sstable::compute_shards_for_this_sstable() has a temporary of type
std::vector<dht::token_range> (aka dht::partition_range_vector), which
allocates a contiguous 300k when loading an sstable from disk. This
causes large allocation warnings (it doesn't really stress the allocator
since this typically happens during startup, but best to clear the warning
anyway).
Fix this by changing the container to by chunked_vector. It is passed
to dht::ring_position_range_vector_sharder, but since we're the only
user, we can change that class to accept the new type.
Fixes#24198.
Closesscylladb/scylladb#26353
Applying lazy evaluation to the BTI encoding of clustering keys
was probably a bad default.
The possible benefits are dubious (because it's quite likely that the laziness
won't allow us to avoid that much work), but the overhead needed to
implement the laziness is large and immediate.
In this patch we get rid of the laziness.
We rewrite lazy_comparable_bytes_from_clustering_position
and lazy_comparable_bytes_from_ring_position
so that they performs the key translation eagerly,
all components to a single bytes_ostream in one synchronous call.
perf_bti_key_translation (microbenchmark added in this series, 1 iteration is 100 translations of a clustering key with 8 cells of int32_type):
```
Before:
test iterations median mad min max allocs tasks inst cycles
lcb_mismatch_test.lcb_mismatch 9233 109.930us 0.000ns 109.930us 109.930us 4356.000 0.000 2615394.3 614709.6
After:
test iterations median mad min max allocs tasks inst cycles
lcb_mismatch_test.lcb_mismatch 50952 19.487us 0.000ns 19.487us 19.487us 198.000 0.000 603120.1 109042.9
```
Enhancement, backport not required.
Closesscylladb/scylladb#26302
* github.com:scylladb/scylladb:
sstables/trie: BTI-translate the entire partition key at once
sstables/trie: avoid an unnecessary allocation of std::generator in last_block_offset()
sstables/trie: perform the BTI-encoding of position_in_partition eagerly
types/comparable_bytes: add comparable_bytes_from_compound
test/perf: add perf_bti_key_translation
This is yet another part in the BTI index project.
Overarching issue: https://github.com/scylladb/scylladb/issues/19191
Previous part: https://github.com/scylladb/scylladb/pull/25626
Next parts: make `ms` the default. Then, general tweaks and improvements. Later, potentially a full `da` format implementation.
This patch series introduces a new, Scylla-only sstable format version `ms`, which is like `me`, but with the index components (Summary.db and Index.db) replaced with BTI index components (Partitions.db and Rows.db), as they are in Cassandra 5.0's `da` format version.
(Eventually we want to just implement `da`, but there are several other changes (unrelated to the index files) between `me` and `da`. By adding this `ms` as an intermediate step we can adapt the new index formats without dragging all the other changes into the mix (and raising the risk of regressions, which is already high)).
The high-level structure of the PR is:
1. Introduce new component types — `Partitions` and `Rows`.
2. Teach `class sstable` to open them when they exist.
3. Teach the sstable writer how to write index data to them.
4. Teach `class sstable` and unit tests how to deal with sstables that have no `Index` or `Summary` (but have `Partitions` and `Rows` instead).
5. Introduce the new sstable version `ms`, specify that it has `Partitions` and `Rows` instead of `Index` and `Summary`.
6. Prepare unit tests for the appearance of `ms`.
7. Enable `ms` in unit tests.
8. Make `ms` enablable via db::config (with a silent fall back to `me` until the new `MS_SSTABLE_FORMAT` cluster feature is enabled).
9. Prepare integration tests for the appearance of `ms`.
10. Enable both `ms` and `me` in tests where we want both versions to be tested.
This series doesn't make `ms` the default yet, because that requires teaching Scylla Manager and a few dtests about the new format first. It can be enabled by setting `sstable_format: ms` in the config.
Per a review request, here is an example from `perf_fast_forward`, demonstrating some motivation for a new format. (Although not the main one. The main motivations are getting rid of restrictions on the RAM:disk ratio, and index read throughput for datasets with tiny partitions). The dataset was populated with `build/release/scylla perf-fast-forward --smp=1 --sstable-format=$VERSION --data-directory=data.$VERSION --column-index-size-in-kb=1 --populate --random-seed=0`.
