In the alternator and cql-pytest test frameworks, we have some convenient
contextmanager-based functions that allows us to create a temporary
resource (e.g., a table) that will be automatically deleted, for
example:
with create_stream_test_table(...) as table:
test_something(table)
However, our implementation of these functions wasn't safe. We had
code looking like:
table = ...
yield table
table.delete()
The thinking was that the cleanup part (the table.delete()) will be
called after the user's code. However, if the user's code threw
(i.e., a failed assertion), the cleanup wasn't called... When the user's
code throws, it looks as if the "yield" throws. So the correct code
should look like:
table = ...
try:
yield table
finally:
table.delete()
Python's contextmanager documentation indeed gives this idiom in its
example.
This patch fixes all contextmanager implementations in our tests to do
the cleanup even if the user's "with" block throws.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210428083748.552203-1-nyh@scylladb.com>
In issue #5021 we noted that Alternator's equality operator needs to be
fixed for the case of comparing two sets, because the equality check needs
to take into account the possibility of different element order.
Unfortunately, we fixed only the equality check operator, but forgot there
is also an inequality operator!
So in this patch we fix the inequality operator, and also add a test for
it that was previously missing.
The implementation of the inequality operator is trivial - it's just the
negation of the equality test. Our pre-existing tests verify that this is
the correct implementation (e.g., if attribute x doesn't exist, then "x = 3"
is false but "x <> 3" is true).
Refs #5021Fixes#8513
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210419141450.464968-1-nyh@scylladb.com>
In issue #5021 we noticed that the equality check in Alternator's condition
expressions needs to handle sets differently - we need to compare the set's
elements ignoring their order. But the implementation we added to fix that
issue was only correct when the entire attribute was a set... In the
general case, an attribute can be a nested document, with only some
inner set. The equality-checking function needs to tranverse this nested
document, and compare the sets inside it as appropriate. This is what
we do in this patch.
This patch also adds a new test comparing equality of a nested document with
some inner sets. This test passes on DynamoDB, failed on Alternator before
this patch, and passes with this patch.
Refs #5021Fixes#8514
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210419184840.471858-1-nyh@scylladb.com>
When a condition expression (ConditionExpression, FilterExpression, etc.)
checks for equality of two item attributes, i.e., "x = y", and when one of
these attributes was missing we correctly returned false.
However, we also need to return false when *both* attributes are missing in
the item, because this is what DynamoDB does in this case. In other words
an unset attribute is never equal to anything - not even to another unset
attribute. This was not happening before this patch:
When x and y were both missing attributes, Alternator incorrectly returned
true for "x = y", and this patch fixes this case. It also fixes "x <> y"
which should to be true when both x and y are unset (but was false
before this patch).
The other comparison operators - <, <=, >, >=, BETWEEN, were all
implemented correctly even before this patch.
This patch also includes tests for all the two-unset-attribute cases of
all the operators listed above. As usual, we check that these tests pass
on both DynamoDB and Alternator to confirm our new behavior is the correct
one - before this patch, two of the new tests failed on Alternator and
passed on DynamoDB.
Fixes#8511
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210419123911.462579-1-nyh@scylladb.com>
This patch avoids an annoying warning
Warning: Unknown config ini key: flake8-ignore
when running one of the pytest-based test projects (cql-pytest,
alternator and redis) on recent versions of pytest.
In commit 2022da2405, we added to the
toplevel Scylla directory a "tox.ini" file with some intention to
configure Python syntax checking. One of the configurations in this
tox.ini is:
[pytest]
flake8-ignore =
E501
It turns out that pytest, if a certain test directory does not have its
own pytest.ini file, looks up in ancestor directory for various
configuration files (the configuration file precedence is described in
https://docs.pytest.org/en/stable/customize.html), and this includes
this tox.ini configuration section. Recent versions of pytest complain
about the "flake8-ignore" configuration parameter, which they don't
recognize. This parameter may be ok (?) if you install a flake8 pytest
plugin, but we do not require users to do this for running these tests.
Moreover, whatever noble intentions this commit and its tox.ini had,
nobody ever followed up on it. The three pytest-based test directories
never adhered to flake8's recommended syntax, and never intended to do
so. None of the developers of these tests use flake8, or seem to wish
to do so. If this ever changes, we can change the pytest.ini or undo this
commit and go back to a top-level tox.ini, but I don't see this happening
anytime soon.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210411085708.300851-1-nyh@scylladb.com>
By far the two slowest Alternator tests when running a development build on
my laptop are
test_gsi.py::test_gsi_projection_include
and
test_gsi.py::test_gsi_projection_keys_only
Each of those takes around 3.2, and the sum of just these two tests is as
much as 10% (!) of all other 600 tests.
