In this series we introduce new system tables and use them for storing the raft metadata
for strongly consistent tables. In contrast to the previously used raft group0 tables, the
new tables can store data on any shard. The tables also allow specifying the shard where
each partition should reside, which enables the tablets of strongly consistent tables to have
their raft group metadata co-located on the same shard as the tablet replica.
The new tables have almost the same schemas as the raft group0 tables. However, they
have an additional column in their partition keys. The additional column is the shard
that specifies where the data should be located. While a tablet and its corresponding
raft group server resides on some shard, it now writes and reads all requests to the
metadata tables using its shard in addition to the group_id.
The extra partition key column is used by the new partitioner and sharder which allow
this special shard routing. The partitioner encodes the shard in the token and the
sharder decodes the shard from the token. This approach for routing avoids any
additional lookups (for the tablet mapping) during operations on the new tables
and it also doesn't require keeping any state. It also doesn't interact negatively
with resharding - as long as tablets (and their corresponding raft metadata) occupy
some shard, we do not allow starting the node with a shard count lower than the
id of this shard. When increasing the shard count, the routing does not change,
similarly to how tablet allocation doesn't change.
To use the new tables, a new implementation of `raft::persistence` is added. Currently,
it's almost an exact copy of the `raft_sys_table_storage` which just uses the new tables,
but in the future we can modify it with changes specific to metadata (or mutation)
storage for strongly consistent tables. The new storage is used in the `groups_manager`,
which combined with the removal of some `this_shard_id() == 0` checks, allows strongly
consistent tables to be used on all shards.
This approach for making sure that the reads/writes to the new tables end up on the correct shards
won in the balance of complexity/usability/performance against a few other approaches we've considered.
They include:
1. Making the Raft server read/write directly to the database, skipping the sharder, on its shard, while using
the default partitioner/sharder. This approach could let us avoid changing the schema and there should be
no problems for reads and writes performed by the Raft server. However, in this approach we would input
data in tables conflicting with the placement determined by the sharder. As a result, any read going through
the sharder could miss the rows it was supposed to read. Even when reading all shards to find a specific value,
there is a risk of polluting the cache - the rows loaded on incorrect shards may persist in the cache for an unknown
amount of time. The cache may also mistakenly remember that a row is missing, even though it's actually present,
just on an incorrect shard.
Some of the issues with this approach could be worked around using another sharder which always returns
this_shard_id() when asked about a shard. It's not clear how such a sharder would implement a method like
`token_for_next_shard`, and how much simpler it would be compared to the current "identity" sharder.
2. Using a sharder depending on the current allocation of tablets on the node. This approach relies on the
knowledge of group_id -> shard mapping at any point in time in the cluster. For this approach we'd also
need to either add a custom partitioner which encodes the group_id in the token, or we'd need to track the
token(group_id) -> shard mapping. This approach has the benefit over the one used in the series of keeping
the partition key as just group_id. However, it requires more logic, and the access to the live state of the node
in the sharder, and it's not static - the same token may be sharded differently depending on the state of the
node - it shouldn't occur in practice, but if we changed the state of the node before adjusting the table data,
we would be unable to access/fix the stale data without artificially also changing the state of the node.
3. Using metadata tables co-located to the strongly consistent tables. This approach could simplify the
metadata migrations in the future, however it would require additional schema management of all co-located
metadata tables, and it's not even obvious what could be used as the partition key in these tables - some
metadata is per-raft-group, so we couldn't reuse the partition key of the strongly consistent table for it. And
finding and remembering a partition key that is routed to a specific shard is not a simple task. Finally, splits
and merges will most likely need special handling for metadata anyway, so we wouldn't even make use of
co-located table's splits and merges.
Fixes [SCYLLADB-361](https://scylladb.atlassian.net/browse/SCYLLADB-361)
[SCYLLADB-361]: https://scylladb.atlassian.net/browse/SCYLLADB-361?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQClosesscylladb/scylladb#28509
* github.com:scylladb/scylladb:
docs: add strong consistency doc
test/cluster: add tests for strongly-consistent tables' metadata persistence
raft: enable multi-shard raft groups for strongly consistent tablets
test/raft: add unit tests for raft_groups_storage
raft: add raft_groups_storage persistence class
db: add system tables for strongly consistent tables' raft groups
dht: add fixed_shard_partitioner and fixed_shard_sharder
raft: add group_id -> shard mapping to raft_group_registry
schema: add with_sharder overload accepting static_sharder reference
This patch enables the per-row TTL feature in CQL (Refs #13000).