This test involves a partition with 1000000 clustering rows (with 32-bit keys and 100-byte values) and ~500 index blocks, and queries a few particular rows from the partition. Since the branching factor for the BIG promoted index is 2 (it's a binary search), the lookup involves ~11.2 sequential page reads per row. The BTI format has a more reasonable branching factor, so it involves ~2.3 page reads per row.
`build/release/scylla perf-fast-forward --smp=1 --data-directory=perf_fast_forward_data/me --run-tests=large-partition-select-few-rows`:
```
offset stride rows iterations avg aio aio (KiB)
500000 1 1 70 18.0 18 128
500001 1 1 647 19.0 19 132
0 1000000 1 748 15.0 15 116
0 500000 2 372 29.0 29 284
0 250000 4 227 56.0 56 504
0 125000 8 116 106.0 106 928
0 62500 16 67 195.0 195 1732
```
`build/release/scylla perf-fast-forward --smp=1 --data-directory=perf_fast_forward_data/ms --run-tests=large-partition-select-few-rows`:
```
offset stride rows iterations avg aio aio (KiB)
500000 1 1 51 5.1 5 20
500001 1 1 64 5.3 5 20
0 1000000 1 679 4.0 4 16
0 500000 2 492 8.0 8 88
0 250000 4 804 16.0 16 232
0 125000 8 409 31.0 31 516
0 62500 16 97 54.0 54 1056
```
Index file size comparison for the default `perf_fast_forward` tables with `--random-seed=0`:
Large partition table (dominated by intra-partition index): 2.4 MB with `me`, 732 kB with `ms`.
For the small partitions table (dominated by inter-partition index): 11 MB with `me`, 8.4 MB with `ms`.
External tests:
I ran SCT test `longevity-mv-si-4days-streaming-test` test on 6 nodes with 30 shards each for 8 hours. No anomalies were observed.
New functionality, no backport needed.
Closesscylladb/scylladb#26215
* github.com:scylladb/scylladb:
test/boost/bloom_filter_test: add test_rebuild_from_temporary_hashes
test/cluster: add test_bti_index.py
test: prepare bypass_cache_test.py for `ms` sstables
sstables/trie/bti_index_reader: add a failure injection in advance_lower_and_check_if_present
test/cqlpy/test_sstable_validation.py: prepare the test for `ms` sstables
tools/scylla-sstable: add `--sstable-version=?` to `scylla sstable write`
db/config: expose "ms" format to the users via database config
test: in Python tests, prepare some sstable filename regexes for `ms`
sstables: add `ms` to `all_sstable_versions`
test/boost/sstable_3_x_test: add `ms` sstables to multi-version tests
test/lib/index_reader_assertions: skip some row index checks for BTI indexes
test/boost/sstable_inexact_index_test: explicitly use a `me` sstable
test/boost/sstable_datafile_test: skip test_broken_promoted_index_is_skipped for `ms` sstables
test/resource: add `ms` sample sstable files for relevant tests
test/boost/sstable_compaction_test: prepare for `ms` sstables.
test/boost/index_reader_test: prepare for `ms` sstables
test/boost/bloom_filter_tests: prepare for `ms` sstables
test/boost/sstable_datafile_test: prepare for `ms` sstables
test/boost/sstable_test: prepare for `ms` sstables.
sstables: introduce `ms` sstable format version
tools/scylla-sstable: default to "preferred" sstable version, not "highest"
sstables/mx/reader: use the same hashed_key for the bloom filter and the index reader
sstables/trie/bti_index_reader: allow the caller to passing a precalculated murmur hash
sstables/trie/bti_partition_index_writer: in add(), get the key hash from the caller
sstables/mx: make Index and Summary components optional
sstables: open Partitions.db early when it's needed to populate key range for sharding metadata
sstables: adapt sstable::set_first_and_last_keys to sstables without Summary
sstables: implement an alternative way to rebuild bloom filters for sstables without Index
utils/bloom_filter: add `add(const hashed_key&)`
sstables: adapt estimated_keys_for_range to sstables without Summary
sstables: make `sstable::estimated_keys_for_range` asynchronous
sstables/sstable: compute get_estimated_key_count() from Statistics instead of Summary
replica/database: add table::estimated_partitions_in_range()
sstables/mx: implement sstable::has_partition_key using a regular read
sstables: use BTI index for queries, when present and enabled
sstables/mx/writer: populate BTI index files
sstables: create and open BTI index files, when enabled
sstables: introduce Partition and Rows component types
sstables/mx/writer: make `_pi_write_m.partition_tombstone` a `sstables::deletion_time`
test_column_family.py::test_sstables_by_key_reader_closed
injects a failure into `index_reader::advance_lower_and_check_if_present`.