The reason why these tests are slow is that they check scanning a GSI
with *projection*. Scylla currently ignores the projection, so the scan
returns the wrong value. Because this is a GSI, which supports only
eventually- consistent reads, we need to retry the read - and did it for
up to 3 seconds!
But this retry only makes sense if the GSI read did not *yet* return
the expected data. But in these xfailing test, we read a *wrong* item
(with too many attributes) almost immediately, and this should indicate
an immediate failure - no amount of retry would help. So in this patch
we detect this case and fail the test immediately instead of wasting
3 seconds in retries.
On my laptop with dev build, this patch reduces the time to run the
entire Alternator test suite from 70 seconds to 63 seconds.
Also, now that we never just waste time until the timeout, we can
increase it to any number, and in this patch we increase it from 3
seconds to 5.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210317183918.1775383-1-nyh@scylladb.com>
In conftest.py we have several fixtures creating shared tables which many
test files can share, so they are marked with the "session" scope - all
the tests in the testing session may share the same instance. This is fine.
Some of test files have additional fixtures for creating special tables
needed only in those files. Those were also, unnecessarily, marked
"session" scope as well. This means that these temporary tables are
only deleted at the very end of test suite, event though they can be
deleted at the end of the test file which needed them. This is exactly
what the "module" fixture scope is, so this patch changes all the
fixtures private to one test file to be "module".
After this patch, the teardown of the last test in the suite goes down
from 4 seconds to just 1.5 seconds (it's still long because there are
still plenty of session-scoped fixtures in conftest.py).
Another small benefit is that the peak disk usage of the test suite is
lower, because some of the temporary tables are deleted sooner.
This patch does not change any test functionality, and also does not
make any test faster - it just changes the order of the fixture
teardowns.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210317175036.1773774-1-nyh@scylladb.com>
Tests are short-lived and use a small amount of data. They
are also often run repeatly, and the data is deleted immediately
after the test. This is a good scenario for using the kernel page
cache, as it can cache read-only data from test to test, and avoid
spilling write data to disk if it is deleted quickly.
Acknowledge this by using the new --kernel-page-cache option for
tests.
This is expected to help on large machines, where the disk can be
overloaded. Smaller machines with NVMe disks probably will not see
a difference.
Closes#8347
By default the boto3 library waits up to 60 second for a response,
and if got no response, it sends the same request again, multiple
times. We already noticed in the past that it retries too many times
thus slowing down failures, so in our test configuration lowered the
number of retries to 3, but the setting of 60-second-timeout plus
3 retries still causes two problems:
1. When the test machine and the build are extremely slow, and the
operation is long (usually, CreateTable or DeleteTable involving
multiple views), the 60 second timeout might not be enough.
2. If the timeout is reached, boto3 silently retries the same operation.
This retry may fail because the previous one really succeeded at
least partially! The symptom is tests which report an error when
creating a table which already exists, or deleting a table which
dooesn't exist.
The solution in this patch is first of all to never do retries - if
a query fails on internal server error, or times out, just report this
failure immediately. We don't expect to see transient errors during
local tests, so this is exactly the right behavior.
The second thing we do is to increase the default timeout. If 1 minute
was not enough, let's raise it to 5 minutes. 5 minutes should be enough
for every operation (famous last words...).
Even if 5 minutes is not enough for something, at least we'll now see
the timeout errors instead of some wierd errors caused by retrying an
operation which was already almost done.
Fixes#8135
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210222125630.1325011-1-nyh@scylladb.com>
The slowest test in test_streams.py is test_list_streams_paged. It is meant
to test the ListStreams operation with paging. The existing test repeated
its test four times, for four different stream types. However, there is
no reason to suspect that the ListStreams operation might somehow be
different for the four stream types... We already have other tests which
create streams of the four types, and uses these streams - we don't
need the test for ListStreams to also test creating the four types.
By doing this test just once, not four times, we can save around 1.5
seconds of test time.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210318073755.1784349-1-nyh@scylladb.com>
In the test test_tracing.py::test_tracing_all, we do some operations and
then need to wait until they appear in the tracing table.
The current code used an exponentially-increasing delay during this wait,
starting with 0.1 seconds and then doubling the delay until we find what
we're looking for.