This patch allows the user to create a new table with one of its columns
designated as the TTL column with a syntax like:
CREATE TABLE tab (
id int PRIMARY KEY,
t text,
expiration timestamp TTL
);
The column marked "TTL" must have the "timestamp", "bigint" or "int"
types (the choice of these types was explained in the previous patch),
and there can only be one such column. We decided not to allow a column
to be both a primary key column and a TTL column - although it would
have worked (it's supported in Alternator), I considered this non-useful
and confusing, and decided not to allow it in CQL. A TTL column also
can't be a static column.
We save the information of which column is the TTL column in a tag which
is read by the "expiration service" - originally a part of Alternator's
TTL implementation. After the previous patch, the expiration service is
running and knows how to understand CQL tables, so the CQL per-row TTL
feature will start to work.
This patch also implements DESC TABLE, printing the word "TTL" in the
right place of the output.
This patch doesn't yet implement ALTER TABLE that should allow enabling
or disabling the TTL column setting on an existing table - we'll do that
in the next patch.
A large collection of functional tests (in test/cqlpy), for every detail
of this feature will be added in a later patch.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Add a schema_builder::with_sharder() overload that accepts a const
reference to dht::static_sharder. This allows schemas to use custom
sharder instances instead of only static sharder configurations.
This is needed to support tables that use custom partitioning and
sharding strategies, such as the incoming raft metadata tables for
strongly consistent tables.
In PR 5b6570be52 we introduced the config option `sstable_compression_user_table_options` to allow adjusting the default compression settings for user tables. However, the new option was hooked into the CQL layer and applied only to CQL base tables, not to the whole spectrum of user tables: CQL auxiliary tables (materialized views, secondary indexes, CDC log tables), Alternator base tables, Alternator auxiliary tables (GSIs, LSIs, Streams).
This gap also led to inconsistent default compression algorithms after we changed the option’s default algorithm from LZ4 to LZ4WithDicts (adf9c426c2).
This series introduces a general “schema initializer” mechanism in `schema_builder` and uses it to apply the default compression settings uniformly across all user tables. This ensures that all base and aux tables take their default compression settings from config.
Fixes#26914.
Backport justification: LZ4WithDicts is the new default since 2025.4, but the config option exists since 2025.2. Based on severity, I suggest we backport only to 2025.4 to maintain consistency of the defaults.
Closesscylladb/scylladb#27204
* github.com:scylladb/scylladb:
db/config: Update sstable_compression_user_table_options description
schema: Add initializer for compression defaults
schema: Generalize static configurators into schema initializers
schema: Initialize static properties eagerly
db: config: Add accessor for sstable_compression_user_table_options
test: Check that CQL and Alternator tables respect compression config
Extend the `static_configurator` mechanism to support initialization of
arbitrary schema properties, not only static ones, by passing a
`schema_builder` reference to the configurator interface.
As part of this change, rename `static_configurator` to
`schema_initializer` to better reflect its broader responsibility.
Add a checkpoint/restore mechanism to allow de-registering an
initializer (useful for testing; will be used in the next patch).
Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
Schemas maintain a set of so-called "static properties". These are not
user-visible schema properties; they are internal values carried by
in-memory `schema` objects for convenience (349bc1a9b6,
https://github.com/scylladb/scylladb/pull/13170#issuecomment-1469848086).
Currently, the initialization of these properties happens when a
`schema_builder` builds a schema (`schema_builder::build()`), by
invoking all registered "static configurators".
This patch moves the initialization of static properties into the
`schema_builder` constructor. With this change, the builder initializes
the properties once, stores them in a data member, and reuses them for
all schema objects that it builds. This doesn't affect correctness as
the values produced by static configurators are "static" by
nature; they do not depend on runtime state.
In the next patch, we will replace the "static configurator" pattern
with a more general pattern that also supports initialization of regular
schema properties, not just static ones. Regular properties cannot be
initialized in `build()` because users may have already explicitly set
values via setters, and there is no way to distinguish between default
values and explicitly assigned ones.
Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
We're extending the logic of DESCRIBE INDEX to include properties of the
underlying materialized view. Tests are provided to ensure the
implementation works as intended.
