Let's remove expr::token and replace all of its functionality with expr::function_call.
expr::token is a struct whose job is to represent a partition key token.
The idea is that when the user types in `token(p1, p2) < 1234`,
this will be internally represented as an expression which uses
expr::token to represent the `token(p1, p2)` part.
The situation with expr::token is a bit complicated.
On one hand side it's supposed to represent the partition token,
but sometimes it's also assumed that it can represent a generic
call to the token() function, for example `token(1, 2, 3)` could
be a function_call, but it could also be expr::token.
The query planning code assumes that each occurence of expr::token
represents the partition token without checking the arguments.
Because of this allowing `token(1, 2, 3)` to be represented
as expr::token is dangerous - the query planning
might think that it is `token(p1, p2, p3)` and plan the query
based on this, which would be wrong.
Currently expr::token is created only in one specific case.
When the parser detects that the user typed in a restriction
which has a call to `token` on the LHS it generates expr::token.
In all other cases it generates an `expr::function_call`.
Even when the `function_call` represents a valid partition token,
it stays a `function_call`. During preparation there is no check
to see if a `function_call` to `token` could be turned into `expr::token`.
This is a bit inconsistent - sometimes `token(p1, p2, p3)` is represented
as `expr::token` and the query planner handles that, but sometimes it might
be represented as `function_call`, which the query planner doesn't handle.
There is also a problem because there's a lot of duplication
between a `function_call` and `expr::token`. All of the evaluation
and preparation is the same for `expr::token` as it's for a `function_call`
to the token function. Currently it's impossible to evaluate `expr::token`
and preparation has some flaws, but implementing it would basically
consist of copy-pasting the corresponding code from token `function_call`.
One more aspect is multi-table queries. With `expr::token` we turn
a call to the `token()` function into a struct that is schema-specific.
What happens when a single expression is used to make queries to multiple
tables? The schema is different, so something that is representad
as `expr::token` for one schema would be represented as `function_call`
in the context of a different schema.
Translating expressions to different tables would require careful
manipulation to convert `expr::token` to `function_call` and vice versa.
This could cause trouble for index queries.
Overall I think it would be best to remove expr::token.
Although having a clear marker for the partition token
is sometimes nice for query planning, in my opinion
the pros are outweighted by the cons.
I'm a big fan of having a single way to represent things,
having two separate representations of the same thing
without clear boundaries between them causes trouble.
Instead of having expr::token and function_call we can
just have the function_call and check if it represents
a partition token when needed.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
get_lhs_receiver looks at the prepared LHS of a binary operator
and creates a receiver corresponding to this LHS expression.
This receiver is later used to prepare the RHS of the binary operator.
It's able to handle a few expression types - the ones that are currently
allowed to be on the LHS.
One of those types is `expr::token`, to handle restrictions like `token(p1, p2) = 3`.
Soon token will be replaced by `expr::function_call`, so the function will need
to handle `function_calls` to the token function.
Although we expect there to be only calls to the `token()` function,
as other functions are not allowed on the LHS, it can be made generic
over all function calls, which will help in future grammar extensions.
The functions call that it can currently get are calls to the token function,
but they're not validated yet, so it could also be something like `token(pk, pk, ck)`.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Printing for function_call is a bit strange.
When printing an unprepared function it prints
the name and then the arguments.
For prepared function it prints <anonymous function>
as the name and then the arguments.
Prepared functions have a name() method, but printing
doesn't use it, maybe not all functions have a valid name(?).
The token() function will soon be represent as a function_call
and it should be printable in a user-readable way.
Let's add an if which prints `token(arg1, arg2)`
instead of `<anonymous function>(arg1, arg2)` when printing
a call to the token function.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
The possible_lhs_values takes an expression and a column
and finds all possible values for the column that make
the expression true.
Apart from finding column values it's also capable of finding
all matching values for the partition key token.
When a nullptr column is passed, possible_lhs_values switches
into token values mode and finds all values for the token.
This interface isn't ideal.