To preserve this tests when BTI indexes are made the default,
we have to add a corresponding error injection to
`bti_index_reader::advance_lower_and_check_if_present`.
Extend the `sstable_format` config enum with a "ms" value,
and, if it's enabled (in the config and in cluster features),
use it for new sstables on the node.
(Before this commit, writing `ms` sstables should only be possible
in unit tests, via internal APIs. After this commit, the format
can be enabled in the config and the database will write it during
normal operation).
As of this commit, the new format is not the default yet.
(But it will become the default in a later commit in the same series).
Introduce `ms` -- a new sstable format version which
is a hybrid of Cassandra's `me` and `da`.
It is based on `me`, but with the index components
(Summary.db and Index.db) replaced with the index
components of `da` (Partitions.db and Rows.db).
As of this patch, the version is never chosen
anywhere for writing sstables yet. It is only introduced.
We will add it to unit tests in a later commit,
and expose it to users in yet later commit.
Partitions.db uses a piece of the murmur hash of the partition key
internally. The same hash is used to query the bloom filter.
So to avoid computing the hash twice (which involves converting the
key into a hashable linearized form) it would make sense to use
the same `hashed_key` for both purposes.
This is what we do in this patch. We extract the computation
of the `hashed_key` from `make_pk_filter` up to its parent
`sstable_set_impl::create_single_key_sstable_reader`,
and we pass this hash down both to `make_pk_filter` and
to the sstable reader. (And we add a pointer to the `hashed_key`
as a parameter to all functions along the way, to propagate it).
The number of parameters to `mx::make_reader` is getting uncomfortable.
Maybe they should be packed into some structs.
Partitions.db internally uses a piece of the partition key murmur
hash (the same hash which is used to compute the token and the
relevant bits in the bloom filter). Before this patch,
the Partitions.db reader computes the hash internally from the
`sstables::partition_key`.
That's a waste, because this hash is usually also computed
for bloom filter purposes just before that.
So in this patch we let the caller pass that hash instead.
The old index interface, without the hash, is kept for convenience.
In this patch we only add a new interface, we don't switch the callers
to it yet. That will happen in the next commit.
Partitions.db internally uses a piece of the partition key murmur
hash (the same hash which is used to compute the token and the
relevant bits in the bloom filter). Before this patch,
the Partitions.db writer computes the hash internally from the
`sstables::partition_key`.
That's a waste, because this hash is also computed for bloom filter
purposes just before that, in the owning sstable writer.
So in this patch we let the caller pass that hash here instead.
In previous patches we (hopefully) modified all users of
Index and Summary components so that they don't longer
need those components to exist. (And can use Partitions and
Rows components instead).
If there's no metadata file with sharding metadata,
the owning shards of an sstable are computed based on the partition key
range within the sstable.
This range is set in `set_first_and_last_keys()`, which
(since another commit in this commit series) reads it
either from the Summary component or from the footer of the Partitions
component, whichever is available.
But in some code paths `set_first_and_last_keys()` is called
before the footer of Partitions is loaded. If the sstable
doesn't have Summary, only Partitions, then the
`set_first_and_last_keys()` will fail. To prevent that,
in those cases we have to open the file and read its footer
early, before the `set_first_and_last_keys()` calls.
Note: the changes in this commit shouldn't matter during
normal operation, in which a Scylla component with sharding
metadata is available. But it might be used when
old and/or incomplete sstables are read.
`sstable::set_first_and_last_keys` currently takes the first and last
key from the Summary component. But if only BTI indexes are used,
this component will be nonexistent. In this case, we can use the first
and last keys written in the footer of Partitions.db.
For efficiency, the cardinality of the bloom filter
(i.e. the number of partition keys which will be written into the sstable)
has to be known before elements are inserted into the filter.
In some cases (e.g. memtables flush) this number is known exactly.
But in others (e.g. repair) it can only be estimated,
and the estimation might be very wrong, leading to an oversized filter.
Because of that, some time ago we added a piece of logic
(ran after the sstable is written, but before it's sealed)
which looks at the actual number of written partitions,
compares it to the initial estimate (on which the size of the bloom
filter was based on), and if the difference is unacceptably large,
it rewrites the bloom filter from partition keys contained in Index.db.