However, it turns out that the delay until the data appears in the table
is deliberately chosen by Scylla - and is always around 2 seconds.
In this case, an exponential delay is really bad - we will usually wait
for around 1 seconds too long after the needed wait of 2 seconds.
So in this patch we replace the exponential delay by a constant delay -
we wait 0.3 seconds between each retry.
This change makes the test test_tracing.py::test_tracing_all finish
in a little over 2 seconds, instead of a little over 3 seconds
before this patch. We cannot reduce this 2 second time any further
unless we make the 2-second tracing delay configurable.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210318000040.1782933-1-nyh@scylladb.com>
The test test_table.py::test_table_streams_on creates tables with various
stream types, and then immediately deletes them without testing anything.
This is a slow test (taking almost a full second on my laptop), and is
redundant because in test_streams.py we have tests which create tables
with streams in the same way - but then actually test that things work
with these streams. So this test might as well be removed, and this is
what we do in this patch.
Removing this test shaves another second from the Alternator test suite's
run time.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210317230530.1780849-1-nyh@scylladb.com>
The test
test_condition_expression.py::test_condition_expression_with_forbidden_rmw
takes half a second to run (dev build, on my laptop), one of the slowest
tests in Alternator's test suite. Part of the reason was that it needlessly
set the same table to forbidden_rmw, multiple times.
Instead of doing that, we switch to using the test_table_s_forbid_rmw
fixture, which is a table like test_table_s but created just once in
forbid_rmw mode.
The result is a faster test (0.05 seconds instead of 0.5 seconds), but
also safer if we ever want to run tests in parallel. It also fixes a
bug in the test: At the end of the test, we intended to double-check
that although the forbid_rmw table forbids read-modify-write operations,
it does allow pure writes. Yet the test did this after clearing the
forbid_rmw mode... So after this patch the test verifies this on the
forbid_rmw table, as intended.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210317222703.1779992-1-nyh@scylladb.com>
The test
test_condition_expression.py::test_condition_expression_with_permissive_write_isolation
Currently takes (on my laptop, dev build) a full two seconds, one of
the slowest tests. It is not surprising it is slow - it runs five other
tests three times each (for three different write isolation modes),
but it doesn't have to be this slow. Before this patch, for each of
the five tests we switch the write isolation mode three times, and
these switches involve schema changes and are fairly slow. So in
this patch we reverse the loop - and switch the write isolation mode
to the outer loop.
This patch halves the runtime of this test - from two seconds to one.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210317221045.1779329-1-nyh@scylladb.com>
The test checks whether slow queries are properly logged
in the system_traces.node_slow_log system table.
The test is deterministic because it uses the threshold of 0ms
to qualify a query as slow, which effectively makes all queries
"slow enough".
Alternator request sizes can be up to 16 MB, but the current implementation
had the Seastar HTTP server read the entire request as a contiguous string,
and then processed it. We can't avoid reading the entire request up-front -
we want to verify its integrity before doing any additional processing on it.
But there is no reason why the entire request needs to be stored in one big
*contiguous* allocation. This always a bad idea. We should use a non-
contiguous buffer, and that's the goal of this patch.
We use a new Seastar HTTPD feature where we can ask for an input stream,
instead of a string, for the request's body. We then begin the request
handling by reading lthe content of this stream into a
vector<temporary_buffer<char>> (which we alias "chunked_content"). We then
use this non-contiguous buffer to verify the request's signature and
if successful - parse the request JSON and finally execute it.
Beyond avoiding contiguous allocations, another benefit of this patch is
that while parsing a long request composed of chunks, we free each chunk
as soon as its parsing completed. This reduces the peak amount of memory
used by the query - we no longer need to store both unparsed and parsed
versions of the request at the same time.
Although we already had tests with requests of different lengths, most
of them were short enough to only have one chunk, and only a few had
2 or 3 chunks. So we also add a test which makes a much longer request
(a BatchWriteItem with large items), which in my experiment had 17 chunks.
The goal of this test is to verify that the new signature and JSON parsing
code which needs to cross chunk boundaries work as expected.
Fixes#7213.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210309222525.1628234-1-nyh@scylladb.com>
We already have a test which shows verify DynamoDB and Alternator
do not allow an index in an attribute path - like a[0].b - to be
a value reference - a[:xyz].b. We forgot to verify that the index
also can't be a name reference - a[#xyz].b is a syntax error. So here
we add a test which confirms that this is indeed the case - DynamoDB
doesn't allow it, and neither does Alternator.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210219123310.1240271-1-nyh@scylladb.com>
Like DynamoDB, Alternator rejects requests larger than some fixed maximum
size (16MB). We had a test for this feature - test_too_large_request,
but it was too blunt, and missed two issues:
Refs #8195
Refs #8196
So this patch adds two better tests that reproduce these two issues:
First, test_too_large_request_chunked verifies that an oversized request
is detected even if the body is sent with chunked encoding.