It's confusing to pass a nullptr column when one wants to
find values for the token. It would be better to have a flag,
or just have a separate function.
Additionally in the future expr::token will be removed
and we will use expr::is_partition_token_for_schema
to find all occurences of the partition token.
expr::is_partition_token_for_schema takes a schema
as an argument, which possible_lhs_values doesn't have,
so it would have to be extended to get the schema from
somewhere.
To fix these two problems let's split possible_lhs_values
into two functions - one that finds possible values for a column,
which doesn't require a schema, and one that finds possible values
for the partition token and requires a schema:
value_set possible_column_values(const column_definition* col, const expression& e, const query_options& options);
value_set possible_partition_token_values(const expression& e, const query_options& options, const schema& table_schema);
This will make the interface cleaner and enable smooth transition
once expr::token is removed.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
In possible_lhs_values there was a message talking
about is_satisifed_by. It looks like a badly
copy-pasted message.
Change it to possibel_lhs_values as it should be.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Just like has_token, replace_token will use
expr::is_partition_token_for_schema to find all instance
of the partition token to replace.
Let's prepare for this change by adding a schema argument
to the function before making the big change.
It's unsued at the moment, but having a separate commit
should make it easier to review.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
In the future expr::token will be removed and checking
whether there is a partition token inside an expression
will be done using expr::is_partition_token_for_schema.
This function takes a schema as an argument,
so all functions that will call it also need
to get the schema from somewhere.
Right now it's an unused argument, but in the future
it will be used. Adding it in a separate commit
makes it easier to review.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Add a function to check whether the expression
represents a partition token - that is a call
to the token function with consecutive partition
key columns as the arguments.
For example for `token(p1, p2, p3)` this function
would return `true`, but for `token(1, 2, 3)` or `token(p3, p2, p1)`
the result would be `false`.
The function has a schema argument because a schema is required
to get the list of partition columns that should be passed as
arguments to token().
Maybe it would be possible to infer the schema from the information
given earlier during prepare_expression, but it would be complicated
and a bit dangerous to do this. Sometimes we operate on multiple tables
and the schema is needed to differentiate between them - a token() call
can represent the base table's partition token, but for an index table
this is just a normal function call, not the partition token.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Add a function that can be used to check
whether a given expression represents a call
to the token() function.
Note that a call to token() doesn't mean
that the expression represents a partition
token - it could be something like token(1, 2, 3),
just a normal function_call.
The code for checking has been taken from functions::get.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Currently trying to do prepare_expression(function_call)
with a nullptr receiver fails.
It should be possible to prepare function calls without
a known receiver.
When the user types in: `token(1, 2, 3)`
the code should be able to figure out that
they are looking for a function with name `token`,
which takes 3 integers as arguments.
In order to support that we need to prepare
all arguments that can be prepared before
attempting to find a function.
Prepared expressions have a known type,
which helps to find the right function
for the given arguments.
Additionally the current code for finding
a function requires all arguments to be
assignment_testable, which requires to prepare
some expression types, e.g column_values.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
try_prepare_expression(constant) used to throw an error
when trying to prepeare expr::constant.
It would be useful to be able to do this
and it's not hard to implement.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Make it possible to do test_assignment for column_values.
It's implemented using the generic expression assignment
testing function.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
test_assignment checks whether a value of some type
can be assigned to a value of different type.
There is no implementation of test_assignment
for expr::constant, but I would like to have one.
Currently there is a custom implementation
of test_assignment for each type of expression,
but generally each of them boils down to checking:
```
type1->is_value_compatible_with(type2)
```
Instead of implementing another type-specific funtion
I added expresion_test_assignment and used it to
implement test_assignment for constant.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
in C++20, compiler generate operator!=() if the corresponding
operator==() is already defined, the language now understands
that the comparison is symmetric in the new standard.
fortunately, our operator!=() is always equivalent to
`! operator==()`, this matches the behavior of the default
generated operator!=(). so, in this change, all `operator!=`
are removed.
in addition to the defaulted operator!=, C++20 also brings to us
the defaulted operator==() -- it is able to generated the
operator==() if the member-wise lexicographical comparison.
