With more GSI features implemented, tests with XPASS status are promoted
to being enabled.
One test case (test_gsi_describe) is partially done as DescribeTable
now contains index names, but we could try providing more attributes
(e.g. IndexSizeBytes and ItemCount from the test case), so the test
is left in the XFAIL state.
The DescribeTable request now contains the list of index names
as well. None of the attributes of the list are marked as 'required'
in the documentation, so currently the implementation provides
index names only.
In order to be able to create a Global Secondary Index over a regular
column, this column is upgraded from being a map entry to being a full
member of the schema. As such, it's possible to use this column
definition in the underlying materialized view's key.
In order to prepare alternator for adding regular columns to schema,
i.e. in order to create a materialized view over them,
the code is changed so that updating no longer assumes that only keys
are included in the table schema.
Since in the future we may want to have more regular columns
in alternator tables' schemas, the code is changed accordingly,
so all regular columns will be fetched instead of just the attribute
map.
If no regular column attributes are passed to PutItem, the attr
collector serializes an empty collection mutation nonetheless
and sends it. It's redundant, so instead, if the attr colector
is empty, the collection does not get serialized and sent to replicas.
Keeping an instance of client_state is a convenient way of being able
to use tracing for alternator. It's also currently used in paging,
so adding a client state to executor removes the need of keeping
a dummy value.
String views used in JSON serialization should use not only the pointer
returned by rapidjson, but also the string length, as it may contain
\0 characters.
Additionally, one unnecessary copy is elided.
Add a link to a longer document (currently, around 40 pages) about
DynamoDB's features and how we implemented or may implement them in
Alternator.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190825121201.31747-2-nyh@scylladb.com>
If a user tries to create a table with a unsupported feature -
a local secondary index, a used-defined encryption key or supporting
streams (CDC), let's refuse the table creation, so the application
doesn't continue thinking this feature is available to it.
The "Tags" feature is also not supported, but it is more harmless
(it is used mostly for accounting purposes) so we do not fail the
table creation because of it.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190818125528.9091-1-nyh@scylladb.com>
In CQL, before a user can create a table, they must create a keyspace to
contain this table and, among other things, specify this keyspace's RF.
But in the DynamoDB API, there is no "create keyspace" operation - the
user just creates a table, and there is no way, and no opportunity,
to specify the requested RF. Presumably, Amazon always uses the same
RF for all tables, most likely 3, although this is not officially
documented anywhere.
The existing code creates the keyspace during Scylla boot, with RF=1.
This RF=1 always works, and is a good choice for a one-node test run,
but was a really bad choice for a real cluster with multiple nodes, so
this patch fixes this choice:
With this patch, the keyspace creation is delayed - it doesn't happen
when the first node of the cluster boots, but only when the user creates
the first table. Presumably, at that time, the cluster is already up,
so at that point we can make the obvious choice automatically: a one-node
cluster will get RF=1, a >=3 node cluster will get RF=3. The choice of
RF is logged - and the choice of RF=1 is considered a warning.
Note that with this patch, keyspace creation is still automatic as it
was before. The user may manually create the keyspace via CQL, to
override this automatic choice. In the future we may also add additional
keyspace configuration options via configuration flags or new REST
requests, and the keyspace management code will also likely change
as we start to support clusters with multiple regions and global
tables. But for now, I think the automatic method is easiest for
users who want to test-drive Alternator without reading lengthy
instructions on how to set up the keyspace.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190820180610.5341-1-nyh@scylladb.com>
We allow BillingMode to be set to either PAY_PER_REQUEST (the default)
or PROVISIONED, although neither mode is fully implemented: In the former
case the payment isn't accounted, and in the latter case the throughput
limits are not enforced.
But other settings for BillingMode are now refused, and we add a new test
to verify that.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190818122919.8431-1-nyh@scylladb.com>
The alternator tests want to exercise many of the DynamoDB API features,
so they need a recent enough version of the client libraries, boto3
and botocore. In particular, only in botocore 1.12.54, released a year
ago, was support for BillingMode added - and we rely on this to create
pay-per-request tables for our tests.
Instead of letting the user run with an old version of this library and
get dozens of mysterious errors, in this patch we add a test to conftest.py
which cleanly aborts the test if the libraries aren't new enough, and
recommends a "pip" command to upgrade these libraries.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190819121831.26101-1-nyh@scylladb.com>
The DescribeTable operation was currently implemented to return the
minimal information that libraries and applications usually need from
it, namely verifying that some table exists. However, this operation
is actually supposed to return a lot more information fields (e.g.,
the size of the table, its creation date, and more) which we currently
don't return.
