In queries like:
```cql
SELECT * FROM t WHERE p = 0 AND c1 = 0 ORDER BY (c1 ASC, c2 ASC)
```
we can skip the requirement to specify ordering for `c1` column.
The `c1` column is restricted by an `EQ` restriction, so it can have
at most one value anyway, there is no need to sort.
This commit makes it possible to write just:
```cql
SELECT * FROM t WHERE p = 0 AND c1 = 0 ORDER BY (c2 ASC)
```
I reorganized the ordering code, I feel that it's now clearer and easier to understand.
It's possible to only introduce a small change to the existing code, but I feel like it becomes a bit too messy.
I tried it out on the [`orderby_disorder_small`](https://github.com/cvybhu/scylla/commits/orderby_disorder_small) branch.
The diff is a bit messy because I moved all ordering functions to one place,
it's better to read [select_statement.cc](https://github.com/cvybhu/scylla/blob/orderby_disorder/cql3/statements/select_statement.cc#L1495-L1658) lines 1495-1658 directly.
In the new code it would also be trivial to allow specifying columns in any order, we would just have to sort them.
For now I commented out the code needed to do that, because the point of this PR was to fix#2247.
Allowing this would require some more work changing the existing tests.
Fixes: #2247Closes#9518
* github.com:scylladb/scylla:
cql-pytest: Enable test for skipping eq restricted columns in order by
cql3: Allow to skip EQ restricted columns in ORDER BY
cql3: Add has_eq_restriction_on_column function
cql3: Reorganize orderings code
Adds a function that checks whether a given expression has eq restrction
on the specified column.
It finds restrictions like
col = ...
or
(col, col2) = ...
IN restrictions don't count, they aren't EQ restrictions
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
... and count_if()' from Avi Kivity
The expression code provides some utilities to examine and manipulate
expressions at prepare time. These are not (or should not be) in the fast
path and so should be optimized for compile time and code footprint
rather than run time.
This series does so by detemplating and deinlining find_in_expression()
and count_if().
Closes#9712
* github.com:scylladb/scylla:
cql3: expr: adjust indentation in recurse_until()
cql3: expr: detemplate count_if()
cql3: expr: detemplate count_if()
cql3: expr: rewrite count_if() in terms of recurse_until()
cql3: expr: deinline recurse_until()
cql3: expr: detemplate find_in_expression
Scylla doesn't support unset values inside UDT.
The old code used to convert unset to null, which seems incorrect.
There is an extra space in the error message to retain compatability with Cassandra.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
This PR finally removes the `term` class and replaces it with `expression`.
* There was some trouble with `lwt_cache_id` in `expr::function_call`.
The current code works the following way:
* for each `function_call` inside a `term` that describes a pk restriction, `prepare_context::add_pk_function_call` is called.
* `add_pk_function_call` takes a `::shared_ptr<cql3::functions::function_call>`, sets its `cache_id` and pushes this shared pointer onto a vector of all collected function calls
* Later when some condiition is met we want to clear cache ids of all those collected function calls. To do this we iterate through shared pointers collected in `prepare_context` and clear cache id for each of them.
This doesn't work with `expr::function_call` because it isn't kept inside a shared pointer.
To solve this I put the `lwt_cache_id` inside a shared pointer and then `prepare_context` collects these shared pointers to cache ids.
I also experimented with doing this without any shared pointers, maybe we could just walk through the expression and clear the cache ids ourselves. But the problem is that expressions are copied all the time, we could clear the cache in one place, but forget about a copy. Doing it using shared pointers more closely matches the original behaviour.
The experiment is on the [term2-pr3-backup-altcache](https://github.com/cvybhu/scylla/tree/term2-pr3-backup-altcache) branch
* `shared_ptr<term>` being `nullptr` could mean:
* It represents a cql value `null`
* That there is no value, like `std::nullopt` (for example in `attributes.hh`)
* That it's a mistake, it shouldn't be possible
A good way to distinguish between optional and mistake is to look for `my_term->bind_and_get()`, we then know that it's not an optional value.