But the idea to rebuild the bloom filters from index files
isn't going to work with BTI indexes, because they don't store
whole partition keys. If we want sstables which don't have Index.db
files, we need some other way to deal with oversized filters.
Partition keys can be recovered from Data.db,
but that would often be way too expensive.
This patch adds another way. We introduce a new component file,
TemporaryHashes. This component, if written at all,
contains the 16-byte murmur hash for every partition key, in order,
and can be used in place of Index to reconstruct the bloom filter.
(Our bloom filters are actually built from the set of murmur hashes of
partition keys. The first step of inserting a partition key into a
filter is hashing the key. Remembering the hashes is sufficient
to build the filter later, without looking at partition keys again.)
As of this patch, if the Index component is not being written,
we don't allocate and populate a bloom filter during the Data.db write.
Instead, we write the murmur hashes to TemporaryHashes, and only
later, after the Data write finishes, we allocate the optimal-size,
bloom filter, we read the hashes back from TemporaryHashes,
and we populate the filter with them.
That is suboptimal.
Writing the hashes to disk (or worse, to S3) and reading
them back is more expensive than building the bloom filter
during the main Data pass.
So ideally it should be avoided in cases where we know
in advance that the partition key count estimate is good enough.
(Which should be the case in flushes and compactions).
But we defer that to a future patch.
(Such a change would involve passing some flag to the sstable writer
if the cardinality estimate is trustworthy, and not creating
TemporaryHashes if the estimate is trustworthy).
Before this patch, `estimated_keys_for_range` assumes the presence
of the Summary component. But we want to make this component optional
in this series.
This patch adds a second branch to this function, for sstables
which don't have a BIG index (in particular, Summary component),
but have a BTI index (Partitions component).
In this case, instead of calculating the estimate as
"fraction of summary overlapping with given range,
multiplied by the total key estimate", we calculate
it as "fraction of Data file overlapping with given range,
multiplied by the total key estimate".
(With an extra conditional for the special case when the given range
doesn't overlap with the sstable's range at all. In this case, if the
ranges are adjacent, the main path could easily return "1 partition"
instead of "0 partitions", due to the inexactness of BTI indexes for
range queries. Returning something non-zero in this case would
be unfortunate, so the extra conditional makes sure that
we return 0).
Currently, `sstable::estimated_keys_for_range` works by
checking what fraction of Summary is covered by the given
range, and multiplying this fraction to the number of all keys.
Since computing things on Summary doesn't involve I/O (because Summary
is always kept in RAM), this is synchronous.
In a later patch, we will modify `sstable::estimated_keys_for_range`
so that it can deal with sstables that don't have a Summary
(because they use BTI indexes instead of BIG indexes).
In that case, the function is going to compute the relevant fraction
by using the index instead of Summary. This will require making
the function asynchronous. This is what we do in this patch.
(The actual change to the logic of `sstable::estimated_keys_for_range`
will come in the next patch. In this one, we only make it asynchronous).
`sstable::get_estimated_key_count()` estimates the partition count from the
size of Summary, and the interval between Summary entries.
But we want to allow writing sstables without a Summary
(i.e. sstables that use BTI indexes instead of BIG indexes),
so we want a way to get the key count without involving Summary.
For that, we can use the `estimated_partition_size` histogram in
Statistics. By counting the histogram entries, we get the exact
number of partitions in the sstable.
A BTI index isn't able to determine if a given key is present in
the sstable, because it doesn't store full keys.
(It only stores prefixes of decorated keys, so it might give false positives).
If the sstable only has BTI index, and no BIG index, then
`sstable::has_partition_key()` will have to be implemented with
with something else than just the index reader.
We might as well ignore the index in any cases and just check
that a regular data read for the given partition returns a non-empty result.
`sstable::has_partition_key` is only used in the
`column_family/sstables/by_key` REST API call that nobody
uses anyway, no point in trying to make special optimizations for it.
This patch teaches `sstable::make_index_reader` how to create
a BTI index reader, from the the `Partitions.db` and `Rows.db`
components, if they exist (in which case they are opened by this point).
In the previous patch we added code responsible
for creating and opening Partitions.db and Rows.db,
but we left those files empty.
In this patch, we populate the files using
`trie::bti_row_index_writer` and `trie::bti_partition_index_writer`.
