46612fe92b
This series adds more context to debugging information in case a view gets out of sync with its base table.
A test was conducted manually, by:
1. creating a table with a secondary index
2. manually deleting computed column information from system_schema.computed_columns
3. restarting the target node
4. trying to write to the index
Here's what's logged right after the index metadata is loaded from disk:
```
ERROR 2020-10-30 12:30:42,806 [shard 0] view - Column idx_token in view ks.t_c_idx_index was not found in the base table ks.t
ERROR 2020-10-30 12:30:42,806 [shard 0] view - Missing idx_token column is caused by an incorrect upgrade of a secondary index. Please recreate index ks.t_c_idx_index to avoid future issues.
```
And here's what's logged during the actual failure - when Scylla notices that there exists
a column which is not computed, but it's also not found in the base table:
```
ERROR 2020-10-30 12:31:25,709 [shard 0] storage_proxy - exception during mutation write to 127.0.0.1: seastar::internal::backtraced<std::runtime_error> (base_schema(): operation unsupported when initialized only for view reads. Missing column in the base table: idx_token Backtrace: 0x1d14513
0x1d1468b
0x1d1492b
0x109bbad
0x109bc97
0x109bcf4
0x1bc4370
0x1381cd3
0x1389c38
0xaf89bf
0xaf9b20
0xaf1654
0xaf1afe
0xb10525
0xb10ad8
0xb10c3a
0xaaefac
0xabf525
0xabf262
0xac107f
0x1ba8ede
0x1bdf749
0x1be338c
0x1bfe984
0x1ba73fa
0x1ba77a4
0x9ea2c8
/lib64/libc.so.6+0x27041
0x9d11cd
--------
seastar::lambda_task<seastar::execution_stage::flush()::{lambda()#1}>
```
Hopefully, this information will make it much easier to solve future problems with out-of-sync views.
Tests: unit(dev)
Fixes #7512
Closes #7513
* github.com:scylladb/scylla:
view: add printing missing base column on errors
view: simplify creating base-dependent info for reads only
view: fix typo: s/dependant/dependent
view: add error logs if a view is out of sync with its base
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++20 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 APIs - CQL and Thrift. 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 in ./docs and on the wiki. There is currently no clear definition of what goes where, so when looking for something be sure to check both. 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 users mailing list and Slack channel are for users to discuss configuration, management, and operations of the ScyllaDB open source.
- The developers mailing list is for developers and people interested in following the development of ScyllaDB to discuss technical topics.