different schema
for this table.
The simplest fix for this problem is to rename the tables. This fix must
get merged in before CDC goes out of experimental.
If the user upgrades his cluster from a pre-rename version, he will simply
have two garbage tables that he is free to delete after upgrading.
sstables and digests need to be regenerated for schema_digest_test since
this commit effectively adds new tables to the system_distributed keyspace.
This doesn't result in schema disagreement because the table is
announced to all nodes through the migration manager.
The header sits in many other headers, but there's a handy
schema_fwd.hh that's tiny and contains needed declarations
for other headers. So replace shema.hh with schema_fwd.hh
in most of the headers (and remove completely from some).
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Message-Id: <20200303102050.18462-1-xemul@scylladb.com>
The cdc_topology_description table will be used internally
by nodes to send new CDC stream generations to other nodes.
The cdc_description table is a user-facing table,
used to inform users about new sets of CDC streams.
Regenerate sstables and digests for schema_change_test.
We don't need to protect this change by a schema feature:
when a node creates these tables, it announces them
to all other nodes. If schema agreement happens before
this migration, all nodes will use a digest calculated
without these tables. If it happens after, then all nodes
will eventually know about these tables and use a digest
calculated with these tables.
This patch introduces a distributed system keyspace, used to hold
system tables that need to be replicated across a set of replicas
(that is, can't use the LocalStrategy).
In following patches, we will use this keyspace to hold a table
containing view building status updates for each node, used to support
range movements and a new nodetool command.
Fixes#3237
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
