Introduce a new table `CDC_GENERATIONS_V3` (`system.cdc_generations_v3`).
The table schema is a copy-paste of the `CDC_GENERATIONS_V2` schema. The
difference is that V2 lives in `system_distributed_keyspace` and writes to it
are distributed using regular `storage_proxy` replication mechanisms based on
the token ring. The V3 table lives in `system_keyspace` and any mutations
written to it will go through group 0.
Extend the `TOPOLOGY` schema with new columns:
- `new_cdc_generation_data_uuid` will be stored as part of a bootstrapping
node's `ring_slice`, it stores UUID of a newly introduced CDC
generation which is used as partition key for the `CDC_GENERATIONS_V3`
table to access this new generation's data. It's a regular column,
meaning that every row (corresponding to a node) will have its own.
- `current_cdc_generation_uuid` and `current_cdc_generation_timestamp`
together form the ID of the newest CDC generation in the cluster.
(the uuid is the data key for `CDC_GENERATIONS_V3`, the timestamp is
when the CDC generation starts operating). Those are static columns
since there's a single newest CDC generation.
When topology coordinator handles a request for node to join, calculate a new
CDC generation using the bootstrapping node's tokens, translate it to mutation
format, and insert this mutation to the CDC_GENERATIONS_V3 table through group 0
at the same time we assign tokens to the node in Raft topology. The partition
key for this data is stored in the bootstrapping node's `ring_slice`.
After inserting new CDC generation data , we need to pick a timestamp for this
generation and commit it, telling all nodes in the cluster to start using the
generation for CDC log writes once their clocks cross that timestamp.
We introduce a separate step to the bootstrap saga, before
`write_both_read_old`, called `commit_cdc_generation`. In this step, the
coordinator takes the `new_cdc_generation_data_uuid` stored in a bootstrapping
node's `ring_slice` - which serves as the key to the table where the CDC
generation data is stored - and combines it with a timestamp which it generates
a bit into the future (as in old gossiper-based code, we use 2 * ring_delay, by
default 1 minute). This gives us a CDC generation ID which we commit into the
topology state as the `current_cdc_generation_id` while switching the saga to
the next step, `write_both_read_old`.
Once a new CDC generation is committed to the cluster by the topology
coordinator, we also need to publish it to the user-facing description tables so
CDC applications know which streams to read from.
This uses regular distributed table writes underneath (tables living in the
`system_distributed` keyspace) so it requires `token_metadata` to be nonempty.
We need a hack for the case of bootstrapping the first node in the cluster -
turning the tokens into normal tokens earlier in the procedure in
`token_metadata`, but this is fine for the single-node case since no streaming
is happening.
When a node notices that a new CDC generation was introduced in
`storage_service::topology_state_load`, it updates its internal data structures
that are used when coordinating writes to CDC log tables.
We include the current CDC generation data in topology snapshot transfers.
Some fixes and refactors included.
Closes#13385
* github.com:scylladb/scylladb:
docs: cdc: describe generation changes using group 0 topology coordinator
cdc: generation_service: add a FIXME
cdc: generation_service: add legacy_ prefix for gossiper-based functions
storage_service: include current CDC generation data in topology snapshots
db: system_keyspace: introduce `query_mutations` with range/slice
storage_service: hold group 0 apply mutex when reading topology snapshot
service: raft_group0_client: introduce `hold_read_apply_mutex`
storage_service: use CDC generations introduced by Raft topology
raft topology: publish new CDC generation to the user description tables
raft topology: commit a new CDC generation on node bootstrap
raft topology: create new CDC generation data during node bootstrap
service: topology_state_machine: make topology::find const
db: system_keyspace: small refactor of `load_topology_state`
cdc: generation: extract pure parts of `make_new_generation` outside
db: system_keyspace: add storage for CDC generations managed by group 0
service: topology_state_machine: better error checking for state name (de)serialization
service: raft: plumbing `cdc::generation_service&`
cdc: generation: `get_cdc_generation_mutations`: take timestamp as parameter
cdc: generation: make `topology_description_generator::get_sharding_info` a parameter
sys_dist_ks: make `get_cdc_generation_mutations` public
sys_dist_ks: move find_schema outside `get_cdc_generation_mutations`
sys_dist_ks: move mutation size threshold calculation outside `get_cdc_generation_mutations`
service/raft: group0_state_machine: signal topology state machine in `load_snapshot`
The tombstone_gc was documented as experimental in version 5.0.
