Test an operation like SET #one = #two, where the RHS has a reference
to a name, rather than the name itself. Also verify that DynamoDB
gives an error if ExpressionAttributeNames includes names not needed
by neither left or right hand side of such assignments.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190708133311.11843-1-nyh@scylladb.com>
In order to serve update requests that depend on read-before-write,
a proper helper function which fetches the existing item with a given
key from the database is added.
This read-before-write mechanism is not considered safe, because it
provides no linearizability guarantees and offers no synchronization
protection. As such, it should be consider a placeholder that works
fine on a single machine and/or no concurrent access to the same key.
The calculate_value utility function is going to need more context
in order to resolve paths present in the right-hand side of update_item
operators: update_info and schema.
Historically, resolving a path checked for key columns, which are not
allowed to be on the left-hand side of the assignment. However, path
resolving will now also be used for right-hand side, where it should
be allowed to use the key value.
In order to implement read-before-write in the future, calculate_value
now accepts an additional parameter: previous_item. If read-before-write
was performed, previous_item will contain an item for the given key
which already exists in the database at the time of the update.
This patch moves the create_test_table() utility function, which creates
a test table with a unique name, from the fixtures (conftest.py) to
util.py. This will allow reusing this function in tests which need to
create tables but not through the existing fixtures. In particular
we will need to do this for GSI (global secondary index) tests
in the next patch.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190708104438.5830-1-nyh@scylladb.com>
The tests we had for BatchWriteItem's refusal to accept duplicate keys
only used test_table_s, with just a hash key. This patch adds tests
for test_table, i.e., a table with both hash and sort keys - to check
that we check duplicates in that case correctly as well.
Moreover, the expanded tests also verify that although identical
keys are not allowed, keys with just one component (hash or sort key)
the same but the other not the same - are fine.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190705191737.22235-1-nyh@scylladb.com>
Even when running against a local Alternator, Boto3 wants to know the
region name, and AWS credentials, even though they aren't actually needed.
For a local run, we can supply garbage values for these settings, to
allow a user who never configured AWS to run tests locally.
Running against "--aws" will, of course, still require the user to
configure AWS.
Also modified the README to be clearer, and more focused on the local
runs.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190708121420.7485-1-nyh@scylladb.com>
For "--aws" tests, use the default region chosen by the user in the
AWS configuration (~/.aws/config or environment variable), instead of
hard-coding "us-east-1".
Patch by Pekka Enberg.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190708105852.6313-1-nyh@scylladb.com>
Calculating value represented as 'v1 + v2' or 'v1 - v2' was previously
implemented with a double type, which offers limited precision.
From now on, these computations are based on big_decimal, which
allows returning values without losing precision.
This patch depends on 'add big_decimal arithmetic operators' series.
Message-Id: <f741017fe3d3287fa70618068bdc753bfc903e74.1562318971.git.sarna@scylladb.com>
Move some common utility functions to a common file "util.py"
instead of repeating them in many test files.
The utility functions include random_string(), random_bytes(),
full_scan(), full_query(), and multiset() (the more general
version, which also supports freezing nested dicts).
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190705081013.1796-1-nyh@scylladb.com>
The idiomatic way to use an std::variant depending the type holds is to use
std::visit. This modern API makes it unnecessary to write many boiler-plate
functions to test and cast the type of the variant, and makes it impossible
to forget one of the options. So in this patch we throw out the old ways,
and welcome the new.
Thanks to Piotr Sarna for the idea.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190704205625.20300-1-nyh@scylladb.com>
This patch adds to Alternator an implementation of the BatchGetItem
operation, which allows to start a number of GetItem requests in parallel
in a single request.
The implementation is almost complete - the only missing feature is the
ability to ask only for non-top-level attributes in ProjectionExpression.
