NOTE: it's not wired yet.
Currently, a shared sstable is rewritten at all shards it belongs
to and only after that, it's deleted. With this new algorithm, a
shared sstable will be read only once and N unshared sstables
will be created, each of them with 1/N of the data. After it's
done, each owner shard will receive its new unshared sstable
replacing its ancestors.
Another benefit is that we'll no longer have resharding resulting
in number of sstables growing considerably after resharding.
A full-sized leveled sstable is usually 160MB, so after resharding,
we could have N files of 160MB/N. Now, leveled strategy will help
resharding. N adjacent sstables of same level will be resharded
together, so we'll end up with N files of N*160MB/N.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
When resharding, we're working with sstables from all shards. So let's say
we're done with resharding of sstable A that belongs to shard 0 and 1 and
sstable B that belongs to shard 1 and 2. SStables were generated for
shards 0, 1, and 2. So shards 0, 1, and 2 need to load the new sstables
and remove the ancestors. Shard 1 for example will remove sstables A and
B (ancestors) and add the new one. Then it comes this new function.
We'll forward new sstables to their target shards using foreign sstable
open info.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
For new resharding, it's important to exclude resharding sstables
from the list of candidates for regular compaction. That's doesn't
affect current resharding because it marks the sstables as
compacting. That won't work with new resharding which will work
with sstables from multiple shards.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
"This series makes several optimizations to sstable mutation reader relevant
for large partitions.
Some highlights:
One optimization is to use the index for skipping across clustering restrictions.
Currently we read whole partition in such cases. That includes the case when
we need to read a static row and then jump to some clustering row in the
middle of the partition. Another case is having more than one clustering
restriction, e.g. selecting multiple single rows from the same partition.
Another optimization is using information from the index for creation of
streamed_mutation. That can save us the cost of reading the partition header
form the data file in case we would not continue reading, but skip to the
middle of that partition. Or we may not even attempt to read anything from
that partition, if after we determine the key that reader will be put behind
other readers, which will exhaust the query limit first.
Another optimization is switching single-partition queries to use the
index_reader infrastructure. Index lookups via index_reader are faster than
find_disk_ranges(). This is also a cleanup, a step towards converting all code
to use the index_reader."
* tag 'tgrabiec/optimize-sstable-reads-with-restrictions-v2' of github.com:cloudius-systems/seastar-dev: (44 commits)
sstables: Remove unused code
sstables: mutation_reader: Use index_reader::advance_to_next_partition() to skip to next partition
sstables: mutation_reader: Use index_reader for single-partition reads
sstables: mutation_reader: Add trace-level logging
sstables: mutation_reader: Move partition reading code to sstable_data_source
sstables: mutation_reader: Move definitions out of the class body
sstables: Move binary_search() to a header
database: Pass partition_range to single_key_sstable_reader to avoid copies and decorating
sstables: index_reader: Introduce advance_to_next_partition()
sstables: index_reader: Introduce advance_and_check_if_present()
sstables: index_reader: Introduce advance_past()
sstables: index_reader: Make copyable
sstables: index_reader: Optimize advancing to extreme positions
sstables: index_reader: Keep two last pages alive
dht: ring_position_view: Add key getter
dht: ring_position_view: Add constructor and factory from ring_position_view
sstables: mutation_reader: Advance to next partition using index in some cases
sstables: index_reader: Expose access to partition key and tombstone
sstables: index_reader: Introduce promoted_index_view
sstables: mutation_reader: Move _index_in_current to sstable_data_source
...
This switches single-partition query to use the index_reader
infrastructure. Index lookups via index_reader are faster than
find_disk_ranges().
perf_fast_forward, rows: 1000000, value size: 100
Before:
Testing forwarding with clustering restriction in a large partition:
pk-scan time [s] frags frag/s aio [KiB] blocked dropped idx hit idx miss idx blk cpu
no 0.002182 2 916 3 152 2 0 0 1 1 88.1%
After:
Testing forwarding with clustering restriction in a large partition:
pk-scan time [s] frags frag/s aio [KiB] blocked dropped idx hit idx miss idx blk cpu
no 0.000758 2 2639 3 152 2 0 0 1 1 48.6%
This is also a cleanup, a step towards converting all code to use the
index_reader.
From now on, major compaction will go through compaction manager.
Major compaction is serialized to reduce disk space requirement.
Each column family will be running either minor and major compaction
at a given time. The only issue is number of small sstables growing
while major compaction is running, but major compaction itself will
reduce the number of tables considerably. If this turns out to be
an issue, we can allow minor to start in parallel to major, but not
the other way around.
Fixes#1156.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <20170417233125.14092-1-raphaelsc@scylladb.com>
* seastar 6b21197...2ebe842 (6):
> Merge "Various improvements to execution stages" from Paweł
> app-template: allow apps to specify a name for help message
> bool_class: avoid initializing object of incomplete type
> app-template: make sure we can still get help with required options
> prometheus: Http handler that returns prometheus 0.4 protobuf or text format
> Update DPDK to 17.02
Includes patch from Pawel to adjust to updated execution_stage interface.
