When draining the view builder, we abort ongoing operations using the
view builder's abort source, which may cause them to fail with
abort_requested_exception or raft::request_aborted exceptions.
Since these failures are expected during shutdown, reduce the log level
in add_new_view from 'error' to 'debug' for these specific exceptions
while keeping 'error' level for unexpected failures.
Closesscylladb/scylladb#26297
(cherry picked from commit 6bc41926e2)
Closesscylladb/scylladb#27536
The PRUNE MATERIALIZED VIEW statement is supposed to remove ghost rows from the
view. Ghost rows are rows in the view with no corresponding row in the base table.
Before this patch, only rows whose primary key columns of the base table had
different values than any of the base rows were treated as ghost rows by the PRUNE
statement. However, view rows which have a column in their primary key that's not
in the base primary can also be ghost rows if this column has a different value
than the base row with the same values of remaining primary key columns. That's
because these rows won't be deleted unless we change value of this column in the
base table to this specific value.
In this patch we add a check for this column in the PRUNE MATERIALIZED VIEW logic.
If this column isn't the same in the base table and the view, these rows are also
deleted.
Fixes https://github.com/scylladb/scylladb/issues/25655Closesscylladb/scylladb#25720
(cherry picked from commit 1f9be235b8)
Closesscylladb/scylladb#25954
Interval map is very susceptible to quadratic space behavior when
it's flooded with many entries overlapping all (or most of)
intervals, since each such entry will have presence on all
intervals it overlaps with.
A trigger we observed was memtable flush storm, which creates many
small "L0" sstables that spans roughly the entire token range.
Since we cannot rely on insertion order, solution will be about
storing sstables with such wide ranges in a vector (unleveled).
There should be no consequence for single-key reads, since upper
layer applies an additional filtering based on token of key being
queried.
And for range scans, there can be an increase in memory usage,
but not significant because the sstables span an wide range and
would have been selected in the combined reader if the range of
scan overlaps with them.
Anyway, this is a protection against storm of memtable flushes
and shouldn't be the common scenario.
It works both with tablets and vnodes, by adjusting the token
range spanned by compaction group accordingly.
Fixes#23634.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
(cherry picked from commit c77f710a0c)
Dropping an index is a schema change of its base table and
a schema drop of the index's materialized view. This combination
of schema changes used to cause issues during view building, because
when a view schema was dropped, it wasn't getting updated with the
new version of the base schema, and while the view building was
in progress, we would update the base schema for the base table
mutation reader and try generating updates with a view schema that
wasn't compatible with the base schema, failing on an `on_internal_error`.
In this patch we add a test for this scenario. We create an index,
halt its view building process using an injection, and drop it.
If no errors are thrown, the test succeeds.
The test was failing before https://github.com/scylladb/scylladb/pull/23337
and is passing afterwards.
(cherry picked from commit bf7bba9634)
The base_dependent_view_info is no longer needed to be shared or
modified in the view_info, so we no longer need to keep it as
a shared pointer.
(cherry picked from commit d77f11d436)
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.
(cherry picked from commit d7bd86591e)
The base info in view schemas no longer changes on base schema
updates, so saving the base info with a view schema from a specific
point in time doesn't provide any additional benefits.
In this patch we remove the code using the base_and_view snapshots
as it's no longer useful.
(cherry picked from commit ea462efa3d)
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
(cherry picked from commit ad55935411)
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
(cherry picked from commit 05fce91945)
In the following patches we'll add the base info instead of the
base schema to various places (schema building, schema registry).
There, we'll sometimes need to update the base_info fields, which
we can't do with const members. There's also a place (global_schema_ptr)
where we won't be able to use the base_info_ptr (a shared pointer to the
base_info), so we can't just use the base_info_ptr everywhere instead.
In this patch we unmark these members as const.
In the following patches we'll remove the methods for changing the
base_info in the view schema, so it will remain effectively const.
(cherry picked from commit 6e539c2b4d)
In the following commits the base_depenedent_view_info will be needed
in many more places. To avoid including the whole db/view/view.hh
or forward declaring (where possible) the base info, we move it to
a separate header which can be included anywhere at almost no cost.