Everything else should work, and this patch also includes tests which,
as usual, pass on DynamoDB and now also on Alternator.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Amazingly, it appears we never tested booting Alternator a second time :-)
Our initialization code creates a new keyspace, and was supposed to ignore
the error if this keyspace already existed - but we thought the error will
come as an exceptional future, which it didn't - it came as a thrown
exception. So we need to change handle_exception() to a try/catch.
With this patch, I can kill Alternator and it will correctly start again.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Operations which take a key as parameter, namely GetItem, UpdateItem,
DeleteItem and BatchWriteItem's DeleteRequest, already fail if the given
key is missing one of the nessary key attributes, or has the wrong types
for them. But they should also fail if the given key has spurious
attributes beyond those actually needed in a key.
So this patch adds this check, and tests to confirm that we do these checks
correctly.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
The PutItem operation, and also the PutRequest of BatchWriteItem, are
supposed to completely replace the item - not to merge the new value with
the previous value. We implemented this wrongly - we just wrote the new
item forgetting a tombstone to remove the old item.
So this patch fixes these operations, and adds tests which confirm the
fix (as usual, these tests pass on DynamoDB, failed on Alternator before
this patch, and pass after the patch).
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Add support for the DeleteItem operation, which deletes an item.
The basic deletion operation is supported. Still not supported are:
1. Parameters to conditionally delete (ConditionalExpression or Expected)
2. Parameters to return pre-delete content
3. ReturnItemCollectionMetrics (statistics relevant for tables with LSI)
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
In BatchWriteItem, we currently only support the PutRequest operation.
If a user tries to use DeleteRequest (which we don't support yet), he
will get a bizarre error. Let's test the request type more carefully,
and print a better error message. This will also be the place where
eventually we'll actually implement the DeleteRequest.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
This patch adds more comprehensive tests for the BatchWriteItem operation,
in a new file batch_test.py. The one test we already had for it was also
moved from test_item.py here.
Some of the test still xfail for two reasons:
1. Support for the DeleteRequest operation of BatchWriteItem is missing.
2. Tests that forbid duplicate keys in the same request are missing.
As usual, all tests succeed on DynamoDB, and hopefully (I tried...)
cover all the BatchWriteItem features.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
DynamoDB has two similar parameters - AttributesToGet and
ProjectionExpression - which are supported by the GetItem, Scan and
Query operations. Until now we supported only the older AttributesToGet,
and this patch adds support to the newer ProjectionExpression.
Besides having a different syntax, the main difference between
AttributesToGet and ProjectionExpression is that the latter also
allows fetching only a specific nested attribute, e.g., a.b[3].c.
We do not support this feature yet, although it would not be
hard to add it: With our current data representation, it means
fetching the top-level attribute 'a', whose value is a JSON, and then
post-filtering it to take out only the '.b[3].c'. We'll do that
later.
This patch also adds more test cases to test_projection_expression.py.
All tests except three which check the nested attributes now pass,
and those three xfail (they succeed on DynamoDB, and fail as expected
on Alternator), reminding us what still needs to be done.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Our GetItem, Query and Scan implementations support the AttributesToGet
parameter to fetch only a subset of the attributes, but we don't yet
support the more elaborate ProjectionExpression parameter, which is
similar but has a different syntax and also allows to specify nested
document paths.
This patch adds existive testing of all the ProjectionExpression features.
All these tests pass against DynamoDB, but fail against the current
Alternator so they are marked "xfail". These tests will be helpful for
developing the ProjectionExpression feature.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
The AttributesToGet parameter - saying which attributes to fetch for each
item - is already supported in the GetItem, Query and Scan operations.
However, we only had a test for it for it for Scan. This patch adds
similar tests also for the GetItem and Query operations.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Yet another test for overwriting a top-level attribute which contains
a nested document - here, overwriting it by just a string.
This test passes. In the current implementation we don't yet support
updates to specific attribute paths (e.g. a.b[3].c) but we do support
well writing and over-writing top-level attributes.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
This patch implements the last (finally!) syntactic feature of the
UpdateExpression - the ability to do SET a=val1+val2 (where, as
before, each of the values can be a reference to a value, an
attribute path, or a function call).