Note: for the row index, we insert the same clustering blocks to
both indexes. The logic for choosing the size of the blocks
hasn't been changed in any way.
Much of this patch has to do with propagating the current range
tombstone down to all places which can start a new clustering block.
The reason we need that is that, for each clustering block,
BIG indexes store the range tombstone succeeding the block
(i.e. the range tombstone in between the given block and its successor)
BTI indexes store the range tombstone preceding the block,
(i.e. the range tombstone in between the given block and its predecessor).
So before the patch there's no code which looks at the current tombstone
when *starting* the block, only when *ending* the block.
This patch adds an extra copy for each `decorated_key`.
This is mostly unavoidable -- the BTI partition writer just
has to remember the key until its successor appears, to find the
common prefix. (We could avoid the key copy if the BTI isn't used, though.
We don't do that in this patch, we just let the copy happen).
This patch adds code responsible for creation and opening
of BTI index components (Rows.db, Partitions.db) when
BTI index writing is enabled.
(It is enabled if the cluster feature is enabled and the relevant
config entry permits it).
The files are empty for now, and are never read.
We will populate and use them in following patches.
BTI indexes are made up of Partition.db and Rows.db files.
In this patch we introduce the corresponding component types.
In Cassandra, BTI is a separate "sstable format", with a new set
of versions. (I.e. `bti-da`, as opposed to `big-me`).
In this patch series, we are doing something different:
we are introducing version `ms`, which is like `me`, except with
`Index.db` and `Summary.db` replaced with `Partitions.db` and `Rows.db`.
With a setup like that, Scylla won't yet be able to read Cassandra's
BTI (`da`) files, because this patch doesn't teach Scylla
about `da`.
(But the way to that is open. It would just require first implementing
several other things which changed between `me` and `da`).
(And, naturally Cassandra will reject `ms` sstables.
But this isn't the first time we are breaking file
compatibility with Cassandra to some degree.
Other examples include encryption and dictionary compression).
Note: Partitions.db and Rows.db contain prefixes of keys,
which is sensitive information, so they have to be encrypted.
There's a test (boost/sstable_compaction_test.cc::tombstone_purge_test)
which tests the value of `_stats.capped_tombstone_deletion_time`.
Before this patch, for "ms" sstables, `to_deletion_time` would have
be called twice for each written partition tombstone, which would fail
the test.
Since `_pi_write_m.partition_tombstone` always ends up being
converted from `tombstone` to `sstables::deletion_time` anyway,
let's just make it a `sstables::deletion_time` to begin with.
This will ensure that `to_deletion_time` will be able to be
only called once per partition tombstone.
Various compaction strategies still have their respective
make_sstable_set() implementation in sstables/sstable_set.cc. Move them
to the appropriate .cc files in compaction/, making the compaction
module more self contained.
sstables/exceptions.hh still hosts some compaction specific exception
types. Move them over to the new compaction/exceptions.hh, to make the
compaction module more self-contained.
Delaying the BTI encoding of partition keys is a good idea,
because most of the time they don't have to be encoded.
Usually the token alone is enough for indexing purposes.
But for the translation of the `partition_key` part itself,
there's no good reason to make it lazy,
especially after we made the translation of clustering keys
eager in a previous commit. Let's get rid of the `std::generator`
and convert all cells of the partition key in one go.
Applying lazy evaluation to the BTI encoding of clustering keys
was probably a bad default.
The benefits are dubious (because it's quite likely that the laziness
won't allow us to avoid that much work), but the overhead needed to
implement the laziness is large and immediate.
In this patch we get rid of the laziness.
We rewrite lazy_comparable_bytes_from_clustering_position
so that it performs the translation eagerly,
all components to a single bytes_ostream.
Note: the name *lazy*_comparable_bytes_from_clustering_position
stays, because the interface is still lazy.
perf_bti_key_translation:
Before:
test iterations median mad min max allocs tasks inst cycles
lcb_mismatch_test.lcb_mismatch 9233 109.930us 0.000ns 109.930us 109.930us 4356.000 0.000 2615394.3 614709.6
After:
test iterations median mad min max allocs tasks inst cycles
lcb_mismatch_test.lcb_mismatch 50952 19.487us 0.000ns 19.487us 19.487us 198.000 0.000 603120.1 109042.9
ScyllaDB offers the `compression` DDL property for configuring compression per user table (compression algorithm and chunk size). If not specified, the default compression algorithm is the LZ4Compressor with a 4KiB chunk size. The same default applies to system tables as well.