The properties can be directly manipulated by the user
via statements like `ALTER TABLE`. To better organize
the structure of `raw_schema`, we encapsulate that data
in the form of a dedicated struct. This change will be
later used for applying multiple properties to `schema_builder`
in one go.
This patch series re-enables support for speculative retry values `0` and `100`. These values have been supported some time ago, before [schema: fix issue 21825: add validation for PERCENTILE values in speculative_retry configuration. #21879
](https://github.com/scylladb/scylladb/pull/21879). When that PR prevented using invalid `101PERCENTILE` values, valid `100PERCENTILE` and `0PERCENTILE` value were prevented too.
Reproduction steps from [[Bug]: drop schema and all tables after apply speculative_retry = '99.99PERCENTILE' #26369](https://github.com/scylladb/scylladb/issues/26369) are unable to reproduce the issue after the fix. A test is added to make sure the inclusive border values `0` and `100` are supported.
Documentation is updated to give more information to the users. It now states that these border values are inclusive, and also that the precision, with automatic rounding, is 1 decimal digit.
Fixes#26369
This is a bug fix. If at any time a client tries to use value >= 99.5 and < 100, the raft error will happen. Backport is needed. The code which introduced inconsistency is introduced in 2025.2, so no backporting to 2025.1.
Closesscylladb/scylladb#26909
* github.com:scylladb/scylladb:
test: cqlpy: add test case for non-numeric PERCENTILE value
schema: speculative_retry: update exception type for sstring ops
docs: cql: ddl.rst: update speculative-retry-options
test: cqlpy: add test for valid speculative_retry values
schema: speculative_retry: allow 0 and 100 PERCENTILE values
Change speculative_retry::to_sstring and speculative_retry::from_sstring
to throw exceptions::configuration_exception instead of std::invalid_argument.
These errors can be triggered by CQL, so appropriate CQL exception should be
used.
Reference: https://github.com/scylladb/scylladb/issues/24748#issuecomment-3025213304
Refs #26369
This patch allows specifying 0 and 100 PERCENTILE values in speculative_retry.
It was possible to specify these values before #21825. #21825 prevented specifying
invalid values, like -1 and 101, but also prevented using 0 and 100.
On top of that, speculative_retry::to_sstring function did rounding when
formatting the string, which introduced inconsistency.
Fixes#26369
Add to the schema object a member that points to the CDC schema object
that is compatible with this schema, if any.
The compatible CDC schema is created and altered with its base schema in
the same group0 operation.
When generating CDC log mutations for some base mutation we want them to
be created using a compatible schema thas has a CDC column corresponding
to each base column. This change will allow us to find the right CDC
schema given a base mutation.
We also update the relevant structures in the schema registry that are
related to learning about schemas and transporting schemas across
shards or nodes.
When transporting a schema as frozen_schema, we need to transport the
frozen cdc schema as well, and set it again when unfreezing and
reconstructing the schema.
When adding a schema to the registry, we need to ensure its CDC schema
is added to the registry as well.
Currently we always set the CDC schema to nullptr and maintain the
previous behavior. We will change it in a later commit. Until then, we
mark all places where CDC schema is passed clearly so we don't forget
it.
Change the schema loader type in the schema_registry to return a
extended_frozen_schema instead of view_schema_and_base_info, and
remove view_schema_and_base_info which is not used anymore.
The casting between them is trivial.
Currently we construct a frozen schema with base info in few places, and
the caller is responsible for constructing the frozen schema and extracting
the base info if it's a view table.
We change it to make it simpler and remove the burden from the caller.
The caller can simply pass the schema_ptr, and the constructor for
extended_frozen_schema will construct the frozen schema and extract
the additional info it needs. This will make it easier to add additional
fields, and reduces code duplication.
We also make temporary castings between extended_frozen_schema and
view_schema_and_base_info for the transition, which are trivial, until
they are combined to a single type.
The namespace usage in this directory is very inconsistent, with files
and classes scattered in:
* global namespace
* namespace compaction
* namespace sstables
With cases, where all three used in the same file. This code used to
live in sstables/ and some of it still retains namespace sstables as a
heritage of that time. The mismatch between the dir (future module) and
the namespace used is confusing, so finish the migration and move all
code in compaction/ to namespace compaction too.