Second, both tests - test_too_large_request_chunked and
test_too_large_request_content_length - verify that the rather limited
(and arguably buggy) Python HTTP client is able to read the 413 status
code - and doesn't report some generic I/O error.
Both tests pass on DynamoDB, but fail on Alternator because of these two
open issues.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210302154555.1488812-1-nyh@scylladb.com>
This patch adds to Alternator support for the CORS (Cross-Origin Resource
Sharing) protocol - a simple extension over the HTTP protocol which
browsers use when Javascript code contacts HTTP-based servers.
Although we usually think of Alternator as being used in a three-tier
application, in some setups there is no middle layer and the user's
browser, running Javascript code, wants to communicate directly with the
database. However, for security reasons, by default Javascript loaded
from domain X is not allowed to communicate with different domains Y.
The CORS protocol is meant to allow this, and Alternator needs to
participate in this protocol if it is to be used directly from Javascript
in browsers.
To implement CORS, Alternator needs to respond to the OPTIONS method
which it didn't allow before - with certain headers based on the
input headers. It also needs to do some of these things for the
regular methods (mostly, POST). The patch includes a comprehensive
test that runs against both Alternator and DynamoDB and shows that
Alternator handles these headers and methods the same as DynamoDB.
Additionally, I tested manually a Javascript DynamoDB client - which
didn't work prior to this patch (the browser reported CORS errors),
and works after this patch.
Fixes#8025.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210217222027.1219319-1-nyh@scylladb.com>
This patch fixes the last missing part of nested attribute support in
UpdateItem - returning the correct attributes when ReturnValues is requested.
When the expression says "a.b = :val" and ReturnValues is set to UPDATED_OLD
or UPDATED_NEW, only the actual updated attribute a.b should be returned, not
the entire top-level attribute a as we did before this patch.
This patch was made very simple because our existing hierarchy_filter()
function already does exactly the right thing, and can trivially be made to
accept any attribute_path_map<T> (in our case attribute_path_map<action>),
not just attrs_to_get as it did until now.
This patch also adds several more checks to the test in test_returnvalues.py
to improve the test's coverage even more. Interestingly, I discovered two
esoteric cases where DynamoDB does something which makes little sense, but
apparently simplified their implementation - but the beautiful thing is that
it also simplifies our implementation! See long comments about these two
cases in the test code.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
This patch adds full support for nested attribute paths (e.g., a.b[3].c)
in UpdateExpression. After in previous patches we already added such
support for ProjectionExpression, ConditionExpression and FilterExpression
this means the nested attribute paths feature is now complete, so we
remove the warning from the documents. However, there is one last loose
end to tie and we will do it in the next patch: After this patch, the
combination of UpdateExpression with nested attributes and ReturnValues
is still wrong, and the test for it in test_returnvalues.py still xfails.
Note that previous patches already implemented support for attribute paths
in expression evaluations - i.e., the right-hand side of UpdateExpression
actions, and in this patch we just needed to implement the left hand side:
When an update action is on an attribute a.b we need to read the entire
content of the top-level a (an RWM operation), modify just the b part of
its json with the result of the action, and finally write back the entire
content of a. Of course everything gets complicated by the fact that we
can have multiple actions on multiple pieces of the same JSON, and we also
need to detect overlapping and conflicting actions (we already have this
detection in the attribute_path_map<> class we introduced in a previous
patch).
I decided to leave one small esoteric difference, reproduced by the xfailing
test_update_expression.py::test_nested_attribute_remove_from_missing_item:
As expected, "SET x.y = :val" fails for an item if its attribute x doesn't
exist or the item itself does not exist. For the update expression
"REMOVE x.y", DynamoDB fails if the attribute x doesn't exist, but oddly
silently passes if the entire item doesn't exist. Alternator does not
currently reproduce this oddity - it will fail this write as well.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
DynamoDB limits the depth of a nested path in expressions (e.g. "a.b.c.d")
to 32 levels. This patch adds the same limit also to Alternator.