It is no longer experimental in version 5.2.
This commit updates the information about the option.
Closes#13469
Update the `Generation switching` section: most of the existing
description landed in `Gossiper-based topology changes` subsection, and
a new subsection was added to describe Raft group 0 based topology
changes. Marked as WIP - we expect further development in this area
soon.
The existing gossiper-based description was also updated a bit.
Fixes https://github.com/scylladb/scylla-doc-issues/issues/823.
This PR extends the note on the Tracing page to explain what is meant by setting the RF to ALL and adds a link for reference.
Closes#12418
* github.com:scylladb/scylladb:
docs: add an explanation to recommendation in the Note box
doc: extend the information about the recommended RF on the Tracing page
The names of these states have been the source of confusion ever since they were introduced. Give them names which better reflects their true meaning and gives less room for misinterpretation. The changes are:
* active/unused -> active
* active/used -> active/need_cpu
* active/blocked -> active/await
Hopefully the new names do a better job at conveying what these states really mean:
* active - a regular admitted permit, which is active (as opposed to an inactive permit).
* active/need_cpu - an active permit which was marked as needing CPU for the read to make progress. This permit prevents admission of new permits while it is in this state.
* active/await - a former active/need_cpu permit, which has to wait on I/O or a remote shard. While in this state, it doesn't block the admission of new permits (pending other criteria such as resource availability).
Closes#13482
* github.com:scylladb/scylladb:
docs/dev/reader-concurrency-semaphore.md: expand on how the semaphore works
reader_permit: give better names to active* states
scylla-sstable currently has two ways to obtain the schema:
* via a `schema.cql` file.
* load schema definition from memory (only works for system tables).
This meant that for most cases it was necessary to export the schema into a CQL format and write it to a file. This is very flexible. The sstable can be inspected anywhere, it doesn't have to be on the same host where it originates form. Yet in many cases the sstable is inspected on the same host where it originates from. In this cases, the schema is readily available in the schema tables on disk and it is plain annoying to have to export it into a file, just to quickly inspect an sstable file.
This series solves this annoyance by providing a mechanism to load schemas from the on-disk schema tables. Furthermore, an auto-detect mechanism is provided to detect the location of these schema tables based on the path of the sstable, but if that fails, the tool check the usual locations of the scylla data dir, the scylla confguration file and even looks for environment variables that tell the location of these. The old methods are still supported. In fact, if a schema.cql is present in the working directory of the tool, it is preferred over any other method, allowing for an easy force-override.
If the auto-detection magic fails, an error is printed to the console, advising the user to turn on debug level logging to see what went wrong.
A comprehensive test is added which checks all the different schema loading mechanisms. The documentation is also updated to reflect the changes.
This change breaks the backward-compatibility of the command-line API of the tool, as `--system-schema` is now just a flag, the keyspace and table names are supplied separately via the new `--keyspace` and `--table` options. I don't think this will break anybody's workflow as this tools is still lightly used, exactly because of the annoying way the schema has to be provided. Hopefully after this series, this will change.
Example:
```
$ ./build/dev/scylla sstable dump-data /var/lib/scylla/data/ks/tbl2-d55ba230b9a811ed9ae8495671e9e4f8/quarantine/me-1-big-Data.db
{"sstables":{"/var/lib/scylla/data/ks/tbl2-d55ba230b9a811ed9ae8495671e9e4f8/quarantine//me-1-big-Data.db":[{"key":{"token":"-3485513579396041028","raw":"000400000000","value":"0"},"clustering_elements":[{"type":"clustering-row","key":{"raw":"","value":""},"marker":{"timestamp":1677837047297728},"columns":{"v":{"is_live":true,"type":"regular","timestamp":1677837047297728,"value":"0"}}}]}]}}
```
As seen above, subdirectories like qurantine, staging etc are also supported.
Fixes: https://github.com/scylladb/scylladb/issues/10126Closes#13448
* github.com:scylladb/scylladb:
test/cql-pytest: test_tools.py: add tests for schema loading
test/cql-pytest: add no_autocompaction_context
docs: scylla-sstable.rst: remove accidentally added copy-pasta
docs: scylla-sstable.rst: remove paragraph with schema limitations
docs: scylla-sstable.rst: update schema section
test/cql-pytest: nodetool.py: add flush_keyspace()
tools/scylla-sstable: reform schema loading mechanism
tools/schema_loader: add load_schema_from_schema_tables()
db/schema_tables: expose types schema
Greatly expand on the details of how the semaphore works.