(cherry picked from commit 32258d8f9a)
In preparation of making the base_info immutable, we want to get rid of
any base_dependent_view_info fields that can change when base schema
is updated.
The _base_regular_columns_in_view_pk and _base_static_columns_in_view_pk
base column_ids of corresponding base columns and they can change
(decrease) when an earlier column is dropped in the base table.
view_updates is the only location where these values are used and calculating
them is not expensive when comparing to the overall work done while performing
a view update - we iterate over all view primary key columns and look them up
in the base table.
With this in mind, we can just calculate them when creating a view_updates
object, instead of keeping them in the base_info. We do that in this patch.
(cherry picked from commit a3d2cd6b5e)
The has_computed_column_depending_on_base_non_primary_key
and is_partition_key_permutation_of_base_partition_key variables
in the view_info depend on the base table so they should be in the
base_dependent_view_info instead of view_info.
(cherry picked from commit a33963daef)
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.
(cherry picked from commit 900687c818)
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
(cherry picked from commit 529ff3efa5)
Closesscylladb/scylladb#22826
The view builder builds a view by going over the entire token ring,
consuming the base table partitions, and generating view updates for
each partition.
A view is considered as built when we complete a full cycle of the
token ring. Suppose we start to build a view at a token F. We will
consume all partitions with tokens starting at F until the maximum
token, then go back to the minimum token and consume all partitions
until F, and then we detect that we pass F and complete building the
view. This happens in the view builder consumer in
`check_for_built_views`.
The problem is that we check if we pass the first token F with the
condition `_step.current_token() >= it->first_token` whenever we consume
a new partition or the current_token goes back to the minimum token.
But suppose that we don't have any partitions with a token greater than
or equal to the first token (this could happen if the partition with
token F was moved to another node for example), then this condition will never be
satisfied, and we don't detect correctly when we pass F. Instead, we
go back to the minimum token, building the same token ranges again,
in a possibly infinite loop.
To fix this we add another step when reaching the end of the reader's
stream. When this happens it means we don't have any more fragments to
consume until the end of the range, so we advance the current_token to
the end of the range, simulating a partition, and check for built views
in that range.
Fixesscylladb/scylladb#21829Closesscylladb/scylladb#22493
(cherry picked from commit 6d34125eb7)
Closesscylladb/scylladb#22607
Now that all topology related code uses host ids there is not point to
maintain ip to id (and back) mappings in the token metadata. After the
patch the mapping will be maintained in the gossiper only. The rest of
the system will use host ids and in rare cases where translation is
needed (mostly for UX compatibility reasons) the translation will be
done using gossiper.
Fixes: scylladb/scylla#21777
* 'gleb/drop-ip-from-tm-v3' of github.com:scylladb/scylla-dev: (57 commits)
hint manager: do not translate ip to id in case hint manager is stopped already
locator: token_metadata: drop update_host_id() function that does nothing now
locator: topology: drop indexing by ips
repair: drop unneeded code
storage_service: use host_id to look for a node in on_alive handler
storage_proxy: translate ips to ids in forward array using gossiper
locator: topology: remove unused functions
storage_service: check for outdated ip in on_change notification in the peers table
storage_proxy: translate id to ip using address map in tablets's describe_ring code instead of taking one from the topology
topology coordinator: change connection dropping code to work on host ids
cql3: report host id instead of ip in error during SELECT FROM MUTATION_FRAGMENTS query
locator: drop unused function from tablet_effective_replication_map
api: view_build_statuses: do not use IP from the topology, but translate id to ip using address map instead
locator: token_metadata: remove unused ip based functions
locator: network_topology_strategy: use host_id based function to check number of endpoints in dcs
gossiper: drop get_unreachable_token_owners functions
storage_service: use gossiper to map ip to id in node_ops operations
storage_service: fix indentation after the last patch
storage_service: drop loops from node ops replace_prepare handling since there can be only one replacing node
token_metadata: drop no longer used functions
...
