Soon, we want to log a warning on too many cell tombstones as well.
Extract the logging code to allow reuse between the row and cell
tombstone warnings.
flat_mutation_reader_v2 was introduced in a pair of commits in 2021:
e3309322c3 "Clone flat_mutation_reader related classes into v2 variants"
08b5773c12 "Adapt flat_mutation_reader_v2 to the new version of the API"
as a replacement for flat_mutation_reader, using range_tombstone_change
instead of range_tombstone to represent represent range tombstones. See
those commits for more information.
The transition was incremental; the last use of the original
flat_mutation_reader was removed in 2022 in commit
026f8cc1e7 "db: Use mutation_partition_v2 in mvcc"
In turn, flat_mutation_reader was introduced in 2017 in commit
748205ca75 "Introduce flat_mutation_reader"
To transition from a mutation_reader that nested rows within
a partition in a separate stream, to a flat reader that streamed
partitions and rows in the same stream.
Here, we reclaim the original name and rename the awkward
flat_mutation_reader_v2 to mutation_reader.
Note that mutation_fragment_v2 remains since we still use the original
for compatibilty, sometimes.
Some notes about the transition:
- files were also renamed. In one case (flat_mutation_reader_test.cc), the
rename target already existed, so we rename to
mutation_reader_another_test.cc.
- a namespace 'mutation_reader' with two definitions existed (in
mutation_reader_fwd.hh). Its contents was folded into the mutation_reader
class. As a result, a few #includes had to be adjusted.
Closesscylladb/scylladb#19356
Previously semaphore mismatch was checked only in multi-partition
queries and if happened, an internal error was thrown.
This commit pushed the check down to `querier_cache`, so each
`lookup_*_querier` method will check for the mismatch.
What's more, if semaphore mismatch occurs, check whether both semaphores belong
to user. If so, log a warning and drop cached reader instead of
throwing an error.
The mismatch can happen if user's scheduling group changed during
a query. We don't want to throw an error then, but drop and reset
cached reader.
In that level no io_priority_class-es exist. Instead, all the IO happens
in the context of current sched-group. File API no longer accepts prio
class argument (and makes io_intent arg mandatory to impls).
So the change consists of
- removing all usage of io_priority_class
- patching file_impl's inheritants to updated API
- priority manager goes away altogether
- IO bandwidth update is performed on respective sched group
- tune-up scylla-gdb.py io_queues command
The first change is huge and was made semi-autimatically by:
- grep io_priority_class | default_priority_class
- remove all calls, found methods' args and class' fields
Patching file_impl-s is smaller, but also mechanical:
- replace io_priority_class& argument with io_intent* one
- pass intent to lower file (if applicatble)
Dropping the priority manager is:
- git-rm .cc and .hh
- sed out all the #include-s
- fix configure.py and cmakefile
The scylla-gdb.py update is a bit hairry -- it needs to use task queues
list for IO classes names and shares, but to detect it should it checks
for the "commitlog" group is present.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Closes#13963
these warnings are found by Clang-17 after removing
`-Wno-unused-lambda-capture` and '-Wno-unused-variable' from
the list of disabled warnings in `configure.py`.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Move mutation-related files to a new mutation/ directory. The names
are kept in the global namespace to reduce churn; the names are
unambiguous in any case.
mutation_reader remains in the readers/ module.
mutation_partition_v2.cc was missing from CMakeLists.txt; it's added in this
patch.
This is a step forward towards librarization or modularization of the
source base.
Closes#12788
Said method calls `compact_mutation_state::start_new_page()` which
requires the kind of the next fragment in the reader. When there is no
fragment (reader is at EOS), we use partition-end. This was a poor
choice: if the reader is at EOS, partition-kind was the last fragment
kind, if the stream were to continue the next fragment would be a
partition-start.
When querier read page with tombstones more than `tombstone_warn_threshold` limit - warning message appeared in logs.
If `tombstone_warn_threshold:0` feature disabled.
Refs scylladb#11410
Define table_id as a distinct utils::tagged_uuid modeled after raft
tagged_id, so it can be differentiated from other uuid-class types,
in particular from table_schema_version.
Fixes#11207
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Instead of a separate partition key and position-in-partition.
This continues the recently started effort to standardize storing of
full positions on `full_position`.
This patch is also a hidden preparation for read_context::save_readers()
multishard_mutation_query.cc) no longer being able to get partition key
from compaction state in the future.
This reverts commit c3bad157e5, reversing
changes made to e66809d051. The checks it
adds are triggered by some dtests. While it's possible the check is
triggered due to an existing problem, better to investigate it out-of-tree.
Fixes#11169.
Instead of a separate partition key and position-in-partition.
This continues the recently started effort to standardize storing of
full positions on `full_position`.
This patch is also a hidden preparation for read_context::save_readers()
multishard_mutation_query.cc) no longer being able to get partition key
from compaction state in the future.