The implementation is not perfect: It adds the values as double-precision
numbers, which can lose precision. So the patch adds a new test which
checks that the precision isn't lost - a test that currently fails
(xfail) on Alternator, but passes on DynamoDB. The pre-existing test
for adding small integer now passes on Alternator.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
In the previous patch we added function-call support in the UpdateExpression
parser. In this patch we add support for one such function - list_append().
This function takes two values, confirms they are lists, and concatenates
them. After this patch only one function remains unimplemented:
if_not_exists().
We also split the test we already had for list_append() into two tests:
One uses only value references (":val") and passes after this patch.
The second test also uses references to other attributes and will only
work after we start supporting read-modify-write.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Until this patch, in update expressions like "SET a = :val", we only
allowed the right-hand-side of the assignment to be a reference to a
value stored in the request - like ":val" in the above example.
But DynamoDB also allows the value to be an attribute path (e.g.,
"a.b[3].c", and can also be a function of a bunch of other values.
This patch adds supports for parsing all these value types.
This patch only adds the correct parsing of these additional types of
values, but they are still not supported: reading existing attributes
(i.e., read-modify-write operations) is still not supported, and
none of the two functions which UpdateExpression needs to support
are supported yet. Nevertheless, the parsing is now correct, and the
the "unknown_function" test starts to pass.
Note that DynamoDB allows the right-hand side of an assignment to be
not only a single value, but also value+value and value-value. This
possibility is not yet supported by the parser and will be added
later.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
The test cases verify that equality-based filtering on non-key
attributes works fine. It also contains test stubs for key filtering
and non-equality attribute filtering.
Filled test table used to have identical non-key attributes for all
rows. These values are now diversified in order to allow writing
filtering test cases.
Filtering is currently only implemented for the equality operator
on non-key attributes.
Next steps (TODO) involve:
1. Implementing filtering for key restrictions
2. Implementing non-key attribute filtering for operators other than EQ.
It, in turn, may involve introducing 'map value restrictions' notion
to Scylla, since now it only allows equality restrictions on map
values (alternator attributes are currently kept in a CQL map).
3. Implementing FilterExpression in addition to deprecated QueryFilter
Before this patch, we read either an attribute name like "name" or
a reference to one "#name", as one type of token - NAME.
However, while attribute paths indeed can use either one, in some other
contexts - such as a function name - only "name" is allowed, so we
need to distinguish between two types of tokens: NAME and NAMEREF.
While separating those, I noticed that we incorrectly allowed a "#"
followed by *zero* alphanumeric characters to be considered a NAMEREF,
which it shouldn't. In other words, NAMEREF should have ALNUM+, not ALNUM*.
Same for VALREF, which can't be just a ":" with nothing after it.
So this patch fixes these mistakes, and adds tests for them.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
DynamoDB complains, and fails an update, if the update contains in
ExpressionAttributeNames or ExpressionAttributeValues names which aren't
used by the expression.
Let's do the same, although sadly this means more work to track which
of the references we've seen and which we haven't.
This patch makes two previously xfail (expected fail) tests become
successful tests on Alternator (they always succeeded against DynamoDB).
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
The existing tests in test_update_expression.py thoroughly tested the
UpdateExpression features which we currently support. But tests for
features which Alternator *doesn't* yet support were partial.
In this patch, we add a large number of new tests to
test_update_expression.py aiming to cover ALL the features of
UpdateExpression, regardless of whether we already support it in
Alternator or not. Every single feature and esoteric edge-case I could
discover is covered in these tests - and as far as I know these tests
now cover the *entire* UpdateExpression feature. All the tests succeed
on DynamoDB, and confirm our understanding of what DynamoDB actually does
on all these cases.