Guard the whole view builder startup routine by holding the semaphore
until it's done instead of releasing it early, so that it's not
intercepted by migration notifications.
The function write_view_build_status takes two lambda functions and
chooses which of them to run depending on the upgrade state. It might
run both of them.
The parameters ks_name and view_name should be passed by value instead
of by reference because they are moved inside each lambda function.
Otherwise, if both lambdas are run, the second call operates on invalid
values that were moved.
When adding a new view for building, first write the status to the
system tables and then add the view building step that will start
building it.
Otherwise, if we start building it before the status is written to the
table, it may happen that we complete building the view, write the
SUCCESS status, and then overwrite it with the STARTED status. The
view_build_status table will remain in incorrect state indicating the
view building is not complete.
Fixesscylladb/scylladb#20638
When starting the view builder, we find all existing views in
`calculate_shard_build_step` and then register a listener for new views.
Between these steps we may yield and create a new view, then we miss
initializing the view build step for the new view, and we won't start
building it.
To fix this we first register the listener and then read existing views,
so a view can't be missed.
Fixesscylladb/scylladb#20338Closesscylladb/scylladb#22184
Replace usages of `boost::algorithm::join()` with `fmt::join()` to improve
performance and reduce dependency on Boost. `fmt::join()` allows direct
formatting of ranges and tuples with custom separators without creating
intermediate strings.
When formatting comma-separated values into another string, fmt::join()
avoids the overhead of temporary string creation that
`boost::algorithm::join()` requires. This change also helps streamline
our dependencies by leveraging the existing fmt library instead of
Boost.Algorithm.
To avoid the ambiguity, some caller sites were updated to call
`seastar::format()` explicitly.
See also
- boost::algorithm::join():
https://www.boost.org/doc/libs/1_87_0/doc/html/string_algo/reference.html#doxygen.join_8hpp
- fmt::join():
https://fmt.dev/11.0/api/#ranges-api
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#22082
Currently, when finishing db::view::calculate_affected_clustering_ranges
we deoverlap, transform and copy all ranges prepared before. This
is all done within a single continuation and can cause stalls.
We fix this by adding yields after each transform and moving elements
to the final vector one by one instead of copying them all at the end.
After this change, the longest continuation in this code will be
deoverlapping the initial ranges (and one transform). While it has
a relatively high computational complexity (we sort all ranges), it
should execute quickly because we're operating on views there and
we don't need to copy the actual bytes. If we encounter a stall there,
we'll need to implement an asynchronous `deoverlap` method.
Fixesscylladb/scylladb#21843Closesscylladb/scylladb#21846
This pull request is continuation of scylladb/scylladb#20688 - contents of the main commit are the same, the only change is the additional commit with a test.
Until this patch, the materialized view flow-control algorithm (https://www.scylladb.com/2018/12/04/worry-free-ingestion-flow-control/) used a constant delay_limit_us hard-coded to one second, which means that when the size of view-update backlog reached the maximum (10% of memory), we delay every request by an additional second - while smaller amounts of backlog will result in smaller delays.
This hard-coded one maximum second delay was considered *huge* - it will slow down a client with concurrency 1000 to just 1000 requests per second - but we already saw some workloads where it was not enough - such as a test workload running very slow reads at high concurrency on a slow machine, where a latency of over one second was expected for each read, so adding a one second latecy for writes wasn't having any noticable affect on slowing down the client.
So this patch replaces the hard-coded default with a live-updateable configuration parameter, `view_flow_control_delay_limit_in_ms`, which defaults to 1000ms as before.
Another useful way in which the new `view_flow_control_delay_limit_in_ms` can be used is to set it to 0. In that case, the view-update flow control always adds zero delay, and in effect - does absolutely nothing. This setting can be used in emergency situations where it is suspected that the MV flow control is not behaving properly, and the user wants to disable it.
The new parameter's help string mentions both these use cases of the parameter.
Fixes#18187
This is new functionality, no need to backport to any open source release.