This series introduces a new configuration option to allow customizing the default for user tables. It also adds some tests for the new functionality.
Fixes#25195.
Closesscylladb/scylladb#26003
* github.com:scylladb/scylladb:
test/cluster: Add tests for invalid SSTable compression options
test/boost: Add tests for SSTable compression config options
main: Validate SSTable compression options from config
db/config: Add SSTable compression options for user tables
db/config: Prepare compression_parameters for config system
compressor: Validate presence of sstable_compression in parameters
compressor: Add missing space in exception message
`compression_parameters` provides two levels of validation:
* syntactic checks - implemented in the constructor
* semantic checks - implemented by `compression_parameters::validate()`
The former are applied implicitly when parsing the options from the
command line or from scylla.yaml. The latter are currently not applied,
but they should.
In lack of a better place, apply them in main, right after joining the
cluster, to make sure that the cluster features have been negotiated.
The feature needed here is the `SSTABLE_COMPRESSION_DICTS`. Validation
will fail if the feature is disabled and a dictionary compression
algorithm has been selected.
Also, mark `validate()` as const so that it can be called from a config
object.
Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
Sstables store a basic schema in the statistics component. The scylla-sstable tool uses this to be able to read and dump sstables in a self-contained manner, without requiring an external schema source.
The problem is that the schema stored int he statistics component is incomplete: it doesn't store column names for key columns, so these have placeholder names in dump outputs where column names are visible.
This is not a disaster but it is confusing and it can cause errors in scripts which want to check the content of sstables, while also knowing the schema and expecting the proper names for key columns.
To make sstables truly self-contained w.r.t. the schema, add a complete schema to the scylla component. This schema contains the names and types of all columns, as well as some basic information about the schema: keyspace name, table name, id and version.
When available, scylla-sstable's schema loader will use this new more complete schema and fall-back to the old method of loading the (incomplete) schema from the statistics component otherwise.
New feature, no backport required.
Closesscylladb/scylladb#24187
* github.com:scylladb/scylladb:
test/boost/schema_loader_test: add specific test with interesting types
test/lib/random_schema: add random_schema(schema_ptr) constructor
test/boost/schema_loader_test: test_load_schema_from_sstable: add fall-back test
tools/schema_loader: add support for loading from scylla-metadata
tools/schema_loader: extract code which load schema from statistics
sstables: scylla_metadata: add schema member
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.
To store the most important schema fields, like id, version, keyspace
name, table name and the list of all columns, along with their kind,
name and type. This will serve as alternative schema source to the one
stored in statistics component. This latter one doesn't store any of the
metatada and neither does primary key names (just the types), so it is
leads to confusion when it is used as schema source for scylla-sstable.
This new schema stored in the scylla-metadata component is not intended
to be a full-schema, equivalent to the one stored in the schema tables,
it is intended to be good enough for scylla-sstable being able to parse
sstables in a self-sufficient manner.
Shorter and cleaner this way. The method is doing parallel_for_each(some_lambda) and the PR only touches the lambda, the outer invocation is probably not worth it to convert plain return into a co_await
Coroutinization enhancement, no need to backport
Closesscylladb/scylladb#26188
* github.com:scylladb/scylladb:
sstables: Restore indentation after previous patch
sstables: Coroutinize filesystem_storage::check_create_links_replay()
SSTable compression is currently configurable only per table, via the
`compression` property in CREATE/ALTER TABLE statements. This is
represented internally via the `compression_parameters` class. We plan
to offer the same options via the configuration as well, to make the
default compression method for user tables configurable.
This patch prepares the ground by making the `compression_parameters`
usable as a `config_file::named_value`, namely:
* Define an extraction operator (required by `boost::program_options`
for parsing the options from command line).
* Define a formatter (required by `named_value::operator()`).
* Define a template specialization for `config_type_for` (required by
`named_value` constructor).
* Define a yaml converter (required for parsing the options from
scylla.yaml).
Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
SSTable compression parameters should always define an algorithm via the
`sstable_compression` sub-option. Add a check in the constructor to
ensure this is always provided (unless no options are given, which is
interpreted as "no compression").
This change has no user-visible effect, since the same check is already
performed at a higher-level, while validating the CQL properties of
CREATE TABLE and ALTER TABLE statements (see `cf_prop_defs::validate()`).