After this patch, test_update_expression.py is a whopper, with 752 lines of
code and 37 separate test functions. 23 out of these 37 tests are still
"xfail" - they succeed on DynamoDB but fail on Alternator, because of
several features we are still missing. Those missing features include
direct updates of nested attributes, read-modify-write updates (e.g.,
"SET a=b" or "SET a=a+1"), functions (e.g., "SET a = list_append(a, :val)"),
the ADD and DELETE operations on sets, and various other small missing
pieces.
The benefit of this whopper test is two-fold: First, it will allow us
to test our implementation as we continue to fill it (i.e., "test-
driven development"). Second, all these tested edge cases basically
"reverse engineer" how DynamoDB's expression parser is supposed to work,
and we will need this knowledge to implement the still-missing features of
UpdateExpression.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
This patch adds an extensive array of tests for UpdateItem's UpdateExpression
support, which was introduced in the previous patch.
The tests include verification of various edge cases of the parser, support
for ":value" and "#name" references, functioning SET and REMOVE operations,
combinations of multiple such operations, and much more.
As usual, all these tests were ran and succeed on DynamoDB, as well as on
Alternator - to confirm Alternator behaves the same as DynamoDB.
There are two tests marked "xfail" (expected to fail), because Alternator
still doesn't support the attribute copy syntax (e.g., "SET a = b",
doing a read-before-write).
There are some additional areas which we don't support - such as the DELETE
and ADD operations or SET with functions - but those areas aren't yet test
in these tests.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
For the UpdateItem operation, so far we supported updates via the
AttributeUpdates parameter, specifying which attributes to set or remove
and how. But this parameter is considered deprecated, and DynamoDB supports
a more elaborate way to modify attributes, via an "UpdateExpression".
In the previous patch we added a function to parse such an UpdateExpression,
and in this patch we use the result of this parsing to actually perform
the required updates.
UpdateExpression is only partially supported after this patch. The basic
"SET" and "REMOVE" operations are supported, but various other cases aren't
fully supported and will be fixed in followup patches. The following
patch will add extensive tests to confirm exactly what works correctly
with the new UpdateExpression support.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
The DynamoDB protocol is based on JSON, and most DynamoDB requests describe
the operation and its parameters via JSON objects such as maps and lists.
However, in some types of requests an "expression" is passed as a single
string, and we need to parse this string. These cases include:
1. Attribute paths, such as "a[3].b.c", are used in projection
expressions as well as inside other expressions described below.
2. Condition expressions, such as "(NOT (a=b OR c=d)) AND e=f",
used in conditional updates, filters, and other places.
3. Update expressions, such as "SET #a.b = :x, c = :y DELETE d"
This patch introduces the framework to parse these expressions, and
an implementation of parsing update expressions. These update expressions
will be used in the UpdateItem operation in the next patch.
All these expression syntaxes are very simple: Most of them could be
parsed as regular expressions, or at most a simple hand-written lexical
analyzer and recursive-descent parser. Nevertheless, we decided to specify
these parsers in the same ANTLR3 language already used in the Scylla
project for parsing CQL, hopefully making these parsers easier to reason
about, and easier to change if needed - and reducing the amount of boiler-
plate code.
The parsing of update expressions is most complete except that in SET
actions, only the "path = value" form is supported and not yet forms
forms such as "path1 = path2" (which does read-before-write) or
"path1 = path1 + value" or "path = function(...)".
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
We need to write more tests for various case of handling
nested documents and nested attributes. Let's collect them
all in the same test file.
This patch mostly moves existing code, but also adds one
small test, test_nested_document_attribute_write, which
just writes a nested document and reads it back (it's
mostly covered by the existing test_put_and_get_attribute_types,
but is specifically about a nested document).
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
We usually run Alternator tests against the local Alternator - testing
against AWS DynamoDB is rarer, and usually just done when writing the
test. So let's make "pytest" without parameters default to testing locally.
To test against AWS, use "pytest --aws" explicitly.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