This patch, although large, is mechanic and only the following kind of
changes are made:
* replace namespace sstable {} with namespace compaction {}
* add namespace compaction {}
* drop/add sstables::
* drop/add compaction::
* move around forward-declarations so they are in the correct namespace
context
This refactoring revealed some awkward leftover coupling between
sstables and compaction, in sstables/sstable_set.cc, where the
make_sstable_set() methods of compaction strategies are implemented.
As requested in #22104, moved the files and fixed other includes and build system.
Moved files:
- combine.hh
- collection_mutation.hh
- collection_mutation.cc
- converting_mutation_partition_applier.hh
- converting_mutation_partition_applier.cc
- counters.hh
- counters.cc
- timestamp.hh
Fixes: #22104
This is a cleanup, no need to backport
Closesscylladb/scylladb#25085
Before for views and indexes it was fetching base schema from db (and
couple other properties). This is a problem once we introduce atomic
tables and views deletion (in the following commit).
Because once we delete table it can no longer be fetched from db object,
and truncation is performed after atomically deleting all relevant
tables/views/indexes.
Now the whole relevant schema will be fetched via global_table_ptr
(table_shards) object.
When describing a table, we need to do it carefully: if some
columns were dropped, we must specify that explicitly by
```
ALTER TABLE {table} DROP {column} USING TIMESTAMP ...
```
in the result of the DESCRIBE statement. Failing to do so
could lead to data resurrection.
However, if a table has been altered many, many times,
we might end up with a huge create statement. Constructing
it could, in turn, trigger an oversized allocation.
Some tests ran into that very problem in fact.
In this commit, we want to mitigate the problem: instead of
allocating a contiguous chunk of memory for the create
statement, we use `fragmented_ostringstream` and `managed_string`
to possibly keep data scattered in memory. It makes handling
`cql3::description` less convenient in the code, but since
the struct is pretty much immediately serialized after
creating it, it's a very good trade-off.
We provide a reproducer. It consistently passes with this commit,
while having about 50% chance of failure before it (based on my
own experiments). Playing with the parameters of the test
doesn't seem to improve that chance, so let's keep it as-is.
Fixesscylladb/scylladb#24018
This commit increases the maximum length of names for keyspaces, tables, materialized views, and indexes from 48 to 192 bytes.
The previous 48-bytes limit was inherited from Cassandra 3 for compatibility. However, this validation was removed in Cassandra 4 and 5 (see CASSANDRA-20389)
and some usage scenarios (such as some feature store workflows generating long table names) now depend on this relaxed constraint.
This change brings ScyllaDB's behavior in line with modern Cassandra versions and better supports these use cases.
The new limit of 192 bytes is derived from underlying filesystem limitations to prevent runtime errors when creating directories for table data.
When a new table is created, ScyllaDB generates a directory for its SSTables. The directory name is constructed from the table name, a dash, and a 32-character UUID.
For a CDC-enabled table, an associated log table is also created, which has the suffix `_scylla_cdc_log` appended to its name.
The directory name for this log table becomes the longest possible representation.
Additionally we reserve 15 bytes for future use, allowing for potential future extensions without breaking existing schemas.
To guarantee that directory creation never fails due to exceeding filesystem name limits, the maximum name length is calculated as follows:
255 bytes (common filesystem limit for a path component)
- 32 bytes (for the 32-character UUID string)
- 1 byte (for the '-' separator)
- 15 bytes (for the '_scylla_cdc_log' suffix)
- 15 bytes (reserved for future use)
----------
= 192 bytes (Maximum allowed name length)
This calculation is similar in principle to the one proposed for Cassandra to fix related directory creation failures (see apache/cassandra/pull/4038).
This patch also updates/adds all associated tests to validate the new 192-byte limit.
The documentation has been updated accordingly.
This reverts commit 0b516da95b, reversing
changes made to 30199552ac. It breaks
cluster.random_failures.test_random_failures.test_random_failures
in debug mode (at least).
Fixes#24513
Before for views and indexes it was fetching base schema from db (and
couple other properties). This is a problem once we introduce atomic
tables and views deletion (in the following commit).
Because once we delete table it can no longer be fetched from db object,
and truncation is performed after atomically deleting all relevant
tables/views/indexes.
Now the whole relevant schema will be fetched via global_table_ptr
(table_shards) object.
This pull request adds support for creating custom indexes (at a metadata level) as long as a supported custom class is provided (currently only vector search).