Closesscylladb/scylladb#21647
* github.com:scylladb/scylladb:
materialized views: test for the MV delay configuration parameter
service: add injection for skipping view update backlog
materialized view: make flow-control maximum delay configurable
This change goes thru locator:topology to use node&
instead of node* where nullptr is not possible. There are
places where the node object is used in unordered_set, in
those cases the node is wrapped in std::reference_wrapper.
Fixesscylladb/scylladb#20357Closesscylladb/scylladb#21863
Replace boost::make_iterator_range() with std::ranges::subrange.
This change improves code modernization and reduces external dependencies:
- Replace boost::make_iterator_range() with std::ranges::subrange
- Remove boost/range/iterator_range.hpp include
- Improve iterator type detection in interval.hh using std::ranges::const_iterator_t<Range>
This is part of ongoing efforts to modernize our codebase and minimize
external dependencies.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#21787
Until this patch, the materialized view flow-control algorithm
(https://www.scylladb.com/2018/12/04/worry-free-ingestion-flow-control/)
used a constant delay_limit_us hard-coded to one second, which means
that when the size of view-update backlog reached the maximum (10%
of memory), we delay every request by an additional second - while
smaller amounts of backlog will result in smaller delays.
This hard-coded one maximum second delay was considered *huge* - it will
slow down a client with concurrency 1000 to just 1000 requests per
second - but we already saw some workloads where it was not enough -
such as a test workload running very slow reads at high concurrency
on a slow machine, where a latency of over one second was expected
for each read, so adding a one second latecy for writes wasn't having
any noticable affect on slowing down the client.
So this patch replaces the hard-coded default with a live-updateable
configuration parameter, `view_flow_control_delay_limit_in_ms`, which
defaults to 1000ms as before.
Another useful way in which the new `view_flow_control_delay_limit_in_ms`
can be used is to set it to 0. In that case, the view-update flow
control always adds zero delay, and in effect - does absolutely
nothing. This setting can be used in emergency situations where it
is suspected that the MV flow control is not behaving properly, and
the user wants to disable it.
The new parameter's help string mentions both these use cases of
the parameter.
Fixes#18187
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
"
This rather large patch series moves storage proxy and some adjacent
services (like migration manager) to use host ids to identify nodes rather
than ips. Messaging service gains a capability to address nodes by host
ids (which allows dropping translations from topology coordinator code
that worked on host ids already) and also makes sure that a node with
incorrect host id will reject a message (can happen during address
changes).
The series gets rid of the raft address map completely and replaces it with
the gossiper address map which is managed by the gossiper since translation
is now done in the layer below raft.
Fixes: scylladb/scylladb#6403
perf-simple-query -- smp 1 -m 1G output
Before:
enable-cache=1
Running test with config: {partitions=10000, concurrency=100, mode=read, frontend=cql, query_single_key=no, counters=no}
Disabling auto compaction
Creating 10000 partitions...
64336.82 tps ( 63.1 allocs/op, 0.0 logallocs/op, 14.1 tasks/op, 41291 insns/op, 24485 cycles/op, 0 errors)
62669.58 tps ( 63.1 allocs/op, 0.0 logallocs/op, 14.1 tasks/op, 41277 insns/op, 24695 cycles/op, 0 errors)
69172.12 tps ( 63.1 allocs/op, 0.0 logallocs/op, 14.2 tasks/op, 41326 insns/op, 24463 cycles/op, 0 errors)
56706.60 tps ( 63.1 allocs/op, 0.0 logallocs/op, 14.1 tasks/op, 41143 insns/op, 24513 cycles/op, 0 errors)
56416.65 tps ( 63.1 allocs/op, 0.0 logallocs/op, 14.1 tasks/op, 41186 insns/op, 24851 cycles/op, 0 errors)
throughput: mean=61860.35 standard-deviation=5395.48 median=62669.58 median-absolute-deviation=5153.75 maximum=69172.12 minimum=56416.65
instructions_per_op: mean=41244.62 standard-deviation=76.90 median=41276.94 median-absolute-deviation=58.55 maximum=41326.19 minimum=41142.80
cpu_cycles_per_op: mean=24601.35 standard-deviation=167.39 median=24512.64 median-absolute-deviation=116.65 maximum=24851.45 minimum=24462.70
After:
enable-cache=1
Running test with config: {partitions=10000, concurrency=100, mode=read, frontend=cql, query_single_key=no, counters=no}
Disabling auto compaction
Creating 10000 partitions...