We're cleaning up sstables in parallel. That means cleanup may need
almost twice the disk space used by all sstables being cleaned up,
if almost all sstables need cleanup and every one will discard an
insignificant portion of its whole data.
Given that cleanup is frequently issued when node is running out of
disk space, we should serialize cleanups in every shard to decrease
the disk space requirement.
Fixes#192.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <20170317022911.10306-1-raphaelsc@scylladb.com>
This patch ensures we upgrade the mutation to the current schema when
generating and pushing view updates, so that the it matches the most
up to date views.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
The write path uses a base schema at a particular version, and we
want it to use the materialized views at the corresponding version.
To achieve this, we need to map the state currently in db::view::view
to a particular schema version, which this patch does by introducing
the view_info class to hold the state previously in db::view::view,
and by having a view schema directly point to it.
The changes in the patch are thus:
1) Introduce view_info to hold the extra view state;
2) Point to the view_info from the schema;
3) Make the functions in the now stateless db::view::view non-member;
4) Remove the db::view::view class.
All changes are structural and don't affect current behavior.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Metrics name should be unique per type.
requests_blocked_memory was registered twice, one as a gauge and one as
derived.
This is not allowed.
Fixes#2165
Signed-off-by: Amnon Heiman <amnon@scylladb.com>
Message-Id: <20170314162826.25521-1-amnon@scylladb.com>
"This series adds various optimisations to counter implementation
(nothing extreme, mostly just avoiding unnecessary operations) as well
as some missing features such as tracing and dropping timed out queries.
Performance was tested using:
perf-simple-query -c4 --counters --duration 60
The following results are medians.
before after diff
write 18640.41 33156.81 +77.9%
read 58002.32 62733.93 +8.2%"
* tag 'pdziepak/optimise-counters/v3' of github.com:cloudius-systems/seastar-dev: (30 commits)
cell_locker: add metrics for lock acquisition
storage_proxy: count counter updates for which the node was a leader
storage_proxy: use counter-specific timeout for writes
storage_proxy: transform counter timeouts to mutation_write_timeout_exception
db: avoid allocations in do_apply_counter_update()
tests/counters: add test for apply reversability
counters: attempt to apply in place
atomic_cell: add COUNTER_IN_PLACE_REVERT flag
counters: add equality operators
counters: implement decrement operators for shard_iterator
counters: allow using both views and mutable_views
atomic_cell: introduce atomic_cell_mutable_view
managed_bytes: add cast to mutable_view
bytes: add bytes_mutable_view
utils: introduce mutable_view
db: add more tracing events for counter writes
db: propagate tracing state for counter writes
tests/cell_locker: add test for timing out lock acquisition
counter_cell_locker: allow setting timeouts
db: propagate timeout for counter writes
...
"Work on this series started with fixing the 'nodetool clearsnapshot'.
The current master code ignores the snapshots in deleted keyspaces (issue #2045).
I noticed that in many places our code has to build the path to some directory/file
it simply had the sstring(<path1>) + "/" + sstring(<path2>) constructs which may cause us issues
if somebody decides to complile/run scylla on not-Unix-based OS, like Microsoft Windows.
I understand that this is a long shot but if we can make it right now - why not to.
The answer is boost::filesystem::path class - its synchronous parts, of course.
I decided to take an initiative and fix the issues above and then use the fixed code for
fixing the issue #2045:
- Fix some minor issues in the existing code.
- Extend the lister class and move it into the separate files outside database.cc.
On the way I've found an issue in the existing code (issue #2071).
This series fixes this one too (PATCH2)."
In the later stages of counter write path a mutation is produced that
already has all cells transformed to counter shards and can be applied
to the memtable and written to the commitlog.
The current interface expectes a frozen mutation, which is suboptimal
for counters. The freeze itself is unaviodable -- it is required by
commitlog, but we can avoid later deserialization of frozen_mutation
when it is applied to the memtable if we pass the unfrozen mutation
along.
Counter write path involves read-modify-write. That read is guaranteed
to query only a single partition, does not care about dead cells and
expects to receive an unserialized mutation as a result.
Standard mutation queries can are able to produce results fit for
counter updates, but the logic involved is much more general (i.e.
slower), hence the addition of new, counter-specific kind of query.
"This introduces an API which allows forward navigation in a stream of mutation
fragments. It allows one to consume only a subset of the stream by iteratively
specifying sub-ranges from which fragments should be returned.
API outline:
When in forwarding mode, the stream does not return all fragments right away,
but only those belonging to the current range. Initially current range only
covers the static row. The stream can be forwarded, even before reaching end-
of-stream for current range, to a later range with fast_forward_to().
Forwarding doesn't change initial restrictions of the stream, it can only be
used to skip over data.
Monotonicity of positions is preserved by forwarding. That is fragments
emitted after forwarding will have greater positions than any fragments
emitted before forwarding.
For any range, all range tombstones relevant for that range which are present
in the original stream will be emitted. Range tombstones emitted before
forwarding which overlap with the new range are not necessarily re-emitted.
When not in forwarding mode, the stream acts as if the current range was equal
to the full range. This implies that fast_forward_to() cannot be
used.
