Calling WebAssembly UDFs requires wasmtime instance. Creating such an instance is expensive,
but these instances can be reused for subsequent calls of the same UDF on various inputs.
This patch introduces a way of reusing wasmtime instances: a wasm instance cache.
The cache stores a wasmtime instance for each UDF and scheduling group. The instances are
evicted using LRU strategy and their size is based on the size of their wasm memories.
The instances stored in the cache are also dropped when the UDF is dropped itself. For that reason,
the first patch modifies the current implementation of UDF dropping, so that the instance dropping may be added
later. The patch also removes the need of compiling the UDF again when dropping it.
The second patch contains the implementation and use of the new cache. The cache is implemented
in `lang/wasm_instance_cache.hh` and the main ways of using it are the `run_script` methods from `wasm.hh`
The third patch adds tests to `test_wasm.py` that check the correctness and performance of the new
cache. The tests confirm the instance reuse, size limits, instance eviction after timeout and after dropping the UDF.
Closes#10306
* github.com:scylladb/scylladb:
wasm: test instances reuse
wasm: reuse UDF instances
schema_tables: simplify merge_functions and avoid extra compilation
This pull request introduces a "synchronous mode" for global views. In this mode, all view updates are applied synchronously as if the view was local.
Marking view as a synchronous one can be done using `CREATE MATERIALIZED VIEW` and `ALTER MATERIALIZED VIEW`. E.g.:
```cql
ALTER MATERIALIZED VIEW ks.v WITH synchronous_updates = true;
```
Marking view as a synchronous one was done using tags (originally used by alternator). No big modifications in the view's code were needed.
Fixes: https://github.com/scylladb/scylla/issues/10545Closes#11013
* github.com:scylladb/scylla:
cql-pytest: extend synchronous mv test with new cases
cql-pytest: allow extra parameters in new_materialized_view
docs: add a paragraph on view synchronous updates
test/boost/cql_query_test: add test setting synchronous updates property
test: cql-pytest: add a test for synchronous mode materialized views
db: view: react to synchronous updates tag
cql3: statements: cf_prop_defs: apply synchronous updates tag
alternator, db: move the tag code to db/tags
cql3: statements: add a synchronous_updates property
This commit defines a new tag key (SYNCHRONOUS_VIEW_UPDATES_TAG_KEY) to
be used for marking "synchronous mode" views. This key is used in
`cf_prop_defs::apply_to_builder` if the properties contain
KW_SYNCHRONOUS_UPDATES.
This property can be used with CREATE MATERIALIZED VIEW and ALTER
MATERIALIZED VIEW statements. Setting it allows global views to enter
"synchronous mode". In this mode, all view updates are also applied
synchronously as if the view was local. This may reduce their
availability, but has the benefit of propagating a potential
inconsistency risk (in form of a write error) to the user, who can
respond to it appropriately (e.g. retry the write or fix the view
later).
In preparation of the relaxation of the grammar to return any expression,
change the whereClause production to return an expression rather than
terms. Note that the expression is still constrained to be a conjunction
of relations, and our filtering code isn't prepared for more.
Before the patch, if the WHERE clause was optional, the grammar would
pass an empty vector of expressions (which is exactly correct). After
the patch, it would pass a default-constructed expression. Now that
happens to be an empty conjunction, which is exactly what's needed, but
it is too accidental, so the patch changes optional WHERE clauses to
explicitly generate an empty conjunction if the WHERE clause wasn't
specified.
Move closer to the goal of accepting a generic expression for WHERE
clause by accepting a generic expression in statement_restrictions. The
various callers will synthesize it from a vector of terms.
std::move(_where_clause) is wrong, because _where_clause is used later
(when analyzing GROUP BY), but also harmless (because the
statement_restrictions constructor accepts it by const reference).
To avoid confusion in the next patch where we'll pass _where_clause
to a different function, remove the bad std::move() in advance here.
When analyzing a WHERE clause, we want to separate individual
factors (usually relations), and later partition them into
partition key, clustering key, and regular column relations. The
first step is separation, for which this helper is added.
Currently, it is not required since the grammar supplies the
expression in separated form, but this will not work once it is
relaxed to allow any expression in the WHERE clause.
A unit test is added.
This is useful for implementing operator==() for expressions, which in
turn require comparing constants, which contain raw_values.
Note that this is not CQL comparison (that would be implemented
in cql3::expr::evaluate() and would return a CQL boolean, not a C++
boolean, but a traditional C++ value comparison.
When executing a wasm UDF, most of the time is spent on
setting up the instance. To minimize its cost, we reuse
the instance using wasm::instance_cache.
This patch adds a wasm instance cache, that stores
a wasmtime instance for each UDF and scheduling group.
The instances are evicted using LRU strategy. The
cache may store some entries for the UDF after evicting
the instance, but they are evicted when the corresponding
UDF is dropped, which greatly limits their number.
The size of stored instances is estimated using the size
of their WASM memories. In order to be able to read the
size of memory, we require that the memory is exported
by the client.
Signed-off-by: Wojciech Mitros <wojciech.mitros@scylladb.com>
This PR removes all code that used classes `restriction`, `restrictions` and their children.
There were two fields in `statement_restrictions` that needed to be dealt with: `_clustering_columns_restrictions` and `_nonprimary_key_restrictions`.
Each function was reimplemented to operate on the new expression representaiion and eventually these fields weren't needed anymore.
After that the restriction classes weren't used anymore and could be deleted as well.
Now all of the code responsible for analyzing WHERE clause and planning a query works on expressions.
