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>
Attributes for reads (GetItem, Query, Scan, ...) and writes (PutItem,
UpdateItem, ...) are now serialized and deserialized in binary form
instead of raw JSON, provided that their type is S, B, BOOL or N.
Optimized serialization for the rest of the types will be introduced
as follow-ups.
Message-Id: <6aa9979d5db22ac42be0a835f8ed2931dae208c1.1559646761.git.sarna@scylladb.com>
Attributes used to be written into the database in raw JSON format,
which is far from optimal. This patch introduces more robust
serializationi routines for simple alternator types: S, B, BOOL, N.
Serialization uses the first byte to encode attribute type
and follows with serializing data in binary form.
More complex types (sets, lists, etc.) are currently still
serialized in raw JSON and will be optimized in follow-up patches.
Message-Id: <10955606455bbe9165affb8ac8fba4d9e7c3705f.1559646761.git.sarna@scylladb.com>
For some unknown reason we put the list of alternator source files
in configure.py inside the "api" list. Let's move it into a separate
list.
We could have just put it in the scylla_core list, but that would cause
frequent and annoying patch conflicts when people add alternator source
files and Scylla core source files concurrently.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
So far for UpdateItem we only supported the old-style AttributeUpdates
parameter, not the newer UpdateExpression. This patch begins the path
to supporting UpdateExpression. First, trying to use *both* parameters
should result in an error, and this patch does this (and tests this).
Second, passing neither parameters is allowed, and should result in
an *empty* item being created.
Finally, since today we do not yet support UpdateExpression, this patch
will cause UpdateItem to fail if UpdateExpression is used, instead of
silently being ignored as we did so far.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
This patch adds two simple tests for nested documents, which pass:
test_nested_document_attribute_overwrite() tests what happens when
we UpdateItem a top-level attribute to a dictionary. We already tested
this works on an empty item in a previous test, but now we check what
happens when the attribute already existed, and already was a dictionary,
and now we update it to a new dictionary. In the test attribute a was
{b:3, c:4} and now we update it to {c:5}. The test verifies that the new
dictionary completely replaces the old one - the two are not merged.
The new value of the attribute is just {c:5}, *not* {b:3, c:5}.
The second test verifies that the AttributeUpdates parameter of
UpdateItem cannot be used to update a just a nested attributes.
Any dots in the attribute name are considered an actual dot - not
part of a path of attribute names.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Comparing two lists of items without regard for order is not trivial.
For this reason some tests in test_query.py only compare arrays of sort
keys, and those tests are fine.
But other tests used a trick of converting a list of items into a
of set_of_frozen_elements() and compare this sets. This trick is almost
correct, but it can miss cases where items repeat.
So in this patch, we replace the set_of_frozen_elements() approach by
a similar one using a multiset (set with repetitions) instead of a set.
A multiset in Python is "collections.Counter". This is the same approach
we started to also used in test_scan.py in a recent patch.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Remove the incomplete and unused function to convert DynamoDB type names
to ScyllaDB type objects:
DynamoDB has a different set of types relevant for keys and for attributes.
We already have a separate function, parse_key_type(), for parsing key
types, and for attributes - we don't currently parse the type names at
all (we just save them as JSON strings), so the function we removed here
wasn't used, and was in fact #if'ed out. It was never completed, and it now
started to decay (the type for numbers is wrong), so we're better off
completely removing it.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
This patch implements a fully working number type for keys, and now
Alternator fully and correctly supports every key type - strings, byte
arrays, and numbers.
The patch also adds a test which verifies that Scylla correctly sorts
number sort keys, and also correctly retrieves them to the full precision
guaranteed by DynamoDB (38 decimal digits).
The implementation uses Scylla's "decimal" type, which supports arbitrary
precision decimal floating point, and in particular supports the precision
specified by DynamoDB. However, "decimal" is actually over-qualified for
this use, so might not be optimal for the more specific requirements of
DynamoDB. So a FIXME is left to optimize this case in the future.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Comparing two lists of items without regard for order is not trivial.
test_scan.py currently has two ways of doing this, both unsatisfactory:
1. We convert each list to a set via set_of_frozen_elements(), and compare
the sets. But this comparison can miss cases where items repeat.
2. We use sorted() on the list. This doesn't work on Python 3 because
it removed the ability to compare (with "<") dictionaries.
So in this patch, we replace both by a new approach, similar to the first
one except we use a multiset (set with repetitions) instead of a set.