Whether stream is in forwarding mode or not is specified when the stream
is created, typically via mutation_source interface.
What's left for later series:
Optimization by providing specialized implementations. This series implements
forwarding support in all mutation sources via generic wrapper which simply
drops fragments."
* tag 'tgrabiec/clustering-fast-forward-to-v2' of github.com:scylladb/seastar-dev:
tests: mutation_source_tests: Verify monotonicty of positions
tests: random_mutation_generator: Spread the keys more
tests: mutation_source_test: Make blobs more easily distinguishable
tests: streamed_mutation: Test that merged stream passes mutation source tests
tests: mutation_source_test: Add tests for forwarding of streamed_mutation
tests: streamed_mutation_assertions: Add methods for navigating the stream
tests: Add range generators to random_mutation_generator
partition_slice_builder: Add with_ranges()
query: Introduce full_clustering_range
streamed_mutation: Add non-owning variant of mutation_from_streamed_mutation()
db: Enable creating forwardable readers via mutation_source
mutation_source: Document liveness requirements
mutation_source: Cleanup
db: Replace virtual_reader_type with mutation_source_opt
partition_version: Refactor make_partition_snapshot_reader() overloads
database: Fix mutation_source created by as_mutation_source() to not ignore trace_state_ptr
memtable: Accept all mutation_source parameters
streamed_mutation: Implement fast_forward_to() in stream merger
streamed_mutation: Add generic implementation of forwardable streamed_mutation
streamed_mutation: Add fast_forward_to() API
position_in_partition: Introduce position_range
position_in_partition: Introduce position constructor for right after the static row
streamed_mutation: Make cast to view non-explicit
streamed_mutation: Make schema() getter non-copying
It was using the state passed via as_mutation_source() instead. Let's
respect mutation_source contract instead, and use the state passed via
mutation_source invocation.
Technically just a cleanup. Alse prerequisite for more cleanup.
On database stop, we do flush memtables and clean up commit log segment usage.
However, since we never actually destroy the distributed<database>, we
don't actually free the commitlog either, and thus never clear out
the remaining (clean) segments. Thus we leave perfectly clean segments
on disk.
This just adds a "release" method to commitlog, and calls it from
database::stop, after flushing CF:s.
Message-Id: <1485784950-17387-1-git-send-email-calle@scylladb.com>
5a0955e89d "db: add operations for
applying counter updates" merged two column_family::apply() overloads
into do_apply() in order to reduce code duplication. Unfortunately,
a call to check_valid_rp() didn't survive that change.
Message-Id: <20170221133800.30411-1-pdziepak@scylladb.com>
Move lister class away from database.cc.
This is a preparation for moving it to the seastar library.
Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
The current implementation of 'nodetool clearsnapshot' command only deletes the snapshots
of the keyspaces that are alive at the time the command is issued (issue #2045).
This, besides not implementing the spec, prevents users from being able to clear
the disk space occupied by snapshots of deleted keyspaces that are no longer needed
(e.g. snapshots created when KS is deleted).
This patch fixes this issue by making the database::clear_snapshot() scan the data directories
looking for the snapshots to be deleted instead of relying on in-memory data structures.
This patch makes column_family::clear_snapshot() method not needed any more.
Fixes#2045
Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
Filter should get all information that the caller has in hand that may be used for filtering.
directory_entry has the following information:
- Type of the entry
- Its name
For the code that used lister filters so far this would be enough, however it's not
hard to imagine a filter that may need the parent directory as well.
We will add the parent directory path in the follow up patches to make the interface
complete.
Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
If show_hidden parameter is set to show_hidden::yes - list hidden entries, otherwise skip them.
By default set to show_hidden::no.
This patch also completely removes default parameters in lister::scan_dir() and replaces them
with a few lister::scan_dir() overloads that ensure that lambdas are always going to
be the last parameter in the parameters list.
Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
There is a possibility that the type of the given entry may not be available
that would manifest in the ENOENT or ENOTDIR value set in the errno
by the fstat() call for this entry. In this case engine().file_type() will return
a not engaged optional<directory_entry_type> value.
Return the future with the std::runtime_error exception in this case.
This will prevent any further usage of the not engaged optional value by the code
in the normal flow.
The exception is going to be propagated to the caller and it's the caller's responsibility
to handle it.
Fixes#2071
Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
"This series uses the newly added histogram and label support to add metrics to
the storage_proxy and to the column_family.
This would add latency and histogram and the missing metrics from column family."
* 'amnon/histogram_metrics' of github.com:cloudius-systems/seastar-dev:
database: add metrics registration for the coloumn family
storage_proxy: add read and write latency histogram
estimated_histogram: returns a metrics histogram
This patch adds a metrics registration to the column_family.
Using label each column metrics is label with its keyspace and column
family name.
Signed-off-by: Amnon Heiman <amnon@scylladb.com>
This patch changes the database apply path so that it also
generates the mutations for the column family's views and
sends them to the paired view replicas.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
This adds to the "write_type" enum also the "VIEW" write type.
To be honest, I don't understand why the "write_type" distinction
is important.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