Closes#11069
* github.com:scylladb/scylla:
cql3: Remove all remaining restrictions code
cql3: Move a function from restrictions class to the test
cql3: Remove initial_key_restrictions
cql3: expr: Remove convert_to_restriction
cql3: Remove _new from _new_nonprimary_key_restrictions
cql3: Remove _nonprimary_key_restrictions field
cql3: Reimplement uses of _nonprimary_key_restrictions using expression
cql3: Keep a map of single column nonprimary key restrictions
cql3: Remove _new from _new_clustering_columns_restrictions
cql3: Remove _clustering_columns_restrictions from statement_restrictions
cql3: Use a variable instead of dynamic cast
cql3: Use the new map of single column clustering restrictions
cql3: Keep a map of single column clustering key restrictions
cql3: Return an expression in get_clustering_columns_restrctions()
cql3: Reimplement _clustering_columns_restrictions->has_supporting_index()
cql3: Don't create single element conjunction
cql3: Add expr::index_supports_some_column
cql3: Reimplement has_unrestricted_components()
cql3: Reimplement _clustering_columns_restrictions->need_filtering()
cql3: Reimplement num_prefix_columns_that_need_not_be_filtered
cql3: Use the new clustering restrictions field instead of ->expression
cql3: Reimplement _clustering_columns_restrictions->size() using expressions
cql3: Reimplement _clustering_columns_restrictions->get_column_defs() using expressions
cql3: Reimplement _clustering_columns_restrictions->is_all_eq() using expressions
cql3: expr: Add has_only_eq_binops function
cql3: Reimplement _clustering_columns_restrictions->empty() using expressions
query_result was the wrong place to put last position into. It is only
included in data-responses, but not on digest-responses. If we want to
support empty pages from replicas, both data and digest responses have
to include the last position. So hoist up the last position to the
parent structure: query::result. This is a breaking change inter-node
ABI wise, but it is fine: the current code wasn't released yet.
Closes#11072
The classes restriction, restrictions and its children
aren't used anywhere now and can be safely removed.
Some includes need to be modified for the code to compile.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
initial_key restrictions was a class used by statement_restrictions
to represent empty restrictions of different types and simplify
restriction merging logic. They are not used anymore and can
be removed.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
The _new prefix was used to distinguish the new field
from the old represenation.
Now the new field has fully replaced the old one
and _new can be removed from its name.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
All code that made use of _nonprimary_key_restrictions
has been modified to use _new_nonprimary_key_restrictions
instead.
The field can be removed.
Additionally the old code responsible for adding new restrictions
can be fully removed, everything is now done using add_restriction.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
All parts of the code that use _nonprimary_key_restrictions
are changed to use _new_nonprimary_key_restrictions instead.
I decided not to split this into multiple commits,
as there isn't a lot of changes and they are
analogous to the ones done before for partition
and clustering columns.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Keep a map of extracted restrictions for each restricted nonprimar column.
This map will be useful, just like the ones for clustering and partition
columns.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
The _new was used to distinguish from the old field
during transition. Now the old field has been deleted
and the new one can take its place.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
All code using the _clustering_columns_restrictions field
has been modified to instead use _new_clustering_columns_restrictions
expression representation.
The old field can now be removed.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
There is a dynamic cast used to determine whether
clustering columns are restricted by a multi column
restriction.
Instead of doing that we can just use the _has_multi_column
variable.
It's also used a few lines higher, which means that
it should be already initialized.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Having this map is useful in a bunch of places.
To keep code simple it could be created from scratch each time,
but it's also used in do_filter, so this could actually
affect performance.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
get_clustering_columns_restrctions() used to return
a shared pointer to the clustering_restrictions class.
Now everything is being converted to expression,
so it should return an expression as well.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
In case the expression is empty and we want to merge it
with a new restriction we can just set the expression
to the new restriction.
Later this will make it easier to distinguish which case
of multi column restrictions are we dealing with.
IN and EQ can only have a single binary operator,
but slice might have two.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Add a function that checks if there is an index
which supports one of the columns present in
the given expression.
This functionality will soon be needed for
clustering and nonprimary columns so it's
good to separate into a reusable function.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
The code is copied from:
single_column_primary_key_restrictions<clustering_key>
::num_prefix_columns_that_need_not_be_filtered
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Instead of writing
_clustering_columns_restrictions->expression
It's better to use the new field:
_new_clustering_columns_restrictions
These expressions should be the same.
It removes another use of the unwanted restrictions field.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Add a function which checks that an expression
contains only binary operators with '='.
Right now this check is done only in a single place,
but soon the same check will have to be done
for clustering columns as well, so the code
is moved to a separate function to prevent duplication.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
All occurences of _clustering_columns_restrictions->empty()
have been replaced with code that operates on the new
expression representation: _new_clustering_columns_restrictions.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Enables parallelization of query like `SELECT MIN(x), MAX(x)`.
Compatibility is ensured under the same cluster feature as
UDA and native aggregates parallelization. (UDA_NATIVE_PARALLELIZED_AGGREGATION)
Enables parallelization of UDA and native aggregates. The way the
query is parallelized is the same as in #9209. Separate reduction
type for `COUNT(*)` is left for compatibility reason.
`mock_get` was created only for forward_service use, thus it only checks for
aggregate functions if no declared function was found.
The reason for this function is, there is no serialization of `cql3::selection::selection`,
so functions lying underneath these selections has to be refound.
Most of this code is copied from `functions::get()`, however `functions::get()` is not used because it requires to
mock or serialize expressions and `functions::find()` is not enough,
because it does not search for dynamic aggregate functions
Moving `function`, `function_name` and `aggregate_function` into
db namespace to avoid including cql3 namespace into query-request.
For now, only minimal subset of cql3 function was moved to db.
Because `selection` is not serializable and it has to be send via network
to parallelize query, we have to mock the selection. To simplify
the mocking, for now only single selectors for aggregate's arguments
are allowed (no casting or other functions as arguments).