* On the other hand `raw_value` cased to bool means:
* `false` - null or unset
* `true` - some value, maybe empty
I ran a simple benchmark on my laptop to see how performance is affected:
```
build/release/test/perf/perf_simple_query --smp 1 -m 1G --operations-per-shard 1000000 --task-quota-ms 10
```
* On master (a21b1fbb2f) I get:
```
176506.60 tps ( 77.0 allocs/op, 12.0 tasks/op, 45831 insns/op)
median 176506.60 tps ( 77.0 allocs/op, 12.0 tasks/op, 45831 insns/op)
median absolute deviation: 0.00
maximum: 176506.60
minimum: 176506.60
```
* On this branch I get:
```
172225.30 tps ( 75.1 allocs/op, 12.1 tasks/op, 46106 insns/op)
median 172225.30 tps ( 75.1 allocs/op, 12.1 tasks/op, 46106 insns/op)
median absolute deviation: 0.00
maximum: 172225.30
minimum: 172225.30
```
Closes#9481
* github.com:scylladb/scylla:
cql3: Remove remaining mentions of term
cql3: Remove term
cql3: Rename prepare_term to prepare_expression
cql3: Make prepare_term return an expression instead of term
cql3: expr: Add size check to evaluate_set
cql3: expr: Add expr::contains_bind_marker
cql3: expr: Rename find_atom to find_binop
cql3: expr: Add find_in_expression
cql3: Remove term in operations
cql3: Remove term in relations
cql3: Remove term in multi_column_restrictions
cql3: Remove term in term_slice, rename to bounds_slice
cql3: expr: Remove term in expression
cql3: expr: Add evaluate_IN_list(expression, options)
cql3: Remove term in column_condition
cql3: Remove term in select_statement
cql3: Remove term in update_statement
cql3: Use internal cql format in insert_prepared_json_statement cache
types: Add map_type_impl::serialize(range of <bytes, bytes>)
cql3: Remove term in cql3/attributes
cql3: expr: Add constant::view() method
cql3: expr: Implement fill_prepare_context(expression)
cql3: expr: add expr::visit that takes a mutable expression
cql3: expr: Add receiver to expr::bind_variable
In old code sets::delayed_value::bind() contained a check that each serialized value is less than certain size.
I missed this when implementing evaluate(), so it's brought back to ensure identical behaviour.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Add a function that checks whether there is a bind marker somewhere inside an expression.
It's important to note, that even when there are no bind markers, there can be other things that prevent immediate evaluation of an expression.
For example an expression can contain calls to nonpure functions.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Some struct inside the expression variant still contained term.
Replace those terms with expression.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
evaluate_IN_list was only defined for a term,
but now we are removing term so it should be also defined for an expression.
The internal code is the same - this function used to convert the term to expression
and then did all operations on expression.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Adds two functions that take a range over pairs of serialized values
and return a serialized map value.
There are 2 functions - one operating on bytes and one operating on managed_bytes.
The version with managed_bytes is used in expression.cc, used to be a local static function.
The bytes version will be used in type_json.cc in the next commit.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Add a method that returns raw_value_view to expr::constant.
It's added for convenience - without it in many places
we would have to write my_value.value.to_view().
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Adds a new function - expr::fill_prepare_context.
This function has the same functionality as term::fill_prepare_context, which will be removed soon.
fill_prepare_context used to take its argument with a const qualifier, but it turns out that the argume>
It sets the cache ids of function calls corresponding to partition key restrictions.
New function doesn't have const to make this clear and avoid surprises.
Added expr::visit that takes an argument without const qualifier.
There were some problems with cache_ids in function_call.
prepare_context used to collect ::shared_ptr<functions::function_call>
of some function call, and then this allowed it to clear
cache ids of all involved functions on demand.
To replicate this prepare_context now collects
shared pointers to expr::function_call cache ids.
It currently collects both, but functions::function_call will be removed soon.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
bind_variable used to have only the type of bound value.
Now this type is replaced with receiver, which describes information about column corresponding to this value.
A receiver contains type, column name, etc.
Receiver is needed in order to implement fill_prepare_context in the next commit.
It's an argument of prepare_context::add_variable_specification.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
sprint() is obsolete. Note some calls where to helper functions that
use sprint(), not to sprint() directly, so both the helpers and
the callers were modified.
A switch statement where every case returns triggers a gcc
warning if the surrounding function doesn't return/abort.
Fix by adding an abort(). The abort() will never trigger since we
have a warning on unhandled switch cases.
A map's value_type has const key, but in two places we omitted
the const. This causes construction of a new value, plus gcc
complaining that we're refering to a temporary.
