This is a follow-up to the previous commit.
Each CDC generation has a timestamp which denotes a logical point in time
when this generation starts operating. That same timestamp is
used to identify the CDC generation. We use this identification scheme
to exchange CDC generations around the cluster.
However, the fact that a generation's timestamp is used as an ID for
this generation is an implementation detail of the currently used method
of managing CDC generations.
Places in the code that deal with the timestamp, e.g. functions which
take it as an argument (such as handle_cdc_generation) are often
interested in the ID aspect, not the "when does the generation start
operating" aspect. They don't care that the ID is a `db_clock::time_point`.
They may sometimes want to retrieve the time point given the ID (such as
do_handle_cdc_generation when it calls `cdc::metadata::insert`),
but they don't care about the fact that the time point actually IS the ID.
In the future we may actually change the specific type of the ID if we
modify the generation management algorithms.
This commit is an intermediate step that will ease the transition in the
future. It introduces a new type, `cdc::generation_id`. Inside it contains
the timestamp, so:
1. if a piece of code doesn't care about the timestamp, it just passes
the ID around
2. if it does care, it can simply access it using the `get_ts` function.
The fact that `get_ts` simply accesses the ID's only field is an
implementation detail.
Using the occasion, we change the `do_handle_cdc_generation_intercept...`
function to be a standard function, not a coroutine. It turns out that -
depending on the shape of the passed-in argument - the function would
sometimes miscompile (the compiled code would not copy the argument to the
coroutine frame).
Each CDC generation always has a timestamp, but the fact that the
timestamp identifies the generation is an implementation detail.
We abstract away from this detail by using a more generic naming scheme:
a generation "identifier" (whatever that is - a timestamp or something
else).
It's possible that a CDC generation will be identified by more than a
timestamp in the (near) future.
The actual string gossiped by nodes in their application state is left
as "CDC_STREAMS_TIMESTAMP" for backward compatibility.
Some stale comments have been updated.
Nodes automatically ensure that the latest CDC generation's list of
streams is present in the streams description table. When a new
generation appears, we only need to update the table for this
generation; old generations are already inserted.
However, we've changed the description table (from
`cdc_streams_descriptions` to `cdc_streams_descriptions_v2`). The
existing mechanism only ensures that the latest generation appears in
the new description table. This commit adds an additional procedure that
rewrites the older generations as well, if we find that it is necessary
to do so (i.e. when some CDC log tables may contain data in these
generations).
The code that creates system keyspace open code a lot of things from
database::create_keyspace(). The patch makes create_keyspace() suitable
for both system and non system keyspaces and uses it to create system
keyspaces as well.
Message-Id: <20210209160506.1711177-1-gleb@scylladb.com>
System raft table will be used as a backend storage for implementing
raft persistence module in Scylla. It combines both raft log,
persisted vote and term, and snapshot info.
The table is partitioned by group id, thus allowing multi-raft
operation. The rest of the table structure mirrors the fields of
corresponding core raft structures defined in `raft.hh`, such as
`raft::log_entry`.
The raft table stores the only the latest snapshot id while
the actual snapshot will be available in a separate table
called `system.raft_snapshots`. The schema of `raft_snapshots`
mirrors the fields of `raft::snapshot` structure.
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
Functions for checking if the keyspace is system/internal were based
on sstring references, which is impractical compared to string views
and may lead to unnecessary creation of sstring instances.
There are few places that initialize db and system_ks and need the
messaging service. Pass the reference to it from main instead of
using the global helpers.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Fixes#6341
Since scylla no longer supports upgrading from a version without the
"new" (dedicated) truncation record table, we can remove support for these
and the migtration thereof.
Make sure the above holds whereever this is committed.
Note that this does not remove the "truncated_at" field in
system.local.
We'd like to use the same uuid both for printing compaction log
messages and to update compaction_history.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Some caller have partition_key_view, but not partition_key, so thy need
to create a temporary and copy just to pass a reference. Change it by
accepting a view.
The learning stage of PAXOS protocol leaves behind an entry in
system.paxos table with the last learned value (which can be large). In
case not all participants learned it successfully next round on the same
key may complete the learning using this info. But if all nodes learned
the value the entry does not serve useful purpose any longer.
The patch adds another round, "prune", which is executed in background
(limited to 1000 simultaneous instances) and removes the entry in
case all nodes replied successfully to the "learn" round. It uses the
ballot's timestamp to do the deletion, so not to interfere with the
next round. Since deletion happens very close to previous writes it will
likely happen in memtable and will never reach sstable, so that reduces
memtable flush and compaction overhead.
Fixes#5779
Message-Id: <20200330154853.GA31074@scylladb.com>
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>
This wrapper just makes sure the system_keyspace::get_saved_tokens
reports non empty result. Move them close together.
As a side effect -- get rid of penultimate global storage_service
reference from size_estimates_virtual_reader (the last one will
be removed soon).
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
"
There's a lot of code around that needs storage service purely to
get the specific feature value (cluster_supports_<something> calls).
This creates several circular dependencies, e.g. storage_service <->
migration_manager one and database <-> storage_servuce. Also features
sit on storage_service, but register themselfs on the feature_service
and the former subscribes on them back which also looks strange.
I propose to keep all the features on feature_service, this keeps the
latter intependent from other components, makes it possible to break
one of the mentioned circle dependencyand heavily relax the other.
Also the set helps us fighting the globals and, after it, the
feature_service can be safely stopped at the very last moment.