A multiset in Python is "collections.Counter".
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Creating and deleting tables is the slowest part of our tests,
so we should lower the number of tables our tests create.
We had a "test_2_tables" fixture as a way to create two
tables, but since our tests already create other tables
for testing different key types, it's faster to reuse those
tables - instead of creating two more unused tables.
On my system, a "pytest --local", running all 38 tests
locally, drops from 25 seconds to 20 seconds.
As a bonus, we also have one fewer fixture ;-)
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
to 1024 bytes, and the entire item to 400 KB which therefore also
limits the size of one attribute. This test checks that we can
reach up to these limits, with binary keys and attributes.
The test does *not* check what happens once we exceed these
limits. In such a case, DynamoDB throws an error (I checked that
manually) but Alternator currently simply succeeds. If in the
future we decide to add artificial limits to Alternator as well,
we should add such tests as well.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
"len" is an unfortunate choice for a variable name, in case one
day the implementation may want to call the built-in "len" function.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
We already have a test for *string* sort-key ordering of items returned
by the Scan operation, and this test adds a similar test for the Query
operation. We verify that items are retrieved in the desired sorted
order (sorted by the aptly-named sort key) and not in creation order
or any other wrong order.
But beyond just checking that Query works as expected (it should,
given it uses the same machinary as Scan), the nice thing about this
test is that it doesn't create a new table - it uses a shared table
and creates one random partition inside it. This makes this test
faster and easier to write (no need for a new fixture), and most
importantly - easily allows us to write similar tests for other
key types.
So this patch also tests the correct ordering of *binary* sort keys.
It helped exposed bugs in previous versions of the binary key implementation.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Simple tests for item operations (PutItem, GetItem) with binary key instead
of string for the hash and sort keys. We need to be able to store such
keys, and then retrieve them correctly.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Until now we only supported string for key columns (hash or sort key).
This patch adds support for the bytes type (a.k.a binary or blob) as well.
The last missing type to be supported in keys is the number type.
Note that in JSON, bytes values are represented with base64 encoding,
so we need to decode them before storing the decoded value, and re-encode
when the user retrieves the value. The decoding is important not just
for saving storage space (the encoding is 4/3 the size of the decoded)
but also for correct *sorting* of the binary keys.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
The DynamoDB API uses base64 encoding to encode binary blobs as JSON
strings. So we need functions to do these conversions.
This code was "inspired" by https://github.com/ReneNyffenegger/cpp-base64
but doesn't actually copy code from it.
I didn't write any specific unit tests for this code, but it will be
exercised and tested in a following patch which tests Alternator's use
of these functions.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
BEGINS_WITH behaves in a special way when a key postfix
consists of <255> bytes. The initial test does not use that
and instead checks UTF-8 characters, but once bytes type
is implemented for keys, it should also test specifically for
corner cases, like strings that consist of <255> byte only.
Message-Id: <fe10d7addc1c9d095f7a06f908701bb2990ce6fe.1558603189.git.sarna@scylladb.com>
BEGINS_WITH statement increments a string in order to compute
the upper bound for a clustering range of a query.
Unfortunately, previous implementation was not correct,
as it appended a <0> byte if the last character was <255>,
instead of incrementing a last-but-one character.
If the string contains <255> bytes only, the upper bound
of the returned upper bound is infinite.
Message-Id: <3a569f08f61fca66cc4f5d9e09a7188f6daad578.1558524028.git.sarna@scylladb.com>
We had several places in the code that need to parse the
ConsistentRead flag in the request. Let's add a function
that does this, and while at it, checks for more error
cases and also returns LOCAL_QUORUM and LOCAL_ONE instead
of QUORUM and ONE.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
As Shlomi suggested in the past, it is more likely that when we
eventually support global tables, we will use LOCAL_QUORUM,
not QUORUM. So let's switch to that now.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
So far, all of the tests in test_item.py (for PutItem, GetItem, UpdateItem),
were arbitrarily done on a test table with both hash key and sort key
(both with string type). While this covers most of the code paths, we still
need to verify that the case where there is *not* a sort key, also works
fine. E.g., maybe we have a bug where a missing clustering key is handled
incorrectly or an error is incorrectly reported in that case?
But in this patch we add tests for the hash-key-only case, and see that
it already works correctly. No bug :-)
We add a new fixture test_table_s for creating a test table with just
a single string key. Later we'll probably add more of these test tables
for additional key types.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