However, it will become useful in later patches, when compression config
options will be introduced.
Although now redundant, keep the sanity check in
`cf_prop_defs::validate()` to maintain consistency of error messages
with Cassandra.
Note also that Cassandra uses 'class' instead of 'sstable_compression'
since version 3.11.10, but Scylla still doesn't support this, see:
https://github.com/scylladb/scylladb/issues/4200
Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
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
Our sstable format selection logic is weird, and hard to follow.
If I'm not misunderstanding, the pieces are:
1. There's the `sstable_format` config entry, which currently
doesn't do anything, but in the past it used to disable
cluster features for versions newer than the specified one.
2. There are deprecated and unused config entries for individual
versions (`enable_sstables_mc_format`, `enable_sstables_md_format`,
etc).
3. There is a cluster feature for each version:
ME_SSTABLE_FORMAT, MD_SSTABLE_FORMAT, etc.
(Currently all sstable version features have been grandfathered,
and aren't checked by the code anymore).
4. There's an entry in `system.scylla_local` which contains the
latest enabled sstable version. (Why? Isn't this directly derived
from cluster features anyway)?
5. There's `sstable_manager::_format` which contains the
sstable version to be used for new writes.
This field is updated by `sstables_format_selector`
based on cluster features and the `system.scylla_local` entry.
I don't see why those pieces are needed. Version selection has the
following constraints:
1. New sstables must be written with a format that supports existing
data. For example, range tombstones with an infinite bound are only
supported by sstables since version "mc". So if a range tombstone
with an infinite bound exists somewhere in the dataset,
the format chosen for new sstables has to be at least as new as "mc".
2. A new format might only be used after a corresponding cluster feature
is enabled. (Otherwise new sstables might become unreadable if they
are sent to another node, or if a node is downgraded).
3. The user should have a way to inhibit format ugprades if he wishes.
So far, constraint (1) has been fulfilled by never using formats older
than the newest format ever enabled on the node. (With an exception
for resharding and reshaping system tables).
Constraint (2) has been fulfilled by calling `sstable_manager::set_format`
only after the corresponsing cluster feature is enabled.
Constraint (3) has been fulfilled by the ability to inhibit cluster
features by setting `sstable_format` by some fixed value.
The main thing I don't like about this whole setup is that it doesn't
let me downgrade the preferred sstable format. After a format is
enabled, there is no way to go back to writing the old format again.
That is no good -- after I make some performance-sensitive changes
in a new format, it might turn out to be a pessimization for the
particular workload, and I want to be able to go back.
This patch aims to give a way to downgrade formats without violating
the constraints. What it does is:
1. The entry in `system.scylla_local` becomes obsolete.
After the patch we no longer update or read it.
As far as I understand, the purpose of this entry is to prevent
unwanted format downgrades (which is something cluster features
are designed for) and it's updated if and only if relevant
cluster features are updated. So there's no reason to have it,
we can just directly use cluster features.
2. `sstable_format_selector` gets deleted.
Without the `system.scylla_local` around, it's just a glorified
feature listener.
3. The format selection logic is moved into `sstable_manager`.
It already sees the `db::config` and the `gms::feature_service`.
For the foreseeable future, the knowledge of enabled cluster features
and current config should be enough information to pick the right formats.
4. The `sstable_format` entry in `db::config` is no longer intended to
inhibit cluster features. Instead, it is intended to select the
format for new sstables, and it becomes live-updatable.
5. Instead of writing new sstables with "highest supported" format,
(which used to be set by `sstables_format_selector`) we write
them with the "preferred" format, which is determined by
`sstable_manager` based on the combination of enabled features
and the current value of `sstable_format`.
Closesscylladb/scylladb#26092
[avi: Pavel found the reason for the scylla_local entry -
it predates stable storage for cluster features]
This is yet another part in the BTI index project.
Overarching issue: https://github.com/scylladb/scylladb/issues/19191
Previous part: https://github.com/scylladb/scylladb/pull/25626
Next parts: introducing the new components, Partitions.db and Rows.db
This is the preparatory, uncontroversial part of https://github.com/scylladb/scylladb/pull/26039, which has been split out to a separate PR to make the main part (which, after a revision, will be posted later) smaller.