Fix by using the correct type.
Now that expression can be nested in its component types
directly, we can remove nested_expression. Most of the patch
adjusts uses to drop the dereference that was needed for
nested_expression.
Make expression a class, holding a unique_ptr to a variant,
instead of just a variant.
This has some advantages:
- the constructor can be properly constrained
- the type can be forward-declared
- the type name is just "expression", rather than
a huge variant. This makes compiler error messages easier
to read.
- the internal indirection allows removal of nested_expression
(later in the series)
Simple wrappers for std::get, std::get_if, std::holds_alternative.
The new names are shorter and IMO more readable.
Call sites are updated.
We will later replace the implementation.
The new expr::visit() is just a wrapper around std::visit(),
but has better constraints. A call to expr::visit() with a
visitor that misses an overload will produce an error message
that points at the missing type. This is done using the new
invocable_on_expression concept. Note it lists the expression
types one by one rather than using template magic, since
otherwise we won't get the nice messages.
Later, we will change the implementation when expression becomes
our own type rather than std::variant.
Call sites are updated.
evaluate_IN_list used term::bind(), but now it's possible
to make it use term::to_expression() and then evaluate(expression)
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Finally we don't need term::bind() to evaluate a term.
We can just convert the term to expression and call evaluate(expression).
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
function_call can be evaluated now.
The code matches the one from functions::function_call::bind.
I needed to add cache id to function_call in order for it ot work properly.
See the blurb in struct function_call for more information.
New code corresponds to bind() in cql3/functions/functions.cc.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
usertype_constructor can now be evaluated.
To evaluate an usertype_constructor we need to know the type,
because the fields have to be in the correct order.
Type has been added to usertype_constructor.
New code corresponds to old bind() of user_types::delayed_value in cql3/user_types.cc.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
collection_constructor can now be evaluated.
There is a bit of a problem, because we don't know the type of an empty collection_constructor,
but luckily empty collection constructors get converted to constants during preparation.
For some reason in the original code when a collection contains unset_value,
the whole collection is automatically evaluated to unset_value. I didn't change this behaviour.
New code corresponds to old bind() of lists::delayed_value in cql3/lists.cc, sets::delayed_value etc.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Tuple constructors can now be evaluated.
New code corresponds to old bind() of tuples::delayed_value::marker in cql3/tuples.cc
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Implement evaluating a bind_variable.
To be able to evaluate a bind_variable we need to know the type of the bound value.
This is why a data_type has been added to the bind_variable struct.
There are some quirks when evaluating a bind_variable.
The first problem occurs when the variable has been sent with an older cql serialization format and contains collections.
In that case the value has to be reserialized to use the newest cql serialization format.
The second problem occurs when there is a set or a map in the value.
The set value sent by the driver might not have the elements in the correct order, contain duplicates etc.
When a set or map is detected in the value it is reserialized as well.
collection_type_impl::reserialize doesn't work for this purpose, because it uses data_value which does not perform sorting or removal.
New code corresponds to old bind() of lists::marker in cql3/lists.cc, sets::marker etc.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Add a function that takes an expression and evaluates it to a constant.
Evaluating specific expression variants will be implemented in the following commits.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
It is useful to have a data_type in *_constructor structs when evaluating.
The resulting constant has a data_type, so we have to find it somehow.
For tuple_constructor we don't have to create a separate tuple_type_impl instance.
For collection_constructor we know what the type is even in case of an empty collection.
For usertype_constructor we know the name, type and order of fields in the user type.
Additionally without a data_type we wouldn't know whether the type is reversed or not.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Add a method that converts given term to the matching expression.
It will be used as an intermediate step when implementing evaluate(expression).
evaluate(term) will convert the term to the expression and then call evaluate(expression).
For terminals this is simply calling get() to serialize the value.
For non-terminals the implementation is more complicated and will be implemeted in the following commits.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
constant is now ready to replace terminal as a final value representation.
Replace bind() with evaluate and shared_ptr<terminal> with constant.
We can't get rid of terminal yet. Sometimes terminal is converted back
to term, which constant can't do. This won't be a problem once we
replace term with expression.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
There was some repeating code in expr::get_elements family
of functions. It has been reduced into one function.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
We need to be able to access elements of a constant.
Adds functions to easily do it.
Those functions check all preconditions required to access elements
and then use partially_deserialize_* or similar.