The exact value of this limit is less important (although it did make
sense to choose the same limit as DynamoDB does), but it's important
to have *some* limit: It's often convenient to handle paths with a
recursive algorithm, and if we allow unlimited path depth, it can
result in unlimited recursion depth, and a crash. Let's avoid this
possibility.
We detect the over-long path while building the parsed::path object
in the parser, and generate a parse error.
This patch also includes a test that verifies that both Alternator
and DynamoDB have the same 32-level nesting limit on paths.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
This patch prepares UpdateItem for updating of nested attribute paths
(e.g., "SET a.b = :val"), but does not yet support them.
Instead of _update_expression holding an unsorted list of "actions",
we change it to hold a attribute_path_map of actions. This will allow
us to process all the actions on a top-level attribute together, and
moreover gets us "for free" the correct checking for overlapping and
conflicting updates - exactly the same checking we already had in
attribute_path_map for ProjectionExpression. Other than this change,
most of this patch is just code movement, not functional changes.
After this patch, the tests for update path overlap and conflict pass:
test_update_expression_multi_overlap_nested and
test_update_expression_multi_conflict_nested.
We can also mark test_update_expression_nested_attribute_rhs as passing -
this test involves an attribute path in the right-hand-side of an update,
but the left-hand-side is still a top-level attribute, so it works (it
actually worked before this patch - it started working when we implemented
attribute paths in expressions, for ConditionExpression and
FilterExpression).
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
We already had many tests for nested attributes in UpdateExpression, but
this patch adds even more:
* Test nested attribute in right-hand-side in assignment: z = a.c.x.
* Test for making multiple changes to the same and different top-level
attributes in the same update.
* Additional cases of overlap between multiple changes.
* Tests for conflict between multiple changes.
* Tests for writing to a nested path on a non-existent attribute or item.
* A stronger test for array append sorts the added items.
As this feature was not yet implemented, these tests fail on Alternator,
and pass on DynamoDB.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
This patch fully implements support for attribute paths (e.g. a.b.c, a.d[3])
for the ConditionExpression in conditional updates, and FilterExpression in
queries and scans. After this patch, all previously-xfailing tests in
test_projection_expression.py and test_filter_expression.py now pass.
The fix is simple: Both ConditionExpression and FilterExpression use the
function calculate_value() to calculate the value of the expression. When
this function calculates the value of a path, it mustn't just take the
top-level attribute - it needs to walk into the specific sub-object as
specified by the attribute path.
This is not the end of attribute path support, UpdateExpression and
ReturnValues are not yet fully supported. This will come in following
patches.
Refs #5024
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Strengthen the tests in test_condition_expression.py for nested attribute
paths (e.g., b.y[1]):
1. The test test_update_condition_nested_attributes only tested successful
conditions involving nested attributes. Let's also add an *unsuccessful*
condition, to verify we don't accidentally pass every condition involving
a nested attribute.
2. Test a case where a non-existant nested attribute is involved in the
condition.
3. In the test for an attribute path with references - "#name1.#name2",
make sure the test doesn't pass if #name2 is silently ignored.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
This patch fully implements support for attribute paths (e.g. a.b.c, a.d[3])
for the ProjectionExpression in the various operations where this parameter
is supported - GetItem, BatchGetItem, Query and Scan. After this patch, all
xfailing tests in test_projection_expression.py now pass.
In the previous patch we remembered in the "attrs_to_get" object not only
the top-level attributes to read from the table, but also how to filter
from it only the desired pieces of the nested document. In this patch we
add a filter() function to do this filtering, and call it in the right
places to post-process the JSON objects we read from the table.
We also had to fix reference resolution in paths to resolve all the
components of the path (e.g., #name1.#name2) and not just the top-level
attribute.
This is not the end of attribute path support, there are still other
expressions (ConditionExpression, UpdateExpression, FilterExpression,
ReturnValues) where they are not yet supported. This will come in following
patches.
Refs #5024
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
In the existing code, the variable "attrs_to_get" is a list of top-level
attributes to fetch for an item. It is used to implement features like
ProjectionExpression or AttributesToGet in GetItem and other places.
However, to support attribute paths (e.g., a.b.c[2]) in ProjectionExpression,
i.e., issue #5024, we need more than that. We still need to know the top-
level attribute "a", because this is the granularity we have in the Scylla
table (all the content inside "a" is serialized as a single JSON); But we
also need to remember exactly which parts *inside* "a" we will need to
extract and return.
So in this patch we add a new type, "attrs_to_get", which is more than
just a list of top-level attributes. Instead, it is a *map*, whose keys
are the top-level attributes, and the value for each of them is a
"hierarchy_filter", an object which describes which part of the attribute
is needed.