65237.35 tps ( 63.1 allocs/op, 0.0 logallocs/op, 14.2 tasks/op, 40733 insns/op, 23145 cycles/op, 0 errors)
59283.09 tps ( 63.1 allocs/op, 0.0 logallocs/op, 14.1 tasks/op, 40624 insns/op, 23948 cycles/op, 0 errors)
70851.03 tps ( 63.1 allocs/op, 0.0 logallocs/op, 14.1 tasks/op, 40625 insns/op, 23027 cycles/op, 0 errors)
70549.61 tps ( 63.1 allocs/op, 0.0 logallocs/op, 14.1 tasks/op, 40650 insns/op, 23266 cycles/op, 0 errors)
68634.96 tps ( 63.1 allocs/op, 0.0 logallocs/op, 14.1 tasks/op, 40622 insns/op, 22935 cycles/op, 0 errors)
throughput: mean=66911.21 standard-deviation=4814.60 median=68634.96 median-absolute-deviation=3638.40 maximum=70851.03 minimum=59283.09
instructions_per_op: mean=40650.89 standard-deviation=47.55 median=40624.60 median-absolute-deviation=27.11 maximum=40733.37 minimum=40622.33
cpu_cycles_per_op: mean=23264.16 standard-deviation=402.12 median=23145.29 median-absolute-deviation=237.63 maximum=23947.96 minimum=22934.59
CI: https://jenkins.scylladb.com/job/scylla-master/job/scylla-ci/13531/
SCT (longevity-100gb-4h with nemesis_selector: ['topology_changes']): https://jenkins.scylladb.com/view/staging/job/scylla-staging/job/gleb/job/move-to-host-id/3/
Tested mixed cluster manually.
"
* 'gleb/move-to-host-id-v2' of github.com:scylladb/scylla-dev: (55 commits)
group0: drop unused field from replace_info struct
test: rename raft_address_map_test to address_map_test and move if from raft tests
raft_address_map: remove raft address map
topology coordinator: do not modify expire state for left/new nodes any more in raft address map
topology coordinator: drop expiring entries in gossiper address map on error injections since raft one is no longer used
group0: drop raft address map dependency from raft_rpc
group0: move raft_ticker_type definition from raft_address_map.hh
storage_service: do not update raft address map on gossiper events
group0: drop raft address map dependency from raft_server_with_timeouts
group0: move group0 upgrade code to host ids
repair: drop raft address map dependency
group0: remove unused raft address map getter from raft_group0
group0: drop raft address map from group0_state_machine dependency since it is not used there any more
group0: remove dependency on raft address map from group0_state_id_handler
gossiper: add get_application_state_ptr that searches by host_id
gossiper: change get_live_token_owners to return host ids
view: move view building to host id
hints: use host id to send hints
storage_proxy: remove id_vector_to_addr since it is no longer used
db: consistency_level: change is_sufficient_live_nodes to work on host ids
...
now that we are allowed to use C++23. we now have the luxury of using
`std::views::transform`.
in this change, we:
- replace `boost::adaptors::transformed` with `std::views::transform`
- use `fmt::join()` when appropriate where `boost::algorithm::join()`
is not applicable to a range view returned by `std::view::transform`.
- use `std::ranges::fold_left()` to accumulate the range returned by
`std::view::transform`
- use `std::ranges::fold_left()` to get the maximum element in the
range returned by `std::view::transform`
- use `std::ranges::min()` to get the minimal element in the range
returned by `std::view::transform`
- use `std::ranges::equal()` to compare the range views returned
by `std::view::transform`
- remove unused `#include <boost/range/adaptor/transformed.hpp>`
- use `std::ranges::subrange()` instead of `boost::make_iterator_range()`,
to feed `std::views::transform()` a view range.
to reduce the dependency to boost for better maintainability, and
leverage standard library features for better long-term support.
this change is part of our ongoing effort to modernize our codebase
and reduce external dependencies where possible.
limitations:
there are still a couple places where we are still using
`boost::adaptors::transformed` due to the lack of a C++23 alternative
for `boost::join()` and `boost::adaptors::uniqued`.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#21700
Modernize the codebase by replacing Boost range adaptors with C++23 standard library views,
reducing external dependencies and leveraging modern C++ language features.
