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https://issues.apache.org/jira/browse/DRILL-7458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17020773#comment-17020773
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ASF GitHub Bot commented on DRILL-7458:
---------------------------------------
paul-rogers commented on pull request #1914: DRILL-7458: Base framework for
storage plugins
URL: https://github.com/apache/drill/pull/1914#discussion_r369228513
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/store/base/BaseStoragePlugin.java
##########
@@ -0,0 +1,229 @@
+/*
+ * 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.store.base;
+
+import java.io.IOException;
+
+import org.apache.calcite.schema.SchemaPlus;
+import org.apache.drill.common.JSONOptions;
+import org.apache.drill.common.exceptions.ChildErrorContext;
+import org.apache.drill.common.exceptions.ExecutionSetupException;
+import org.apache.drill.common.exceptions.UserException;
+import org.apache.drill.common.logical.StoragePluginConfig;
+import org.apache.drill.exec.metastore.MetadataProviderManager;
+import org.apache.drill.exec.ops.ExecutorFragmentContext;
+import org.apache.drill.exec.physical.base.AbstractGroupScan;
+import
org.apache.drill.exec.physical.impl.scan.framework.ManagedScanFramework.ScanFrameworkBuilder;
+import org.apache.drill.exec.proto.UserBitShared.CoreOperatorType;
+import org.apache.drill.exec.record.CloseableRecordBatch;
+import org.apache.drill.exec.server.DrillbitContext;
+import org.apache.drill.exec.server.options.SessionOptionManager;
+import org.apache.drill.exec.store.AbstractStoragePlugin;
+import org.apache.drill.exec.store.SchemaConfig;
+import org.apache.drill.exec.store.SchemaFactory;
+import org.apache.drill.exec.store.StoragePlugin;
+import org.apache.drill.exec.store.StoragePluginRegistry;
+import org.apache.drill.shaded.guava.com.google.common.base.Preconditions;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.fasterxml.jackson.annotation.JsonTypeName;
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+/**
+ * Base class for non-DFS storage plugins. Provides a number of convinces to
+ * abstract away some of the complexity around such plugins. The
+ * {@link StoragePluginOptions} class captures the many options that would
+ * otherwise be specified by overriding methods. The
+ * {@link BaseScanFactory} class provides methods to create various
+ * objects during planning and execution.
+ *
+ * @param <C> the storage plugin configuration class
+ */
+
+public abstract class BaseStoragePlugin<C extends StoragePluginConfig>
+ extends AbstractStoragePlugin {
+
+ private static final Logger logger =
LoggerFactory.getLogger(BaseStoragePlugin.class);
+ protected static final ObjectMapper DEFAULT_MAPPER = new ObjectMapper();
Review comment:
Bingo! You hit on a nasty issue. Yes, Drill adds on all kinds of helpful
ser/des. But, as it turns out, there is no good way to get that mapper into
this class. I hit this very issue when trying to change the mock plugin: it
can't deserialize things like `ColumnMetadata` which require help.
Most plugins do exactly what is done here because the scan spec tends to be
simple.
A larger question is why the heck we serialize the scan spec: it never
leaves the planner. There is probably some hacky reason it was done this way.
Do you know of a way to get Drill's mapper into this class without changing
the constructor?
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> Base storage plugin framework
> -----------------------------
>
> Key: DRILL-7458
> URL: https://issues.apache.org/jira/browse/DRILL-7458
> Project: Apache Drill
> Issue Type: Improvement
> Reporter: Paul Rogers
> Assignee: Paul Rogers
> Priority: Major
> Labels: doc-impacting
> Fix For: 1.18.0
>
>
> The "Easy" framework allows third-parties to add format plugins to Drill with
> moderate effort. (The process could be easier, but "Easy" makes it as simple
> as possible given the current structure.)
> At present, no such "starter" framework exists for storage plugins. Further,
> multiple storage plugins have implemented filter push down, seemingly by
> copying large blocks of code.
> This ticket offers a "base" framework for storage plugins and for filter
> push-downs. The framework builds on the EVF, allowing plugins to also support
> project push down.
> The framework has a "test mule" storage plugin to verify functionality, and
> was used as the basis of an REST-like plugin.
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