This patch includes the code which converts the AttributesToGet and
ProjectionExpression into the new attrs_to_get structure. During this
conversion, we recognize two kinds of errors which DynamoDB complains
about: We recognize "overlapping" attributes (e.g., requesting both
a.b and a.b.c) and "conflicting" attributes (e.g, requesting both
a.b and a[1]). After this, two xfailing tests we had for detecting
these overlap and conflicts finally pass and their "xfail" label is
removed.
After this patch, we have the attrs_to_get object which can allow us
to filter only the requested pieces of the top-level attributes, but
we don't use it yet - so this patch is not enough for complete support
of attribute paths in ProjectionExpression. We will complete this
support in the next patch.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
This patch adds more tests for attribute paths in ProjectionExpression,
that deal with document paths which do not fit the content of the item -
e.g., trying to ask for "a.b[3]" when a.b is not a list but rather an
integer or a dictionary.
Moreover, we note that if you try to ask for "a.b, a[2]", DynamoDB
fails this request as a "conflict". The reasoning is that no single
item can ever have both a.b and a[2] (the first is only valid for
dictionaries, the second for lists). It's not clear to me why we
still can't return whichever of the two actually is relevant, but
the fact is that DynamoDB does not allow it.
The new tests fail on Alternator (marked xfailed) and pass on DynamoDB.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
We have 7 xfailing tests for usage of nested attribute paths (e.g.,
"a.b.c[7]") in a ProjectionExpression. But some of these tests were too
"easy" to pass - a trivial and *wrong* implementation that just ignores
the path and uses the top level attribute (in the above example, "a"),
would cause some of them to start passing.
So this patch strengthens these tests. They still pass on AWS DynamoDB,
and now continue to fail with the aforementioned broken implementation.
Refs #5024.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
The first condition expressions we implemented in Alternator were the old
"Expected" syntax of conditional updates. That implementation had some
specific assumptions on how it handles errors: For example, in the "LT"
operator in "Expected", the second operand is always part of the query, so
an error in it (e.g., an unsupported type) resulted it a ValidationException
error.
When we implemented ConditionExpression and FilterExpression, we wrongly
used the same functions check_compare(), check_BETWEEN(), etc., to implement
them. This results in some inaccurate error handling. The worst example is
what happens when you use a FilterExpression with an expression such as
"x < y" - this filter is supposed to silently skip items whose "x" and "y"
attributes have unsupported or different types, but in our implementation
a bad type (e.g., a list) for y resulted in a ValidationException which
aborted the entire scan! Interestingly, in once case (that of BEGINS_WITH)
we actually noticed the slightly different behavior needed and implemented
the same operator twice - with ugly code duplication. But in other operators
we missed this problem completely.
This patch first adds extensive tests of how the different expressions
(Expected, QueryFilter, FilterExpression, ConditionExpression) and the
different operators handle various input errors - unsupported types,
missing items, incompatible types, etc. Importantly, the tests demonstrate
that there is often different behavior depending on whether the bad
input comes from the query, or from the item. Some of the new tests
fail before this patch, but others pass and were useful to verify that
the patch doesn't break anything that already worked correctly previously.
As usual, all the tests pass on Cassandra.
Finally, this patch *fixes* all these problems. The comparison functions
like check_compare() and check_BETWEEN() now not only take the operands,
they also take booleans saying if each of the operands came from the
query or from an item. The old-syntax caller (Expected or QueryFilter)
always say that the first operand is from the item and the second is
from the query - but in the new-syntax caller (ConditionExpression or
FilterExpression) any or all of the operands can come from the query
and need verification.
The old duplicated code for check_BEGINS_WITH() - which a TODO to remove
it - is finally removed. Instead we use the same idea of passing booleans
saying if each of its operands came from an item or from the query.
Fixes#8043
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Our test for tracing Alternator requests can't be sure when tracing a request
finished, because tracing is asynchronous and has no official ending signal.
So before we can conclude that tracing failed, we need to wait until a
timeout, which in the current code was roughly 6.4 seconds (the timeout
logic is unnecessarily convoluted, but to make a long story short it has
exponential sleeps starting with 0.1 second and ending with 3.2 seconds,
totaling 6.4 seconds).
It turns out that sporadically, in test runs on overcommitted test machines
with the very slow debug build, we fail this test with this timeout.