Key Changes:
- Replace `boost::adaptors::filtered` with `std::views::filter`
- Remove `#include <boost/range/adaptor/filtered.hpp>`
- Utilize standard library range views
Motivation:
- Reduce project's external dependency footprint
- Leverage standard library's range and view capabilities
- Improve long-term code maintainability
- Align with modern C++ best practices
Implementation Challenges and Considerations:
1. Range Conversion and Move Semantics
- `std::ranges::to` adaptor requires rvalue references
- Necessitated updates to variable and parameter constness
- Example: `cql3/restrictions/statement_restrictions.cc` modified to remove `const`
from `common` to enable efficient range conversion
2. Range Iteration and Mutation
- Range views may mutate internal state during iteration
- Cannot pass ranges by const reference in some scenarios
- Solution: Pass ranges by rvalue reference to explicitly indicate
state invalidation
Limitations:
- One instance of `boost::adaptors::filtered` temporarily preserved
due to lack of a C++23 alternative for `boost::join()`
- A comprehensive replacement will be addressed in a follow-up change
This change is part of our ongoing effort to modernize the codebase,
reducing external dependencies and adopting modern C++ practices.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#21648
The semantics of Scylla's materialized views may vary depending on how their
primary keys correspond to the base table's one. One of the differences is
how we handle writes to columns in the base table that are not selected by
a view:
* Case 1: The view's PK is a permutation of the base table's PK:
Since the view's primary key cannot be changed in an update, a row in
the view remains alive as long as the corresponding row in the base table
is alive.
The tricky part comes when the base table has columns that are NOT selected
by the view. CQL3 used to not allow for defining a table that didn't have
any other columns besides its primary key. Also, when inserting a row into
a table, it was mandatory to provide at least one value aside from the
primary key. At some point it changed [1] and the implementation of the
solution relied on the notion of the row marker.
Putting the details aside, consider the following scenario:
(i) the base table has a primary key consisting of columns
c_1, ..., c_k, and it has regular columns rc_1, ..., rc_n,
(ii) the primary key of an MV defined on that table consists of
a permutation of c_1, ..., c_k. The MV doesn't select at least
one of the regular columns of the base table. Without loss of
generality, let that unselected column be rc_1.
(iii) the base table has a row R whose only non-null value is the one
in the regular column rc_1.
Now, what will R correspond to in the MV? The base table doesn't have a row
marker, but all of its regular columns in the MV will be NULLs. That's NOT
allowed.
To solve that problem, all unselected columns have corresponding virtual
columns in the MV; the only information they provide is whether there is
a value in the base table or not. This way, the MV knows if a row is still
alive or not.
For that reason, we send view updates to virtual columns in the following
cases:
(i) the value in the column changes from NULL to a value, i.e. it's
created,
(ii) the value in the column exists, but its TTL has been updated.
* Case 2: The view's PK has one more column that the base table's one:
Since the primary key of the view has a regular column C from the base
table, it is guaranteed that if there's a row in the MV, the corresponding
row in the base table can remain alive: since C is part of the view's PK,
it must have a value, so the row in the base table has a value in C too.
The problem with virtual columns from the previous case doesn't manifest
in this one. The liveness of the cell in C determines the liveness of
the whole row in the view.
The semantics gets more complex, but the conclusion is this: in case 1,
virtual columns exist and we may need to generate view updates for them,
while in case 2 virtual columns do NOT exist and so we don't generate
view updates for them.
What changes in this patch is we adjust the code to it. If a view has
a regular column from the base table as part of its primary key, we
no longer emit view updates when we change a column unselected by that
view. It is purely an OPTIMIZATION change.