Organize the content into thematic chapters to improve navigation.
Improve formatting while at it.
The names of these states have been the source of confusion ever since
they were introduced. Give them names which better reflects their true
meaning and gives less room for misinterpretation. The changes are:
* active/unused -> active
* active/used -> active/need_cpu
* active/blocked -> active/await
Hopefully the new names do a better job at conveying what these states
really mean:
* active - a regular admitted permit, which is active (as opposed to
an inactive permit).
* active/need_cpu - an active permit which was marked as needing CPU for
the read to make progress. This permit prevents admission of new
permits while it is in this state.
* active/await - a former active/need_cpu permit, which has to wait on
I/O or a remote shard. While in this state, it doesn't block the
admission of new permits (pending other criteria such as resource
availability).
Related: https://github.com/scylladb/scylla-enterprise/issues/2794
This commit adds the information about the metric changes
in version 2023.1 compared to version 5.2.
This commit is part of the 5.2-to-2023.1 upgrade guide and
must be backported to branch-5.2.
Closes#13506
The above file contained a paragraph explaining the limitations of
`scylla-sstable.rst` w.r.t. automatically finding the schema. This no
longer applies so remove it.
The schema is
CREATE TABLE system.sstables (
location text,
generation bigint,
format text,
status text,
uuid uuid,
version text,
PRIMARY KEY (location, generation)
)
A sample entry looks like:
location | generation | format | status | uuid | version
---------------------------------------------------------------------+------------+--------+--------+--------------------------------------+---------
/data/object_storage_ks/test_table-d096a1e0ad3811ed85b539b6b0998182 | 2 | big | sealed | d0a743b0-ad38-11ed-85b5-39b6b0998182 | me
The uuid field points to the "folder" on the storage where the sstable
components are. Like this:
s3
`- test_bucket
`- f7548f00-a64d-11ed-865a-0c1fbc116bb3
`- Data.db
- Index.db
- Filter.db
- ...
It's not very nice that the whole /var/lib/... path is in fact used as
location, it needs the PR #12707 to fix this place.
Also, the "status" part is not yet fully functional, it only supports
three options:
- creating -- the same as TemporaryTOC file exists on disk
- sealed -- default state
- deleting -- the analogy for the deletion log on disk
The latter needs support from the distributed_loader, which's not yet
there. In fact, distributes_loader also needs to be patched to actualy
select entries from this table on load. Also it needs the mentioned
PR #12707 to support staging and quarantine sstables.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
After a failed topology operation, like bootstrap / decommission /
removenode, the cluster might contain a garbage entry in either token
ring or group 0. This entry can be cleaned-up by executing removenode on
any other node, pointing to the node that failed to bootstrap or leave
the cluster.
Document this procedure, including a method of finding the host ID of a
garbage entry.
Add references in other documents.
Fixes: #13122Closes#13186
This PR reverts the scylla sstable schema loading improvements as they fail in CI every other run. I am already working on fixes for these but I am not sure I understand all the failures so it is best to revert and re-post the series later.
Fixes: #13404Fixes: #13410Closes#13419
* github.com:scylladb/scylladb:
Revert "Merge 'tool/scylla-sstable: more flexibility in obtaining the schema' from Botond Dénes"
Revert "tools/schema_loader: don't require results from optional schema tables"
Related: https://github.com/scylladb/scylla-enterprise/issues/2770
This commit adds the upgrade guide from ScyllaDB Open Source 5.2
to ScyllaDB Enterprise 2023.1.
This commit does not cover metric updates (the metrics file has no
content, which needs to be added in another PR).
As this is an upgrade guide, this commit must be merged to master and
backported to branch-5.2 and branch-2023.1 in scylla-enterprise.git.
Closes#13294
This reverts commit 32fff17e19, reversing
changes made to 164afe14ad.
This series proved to be problematic, the new test introduced by it
failing quite often. Revert it until the problems are tracked down and
fixed.
The commitlog api originally implied that the commitlog_directory would contain files from a single commitlog instance. This is checked in segment_manager::list_descriptors, if it encounters a file with an unknown prefix, an exception occurs in `commitlog::descriptor::descriptor`, which is logged with the `WARN` level.