under some circumstances, this is exactly what we need. so,
in this change, if the operator==() is also implemented as
a lexicographical comparison of all memeber variables of the
class/struct in question, it is implemented using the default
generated one by removing its body and mark the function as
`default`. moreover, if the class happen to have other comparison
operators which are implemented using lexicographical comparison,
the default generated `operator<=>` is used in place of
the defaulted `operator==`.
sometimes, we fail to mark the operator== with the `const`
specifier, in this change, to fulfil the need of C++ standard,
and to be more correct, the `const` specifier is added.
also, to generate the defaulted operator==, the operand should
be `const class_name&`, but it is not always the case, in the
class of `version`, we use `version` as the parameter type, to
fulfill the need of the C++ standard, the parameter type is
changed to `const version&` instead. this does not change
the semantic of the comparison operator. and is a more idiomatic
way to pass non-trivial struct as function parameters.
please note, because in C++20, both operator= and operator<=> are
symmetric, some of the operators in `multiprecision` are removed.
they are the symmetric form of the another variant. if they were
not removed, compiler would, for instance, find ambiguous
overloaded operator '=='.
this change is a cleanup to modernize the code base with C++20
features.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closes#13687
column_specification::name is a shared pointer, so it should be
dereferenced before printing - because we want to print the name, not
the pointer.
Fix a few instances of this mistake in prepare_expr.cc. Other instances
were already correct.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Spans are more flexible and can be constructed from any contiguous
container (such as small_vector), or a subrange of such a container.
This can save allocations, so change the signature to accept a span.
Spans cannot be constructed from std::initializer_list, so one such
call site is changed to use construct a span directly from the single
argument.
before this change, we just print out the addresses of the elements
in `column_defs`, if the arguments passed to `token()` function are
not valid. this is not quite helpful from the user's perspective. as
user would be more interested in the values. also, we could print
more accurate error message for different error.
in this change, following Cassandra 4.1's behavior, three cases are
identified, and corresponding errors are returned respectively:
* duplicated partition keys
* wrong order of partition key
* missing keys
where, if the partition key order is wrong, instead of printing the
keys specified by user, the correct order is printed in the error
message for helping user to correct the `token()` function.
for better performance, the checks are performed only if the keys
do not match, based on the assumption that the error handling path
is not likely to be executed.
tests are added accordingly. they tested with Canssandra 4.1.1 also.
Fixes#13468
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closes#13470
serialize_listlike() is called with a range of either managed_bytes
or managed_bytes_opt. If the former, then iterating and assigning
to a loop induction variable of type managed_byted_opt& will bind
the reference to a temporary managed_bytes_opt, which gcc dislikes.
Fix by performing the binding in a separate statement, which allows
for lifetime extension.
CQL supports type casting using C-style casts.
For example it's possible to do: `blob_column = (blob)funcReturningInt()`
This functionality is pretty limited, we only allow such casts between types that have a compatible binary representation. Compatible means that the bytes will stay unchanged after the conversion.
This means that it's legal to cast an int to blob (int is just a 4 byte blob), but it's illegal to cast a bigint to int (change 4 bytes -> 8 bytes).
This simplifies things, to cast we can just reinterpret the value as the other type.
Another use of C-style casts are type hints. Sometimes it's impossible to infer the exact type of an expression from the context. In such cases the type can be specified by casting the expression to this type.
For example: `overloadedFunction((int)?)`
Without the cast it would be impossible to guess what should be the bind marker's type. The function is overloaded, so there are many possible argument types. The type hint specifies that the bind marker has type int.
An interesting thing is that such casts don't have to be explicit. CQL allows to put an int value in a place where a blob value is expected and it will be automatically converted without any explicit casting.
---
I started looking at our implementation of casts because of #12900. In there the author expressed the need to specify a type hint for bind marker used to pass the WASM code. It could be either `(text)?` for text WASM, or `(blob)?` for binary WASM. This specific use of type hints wasn't supported because there was no `receiver` and the implementation of `prepare_expression` didn't handle that. Preparing casts without a receiver should be easy to implement - we can infer the type of the expression by looking at the type to which the expression is cast.