[1]: https://issues.apache.org/jira/browse/CASSANDRA-4361Fixesscylladb/scylladb#21652Closesscylladb/scylladb#21653
now that we are allowed to use C++23. we now have the luxury of using
`std::ranges::find_if`.
in this change, we:
- replace `boost::find_if` with `std::ranges::find_if`
- remove all `#include <boost/range/algorithm/find_if.hpp>`
to reduce the dependency to boost for better maintainability, and
leverage standard library features for better long-term support.
this change is part of our ongoing effort to modernize our codebase
and reduce external dependencies where possible.
Signed-off-by: Kefu Chai <kefu.chai@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>
now that we are allowed to use C++23. we now have the luxury of using
`std::ranges::any_of`.
in this change, we replace `boost::algorithm::any_of` with
`std::ranges::any_of`
to reduce the dependency to boost for better maintainability, and
leverage standard library features for better long-term support.
this change is part of our ongoing effort to modernize our codebase
and reduce external dependencies where possible.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
This pattern is -- if requested (by test) suspend code execution until requestor (the test) explicitly wakes it up. For that the injected place should inject a lambda that is called with so called "handler" at hand and try to read message from the handler. In many cases the inner lambda additionally prints a message into logs that tests waits upon to make sure injection was stepped on. In the end of the day this "breakpoint" is injected like
```
co_await inject("foo", [] (auto& handler) {
log.info("foo waiting");
co_await handler.wait_for_message(timeout);
});
```
This PR makes breakpoints shorter and more unified, like this
```
co_await inject("foo", wait_for_message(timeout));
```
where `wait_for_message` is a wrapper structure used to pick new `inject()` overload.
Closesscylladb/scylladb#21342
* github.com:scylladb/scylladb:
sstables: Use inject(wait_for_message_overload)
treewide,error_injection: Use inject(wait_for_message) and fix tests
treewide,error_injection: Use inject(wait_for_message) overload
error_injection: Add inject() overload with wait_for_message wrapper
View building is an expensive process that takes a long time to complete.
During the build, it's impact on other work should be minimized, even at
the expense of slightly slowing it down.
Instead, view building is currently performed in the the same scheduling
group (gossip) as other high-priority tasks, in particular raft processing,
which slows it down, making races more likely and increasing the number
of retries that need to be done.
While view building is still initiated in the gossip group (as it's the
result of adding a view, which is a schema change), in this patch the bulk
of the view building work is moved to a low-priority, maintenance scheduling
group (named "streaming" after its main use case).
Additionally, a test is added, where we make sure that the scheduling
group is the one most used when building a view.
Fixes https://github.com/scylladb/scylladb/issues/21232Closesscylladb/scylladb#21326
To reduce the dependency load, replace use of boost ranges
with the std equivalent.
Files that lost the indirect boost dependency have it added as a
direct dependency.
Many places want to inject a handler that waits for external kick. Now
there's convenience inject() method overload for this. It will result in
extra messages in logs, but so far no code/test cares about it.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
now that we are allowed to use C++23. we now have the luxury of using
`std::views::values`.
in this change, we:
- replace `boost::adaptors::map_values` with `std::views::values`
- update affected code to work with `std::views::values`
- the places where we use `boost::join()` are not changed, because
we cannot use `std::views::concat` yet. this helper is only
available in C++26.
to reduce the dependency to boost for better maintainability, and
leverage standard library features for better long-term support.
this change is part of our ongoing effort to modernize our codebase
and reduce external dependencies where possible.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#21265
When writing to some tables with materialized views, we need to read from the base table first to perform a delete of the old view row. When doing so, the memory used for the read is tracked by the user read concurrency semaphore. When we have a large number of such reads, we may use up all of the semaphore units, causing the following reads to be queued. When we have some user reads coming at the same time, these reads can have very high latency due to the write workload on the base table. We want to avoid this, so that the write workload doesn't have a high impact on the latency of the read workload.
This is fixed in this patch by adding a separate read concurrency semaphore just for view update read-before-writes. With the new semaphore, even if there are many view update read-before-writes, they will be queued on a different semaphore than the user reads, and they won't impact their latency.