A new schema commitlog was added recently, which shares the filesystem directory with the main commitlog. This causes warnings to be emitted on each boot. This patch solves the warnings problem by moving the schema commitlog to a separate directory. In addition, the user can employ the new `schema_commitlog_directory` parameter to move the schema commitlog to another disk drive.
This is expected to be released in 5.3.
As #13134 (raft tables->schema commitlog) is also scheduled for 5.3, and it already requires a clean rolling restart (no cl segments to replay), we don't need to specifically handle upgrade here.
Fixes: #11867Closes#13263
* github.com:scylladb/scylladb:
commitlog: use separate directory for schema commitlog
schema commitlog: fix commitlog_total_space_in_mb initialization
The commitlog api originally implied that
the commitlog_directory would contain files
from a single commitlog instance. This is
checked in segment_manager::list_descriptors,
if it encounters a file with an unknown
prefix, an exception occurs in
commitlog::descriptor::descriptor, which is
logged with the WARN level.
A new schema commitlog was added recently,
which shares the filesystem directory with
the main commitlog. This causes warnings
to be emitted on each boot. This patch
solves the warnings problem by moving
the schema commitlog to a separate directory.
In addition, the user can employ the new
schema_commitlog_directory parameter to move
the schema commitlog to another disk drive.
By default, the schema commitlog directory is
nested in the commitlog_directory. This can help
avoid problems during an upgrade if the
commitlog_directory in the custom scylla.yaml
is located on a separate disk partition.
This is expected to be released in 5.3.
As #13134 (raft tables->schema commitlog)
is also scheduled for 5.3, and it already
requires a clean rolling restart (no cl
segments to replay), we don't need to
specifically handle upgrade here.
Fixes: #11867
`scylla-sstable` currently has two ways to obtain the schema:
* via a `schema.cql` file.
* load schema definition from memory (only works for system tables).
This meant that for most cases it was necessary to export the schema into a `CQL` format and write it to a file. This is very flexible. The sstable can be inspected anywhere, it doesn't have to be on the same host where it originates form. Yet in many cases the sstable *is* inspected on the same host where it originates from. In this cases, the schema is readily available in the schema tables on disk and it is plain annoying to have to export it into a file, just to quickly inspect an sstable file.
This series solves this annoyance by providing a mechanism to load schemas from the on-disk schema tables. Furthermore, an auto-detect mechanism is provided to detect the location of these schema tables based on the path of the sstable, but if that fails, the tool check the usual locations of the scylla data dir, the scylla confguration file and even looks for environment variables that tell the location of these. The old methods are still supported. In fact, if a `schema.cql` is present in the working directory of the tool, it is preferred over any other method, allowing for an easy force-override.
If the auto-detection magic fails, an error is printed to the console, advising the user to turn on debug level logging to see what went wrong.
A comprehensive test is added which checks all the different schema loading mechanisms. The documentation is also updated to reflect the changes.
This change breaks the backward-compatibility of the command-line API of the tool, as `--system-schema` is now just a flag, the keyspace and table names are supplied separately via the new `--keyspace` and `--table` options. I don't think this will break anybody's workflow as this tools is still lightly used, exactly because of the annoying way the schema has to be provided. Hopefully after this series, this will change.
Example:
```
$ ./build/dev/scylla sstable dump-data /var/lib/scylla/data/ks/tbl2-d55ba230b9a811ed9ae8495671e9e4f8/quarantine/me-1-big-Data.db
{"sstables":{"/var/lib/scylla/data/ks/tbl2-d55ba230b9a811ed9ae8495671e9e4f8/quarantine//me-1-big-Data.db":[{"key":{"token":"-3485513579396041028","raw":"000400000000","value":"0"},"clustering_elements":[{"type":"clustering-row","key":{"raw":"","value":""},"marker":{"timestamp":1677837047297728},"columns":{"v":{"is_live":true,"type":"regular","timestamp":1677837047297728,"value":"0"}}}]}]}}
```
As seen above, subdirectories like `qurantine`, `staging` etc are also supported.