But while reading `prepare_expression` for `expr::cast` I noticed that the code there is a bit strange. The implementation prepared the expression to cast using the original `receiver` instead of a receiver with the cast type. This caused some issues because of which casting didn't work as expected.
For example it was possible to do:
```cql
blob_column = (blob)funcReturningInt()
```
But this didn't work at all:
```cql
blob_column = (blob)(int)12323
```
It tried to prepare `untyped_contant(12323)` with a `blob` receiver, which fails.
This makes `expr::cast` useless for casting. Casting when the representation is compatible is already implicit. I couldn't find a single case where adding a cast would change the behavior in any way.
There was some use for it as a type hint to choose a specific overload of a function, but it was worthless for casting.
Cassandra has the same issue, I created a `cql-pytest` test and it showed that we behave in the same way as Cassandra does.
I decided to improve this. By preparing the expression using a receiver with the cast type, `expr::cast` becomes actually useful for casting values. Things like `(blob)(int)12323` now work without any issues.
This diverges from the behavior in Cassandra, but it's an extension, not a breaking incompatibility.
---
This PR improves `prepare_expression` for `expr::cast` in the following ways:
1) Support for more complex casts by preparing the expression using a different receiver. This makes casts like `(blob)(int)123` possible
2) Support preparing `expr::cast` without a receiver. Type inference chooses the cast type as the type of the expression.
3) Add pytest tests for C-style casts
`2)` Is needed for #12900, the other changes is just something I decided to do since I was already working on this piece of code.
Closes#13053
* github.com:scylladb/scylladb:
expr_test: more tests for preparing bind variables with type hints
prepare_expr: implement preparing expr::cast with no receiver
prepare_expr: use :user formatting in cast_prepare_expression
prepare_expr: remove std::get<> in cast_prepare_expression
prepare_expr: improve cast_prepare_expression
prepare_expr: improve readability in cast_prepare_expression
cql-pytest: test expr::cast in test_cast.py
Type inference in cast_prepare_expression was very limited.
Without a receiver it just gave up and said that it can't
infer the type.
It's possible to infer the type - an expression that
casts something to type bigint also has type bigint.
This can be implemented by creating a fake receiver
when the caller didn't specify one.
Type of this fake receiver will be c.type
and c.arg will be prepared using this receiver.
Note that the previous change (changing receiver
to cast_type_receiver in prepare_expression) is required
to keep the behaviour consistent.
Without it we would sometimes prepare c.arg using the
original receiver, and sometimes using a receiver
with type c.type.
Currently it's impossible to test this change
on live code. Every place that uses expr::cast
specifies a receiver.
A unit test is all that can be done at the moment
to ensure correctness.
In the future this functionality will be used in UDFs.
In https://github.com/scylladb/scylladb/pull/12900
it was requested to be able to use a type hint
to specify whether WASM code of the function
will be sent in binary or text form.
The user can convey this by typing
either `(blob)?` or `(text)?`.
In this case there will be no receiver
and type inference would fail.
After this change it will work - it's now possible
to prepare either of those and get an expression
with a known type.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
By default expressions are printed using the {:debug} formatting,
wich is intended for internal use. Error messages should use the
{:user} formatting instead.
cast_prepare_expression uses the default formatting in a few places
that are user facing, so let's change it to use {:user} formatting.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
A few times throughout cast_prepare_expression there's
a line which uses std::get<> to get the raw type of the cast.
`std::get<shared_ptr<cql3_type::raw>>(c.type)`
This is a dangerous thing to do. It might turn out that the variant
holds a different alternative and then it'll start throwing bad_variant_access.
In this case this would happen if someone called cast_prepare_expression
on an expression that is already prepared.
It's possible to modify the code in a way that avoids doing the std::get
altogether.
It makes the code more resilient and gives me a piece of mind.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Preparing expr::cast had some artificial limitations.