The second issue fixed by this patch is the concurrency of the view updates that is currently unlimited. Because of that view updates may take up so much memory that they we may run out of memory.
This is fixed by using the read admission on the view update concurrency semaphore.
This limits the number of concurrent view update reads to
max_count_concurrent_view_update_reads, all other incoming view update reads are
queued using just a small chunk of memory. Without this, the reads would also get
queued after exceeding view_update_reader_concurrency_semaphore_serialize_limit_multiplier, but they would take much more memory while staying in the queue.
The new semaphore has half the capacity of the regular user read concurrency semahpore and is currently used only for user writes - is't used independently of the scheduling group on which we base the read semaphore selection, but we use a different code path for streaming (not database::do_apply) and we shouldn't have view updates in system writes or during compaction.
This patch also adds a test to confirm that the view update workload doesn't impact the read latency, as well as a test which confirms that we do not run out of memory even under heavy view udpate workload.
The issue of view updates causing increased latencies most often occurs in the following scenario:
* we have a medium to high write workload to a table with a materialized view which requires reading from the base table before sending the update to delete the old rows
* we have any read workload
* one replica is slower or is handling more writes due to an imbalance of data distribution
* we write with a cl<ALL, the mentioned replica is replying to write requests slower while new ones keep being sent to it.
* each write performs a read first taking resources from the user read concurrency semaphore, so when enough writes accumulate the reads using the semaphore start getting queued
* the queue is shared by regular reads and view update reads. When there's enough view update reads in the queue, regular reads start getting increased latencies
An sct test (perf-regression-latency-mv-read-concurrency) was prepared to somewhat resemble this scenario:
* the tables were prepared satisfying the conditions above
* we use a medium write workload and a very low read workload
* the imbalance is achieved by writing to just a few (10) partitions - some replicas (and shards) can have twice or more used partitions than others. We also keep writing to a limited (though high) number of rows, to cause overwrites which require reading before sending the view update
* to minimize the test case, we use a cluster of 3 nodes and rf=2, we write with cl=ONE to have background replica writes and read with cl=ALL to wait for the slower replica to respond.
In the test above:
* without the fix, the latency of reads increases over 50s
* with the fix, the latency of reads stays below 20ms
Fixes https://github.com/scylladb/scylladb/issues/8873
Fixes https://github.com/scylladb/scylladb/issues/15805
The patch is not that small and it isn't fixing a regression, so no backports
Closesscylladb/scylladb#20887
* github.com:scylladb/scylladb:
test: add test for high view update concurrency causing bad_allocs
test: add test for high view update concurrency degrading read latency
mv: add a dedicated read concurrency semaphore for view update read before writes
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
the log.hh under the root of the tree was created keep the backward
compatibility when seastar was extracted into a separate library.
so log.hh should belong to `utils` directory, as it is based solely
on seastar, and can be used all subsystems.
in this change, we move log.hh into utils/log.hh to that it is more
modularized. and this also improves the readability, when one see
`#include "utils/log.hh"`, it is obvious that this source file
needs the logging system, instead of its own log facility -- please
note, we do have two other `log.hh` in the tree.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
This commit add a test for checking whether a large view update workload
impacts the latency of other user reads.
In the test, we first create a table for reads and another table with
a materialized view. We then start writing to the table with the view
with a limited number of rows - when overwriting, we need to read the
previous value of the row to prepare a delete of the old row in the view.
This should not impact the latency of the read workload from the other
table that we start at the same time. The test fails if any of the reads
times out.
To reach the failing state more consistantly, we use add a sleep after
reading the old value of the base row, to keep the reader concurrency
semaphore units longer. At the same time, we use a lower threshold for
queueing reads on the semaphore, to see the impact of view update reads
earlier.
Because of the high load, the writes may timeout, but that's expected
- we fail the test only if the user reads time out.
This includes way too much, including <boost/regex.hpp>, which is huge.
Drop includes of adaptors.hpp and replace by what is needed.
Closesscylladb/scylladb#21187