Fixes: https://github.com/scylladb/scylladb/issues/10126Closes#13075
* github.com:scylladb/scylladb:
docs/operating-scylla/admin-tools: scylla-sstable.rst: update schema section
test/cql-pytest: test_tools.py: add test for schema loading
test/cql-pytest: nodetool.py: add flush_keyspace()
tools/scylla-sstable: reform schema loading mechanism
tools/schema_loader: add load_schema_from_schema_tables()
db/schema_tables: expose types schema
Fixes https://github.com/scylladb/scylladb/issues/13106
This commit removes the information that BYPASS CACHE
is an Enterprise-only feature and replaces that info
with the link to the BYPASS CACHE description.
Closes#13316
This commit removes the Enterprise upgrade guides from
the Open Source documentation. The Enterprise upgrade guides
should only be available in the Enterprise documentation,
with the source files stored in scylla-enterprise.git.
In addition, this commit:
- adds the links to the Enterprise user guides in the Enterprise
documentation at https://enterprise.docs.scylladb.com/
- adds the redirections for the removed pages to avoid
breaking any links.
This commit must be reverted in scylla-enterprise.git.
Closes#13298
The patch series introduces linearisable topology changes using
raft protocol. The state machine driven by raft is described in
"service: Introduce topology state machine". Some explanations about
the implementation can be found in "storage_service: raft topology:
implement topology management through raft".
The code is not ready for production. There is not much in terms of error
handling and integration with the rest of the system is not even started.
For full integration request fencing will need to be implemented and
token_metadata has to be extended to support not just "pending" nodes
but concepts of "read replica set" and "write replica set".
The code may be far from be usable, but it is hidden behind the
"experimental raft" flag and having it in tree will relieve me from
constant rebase burden.
* 'raft-topology-v6' of github.com:scylladb/scylla-dev:
storage_service: fix indentation from previous patch
storage_service: raft topology: implement topology management through raft
service: raft: make group0_guard move assignable
service: raft: wire up apply() and snapshot transfer for topology in group0 state machine
storage_service: raft topology: introduce a function that applies topology cmd to local state machine
storage_service: raft topology: introduce a raft monitor and topology coordinator fibers
storage_service: raft topology: introduce snapshot transfer code for the topology table
raft topology: add RAFT_TOPOLOGY_CMD verb that will be used by topology coordinator to communicated with nodes
bootstrapper: Add get_random_bootstrap_tokens function
service: raft: add support for topology_change command into raft_group0_client
service: raft: introduce topology_change group0 command
system_keyspace: add a table to persist topology change state machine's state
service: Introduce topology state machine data structures
storage_proxy: not consult topology on local table write
Hey y'all!
Me and @malusev998 are maintaining a updated version of the [PHP Driver ](https://github.com/he4rt/scylladb-php-driver) together with @he4rt community and it had a bunch of improvements on these last month.
Before it was working only at PHP 7.1 (DataStax branch), and at our branch we have it working at PHP 8.1 and 8.2.
We are also using the ScyllaDB C++ Driver on this project and I think that is a good idea to point new users for this project since it's the most updated PHP Driver maintained now.
What do y'all think about that?
Closes#13218
* github.com:scylladb/scylladb:
fix: links to php driver
fix: adding php versions into driver's description
docs: scylladb better php driver
Point to the difference between the official MurmurHash3 and Scylla / Cassandra implementation
Update docs/glossary.rst
Co-authored-by: Anna Stuchlik <37244380+annastuchlik@users.noreply.github.com>
Closes#11369
The topology state machine will track all the nodes in a cluster,
their state, properties (topology, tokens, etc) and requested actions.
Node state can be one of those:
none - the node is not yet in the cluster
bootstrapping - the node is currently bootstrapping
decommissioning - the node is being decommissioned
removing - the node is being removed
replacing - the node is replacing another node
normal - the node is working normally
rebuild - the node is being rebuilt
left - the node is left the cluster
Nodes in state left are never removed from the state.
Tokens also can be in one of the states:
write_both_read_old - writes are going to new and old replica, but reads are from
old replicas still
write_both_read_new - writes still going to old and new replicas but reads are
from new replica
owner - tokens are owned by the node and reads and write go to new
replica set only
Tokens that needs to be move start in 'write_both_read_old' state. After entire
cluster learns about it streaming start. After the streaming tokens move
to 'write_both_read_new' state and again the whole cluster needs to learn about it
and make sure no reads started before that point exist in the system.
After that tokens may move to 'owner' state.
topology_request is the field through which a topology operation request
can be issued to a node. A request is one of the topology operation
currently supported: join, leave, replace or remove.