So this patch increases the timeout to 51.2 seconds. It should be more
than enough for everyone. Famous last words :-)
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20210204151554.582260-1-nyh@scylladb.com>
In test_streams.py we had some code to get a list of shards and iterators
duplicated three times. Put it in a function, shards_and_latest_iterators(),
to reduce this duplication.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20201006112421.426096-1-nyh@scylladb.com>
In Alternator's expression parser in alternator/expressions.g, a list can be
indexed by a '[' INTEGER ']'. I had doubts whether maybe a value-reference
for the index, e.g., "something[:xyz]", should also work. So this patch adds
a test that checks whether "something[:xyz]" works, and confirms that both
DynamoDB and Alternator don't accept it and consider it a syntax error.
So Alternator's parser is correct to insist that the index be a literal
integer.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20201214100302.2807647-1-nyh@scylladb.com>
Alternator tracing tests require the cluster to have the 'always'
isolation level configured to work properly. If that's not the case,
the tests will fail due to not having CAS-related traces present
in the logs. In order to help the users fix their configuration,
a helper message is printed before the test case is performed.
Automatic tests do not need this, because they are all ran with
matching isolation level, but this message could greatly improve
the user experience for manual tests.
Message-Id: <62bcbf60e674f57a55c9573852b6a28f99cbf408.1607949754.git.sarna@scylladb.com>
The outcome of alternator tracing tests was that tracing probability
was always set to 0 after the test was finished. That makes sense
for most test runs, but manual tests can work on existing clusters
with tracing probability set to some other value. Due to preserve
previous trace probability, the value is now extracted and stored,
so that it can be restored after the test is done.
Message-Id: <94f829b63f92847b4abb3b16f228bf9870f90c2e.1607949754.git.sarna@scylladb.com>
Three tests in test_streams.py run update_table() on a table without
waiting for it to complete, and then call update_table() on the same
table or delete it. This always works in Scylla, and usually works in
AWS, but if we reach the second call, it may fail because the previous
update_table() did not take effect yet. We sometimes see these failures
when running the Alternator test suite against AWS.
So in this patch, after an each update_table() we wait for the table
to return from UPDATING to ACTIVE status.
The entire Alternator test suite now passes (or skipped) on AWS,
so: Fixes#7778.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20201213164931.2767236-1-nyh@scylladb.com>
The test test_query_filter.py::test_query_filter_paging fails on AWS
and shouldn't fail, so this patch fixes the test. Note that this is
only a test problem - no fix is needed for Alternator itself.
The test reads 20 results with 1-result pages, and assumed that
21 pages are returned. The 21st page may happen because when the
server returns the 20th, it might not yet know there will be no
additional results, so another page is needed - and will be empty.
Still a different implementation might notice that the last page
completed the iteration, and not return an extra empty page. This is
perfectly fine, and this is what AWS DynamoDB does today - and should
not be considered an error.
Refs #7778
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20201213143612.2761943-1-nyh@scylladb.com>
When request signature checking is enabled in Alternator, each request
should come with the appropriate Authorization header. Most errors in
this preparing this header will result in an InvalidSignatureException
response; But DynamoDB returns a more specific error when this header is
completely missing: MissingAuthenticationTokenException. We should do the
same, but before this patch we return InvalidSignatureException also for
a missing header.
The test test_authorization.py::test_no_authorization_header used to
enshrine our wrong error message, and failed when run against AWS.
After this patch, we fix the error message and the test - which now
passes against both Alternator and AWS.
Refs #7778.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20201213133825.2759357-1-nyh@scylladb.com>
UpdateItem's "ADD" operation usually adds elements to an existing set
or adds a number to an existing counter. But it can *also* be used
to create a new set or counter (as if adding to an empty set or zero).
We unfortunately did not have a test for this case (creating a new set
or counter), and when I wrote such a test now, I discovered the
implementation was missing. So this patch adds both the test and the
implementation. The new test used to fail before this patch, and passes
with it - and passes on DynamoDB.
Note that we only had this bug for the newer UpdateItem syntax.
For the old AttributeUpdates syntax, we already support ADD actions
on missing attributes, and already tested it in test_update_item_add().
I just forgot to test the same thing for the newer syntax, so I missed
this bug :-(
Fixes#7763.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20201207085135.2551845-1-nyh@scylladb.com>
Whereas in CQL the client can pass a timeout parameter to the server, in
the DynamoDB API there is no such feature; The server needs to choose
reasonable timeouts for its own internal operations - e.g., writes to disk,
querying other replicas, etc.