Tests: unit(dev), manual debug build start-stop
"
* 'br-features-to-service-5' of https://github.com/xemul/scylla:
gossiper: Avoid string merge-split for nothing
features: Stop on shutdown
storage_service: Remove helpers
storage_service: Prepare to switch from on-board feature helpers
cql3: Check feature in .validate
database: Use feature service
storage_proxy: Use feature service
migration_manager: Use feature service
start: Pass needed feature as argument into migrate_truncation_records
features: Unfriend storage_service
features: Simplify feature registration
features: Introduce known_feature_set
features: Move disabled features set from storage_service
features: Move schema_features helper
features: Move all features from storage_service to feature_service
storage_service: Use feature_config from _feature_service
features: Add feature_config
storage_service: Kill set_disabled_features
gms: Move features stuff into own .cc file
migration_manager: Move some fns into class
This will be used to persist CDC streams generation timestamp
proposed by a joining node in case the node crashes or restarts,
similarly to the way tokens are persisted.
The get_saved_cdc_streams_timestamp method retrieves the generation
timestamp from the system table. It will be used by a restarting
node.
The update_cdc_streams_timestamp method saves CDC stream
generation timestamp of the calling node in the system table.
A joining node will persist the timestamp before it proposes it to other
nodes.
This change introduces system.clients table, which provides
information about CQL clients connected.
PK is the client's IP address, CK consists of outgoing port number
and client_type (which will be extended in future to thrift/alternator/redis).
Table supplies also shard_id and username. Other columns,
like connection_stage, driver_name, driver_version...,
are currently empty but exist for C* compatibility and future use.
This is an ordinary table (i.e. non-virtual) and it's updated upon
accepting connections. This is also why C*'s column request_count
was not introduced. In case of abrupt DB stop, the table should not persist,
so it's being truncated on startup.
Resolves#4820
Addition of cdc column in scylla_tables changes how schema
digests are calculated, and affect the ABI of schema update
messages (adding a column changes other columns' indexes
in frozen_mutation).
To fix this, extend the schema_tables mechanism with support
for the cdc column, and adjust schemas and mutations to remove
that column when sending schemas during upgrade.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
I used the following as a reference:
https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/db/virtual/ClientsTable.java
At this moment there is only info about IP, clients outgoing port,
client 'type' (i.e. CQL/thrift/alternator), shard ID and username.
Column `request_count' is NOT present and CK consists of
(`port', `client_type'), contrary to what C*'s has: (`port').
Code that notifies `system.clients` about new connections goes
to top-level files `connection_notifier.*`. Currently only CQL
clients are observed, but enum `client_type` can be used in future
to notify about connections with other protocols.
invoke_on() guarantees that captures object won't be destroyed until the
future returned by the invoked function is resolved so there's no need
to move key, token, proposal for calling paxos_state::*_impl helpers.
Paxos protocol relies on replicas having a state that persists over
crashes/restarts. This patch defines such state and stores it in the
database itself in the paxos table to make it persistent.
The stored state is:
in_progress_ballot - promised ballot
proposal - accepted value
proposal_ballot - the ballot of the accepted value
most_recent_commit - most recently learned value
most_recent_commit_at - the ballot of the most recently learned value
This is analogous to the system.large_rows table, but holds individual
cells, so it also needs the column name.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
This is analogous to the system.large_partitions table, but holds
individual rows, so it also needs the clustering key of the large
rows.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
Fixes#4083
Instead of sharded collection in system.local, use a
dedicated system table (system.truncated) to store
truncation positions. Makes query/update easier
and easier on the query memory.
The code also migrates any existing truncation
positions on startup and clears the old data.
get_compaciton_history can return big chunk of data.
To prevent large memory allocation, the get_compaction_history now read
each compaction_history record and use the http stream to send it.
Fixes#4152
Signed-off-by: Amnon Heiman <amnon@scylladb.com>
system_keyspace is an implementation detail for most of its users, not
part of the interface, as it's only used to store internal data. Therefore,
including it in a header file causes unneeded dependencies.
This patch removes a dependency between views and system_keyspace.hh
by moving view_name and view_build_progress into a separate header file,
and using forward declarations where possible. This allows us to
remove an inclusion of system_keyspace.hh from a header file (the last
one), so that further changes to system_keyspace.hh will cause fewer
recompilations.
Message-Id: <20181228215736.11493-1-avi@scylladb.com>
This patch adds a function that clears the view build in-progress
status for the current shard, similar to the existing one that clears
it across all shards.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
This commit adds a system.large_partitions table, which can be used
to trace largest partitions of a cluster.
Schema: (
keyspace_name text,
table_name text,
sstable_name text,
partition_size bigint,
key text,
compaction_time timestamp,
PRIMARY KEY((keyspace_name, table_name), sstable_name, partition_size, key)
) WITH CLUSTERING ORDER BY (partition_size DESC);
References #3292
This patch implements an API to access the MV-related system tables,
which pertain to the view building process.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
When building a materialized view, we divide our work by shard, so we
need to register which shard did what work in the in-progress system
table. We also add the token we started at, which will enable some
optimizations in the view building code.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Allows extensions/config listeners to potentially augument
(system) schemas at boot time. This is only useful for schemas
who do not pass through system_schema tables.
Some places remained where code looked directly at
system_keyspace::NAME to determine iff a ks is
considered special/system/protected. Including
schema digest calculation.
Export "is_system_keyspace" and use accordingly.
Message-Id: <1500469809-23546-1-git-send-email-calle@scylladb.com>
