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https://issues.apache.org/jira/browse/DRILL-7278?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16854852#comment-16854852
]
ASF GitHub Bot commented on DRILL-7278:
---------------------------------------
arina-ielchiieva commented on pull request #1797: DRILL-7278: Refactor result
set loader projection mechanism
URL: https://github.com/apache/drill/pull/1797#discussion_r289941138
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/scan/project/projSet/TypeConverter.java
##########
@@ -0,0 +1,168 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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 org.apache.drill.exec.physical.impl.scan.project.projSet;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.drill.common.exceptions.CustomErrorContext;
+import org.apache.drill.common.exceptions.UserException;
+import org.apache.drill.exec.record.metadata.ColumnMetadata;
+import org.apache.drill.exec.record.metadata.TupleMetadata;
+import org.apache.drill.exec.vector.accessor.convert.ColumnConversionFactory;
+import org.apache.drill.exec.vector.accessor.convert.StandardConversions;
+import
org.apache.drill.exec.vector.accessor.convert.StandardConversions.ConversionDefn;
+import
org.apache.drill.exec.vector.accessor.convert.StandardConversions.ConversionType;
+
+public class TypeConverter {
+ private static final org.slf4j.Logger logger =
+ org.slf4j.LoggerFactory.getLogger(TypeConverter.class);
+
+ public static class Builder {
+ private TupleMetadata providedSchema;
+ private TypeConverter.CustomTypeTransform transform;
+ private Map<String, String> properties;
+ private CustomErrorContext errorContext;
+
+ public Builder providedSchema(TupleMetadata schema) {
+ providedSchema = schema;
+ return this;
+ }
+
+ public Builder transform(TypeConverter.CustomTypeTransform transform) {
+ this.transform = transform;
+ return this;
+ }
+
+ public Builder properties(Map<String, String> properties) {
+ this.properties = properties;
+ return this;
+ }
+
+ public Builder setConversionProperty(String key, String value) {
+ if (key == null || value == null) {
+ return this;
+ }
+ if (properties == null) {
+ properties = new HashMap<>();
+ }
+ properties.put(key, value);
+ return this;
+ }
+
+ public Builder errorContext(CustomErrorContext errorContext) {
+ this.errorContext = errorContext;
+ return this;
+ }
+
+ public TypeConverter build() {
+ return new TypeConverter(this);
+ }
+ }
+
+ public static interface CustomTypeTransform {
+ ColumnConversionFactory transform(ColumnMetadata inputDefn,
+ Map<String, String> properties,
+ ColumnMetadata outputDefn, ConversionDefn defn);
+ }
+
+ private final TupleMetadata providedSchema;
+ private final TypeConverter.CustomTypeTransform customTransform;
+ private final Map<String, String> properties;
+ private final CustomErrorContext errorContext;
+
+ public static Builder builder() { return new Builder(); }
+
+ public TypeConverter(Builder builder) {
+ this.providedSchema = builder.providedSchema;
+ this.customTransform = builder.transform;
+ this.properties = builder.properties;
+ this.errorContext = builder.errorContext;
+ }
+
+ public TypeConverter(TypeConverter parent,
+ TupleMetadata childSchema) {
+ this.providedSchema = childSchema;
+ this.customTransform = parent.customTransform;
+ this.properties = parent.properties;
+ this.errorContext = parent.errorContext;
+ }
+
+ public TupleMetadata providedSchema() { return providedSchema; }
+
+ public ColumnConversionFactory conversionFactory(ColumnMetadata inputSchema,
+ ColumnMetadata outputCol) {
+ if (outputCol == null) {
+ return customConversion(inputSchema);
+ } else {
+ return schemaBasedConversion(inputSchema, outputCol);
+ }
+ }
+
+ private ColumnConversionFactory customConversion(ColumnMetadata inputSchema)
{
+ if (customTransform == null) {
+ return null;
+ }
+ return customTransform.transform(inputSchema, properties, null, null);
+ }
+
+ public ColumnConversionFactory schemaBasedConversion(ColumnMetadata
inputSchema,
+ ColumnMetadata outputCol) {
+
+ // Custom transforms take priority. Allows replacing the standard
+ // conversions. Also allows conversions between the same type, such
+ // as rescaling units.
+
+ ConversionDefn defn = StandardConversions.analyze(inputSchema, outputCol);
+ if (customTransform != null) {
Review comment:
Do you think it could be better if instead of checking for nulls we could
have some dummy implementation that does nothing?
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> Refactor result set loader projection mechanism
> -----------------------------------------------
>
> Key: DRILL-7278
> URL: https://issues.apache.org/jira/browse/DRILL-7278
> Project: Apache Drill
> Issue Type: Improvement
> Affects Versions: 1.16.0
> Reporter: Paul Rogers
> Assignee: Paul Rogers
> Priority: Major
> Fix For: 1.17.0
>
>
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