Until now, Alternator had a fixed timeout of 10 seconds for its
requests. This choice was reasonable - it is much higher than we expect
during normal operations, and still lower than the client-side timeouts
that some DynamoDB libraries have (boto3 has a one-minute timeout).
However, there's nothing holy about this number of 10 seconds, some
installations might want to change this default.
So this patch adds a configuration option, "--alternator-timeout-in-ms",
to choose this timeout. As before, it defaults to 10 seconds (10,000ms).
In particular, some test runs are unusually slow - consider for example
testing a debug build (which is already very slow) in an extremely
over-comitted test host. In some cases (see issue #7706) we noticed
the 10 second timeout was not enough. So in this patch we increase the
default timeout chosen in the "test/alternator/run" script to 30 seconds.
Please note that as the code is structured today, this timeout only
applies to some operations, such as GetItem, UpdateItem or Scan, but
does not apply to CreateTable, for example. This is a pre-existing
issue that this patch does not change.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20201207122758.2570332-1-nyh@scylladb.com>
When an Alternator table has partition keys or sort keys of type "bytes"
(blobs), a Scan or Query which required paging used to fail - we used
an incorrect function to output LastEvaluatedKey (which tells the user
where to continue at the next page), and this incorrect function was
correct for strings and numbers - but NOT for bytes (for bytes, we
need to encode them as base-64).
This patch also includes two tests - for bytes partition key and
for bytes sort key - that failed before this patch and now pass.
The test test_fetch_from_system_tables also used to fail after a
Limit was added to it, because one of the tables it scans had a bytes
key. That test is also fixed by this patch.
Fixes#7768
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20201207175957.2585456-1-nyh@scylladb.com>
The test test_fetch_from_system_tables tests Alternator's system-table
feature by reading from all system tables. The intention was to confirm
we don't crash reading any of them - as they have different schemas and
can run into different problems (we had such problems in the initial
implementation). The intention was not to read *a lot* from each table -
we only make a single "Scan" call on each, to read one page of data.
However, the Scan call did not set a Limit, so the single page can get
pretty big.
This is not normally a problem, but in extremely slow runs - such as when
running the debug build on an extremely overcommitted test machine (e.g.,
issue #7706) reading this large page may take longer than our default
timeout. I'll send a separate patch for the timeout issue, but for now,
there is really no reason why we need to read a big page. It is good
enough to just read 50 rows (with Limit=50). This will still read all
the different types and make the test faster.
As an example, in the debug run on my laptop, this test spent 2.4
seconds to read the "compaction_history" table before this patch,
and only 0.1 seconds after this patch. 2.4 seconds is close to our
default timeout (10 seconds), 0.1 is very far.
Fixes#7706
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20201207075112.2548178-1-nyh@scylladb.com>
Add new alternator-streams experimental flag for
alternator streams control.
CDC becomes GA and won't be guarded by an experimental flag any more.
Alternator Streams stay experimental so now they need to be controlled
by their own experimental flag.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
Add a test that better clarifies what StartingSequenceNumber returned by
DescribeStream really guarantees (this question was raised in a review
of a different patch). The main thing we can guarantee is that reading a
shard from that position returns all the information in that shard -
similar to TRIM_HORIZON. This test verifies this, and it passes.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20201112081250.862119-1-nyh@scylladb.com>
DescribeTable should return a UUID "TableId" in its reponse.
We alread had it for CreateTable, and now this patch adds it to
DescribeTable.
The test for this feature is no longer xfail. Moreover, I improved
the test to not only check that the TableId field is present - it
should also match the documented regular expression (the standard
representation of a UUID).
Refs #5026
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20201104114234.363046-1-nyh@scylladb.com>
The main goal of this this series is to fix issue #6951 - a Query (or Scan) with
a combination of filtering and projection parameters produced wrong results if
the filter needs some attributes which weren't projected.
This series also adds new tests for various corner cases of this issue. These
new tests also pass after this fix, or still fail because some other missing
feature (namely, nested attributes). These additional tests will be important if
we ever want to refactor or optimize this code, because they exercise some rare
corner code paths at the intersection of filtering and projection.
This series also fixes some additional problems related to this issue, like
combining old and new filtering/projection syntaxes (should be forbidden), and
even one fix to a wrong comment.
Closes#7328
* github.com:scylladb/scylla:
alternator test: tests for nested attributes in FilterExpression
alternator test: fix comment
alternator tests: additional tests for filter+projection combination
alternator: forbid combining old and new-style parameters
alternator: fix query with both projection and filtering
