Implement SUBSTRING function pushdown for Teradata connector #37
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| /* | ||
| * 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 io.trino.plugin.teradata; | ||
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| import io.trino.matching.Capture; | ||
| import io.trino.matching.Captures; | ||
| import io.trino.matching.Pattern; | ||
| import io.trino.plugin.base.expression.ConnectorExpressionRule; | ||
| import io.trino.plugin.jdbc.QueryParameter; | ||
| import io.trino.plugin.jdbc.expression.ParameterizedExpression; | ||
| import io.trino.spi.expression.Call; | ||
| import io.trino.spi.expression.ConnectorExpression; | ||
| import io.trino.spi.expression.FunctionName; | ||
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| import java.util.List; | ||
| import java.util.Optional; | ||
| import java.util.stream.Stream; | ||
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| import static io.trino.matching.Capture.newCapture; | ||
| import static io.trino.plugin.base.expression.ConnectorExpressionPatterns.argument; | ||
| import static io.trino.plugin.base.expression.ConnectorExpressionPatterns.argumentCount; | ||
| import static io.trino.plugin.base.expression.ConnectorExpressionPatterns.call; | ||
| import static io.trino.plugin.base.expression.ConnectorExpressionPatterns.expression; | ||
| import static io.trino.plugin.base.expression.ConnectorExpressionPatterns.functionName; | ||
| import static java.lang.String.format; | ||
| import static java.util.stream.Collectors.toList; | ||
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| public class RewriteSubstring | ||
| implements ConnectorExpressionRule<Call, ParameterizedExpression> | ||
| { | ||
| private static final Capture<ConnectorExpression> VALUE = newCapture(); | ||
| private static final Capture<ConnectorExpression> START = newCapture(); | ||
| private static final Capture<ConnectorExpression> LENGTH = newCapture(); | ||
|
Check failure on line 44 in plugin/trino-teradata/src/main/java/io/trino/plugin/teradata/RewriteSubstring.java
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| public static final FunctionName SUBSTRING_FUNCTION_NAME = new FunctionName("substring"); | ||
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| @Override | ||
| public Pattern<Call> getPattern() | ||
| { | ||
| return call() | ||
| .with(functionName().equalTo(SUBSTRING_FUNCTION_NAME)) | ||
| .with(argumentCount().matching(count -> count == 2 || count == 3)) | ||
| .with(argument(0).matching(expression().capturedAs(VALUE))) | ||
| .with(argument(1).matching(expression().capturedAs(START))); | ||
| } | ||
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| @Override | ||
| public Optional<ParameterizedExpression> rewrite(Call call, Captures captures, RewriteContext<ParameterizedExpression> context) | ||
| { | ||
| Optional<ParameterizedExpression> value = context.defaultRewrite(captures.get(VALUE)); | ||
| Optional<ParameterizedExpression> start = context.defaultRewrite(captures.get(START)); | ||
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| if (value.isEmpty() || start.isEmpty()) { | ||
| return Optional.empty(); | ||
| } | ||
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| if (call.getArguments().size() == 3) { | ||
| // Optional<ParameterizedExpression> length = context.defaultRewrite(captures.get(LENGTH)); | ||
|
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| Optional<ParameterizedExpression> length = context.defaultRewrite(call.getArguments().get(2)); | ||
| if (length.isEmpty()) { | ||
| return Optional.empty(); | ||
| } | ||
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| return Optional.of(new ParameterizedExpression( | ||
| format("SUBSTRING(%s FROM %s FOR %s)", | ||
| value.get().expression(), | ||
| start.get().expression(), | ||
| length.get().expression()), | ||
| combineParameters(value.get(), start.get(), length.get()))); | ||
| } | ||
| else { | ||
| return Optional.of(new ParameterizedExpression( | ||
| format("SUBSTRING(%s FROM %s)", | ||
| value.get().expression(), | ||
| start.get().expression()), | ||
| combineParameters(value.get(), start.get()))); | ||
| } | ||
| } | ||
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| private List<QueryParameter> combineParameters(ParameterizedExpression... expressions) | ||
| { | ||
| return Stream.of(expressions) | ||
| .flatMap(expr -> expr.parameters().stream()) | ||
| .collect(toList()); | ||
| } | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,135 @@ | ||
| /* | ||
| * 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 io.trino.plugin.teradata; | ||
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| import com.google.common.collect.ImmutableList; | ||
| import io.trino.matching.Capture; | ||
| import io.trino.matching.Captures; | ||
| import io.trino.matching.Pattern; | ||
| import io.trino.plugin.base.projection.ProjectFunctionRule; | ||
| import io.trino.plugin.jdbc.JdbcColumnHandle; | ||
| import io.trino.plugin.jdbc.JdbcExpression; | ||
| import io.trino.plugin.jdbc.JdbcTypeHandle; | ||
| import io.trino.plugin.jdbc.QueryParameter; | ||
| import io.trino.plugin.jdbc.expression.ParameterizedExpression; | ||
| import io.trino.spi.connector.ConnectorTableHandle; | ||
| import io.trino.spi.expression.Call; | ||
| import io.trino.spi.expression.ConnectorExpression; | ||
| import io.trino.spi.expression.FunctionName; | ||
| import io.trino.spi.expression.Variable; | ||
| import io.trino.spi.type.VarcharType; | ||