The patch contains:
- a change in CREATE INDEX statement that allows for the USING keyword to be present as long as one of the supported classes is used
- support for describing custom indexes in the DESCRIBE statement
- unit tests
Co-authored by: @Balwancia
Closesscylladb/scylladb#23720
* github.com:scylladb/scylladb:
test/cqlpy: add custom index tests
index: support storing metadata for custom indices
Added function returning custom index class name.
Added printing custom index class name when using DESCRIBE.
Changed validation to reflect current support of indices.
In the previous commits we made sure that the base info is not dependent
on the base schema version, and the info dependent on the base schema
version is calculated when it's needed. In this patch we remove the
unnecessary re-setting of the base_info.
The set_base_info method isn't removed completely, because it also has
a secondary function - zeroing the view_info fields other than base_info.
Because of this, in this patch we rename it accordingly and limit its
use to the updates caused by a base schema change.
The base info now only contains values which are not reliant on the
base schema version. We remove the the base schema from the base info
to make it immutable regardless of base schema version, at the point
of this patch it's also not needed anywhere - the new base info can
replace the base schema in most places, and in the few (view_updates)
where we need it, we pull the most recent base schema version from
the database.
After this change, the base info no longer changes in a view schema
after creation, so we'll no longer get errors when we try generating
view updates with a base_info that's incompatible with a specific
base schema version.
Fixes#9059Fixes#21292Fixes#22410
In the following patch we plan to remove the base schema from the base_info
to make the base_info immutable. To do that, we first prepare the schema
registry for the change; we need to be able to create view schemas from
frozen schemas there and frozen schemas have no information about the base
table. Unless we do this change, after base schemas are removed from the
base info, we'll no longer be able to load a view schema to the schema registry
without looking up the base schema in the database.
This change also required some updates to schema building:
* we add a method for unfreezing a view schema with base info instead of
a base schema
* we make it possible to use schema_builder with a base info instead of
a base schema
* we add a method for creating a view schema from mutations with a base info
instead of a base schema
* we add a view_info constructor withat base info instead of a base schema
* we update the naming in schema_registry to reflect the usage of base info
instead of base schema
Currently, the base_info may or may not be set in view schemas.
Even when it's set, it may be modified. This necessitates extra
checks when handling view schemas, as well as potentially causing
errors when we forget to set it at some point.
Instead, we want to make the base info an immutable member of view
schemas (inside view_info). The first step towards that is making
sure that all newly created schemas have the base info set.
We achieve that by requiring a base schema when constructing a view
schema. Unfortunately, this adds complexity each time we're making
a view schema - we need to get the base schema as well.
In most cases, the base schema is already available. The most
problematic scenario is when we create a schema from mutations:
- when parsing system tables we can get the schema from the
database, as regular tables are parsed before views
- when loading a view schema using the schema loader tool, we need
to load the base additionally to the view schema, effectively
doubling the work
- when pulling the schema from another node - in this case we can
only get the current version of the base schema from the local
database
Additionally, we need to consider the base schema version - when
we generate view updates the version of the base schema used for
reads should match the version of the base schema in view's base
info.
This is achieved by selecting the correct (old or new) schema in
`db::schema_tables::merge_tables_and_views` and using the stored
base schema in the schema_registry.
In this series we implement the UpdateTable operation to add a GSI to an existing table, or remove a GSI from a table. As the individual commit messages will explained, this required changing how Alternator stores materialized view keys - instead of insisting that these key must be real columns (that is **not** the case when adding a GSI to an existing table), the materialized view can now take as its key any Alternator attribute serialized inside the ":attrs" map holding all non-key attributes. Fixes#11567.
We also fix the IndexStatus and Backfilling attributes returned by DescribeTable - as DynamoDB API users use this API to discover when a newly added GSI completed its "backfilling" (what we call "view building") stage. Fixes#11471.
This series should not be backported lightly - it's a new feature and required fairly large and intrusive changes that can introduce bugs to use cases that don't even use Alternator or its UpdateTable operations - every user of CQL materialized views or secondary indexes, as well as Alternator GSI or LSI, will use modified code. **It should be backported to 2025.1**, though - this version was actually branched long after this PR was sent, and it provides a feature that was promised for 2025.1.