Things like this worked:
`blob_col = (blob)funcReturnsInt()`
But this didn't:
`blob_col = (blob)(int)1234`
This is caused by the line:
`prepare_expression(c.arg, db, keyspace, schema_opt, receiver)`
Here the code prepares the expression to be cast using the original
receiver which was passed to cast_prepare_expression.
In the example above this meant that it tried to prepare
untyped_constant(1234) using a receiver with type blob.
This failed because an integer literal is invalid for a blob column.
To me it looks like a mistake. What it should do instead
is prepare the int literal using the type (int) and then
see if int can be cast to blob, by checking if these types
have compatible binary representation.
This can be achieved by using `cast_type_receiver` instead of `receiver`.
Making this small change makes it possible to use the cast
in many situations where it was previously impossible.
The tests have to be updated to reflect the change,
some of them ow deviate from Cassandra, so they have
to be marked scylla_only.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
cast_prepare_expression takes care of preparing expr::cast,
which is responsible for CQL C-style casts.
At the first glance it can be hard to figure out what exactly
does it do, so I added some comments to make things clearer.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
There was a bug in `expr::search_and_replace`.
It doesn't preserve the `order` field of binary_operator.
`order` field is used to mark relations created
using the SCYLLA_CLUSTERING_BOUND.
It is a CQL feature used for internal queries inside Scylla.
It means that we should handle the restriction as a raw
clustering bound, not as an expression in the CQL language.
Losing the SCYLLA_CLUSTERING_BOUND marker could cause issues,
the database could end up selecting the wrong clustering ranges.
Fixes: #13055
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Closes#13056
these warnings are found by Clang-17 after removing
`-Wno-unused-lambda-capture` and '-Wno-unused-variable' from
the list of disabled warnings in `configure.py`.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Currently, evaluation of a subscript expression x[y] requires that
x be a column_value, but that's completely artificial. Generalize
it to allow any expression.
This is needed after we transform a LWT IF condition from
"a[x] = y" to "func(a)[x] = y", where func casts a from a
map represention of a list back to a list; but it's also generally
useful.
LWT and some list operations represent lists using a form like
their mutations, so that the mutation list keys can be recovered
and used to update the list. But the evaluation machinery knows
nothing about that, and will return the map-form even though the type
system thinks it is a list.
To handle that, add a utility to rewrite the expression so
that the value is re-serialized into the expected list form. The
rewrite is implemented as a scalar function taking the map form and
returning the list form.
Partial clustering keys can exist in COMPACT STORAGE tables (though they
are exceedingly rare), and when LWT materializes a static row. Harden
extract_column_value() so it is ready for them.
Expression evaluation works with the evaluation_input structure to
compute values. As we move LWT column_condition towards expressions,
we'll start using evaluation_input, so provide this helper to ease
the transition.
Both LWT IF clause and SELECT WHERE clause check that a duration type
isn't used in an ordered comparison, since duration types are unordered
(is 1mo more or less than 30d?). As a first step towards centralizing this
check, move the check from restrictions into prepare. When LWT starts using
prepare, the duplication will be removed.
The error message was changed: the word "slice" is an internal term, and
a comparison does not necessarily have to be in a restriction (which is
also an internal term).
Tests were adjusted.
Compiling a pattern is expensive and so we should try to do it
at prepare time, if the pattern is a constant. Add an optimizer
that looks for such cases and replaces them with a unary function
that embeds the compiled pattern.
This isn't integrated yet with prepare_expr(), since the filtering
code isn't ready for generic expressions. Its first user will be LWT,
which contains the optimization already (filtering had it as well,
but lost it sometime during the expression rewrite).
A unit test is added.
Function call evaluation rejects NULL inputs, unnecssarily. Functions
work well with NULL inputs. Fix by relaxing the check.
This currently has no impact because functions are not evaluated via
expressions, but via selectors.
LWT IF clause interprets equality differently from SQL (and the
rest of CQL): it thinks NULL equals NULL. Currently, it implements
binary operators all by itself so the fact that oper_t::EQ (and
friends) means something else in the rest of the code doesn't
bother it. However, we can't unify the code (in
column_condition.cc) with the rest of expression evaluation if
the meaning changes in different places.