This series contains several small fixes and changes to BTI-related code added earlier, which either have to be done (i.e. propagating `reader_permit` to IO calls in index reads) or just deserved to be done. There's no single theme for the changes in this PR, refer to the individual commits for details.
The changes are for the sake of new and unreleased code. No backporting should be done.
Closesscylladb/scylladb#26075
* github.com:scylladb/scylladb:
sstables/mx/reader: remove mx::make_reader_with_index_reader
test/boost/bti_index_test: fix indentation
sstables/trie/bti_index_reader: in last_block_offset(), return offset from the beginning of partition, not file
sstables/trie: support reader_permit and trace_state properly
sstables/trie/bti_node_reader: avoid calling into `cached_file` if the target position is already cached
sstables/trie/bti_index_reader: get rid of the seastar::file wrapper in read_row_index_header
sstables/trie/bti_index_reader: support BYPASS CACHE
test/boost/bti_index_test: use read_bti_partitions_db_footer where appropriate
sstables/trie: change the signature of bti_partition_index_writer::finish
sstables/bti_index: improve signatures of special member functions in index writers
streaming/stream_transfer_task: coroutinize `estimate_partitions()`
types/comparable_bytes: add a missing implementation for date_type_impl
sstables: remove an outdated FIXME
storage_service: delete `get_splits()`
sstables/trie: fix some comment typos in bti_index_reader.cc
sstables/mx/writer: rename _pi_write_m.tomb to partition_tombstone
When `mx::make_reader` is used to construct an sstable reader,
it constructs its own index reader internally.
`mx::make_reader_with_index_reader` was originally added
as a variant of `mx::make_reader` which can be used to inject
a custom `index_reader` for testing that the mx Data reader
tolerates inexact indexes.
But now we want the ability to choose between BIG index readers
and BTI index readers if both are present. And at this point,
it seems to me that it makes sense to just construct the index
reader in the caller and pass it via argument to `mx::make_reader`
instead of putting the index selection inside it.
So that's what we do in this patch. And we remove `mx::make_reader_with_index_reader`
because it's no longer different from `mx::make_reader`.
Before this patch, `bti_index_reader::last_block_offset()` returns the
offset of the last block within the file.
But the old `index_reader::last_block_offset()` returns the offset
within the partition, and that's what the callers (i.e. reversed
sstable reader) expect.
Fix `bti_index_reader::last_block_offset()` (and the corresponding
comment and test) to match `index_reader::last_block_offset()`.
Before this patch, `reader_permit` taken by `bti_index_reader`.
wasn't actually being passed down to disk reads. In this patch,
we fix this FIXME by propagating the permit down to the I/O
operations on the `cached_file`.
Also, it didn't take `trace_state_ptr` at all.
In this patch, we add a `trace_state_ptr` argument and propagate
it down to disk reads.
(We combine the two changes because the permit and the trace state
are passed together everywhere anyway).
Small optimization. In some places we call `load` on a position
that is in the currently-held page. In those cases we are needlessly
calling `cached_file::get_shared_page` for the same page again,
adding some work and some noise in CQL tracing. This patch adds
an `if` against that.
Before this patch, the "stack" of wrappers in `read_row_index_header`
is:
- row_index_header_parser
- continuous_data_consumer
- input_stream
- file_data_source_impl
- cached_file_impl
- cached_file::stream
- cached_file
The `cached_file_impl` and `file_data_source_impl` are superfluous.
We don't need to pretent the `cached_file` is a `seastar::file`,
in particular we don't need random reads.
We can use `cached_file::stream` to provide buffers for `input_stream`
directly.
Note: we use the `cached_file::stream` without any size hints (readahead).
This means that parsing a large partition key -- which spans many pages -- might
require multiple serialized disk fetches. This could be improved
(e.g. if the first two bytes of the entry, which contain the partition key,
are in the cached page, we could make a size hint out of them) but
we ignore this for now, under the assumption that multi-page partition
keys are a fringe use case.
Before this patch, `bti_index_reader` doesn't have a good
way to implement BYPASS CACHE.
In this patch we add a way, similar to what `index_reader` does:
we allow the caller to pass in the `cached_file` via a shared pointer.
If the caller wants the loads done by the index reader to remain cached,
he can pass in the `cached_file` owned by the `sstable`, shared by all
caching index readers.
If the caller doesn't want the loads to remain cached, he can pass
in a fresh `cached_file` which will be privately owned by the index
reader, and will be evicted when the index reader dies.