Closesscylladb/scylladb#21989
* github.com:scylladb/scylladb:
alternator: fix view build on oversized GSI key attribute
mv: clean up do_delete_old_entry
test/alternator: unflake test for IndexStatus
test/alternator: work around unrelated bug causing test flakiness
docs/alternator: adding a GSI is no longer an unimplemented feature
test/alternator: remove xfail from all tests for issue 11567
alternator: overhaul implementation of GSIs and support UpdateTable
mv: support regular_column_transformation key columns in view
alternator: add new materialized-view computed column for item in map
build: in cmake build, schema needs alternator
build: build tests with Alternator
alternator: add function serialized_value_if_type()
mv: introduce regular_column_transformation, a new type of computed column
alternator: add IndexStatus/Backfilling in DescribeTable
alternator: add "LimitExceededException" error type
docs/alternator: document two more unimplemented Alternator features
This patch removes expansion of "SELECT *" in DESC MATERIALIZED VIEW.
Instead of explicitly printing each column, DESC command will now just
use SELECT *, if view was created with it. Also, adds a correspodning test.
Fixes#21154Closesscylladb/scylladb#21962
This patch adds a new computed column class for materialized views,
extract_from_attrs_column_computation
which is Alternator-specific and knows how to extract a value (of a
known type) from an attribute stored in Alternator's map-of-all-nonkey-
attributes ":attrs".
We'll use this new computed column in the next patch to reimplement GSI.
The new computed-column class is based on regular_column_transformation
introduced in the previous patch. It is not yet wired to anything:
The MV code cannot handle any regular_column_transformation yet, and
Alternator will not yet use it to create a GSI. We'll do those things
in the following patches.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Unlike with vnodes, each tablet is served only by a single
shard, and it is associated with a memtable that, when
flushed, it creates sstables which token-range is confined
to the tablet owning them.
On one hand, this allows for far better agility and elasticity
since migration of tablets between nodes or shards does not
require rewriting most if not all of the sstables, as required
with vnodes (at the cleanup phase).
Having too few tablets might limit performance due not
being served by all shards or by imbalance between shards
caused by quantization. The number of tabelts per table has to be
a power of 2 with the current design, and when divided by the
number of shards, some shards will serve N tablets, while others
may serve N+1, and when N is small N+1/N may be significantly
larger than 1. For example, with N=1, some shards will serve
2 tablet replicas and some will serve only 1, causing an imbalance
of 100%.
Now, simply allocating a lot more tablets for each table may
theoretically address this problem, but practically:
a. Each tablet has memory overhead and having too many tablets
in the system with many tables and many tablets for each of them
may overwhelm the system's and cause out-of-memory errors.
b. Too-small tablets cause a proliferation of small sstables
that are less efficient to acces, have higher metadata overhead
(due to per-sstable overhead), and might exhaust the system's
open file-descriptors limitations.
The options introduced in this change can help the user tune
the system in two ways:
1. Sizing the table to prevent unnecessary tablet splits
and migrations. This can be done when the table is created,
or later on, using ALTER TABLE.
2. Controlling min_per_shard_tablet_count to improve
tablet balancing, for hot tables.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
This commit addresses issue #21825, where invalid PERCENTILE values for
the `speculative_retry` setting were not properly handled, causing potential
server crashes. The valid range for PERCENTILE is between 0 and 100, as defined
in the documentation for speculative retry options, where values above 100 or
below 0 are invalid and should be rejected.
The added validation ensures that such invalid values are rejected with a clear
error message, improving system stability and user experience.
Fixes#21825Closesscylladb/scylladb#21879
Currently, when we load a frozen schema into the registry, we lose
the base info if the schema was of a view. Because of that, in various
places we need to set the base info again, and in some codepaths we
may miss it completely, which may make us unable to process some
requests (for example, when executing reverse queries on views).
Even after setting the base info, we may still lose it if the schema
entry gets deactivated due to all `schema_ptr`s temporarily dying.
To fix this, this patch adds the base schema to the registry, alongside
the view schema. We store just the frozen base schema, so that we can
transfer it across shards. With the base schema, we can now set the base
info when returning the schema from the registry. As a result, we can now
assume that all view schemas returned by the registry have base_info set.
In this series we also make sure that the view schemas in the registry are
kept up-to-date in regards to base schema changes.