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| import java.sql.JDBCType; | ||
| import java.util.List; | ||
| import java.util.Optional; | ||
| import java.util.stream.Stream; | ||
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| import static io.trino.matching.Capture.newCapture; | ||
| import static io.trino.plugin.base.expression.ConnectorExpressionPatterns.argument; | ||
| import static io.trino.plugin.base.expression.ConnectorExpressionPatterns.argumentCount; | ||
| import static io.trino.plugin.base.expression.ConnectorExpressionPatterns.call; | ||
| import static io.trino.plugin.base.expression.ConnectorExpressionPatterns.expression; | ||
| import static io.trino.plugin.base.expression.ConnectorExpressionPatterns.functionName; | ||
| import static io.trino.plugin.base.expression.ConnectorExpressionPatterns.type; | ||
| import static java.lang.String.format; | ||
| import static java.util.stream.Collectors.toList; | ||
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| public class RewriteSubstringFunction | ||
| implements ProjectFunctionRule<JdbcExpression, ParameterizedExpression> | ||
| { | ||
| private static final Capture<ConnectorExpression> VALUE = newCapture(); | ||
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| private static final Pattern<Call> PATTERN = call() | ||
| .with(functionName().equalTo(new FunctionName("substring"))) | ||
| .with(type().matching(type -> type instanceof VarcharType)) | ||
| .with(argumentCount().matching(count -> count >= 2 && count <= 3)) | ||
| .with(argument(0).matching(expression().capturedAs(VALUE).with(type().matching(type -> type instanceof VarcharType)))); | ||
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| @Override | ||
| public Pattern<? extends ConnectorExpression> getPattern() | ||
| { | ||
| return PATTERN; | ||
| } | ||
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| @Override | ||
| public Optional<JdbcExpression> rewrite(ConnectorTableHandle handle, ConnectorExpression projectionExpression, Captures captures, RewriteContext<ParameterizedExpression> context) | ||
| { | ||
| Call call = (Call) projectionExpression; | ||
| ConnectorExpression valueExpression = captures.get(VALUE); | ||
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| // Get JDBC type handle for the value expression | ||
| JdbcTypeHandle typeHandle = getTypeHandle(valueExpression, context); | ||
| if (typeHandle == null) { | ||
| return Optional.empty(); | ||
| } | ||
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| // Only rewrite for plain VARCHAR JDBC type named "varchar" | ||
| if (JDBCType.valueOf(typeHandle.jdbcType()) != JDBCType.VARCHAR || | ||
|
sc250072 marked this conversation as resolved.
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| !typeHandle.jdbcTypeName().map(name -> name.equalsIgnoreCase("varchar")).orElse(false)) { | ||
| return Optional.empty(); | ||
| } | ||
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| Optional<ParameterizedExpression> value = context.rewriteExpression(valueExpression); | ||
| if (value.isEmpty()) { | ||
| return Optional.empty(); | ||
| } | ||
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| String expression; | ||
| List<QueryParameter> parameters; | ||
| if (call.getArguments().size() == 2) { | ||
| // Two argument SUBSTRING(value, start) | ||
| Optional<ParameterizedExpression> start = context.rewriteExpression(call.getArguments().get(1)); | ||
| if (start.isEmpty()) { | ||
| return Optional.empty(); | ||
| } | ||
| expression = format("SUBSTRING(%s FROM %s)", value.get().expression(), start.get().expression()); | ||
| parameters = combineParameters(value.get(), start.get()); | ||
| } | ||
| else if (call.getArguments().size() == 3) { | ||
| // Three argument SUBSTRING(value, start, length) | ||
| Optional<ParameterizedExpression> start = context.rewriteExpression(call.getArguments().get(1)); | ||
| Optional<ParameterizedExpression> length = context.rewriteExpression(call.getArguments().get(2)); | ||
| if (start.isEmpty() || length.isEmpty()) { | ||
| return Optional.empty(); | ||
| } | ||
| expression = format("SUBSTRING(%s FROM %s FOR %s)", | ||
| value.get().expression(), | ||
| start.get().expression(), | ||
| length.get().expression()); | ||
| parameters = combineParameters(value.get(), start.get(), length.get()); | ||
| } | ||
| else { | ||
| return Optional.empty(); | ||
| } | ||
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| return Optional.of(new JdbcExpression(expression, ImmutableList.copyOf(parameters), typeHandle)); | ||
| } | ||
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| private JdbcTypeHandle getTypeHandle(ConnectorExpression expression, RewriteContext<ParameterizedExpression> context) | ||
| { | ||
| if (expression instanceof Variable variable) { | ||
| return ((JdbcColumnHandle) context.getAssignment(variable.getName())).getJdbcTypeHandle(); | ||
| } | ||
| // For non-variable expressions, we might need to derive the type handle differently | ||
| // This is a simplified approach - you might need more sophisticated type handling | ||
| return new JdbcTypeHandle(JDBCType.VARCHAR.getVendorTypeNumber(), Optional.of("varchar"), Optional.empty(), Optional.empty(), Optional.empty(), Optional.empty()); | ||
| } | ||
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| private List<QueryParameter> combineParameters(ParameterizedExpression... expressions) | ||
| { | ||
| return Stream.of(expressions) | ||
| .flatMap(expr -> expr.parameters().stream()) | ||
| .collect(toList()); | ||
| } | ||
| } | ||
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