a30ce98bc4
Several sstable_compaction_test cases run prohibitively slowly on S3 and GCS backends — some taking 4+ minutes — because they create hundreds of SSTables sequentially over high-latency HTTP connections and perform redundant validation (checksumming) round-trips on every one. The twcs_reshape_with_disjoint_set S3 variant was even disabled entirely because of this. The changes apply three complementary optimizations, per-test: **Skip SSTable validation on remote storage.** The compaction tests verify strategy logic, not data integrity. SSTable validation triggers additional read-back I/O which is cheap on local disk but expensive over HTTP. A `do_validate` flag now conditionally skips validation when the storage backend is not local. **Parallelize SSTable creation with async coroutines.** A new `make_sstable_containing_async` coroutine overload is added alongside the existing synchronous `make_sstable_containing`. Sequential creation loops are replaced with `parallel_for_each` using coroutine lambdas that call the async overload directly, overlapping S3/GCS uploads without spawning a dedicated Seastar thread per SSTable. The async validation path performs the same content checks as the synchronous version (mutation merging and `is_equal_to_compacted` assertions). Operations that depend on the created SSTables (e.g. `add_sstable_and_update_cache`, `owned_token_ranges` population) remain sequential. **Reduce SSTable count for remote variants.** Tests like twcs_reshape_with_disjoint_set and stcs_reshape_overlapping used a hardcoded count of 256. The count is now a function parameter (default 256 for local, 64 for S3/GCS), which is sufficient to exercise the compaction strategy logic while avoiding excessive remote I/O. Infrastructure changes: S3 endpoint max_connections raised from the default to 32 to support the higher upload concurrency, and trace-level logging added for s3, gcp_storage, http, and default_http_retry_strategy to aid future debugging. The previously disabled twcs_reshape_with_disjoint_set_s3_test is re-enabled with these optimizations. Fixes: https://scylladb.atlassian.net/browse/SCYLLADB-1428 Fixes: https://scylladb.atlassian.net/browse/SCYLLADB-1843 No backport needed — this is a test-only performance improvement. Closes scylladb/scylladb#29416 * github.com:scylladb/scylladb: test: optimize compaction_strategy_cleanup_method for remote storage test: optimize stcs_reshape_overlapping for remote storage test: optimize twcs_reshape_with_disjoint_set for remote storage test: parallelize SSTable creation in cleanup_during_offstrategy_incremental test: parallelize SSTable creation in run_incremental_compaction_test test: parallelize SSTable creation in offstrategy_sstable_compaction test: parallelize SSTable creation in twcs_partition_estimate test: add trace-level logging for S3 and HTTP in compaction tests test: make sstable test utilities natively async The original make_memtable used seastar::thread::yield() for preemption, which required all callers to run inside a seastar::thread context. This prevented the utilities from being used directly in coroutines or parallel_for_each lambdas. Make the primary functions — make_memtable, make_sstable_containing, and verify_mutation — return future<> directly. Callers now .get() explicitly when in seastar::thread context, or co_await when in a coroutine. make_memtable now uses coroutine::maybe_yield() instead of seastar::thread::yield(). verify_mutation is converted to coroutines as well. Requested in: https://github.com/scylladb/scylladb/pull/29416#pullrequestreview-4112296282 test: move make_memtable out of external_updater in row_cache_test test: increase S3 max connections for compaction tests
Scylla
What is Scylla?
Scylla is the real-time big data database that is API-compatible with Apache Cassandra and Amazon DynamoDB. Scylla embraces a shared-nothing approach that increases throughput and storage capacity to realize order-of-magnitude performance improvements and reduce hardware costs.
For more information, please see the ScyllaDB web site.
Build Prerequisites
Scylla is fairly fussy about its build environment, requiring very recent versions of the C++23 compiler and of many libraries to build. The document HACKING.md includes detailed information on building and developing Scylla, but to get Scylla building quickly on (almost) any build machine, Scylla offers a frozen toolchain. This is a pre-configured Docker image which includes recent versions of all the required compilers, libraries and build tools. Using the frozen toolchain allows you to avoid changing anything in your build machine to meet Scylla's requirements - you just need to meet the frozen toolchain's prerequisites (mostly, Docker or Podman being available).
Building Scylla
Building Scylla with the frozen toolchain dbuild is as easy as:
$ git submodule update --init --force --recursive
$ ./tools/toolchain/dbuild ./configure.py
$ ./tools/toolchain/dbuild ninja build/release/scylla
For further information, please see:
- Developer documentation for more information on building Scylla.
- Build documentation on how to build Scylla binaries, tests, and packages.
- Docker image build documentation for information on how to build Docker images.
Running Scylla
To start Scylla server, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --workdir tmp --smp 1 --developer-mode 1
This will start a Scylla node with one CPU core allocated to it and data files stored in the tmp directory.
The --developer-mode is needed to disable the various checks Scylla performs at startup to ensure the machine is configured for maximum performance (not relevant on development workstations).
Please note that you need to run Scylla with dbuild if you built it with the frozen toolchain.
For more run options, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --help
Testing
See test.py manual.
Scylla APIs and compatibility
By default, Scylla is compatible with Apache Cassandra and its API - CQL. There is also support for the API of Amazon DynamoDB™, which needs to be enabled and configured in order to be used. For more information on how to enable the DynamoDB™ API in Scylla, and the current compatibility of this feature as well as Scylla-specific extensions, see Alternator and Getting started with Alternator.
Documentation
Documentation can be found here. Seastar documentation can be found here. User documentation can be found here.
Training
Training material and online courses can be found at Scylla University. The courses are free, self-paced and include hands-on examples. They cover a variety of topics including Scylla data modeling, administration, architecture, basic NoSQL concepts, using drivers for application development, Scylla setup, failover, compactions, multi-datacenters and how Scylla integrates with third-party applications.
Contributing to Scylla
If you want to report a bug or submit a pull request or a patch, please read the contribution guidelines.
If you are a developer working on Scylla, please read the developer guidelines.
Contact
- The community forum and Slack channel are for users to discuss configuration, management, and operations of ScyllaDB.
- The developers mailing list is for developers and people interested in following the development of ScyllaDB to discuss technical topics.