This patch adds a new test file, test_describe_table.py, testing all
these additional attributes that DescribeTable is supposed to return.
Several of the tests are marked xfail (expected to fail) because we
did not implement these attributes yet.
The test is exhaustive except for attributes that have to do with four
major features which will be tested together with these features: GSI,
LSI, streams (CDC), and backup/restore.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190816132546.2764-1-nyh@scylladb.com>
Currently Alternator starts all Scylla requests (including both reads
and writes) without any timeout set. Because of bugs and/or network
problems, Requests can theoretically hang and waste Scylla request for
hours, long after the client has given up on them and closed their
connection.
The DynamoDB protocol doesn't let a user specify which timeout to use,
so we should just use something "reasonable", in this patch 10 seconds.
Remember that all DynamoDB read and write requests are small (even scans
just scan a small piece), so 10 seconds should be above and beyond
anything we actually expect to see in practice.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190812105132.18651-1-nyh@scylladb.com>
So far we had the "--alternator-port" option allowing to configure the port
on which the Alternator server listens on, but the server always listened
to any address. It is important to also be able to configure the listen
address - it is useful in tests running several instances of Scylla on
the same machine, and useful in multi-homed machines with several interfaces.
So this patch adds the "--alternator-address" option, defaulting to 0.0.0.0
(to listen on all interfaces). It works like the many other "--*-address"
options that Scylla already has.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190808204641.28648-1-nyh@scylladb.com>
It turns out that recent rjson patches introduced some buggy
tabs instead of spaces due to bad IDE configuration. The indentation
is restored to spaces.
Until now, filtering in alternator was possible only for non-key
column equality relations. This commit adds support for equality
relations for key columns.
Alternator allows passing hash and sort key restrictions
as filters - it is, however, better to incorporate these restrictions
directly into partition and clustering ranges, if possible.
It's also necessary, as optimizations inside restrictions_filter
assume that it will not be fed unneeded rows - e.g. if filtering
is not needed on partition key restrictions, they will not be checked.
Currently the only utility function for getting key bytes
from JSON was to parse a document with the following format:
"key_column_name" : { "key_column_type" : VALUE }.
However, it's also useful to parse only the inner document, i.e.:
{ "key_column_type" : VALUE }.
Three metrics related to filtering are added to alternator:
- total rows read during filtering operations
- rows read and matched by filtering
- rows read and dropped by filtering
Some underlying operations (e.g. paging) make use of cql_stats
structure from CQL3. As such, cql_stats structure is added
to alternator stats in order to gather and use these statistics.
Read-before-write stat counters were already introduced, but the metrics
needs to be added to a metric group as well in order to be available
for users.
This patch adds partial support for GSI (Global Secondary Index) in
Alternator, implemented using a materialized view in Scylla.
This initial version only supports the specific cases of the index indexing
a column which was already part of the base table's key - e.g., indexing
what used to be a sort key (clustering key) in the base table. Indexing
of non-key attributes (which today live in a map) is not yet supported in
this version.
Creation of a table with GSIs is supported, and so is deleting the table.
UpdateTable which adds a GSI to an existing table is not yet supported.
Query and Scan operations on the index are supported.
DescribeTable does not yet list the GSIs as it should.
Seven previously-failing tests now pass, so their "xfail" tag is removed.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190808090256.12374-1-nyh@scylladb.com>
The rapidjson library needs to be used with caution in order to
provide maximum performance and avoid undefined behavior.
Comments added to rjson.hh describe provided methods and potential
pitfalls to avoid.
Message-Id: <ba94eda81c8dd2f772e1d336b36cae62d39ed7e1.1565270214.git.sarna@scylladb.com>
With libjsoncpp we were forced to work around the problem of
non-noexcept constructors by using an intermediate unique pointer.
Objects provided by rapidjson have correct noexcept specifiers,
so the workaround can be dropped.
Profiling alternator implied that JSON parsing takes up a fair amount
of CPU, and as such should be optimized. libjsoncpp is a standard
library for handling JSON objects, but it also proves slower than
rapidjson, which is hereby used instead.
The results indicated that libjsoncpp used roughly 30% of CPU
for a single-shard alternator instance under stress, while rapidjson
dropped that usage to 18% without optimizations.
Future optimizations should include eliding object copying, string copying
and perhaps experimenting with different JSON allocators.
Migrating from libjsoncpp to rapidjson proved to be beneficial
for parsing performance. As a first step, a set of helper functions
is provided to ease the migration process.