Fixes https://github.com/scylladb/scylladb/issues/21354
This issue is a bug, so adding backport labels 6.1 and 6.2
Closesscylladb/scylladb#21862
* github.com:scylladb/scylladb:
test: add test for schema registry maintaining base info for views
schema_registry: avoid setting base info when getting the schema from registry
schema_registry: update cached base schemas when updating a view
schema_registry: cache base schemas for views
db: set base info before adding schema to registry
This string conversion functions are not in any fast path. Deinlining
them moves a <boost/lexical_cast.hpp> include out of a common header file.
Some files accessed on boost::iterator_range via lexical_cast.hpp,
so they gain a new dependency.
Closesscylladb/scylladb#21950
Currently, when we load a frozen schema into the registry, we lose
the base info if the schema was of a view. Because of that, in various
places we need to set the base info again, and in some codepaths we
may miss it completely, which may make us unable to process some
requests (for example, when executing reverse queries on views).
Even after setting the base info, we may still lose it if the schema
entry gets deactivated.
To fix this, this patch adds the base schema to the registry, alongside
the view schema. With the base schema, we can now set the base
info when returning the schema from the registry. As a result, we can now
assume that all view schemas returned by the registry have base_info set.
To store the base schema, the loader methods now have to return the base
schema alongside the view schema. At the same time, when loading into
the registry, we need to check whether we're loading a view schema, and if
so, we need to also provide the base schema. When inserting a regular table
schema, the base schema should be a disengaged optional.
Schema of system tables is defined statically and table_schema_version needs to be explicitly set in code like this:
```
builder.with_version(system_keyspace::generate_schema_version(table_id, version_offset));
```
Whenever schema is changed, the schema version needs to change, otherwise we hit undefined behavior when trying to interpret mutation data created with the old schema using the new schema.
It's not obvious that one needs to do that and developers often forget to do that. There were several instances of mistakes of omission, some caught during review, some not, e.g.: 31ea74b96e.
This patch changes definitions to call the new `schema_builder::with_hash_version()`, which will make the schema builder compute version from schema definition so that changes of the schema will automatically change the version. This way we no longer rely on the developer to remember to bump the version offset.
All nodes should arrive at the same version, which is verified by existing `test_group0_schema_versioning` and a new unit test: `test_system_schema_version_is_stable`.
Closesscylladb/scylladb#21602
* github.com:scylladb/scylladb:
system_tables: Compute schema version automatically
schema_builder: Introduce with_hash_version()
schema: Store raw_view_info in schema::raw_schema
schema: Remove dead comment
hashing: Add hasher for unordered_map
hashing: Add hasher for unique_ptr
hashing: Add hasher for double
[avi: add missing include <memory> to hashing.hh]
Our "sstring_view" is an historic alias for the standard std::string_view.
The patch changes the last remaining random uses of this old alias across
our source directory to the standard type name.
After this patch, there are no more uses of the "sstring_view" alias.
It will be removed in the following patch.
Refs #4062.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
For historic reasons, we have (in bytes.hh) a type sstring_view which
is an alias for std::string_view - since the same standard type can hold
a pointer into both a seastar::sstring and std::string.
This alias in unnecessary and misleading to new developers (who might
assume it is somehow different from std::string_view). This patch doesn't
yet remove all occurances of sstring_view (the request in #4062), but
begins to do it by renaming one commonly-used function, to_sstring_view(bytes)
to to_string_view() and of course changes all its uses to the new name.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Currently, if version is missing, we use a unique timeuuid as the
version. It's not useful for creating static schema of system tables
because to achieve the same version on all the nodes, version needs to
be provided externally.
This patch introduces a way to build the schema with version computed
from schema definition, so we can have a stable version which is the
same on all machines.
Will be used for reliable computation of schema version for system
tables. System tables currently set the version statically and we rely
on the developer to bump up the version manually when the definition
changes. We cannot use mutation hash, since system tables are
initialized too rearly (mutation hash needs system schema to be
already there). This is a very error prone process, as it is easy to
forget to do so, and the issue comes up only when testing mixed
clusters.
It will be used for hashing, which will work with raw_schema.
Also, it's more in-line with the current design, where basic information
is kept in raw_schema and other fields are derived from it.
Recently, seastar rpc started accepting std::type_identity in addition
to boost::type as a type marker (while labeling the latter with an
ominous deprecation warning). Reduce our depedendency on boost
by switching to std::type_identity.
It's somewhat common to ask for the partition key and clustering key
columns, or for the static and regular columsn. Provide accessors for them
rather than requiring the user to glue them.
Some callers are converted.
Closesscylladb/scylladb#21191