It's much more convenient than using partially_deserialize directly.
get_list_of_tuples_elements is useful with IN restrictions like
(a, b) IN [(1, 2), (3, 4)].
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Start using evaluate_to_raw_value instead of bind_and_get.
This is a step towards using only evaluate.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
A list representing IN values might contain NULLs before evaluation.
We can remove them during evaluation, because nothing equals NULL.
If we don't remove them, there are gonna be errors, because a list can't contain NULLs.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Adds the functions:
constant evaluate(term*, const query_options&);
raw_value_view evaluate(term*, const query_options&);
These functions take a term, bind it and convert the terminal
to constant or raw_value_view.
In the future these functions will take expression instead of term.
For that to happen bind() has to be implemented on expression,
this will be done later.
Also introduces terminal::get_value_type().
In order to construct a constant from terminal we need to know the type.
It will be implemented in the following commits.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Adds constant to the expression variant:
struct constant {
raw_value value;
data_type type;
};
This struct will be used to represent constant values with known bytes and type.
This corresponds to the terminal from current design.
bool is removed from expression, now constant is used instead.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
This reverts commit e9343fd382, reversing
changes made to 27138b215b. It causes a
regression in v2 serialization_format support:
collection_serialization_with_protocol_v2_test fails with: marshaling error: read_simple_bytes - not enough bytes (requested 1627390306, got 3)
Fixes#9360
constant is now ready to replace terminal as a final value representation.
Replace bind() with evaluate and shared_ptr<terminal> with constant.
We can't get rid of terminal yet. Sometimes terminal is converted back
to term, which constant can't do. This won't be a problem once we
replace term with expression.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
There was some repeating code in expr::get_elements family
of functions. It has been reduced into one function.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
We need to be able to access elements of a constant.
Adds functions to easily do it.
Those functions check all preconditions required to access elements
and then use partially_deserialize_* or similar.
It's much more convenient than using partially_deserialize directly.
get_list_of_tuples_elements is useful with IN restrictions like
(a, b) IN [(1, 2), (3, 4)].
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Start using evaluate_to_raw_value instead of bind_and_get.
This is a step towards using only evaluate.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
A list representing IN values might contain NULLs before evaluation.
We can remove them during evaluation, because nothing equals NULL.
If we don't remove them, there are gonna be errors, because a list can't contain NULLs.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Adds the functions:
constant evaluate(term*, const query_options&);
raw_value_view evaluate(term*, const query_options&);
These functions take a term, bind it and convert the terminal
to constant or raw_value_view.
In the future these functions will take expression instead of term.
For that to happen bind() has to be implemented on expression,
this will be done later.
Also introduces terminal::get_value_type().
In order to construct a constant from terminal we need to know the type.
It will be implemented in the following commits.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Adds constant to the expression variant:
struct constant {
raw_value value;
data_type type;
};
This struct will be used to represent constant values with known bytes and type.
This corresponds to the terminal from current design.
bool is removed from expression, now constant is used instead.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
column_value_tuple overlaps both column_value and tuple_constructor
(in different respects) and can be replaced by a combination: a
tuple_constructor of column_value. The replacement is more expressive
(we can have a tuple of column_value and other expression types), though
the code (especially grammar) do not allow it yet.
So remove column_value_tuple and replace it everywhere with
tuple_constructor. Visitors get the merged behavior of the existing
tuple_constructor and column_value_tuple, which is usually trivial
since tuple_constructor and column_value_tuple came from different
hierarchies (term::raw and relation), so usually one of the types
just calls on_internal_error().
The change results in awkwards casts in two areas: WHERE clause
filtering (equal() and related), and clustering key range evaluations
(limits() and related). When equal() is replaced by recursive
evaluate(), the casts will go way (to be replaced by the evaluate())
visitor. Clustering key range extraction will remain limited
to tuples of column_value, so the prepare phase will have to vet
the expressions to ensure the casts don't fail (and use the
filtering path if they will).
Tests: unit (dev)
Closes#9274
Introduce a general-purpose search and replace function to manipulate
expressions, and use it to simplify replace_column_def() and
replace_token().
Closes#9259
* github.com:scylladb/scylla:
cql3: expr: rewrite replace_token in terms of search_and_replace()
cql3: expr: rewrite replace_column_def in terms of search_and_replace()
cql3: expr: add general-purpose search-and-replace