Now that we use emit_only_live_rows::no everywhere we can remove this
template parameters. Only the template parameter is removed, the
internal logic around it is left in place (will be removed in a next
patch), by hard-wiring `only_live()`.
emit_only_live_rows is a convenience so downstream consumers of the
mutation compactors don't have to check the `bool is_live` already
passed to them. This convenience however causes a template parameter and
additional logic for the compactor. As the most prominent of these
consumers (the query result builder) will soon have to switch to
emit_only_live_rows::no for other reasons anyway (it will want to count
tombstones), we take the opportunity to switch everybody to ::no. This
can be done with very little additional complexity to these consumer --
basically an additional if or two.
This prepares the ground for removing this template parameter and the
associate logic from the compactor.
Soon, the currently two distinct types of queriers will be merged, as
the template parameter differentiating them will be gone. This will make
using type based overload for insert() impossible, as 2 out of the 3
types will be the same. Use different names instead.
The change is mostly mechanical: update all compactor instances to the
_v2 variant and update all call-sites, of which there is not that many.
As a consequence of this patch, queries -- both single-partition and
range-scans -- now do the v2->v1 conversion in the consumers, instead of
in the compactor.
Mostly mechanical transformation. The main difference is in the detached
compaction state, from which we now get the range tombstone change,
instead of the range tombstone list. The code around this is a bit
awkward, will become simpler when compactor drops v1 support.
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.
Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.
The changes we applied mechanically with a script, except to
licenses/README.md.
Closes#9937
The shard_mutation_querier is left using a v1 reader in its API as the
multishard query code is not ready yet. When saving this reader it is
upgraded to v2 and on lookup it is downgraded to v1. This should cancel
out thanks to upgrade/downgrade unwrapping.
Said wrapper was conceived to make unmovable `compact_mutation` because
readers wanted movable consumers. But `compact_mutation` is movable for
years now, as all its unmovable bits were moved into an
`lw_shared_ptr<>` member. So drop this unnecessary wrapper and its
unnecessary usages.
The reader_lifecycle_policy API was created around the idea of shard
readers (optionally) being saved and reused on the next page. To do
this, the lifecycle policy has to also be able to control the lifecycle
of by-reference parameters of readers: the slice and the range. This was
possible from day 1, as the readers are created through the lifecycle
policy, which can intercept and replace the said parameters with copies
that are created in stable storage. There was one whole in the design
though: fast-forwarding, which can change the range of the read, without
the lifecycle policy knowing about this. In practice this results in
fast-forwarded readers being saved together with the wrong range, their
range reference becoming stale. The only lifecycle implementation prone
to this is the one in `multishard_mutation_query.cc`, as it is the only
one actually saving readers. It will fast-forward its reader when the
query happens over multiple ranges. There were no problems related to
this so far because no one passes more than one range to said functions,
but this is incidental.
This patch solves this by adding an `update_read_range()` method to the
lifecycle policy, allowing the shard reader to update the read range
when being fast forwarded. To allow the shard reader to also have
control over the lifecycle of this range, a shared pointer is used. This
control is required because when an `evictable_reader` is the top-level
reader on the shard, it can invoke `create_reader()` with an edited
range after `update_read_range()`, replacing the fast-forwarded-to
range with a new one, yanking it out from under the feet of the
evictable reader itself. By using a shared pointer here, we can ensure
the range stays alive while it is the current one.
Push down reversing to the mutation-sources proper, instead of doing it
on the querier level. This will allow us to test reverse reads on the
mutation source level.
The `max_size` parameter of `consume_page()` is now unused but is not
removed in this patch, it will be removed in a follow-up to reduce
churn.
Add the content of the compaction stats introduced in the previous patch
to the tracing data. This will help diagnose query performance related
problems caused by tombstones.
We define the native reverse format as a reversed mutation fragment
stream that is identical to one that would be emitted by a table with
the same schema but with reversed clustering order. The main difference
to the current format is how range tombstones are handled: instead of
looking at their start or end bound depending on the order, we always
use them as-usual and the reversing reader swaps their bounds to
facilitate this. This allows us to treat reversed streams completely
transparently: just pass along them a reversed schema and all the
reader, compacting and result building code is happily ignorant about
the fact that it is a reversed stream.
The querier cache refuses to cache queriers that read in reverse. These
queriers are also not closed, with the caller having no way to determine
whether the querier it just moved into `insert()` needs a close
afterwards or not, requiring a `close()` on the moved-from querier just
to be sure.
Avoid this by consistently closing all passed-in queriers, including
those the cache refuses to save. For this, the internal
`insert_querier()` methods has to be made a member to be able to use the
closing gate.
Close the _closing_gate to wait on background
close of dropped queries, and close all remaining queriers.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Make sure to close the dropped querier before it's destroyed.
The operation is moved to the background so not to penelize
the common path.
A following patch will add a querier_cache::close() method
that will close _closing_gate to wait on the querier close
(among other things it needs to wait on :)).
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
In preparation to closing the querier in the background
before dropping it.
With that, stats need not be passed as a parameter,
but rather the _stats member can be used directly.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Depening on the variant _reader contents, either close
the reader or unregister the inactive reader and close it.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
