com.datastax.dse.driver.api.core.metadata.schema.DseFunctionMetadata Maven / Gradle / Ivy
/*
* Copyright DataStax, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.datastax.dse.driver.api.core.metadata.schema;
import com.datastax.oss.driver.api.core.CqlIdentifier;
import com.datastax.oss.driver.api.core.metadata.schema.FunctionMetadata;
import com.datastax.oss.driver.api.core.type.DataType;
import com.datastax.oss.driver.internal.core.metadata.schema.ScriptBuilder;
import edu.umd.cs.findbugs.annotations.NonNull;
import java.util.List;
import java.util.Optional;
/**
* Specialized function metadata for DSE.
*
* It adds support for the DSE-specific {@link #getDeterministic() DETERMINISTIC} and {@link
* #getMonotonicity() MONOTONIC} keywords.
*/
public interface DseFunctionMetadata extends FunctionMetadata {
/** The monotonicity of a function. */
enum Monotonicity {
/**
* Indicates that the function is fully monotonic on all of its arguments. This means that it is
* either entirely non-increasing or non-decreasing. Full monotonicity is required to use the
* function in a GROUP BY clause.
*/
FULLY_MONOTONIC,
/**
* Indicates that the function is partially monotonic, meaning that partial application over
* some of the its arguments is monotonic. Currently (DSE 6.0.0), CQL only allows partial
* monotonicity on exactly one argument. This may change in a future CQL version.
*/
PARTIALLY_MONOTONIC,
/** Indicates that the function is not monotonic. */
NOT_MONOTONIC,
}
/** @deprecated Use {@link #getDeterministic()} instead. */
@Deprecated
boolean isDeterministic();
/**
* Indicates if this function is deterministic. A deterministic function means that given a
* particular input, the function will always produce the same output.
*
*
This method returns {@linkplain Optional#empty() empty} if this information was not found in
* the system tables, regardless of the actual function characteristics; this is the case for all
* versions of DSE older than 6.0.0.
*
* @return Whether or not this function is deterministic; or {@linkplain Optional#empty() empty}
* if such information is not available in the system tables.
*/
default Optional getDeterministic() {
return Optional.of(isDeterministic());
}
/** @deprecated use {@link #getMonotonicity()} instead. */
@Deprecated
boolean isMonotonic();
/**
* Returns this function's {@link Monotonicity}.
*
* A function can be either:
*
*
* - fully monotonic. In that case, this method returns {@link Monotonicity#FULLY_MONOTONIC},
* and {@link #getMonotonicArgumentNames()} returns all the arguments;
*
- partially monotonic, meaning that partial application over some of the arguments is
* monotonic. Currently (DSE 6.0.0), CQL only allows partial monotonicity on exactly one
* argument. This may change in a future CQL version. In that case, this method returns
* {@link Monotonicity#PARTIALLY_MONOTONIC}, and {@link #getMonotonicArgumentNames()}
* returns a singleton list;
*
- not monotonic. In that case, this method return {@link Monotonicity#NOT_MONOTONIC} and
* {@link #getMonotonicArgumentNames()} returns an empty list.
*
*
* Full monotonicity is required to use the function in a GROUP BY clause.
*
*
This method returns {@linkplain Optional#empty() empty} if this information was not found in
* the system tables, regardless of the actual function characteristics; this is the case for all
* versions of DSE older than 6.0.0.
*
* @return this function's {@link Monotonicity}; or {@linkplain Optional#empty() empty} if such
* information is not available in the system tables.
*/
default Optional getMonotonicity() {
return Optional.of(
isMonotonic()
? Monotonicity.FULLY_MONOTONIC
: getMonotonicArgumentNames().isEmpty()
? Monotonicity.NOT_MONOTONIC
: Monotonicity.PARTIALLY_MONOTONIC);
}
/**
* Returns a list of argument names that are monotonic.
*
* See {@link #getMonotonicity()} for explanations on monotonicity, and the possible values
* returned by this method.
*
*
NOTE: For versions of DSE older than 6.0.0, this method will always return an empty list,
* regardless of the actual function characteristics.
*
* @return the argument names that the function is monotonic on.
*/
@NonNull
List getMonotonicArgumentNames();
@NonNull
@Override
default String describe(boolean pretty) {
ScriptBuilder builder = new ScriptBuilder(pretty);
builder
.append("CREATE FUNCTION ")
.append(getKeyspace())
.append(".")
.append(getSignature().getName())
.append("(");
boolean first = true;
for (int i = 0; i < getSignature().getParameterTypes().size(); i++) {
if (first) {
first = false;
} else {
builder.append(",");
}
DataType type = getSignature().getParameterTypes().get(i);
CqlIdentifier name = getParameterNames().get(i);
builder.append(name).append(" ").append(type.asCql(false, pretty));
}
builder
.append(")")
.increaseIndent()
.newLine()
.append(isCalledOnNullInput() ? "CALLED ON NULL INPUT" : "RETURNS NULL ON NULL INPUT")
.newLine()
.append("RETURNS ")
.append(getReturnType().asCql(false, true))
.newLine();
// handle deterministic and monotonic
if (getDeterministic().orElse(false)) {
builder.append("DETERMINISTIC").newLine();
}
if (getMonotonicity().isPresent()) {
switch (getMonotonicity().get()) {
case FULLY_MONOTONIC:
builder.append("MONOTONIC").newLine();
break;
case PARTIALLY_MONOTONIC:
builder.append("MONOTONIC ON ").append(getMonotonicArgumentNames().get(0)).newLine();
break;
default:
break;
}
}
builder
.append("LANGUAGE ")
.append(getLanguage())
.newLine()
.append("AS '")
.append(getBody())
.append("';");
return builder.build();
}
}