To prepare for this, introduce a null_handling_style field to
binary_operator that defaults to `sql` but can be changed to
`lwt_nulls` to indicate this special semantic.
A few unit tests are added. LWT itself still isn't modified.
Currently, evaluate_binop_sides() returns std::nullopt if either
side is NULL.
Since we wish to to add binary operators that do consider NULL on
each side, make evaluate_binop_sides return the original NULLs
instead (as managed_bytes_opt).
Utimately I think evaluate_binop_sides() should disappear, but before
that we have to improve unset value checking.
We have a cql3::expr::expression::printer wrapper that annotates
an expression with a debug_mode boolean prior to formatting. The
fmt library, however, provides a much simpler alterantive: a custom
format specifier. With this, we can write format("{:user}", expr) for
user-oriented prints, or format("{:debug}", expr) for debug-oriented
prints (if nothing is specified, the default remains debug).
This is done by implementing fmt::formatter::parse() for the
expression type, can using expression::printer internally.
Since sometimes we pass expression element types rather than
the expression variant, we also provide a custom formatter for all
ExpressionElement Types.
Uses for expression::printer are updated to use the nicer syntax. In
one place we eliminate a temporary that is no longer needed since
ExpressionElement:s can be formatted directly.
Closes#12702
`evaluation_inputs` is a struct which contains data needed to evaluate expressions - values of columns, bind variables and other data.
`is_on_of()` is a function used to to evaluate `IN` restrictions. It checks whether the LHS is one of elements on the RHS list.
Generally when evaluating expressions we get the `evaluation_inputs` as an argument and we should pass them along to any functions that evaluate subexpressions.
`is_one_of()` got the inputs as an argument, but didn't pass them along to `equal()`, instead it creates new empty `evaluation_inputs{}` and gives that to `equal()`.
At first [I thought this was a bug](https://github.com/scylladb/scylladb/pull/12356#discussion_r1084300969) - with missing information there could be a crash if `equal()` tried to evaluate an expression with a `bind_variable`.
It turns out that in this particular case `equal()` won't use the `evaluation_inputs` at all. The LHS and RHS passed to it are just constant values, which were already evaluated to serialized bytes before calling `evaluate()`, so there is no bug.
It's still better to pass the inputs argument along if possible. If in the future `equal()` required these inputs for some reason, missing inputs could lead to an unexpected crash.
I couldn't find any tests that would detect this case, so such a bug could stay undetected until an unhappy user finds it because their cluster crashed.
I added some tests to make sure that it's covered from now on.
Closes#12701
* github.com:scylladb/scylladb:
cql-pytest: test filtering using list with bind variable
test/expr_test: test <int_value> IN (123, ?, 456)
cql3: expr: don't pass empty evaluation_inputs in is_one_of
evaluation_inputs is a struct which contains
data needed to evaluate expressions - values
of columns, bind variables and other data.
is_on_of() is a function used to to evaluate
IN restrictions. It checks whether the LHS
is one of elements on the RHS list.
Generally when evaluating expressions we get
the evaluation_inputs{} as an argument and
we should pass them along to any functions
that evaluate subexpressions.
is_one_of() got the inputs as an argument,
but didn't pass them along to equal(),
instead it creates new empty evaluation_inputs{}
and gives that to equal().
At first I thought this was a bug - with missing
information there could be a crash if equal()
tried to evaluate an expression with a bind_variable.
It turns out that in this particular case equal()
won't use the evaluation_inputs{} at all.
The LHS and RHS passed to it are just constant values,
which were already evaluated to serialized bytes
before calling evaluate().
It's still better to pass the inputs argument along
if possible. If in the future equal() required
these inputs for some reason, missing inputs
could lead to an unexpected crash.
I couldn't find any tests that would detect this case,
so such a bug could stay undetected until an unhappy user
finds it because their cluster crashed.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
since format_to() is defined included by both fmt and std namepaces,
without specifying which one to use, we'd fail to build with the
standard library which implements std::format_to(). yes, we are
`using namespace std` somewhere.
this change should address the FTBFS with GCC-13.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
The CQL protocol and specification call for lists with NULLs in
some places. For example, the statement:
```cql
UPDATE tab
SET x = 3
IF y IN (1, 2, NULL)
WHERE pk = 4
```
has a list `(1, 2, NULL)` that contains NULL. Although the syntax is tuple-like, the value is a list;
consider the same statement as a prepared statement:
```cql
UPDATE tab
SET x = :x
IF y IN :y_values
WHERE pk = :pk
```
`:y_values` must have a list type, since the number of elements is unknown.
Currently, this is done with special paths inside LWT that bypass normal
evaluation, but if we want to unify those paths, we must allow NULLs in
lists (except in storage). This series does that.
Closes#12411
* github.com:scylladb/scylladb:
test: materialized view: add test exercising synthetic empty-type columns
cql3: expr: relax evaluate_list() to allow allow NULL elements
types: allow lists with NULL
test: relax NULL check test predicate
cql3, types: validate listlike collections (sets, lists) for storage
types: make empty type deserialize to non-null value
prepare_expression didn't allow to prepare binary_operators.
so it's now implemented.
If prepare_binary_operator is unable to infer
the types it will fail with an exception instead
of returning std::nullopt, but we can live with
that for now.
Preparing binary_operators inside the WHERE
clause is currently more complicated than just
calling prepare_binary_operator. Preparation
of the WHERE clause is done inside statement_restrictions
constructor. It's done by iterating over all binary_operators,
validating them and then preparing. The validation contains
additional checks with custom error messages.
Preparation has to be done after validation,
because otherwise the error messages will change
and some tests will start failing.
Because of that we can't just call prepare_expression
on the WHERE clause yet.
It's still useful to have the ability to prepare
binary_operators using prepare_expression.
In cases where we know that the WHERE clause is valid,
we can just call prepare_expression and be done with it.
Once grammar is fully relaxed the artificial constraints
checked by the validation code will be removed and
it will be possible to prepare the whole WHERE clause
using just prepare_expression.
prepare_expression does a bit more than
prepare_binary_operator. In case where
both sides of the binary_operator are known
it will evaluate the whole binary_operator
to a constant value.
Query analysis code is NOT ready
to encounter constant boolean values inside
the WHERE clause, so for the WHERE we still use
prepare_binary_operator which doesn't
evaluate the binary_operator to a
constant value.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
When preparing a binary operator we first prepare the LHS,
which gives us information about its type and allows
to infer the desired type of RHS.
Then the RHS is prepared with the expectation that it
is compatible with the inferred type.
This is enough for all types of operations apart
from IS NOT NULL.
For IS NOT we should also check that the RHS value
is actually null. It's not enough to check that
RHS is of right type.
Before this change preparing `int_col IS NOT 123`
would end in success, which is wrong.
The missing check doesn't cause any real problems,
it's impossible for the user to produce such input
because the parser will reject it.
Still it's better to have the check because
in the future the grammar might get more relaxed
and the parser could become more generic,
making it possible to write such things.
It would be better to introduce unary_operators,
but that's a bigger change.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
For some reason we passed an empty keyspace name
to prepare_expression when preparing the LHS
of a binary operator.
This doesn't look correct. We have keyspace
name available from the schema_ptr so let's use that.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
prepare_binary_operator takes a schema_ptr,
but it would be useful to take a reference to schema instead.
Every schema_ptr can be easily converted to a reference
so there is no loss of functionality.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Tests are similarly relaxed. A test is added in lwt_test to show
that insertion of a list with NULL is still rejected, though we
allow NULLs in IF conditions.
One test is changed from a list of longs to a list of ints, to
prevent churn in the test helper library.
When we start allowing NULL in lists in some contexts, the exact
location where an error is raised (when it's disallowed) will
change. To prepare for that, relax the exception check to just
ensure the word NULL is there, without caring about the exact
wording.
