Author: pradeepkth
Date: Thu Dec 17 19:15:17 2009
New Revision: 891847
URL: http://svn.apache.org/viewvc?rev=891847&view=rev
Log:
additional file missed in previous commit
Added:
hadoop/pig/branches/load-store-redesign/src/org/apache/pig/LoadPushDown.java
Added:
hadoop/pig/branches/load-store-redesign/src/org/apache/pig/LoadPushDown.java
URL:
http://svn.apache.org/viewvc/hadoop/pig/branches/load-store-redesign/src/org/apache/pig/LoadPushDown.java?rev=891847&view=auto
==============================================================================
---
hadoop/pig/branches/load-store-redesign/src/org/apache/pig/LoadPushDown.java
(added)
+++
hadoop/pig/branches/load-store-redesign/src/org/apache/pig/LoadPushDown.java
Thu Dec 17 19:15:17 2009
@@ -0,0 +1,236 @@
+/*
+ * 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.pig;
+
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.pig.impl.logicalLayer.FrontendException;
+
+/**
+ * This interface defines how to communicate to Pig what functionality can
+ * be pushed into the loader. If a given loader does not implement this
interface
+ * it will be assumed that it is unable to accept any functionality for push
down.
+ */
+public interface LoadPushDown {
+
+ /**
+ * Set of possible operations that Pig can push down to a loader.
+ */
+ enum OperatorSet {PROJECTION};
+
+ /**
+ * Determine the operators that can be pushed to the loader.
+ * Note that by indicating a loader can accept a certain operator
+ * (such as selection) the loader is not promising that it can handle
+ * all selections. When it is passed the actual operators to
+ * push down it will still have a chance to reject them.
+ * @return list of all features that the loader can support
+ */
+ List<OperatorSet> getFeatures();
+
+ /**
+ * Indicate to the loader fields that will be needed. This can be useful
for
+ * loaders that access data that is stored in a columnar format where
indicating
+ * columns to be accessed a head of time will save scans. If the loader
+ * function cannot make use of this information, it is free to ignore it.
+ * @param requiredFieldList RequiredFieldList indicating which columns
will be needed.
+ */
+ public RequiredFieldResponse pushProjection(RequiredFieldList
+ requiredFieldList) throws FrontendException;
+
+ public static class RequiredField implements Serializable {
+
+ private static final long serialVersionUID = 1L;
+
+ // will hold name of the field (would be null if not supplied)
+ private String alias;
+
+ // will hold the index (position) of the required field (would be -1
if not supplied), index is 0 based
+ private int index;
+
+ // A list of sub fields in this field (this could be a list of hash
keys for example).
+ // This would be null if the entire field is required and no specific
sub fields are required.
+ // In the initial implementation only one level of subfields will be
populated.
+ private List<RequiredField> subFields;
+
+ // true for atomic types like INTEGER, FLOAT, DOUBLE, CHARARRAY,
BYTEARRAY, LONG and when all
+ // subfields from complex types like BAG, TUPLE and MAP are required
+ private boolean allSubFieldsRequired;
+
+ // Type of this field - the value could be any current PIG DataType
(as specified by the constants in DataType class).
+ private byte type;
+
+ /**
+ * @return the alias
+ */
+ public String getAlias() {
+ return alias;
+ }
+
+ /**
+ * @return the index
+ */
+ public int getIndex() {
+ return index;
+ }
+
+
+ /**
+ * @return the required sub fields. The return value is null if all
+ * subfields are required
+ */
+ public List<RequiredField> getSubFields() {
+ return subFields;
+ }
+
+ public void setSubFields(List<RequiredField> subFields)
+ {
+ this.subFields = subFields;
+ }
+
+ /**
+ * @return the type
+ */
+ public byte getType() {
+ return type;
+ }
+
+ /**
+ * @return true if all sub fields are required, false otherwise
+ */
+ public boolean isAllSubFieldsRequired() {
+ return allSubFieldsRequired;
+ }
+
+
+ public void setType(byte t) {
+ type = t;
+ }
+
+ public void setIndex(int i) {
+ index = i;
+ }
+
+ public void setAlias(String alias)
+ {
+ this.alias = alias;
+ }
+
+ @Override
+ public String toString() {
+ if (index != -1)
+ return "" + index;
+ else if (alias != null)
+ return alias;
+ return "";
+ }
+ }
+
+ public static class RequiredFieldList implements Serializable {
+ // Implementation of the private fields is subject to change but the
+ // getter() interface should remain
+
+ private static final long serialVersionUID = 1L;
+
+ // list of Required fields, this will be null if all fields are
required
+ private List<RequiredField> fields = new ArrayList<RequiredField>();
+
+ // flag to indicate if all fields are required. The Loader
implementation should check this flag first and look at the fields ONLY if this
is true
+ private boolean allFieldsRequired;
+
+ private String signature;
+
+ /**
+ * @return the required fields - this will be null if all fields are
+ * required
+ */
+ public List<RequiredField> getFields() {
+ return fields;
+ }
+
+ public RequiredFieldList(String signature) {
+ this.signature = signature;
+ }
+
+ public String getSignature() {
+ return signature;
+ }
+
+ /**
+ * @return true if all fields are required, false otherwise
+ */
+ public boolean isAllFieldsRequired() {
+ return allFieldsRequired;
+ }
+
+ public void setAllFieldsRequired(boolean allRequired) {
+ allFieldsRequired = allRequired;
+ }
+
+ @Override
+ public String toString() {
+ StringBuffer result = new StringBuffer();
+ if (allFieldsRequired)
+ result.append("*");
+ else {
+ result.append("[");
+ for (int i = 0; i < fields.size(); i++) {
+ result.append(fields.get(i));
+ if (i != fields.size() - 1)
+ result.append(",");
+ }
+ result.append("]");
+ }
+ return result.toString();
+ }
+
+ public void add(RequiredField rf)
+ {
+ fields.add(rf);
+ }
+ }
+
+ public static class RequiredFieldResponse {
+ // the loader should pass true if it will return data containing
+ // only the List of RequiredFields in that order. false if it
+ // will return all fields in the data
+ private boolean requiredFieldRequestHonored;
+
+ public RequiredFieldResponse(boolean requiredFieldRequestHonored) {
+ this.requiredFieldRequestHonored = requiredFieldRequestHonored;
+ }
+
+ // true if the loader will return data containing only the List of
+ // RequiredFields in that order. false if the loader will return all
+ // fields in the data
+ public boolean getRequiredFieldResponse() {
+ return requiredFieldRequestHonored;
+ }
+
+ // the loader should pass true if the it will return data containing
+ // only the List of RequiredFields in that order. false if the it
+ // will return all fields in the data
+ public void setRequiredFieldResponse(boolean honored) {
+ requiredFieldRequestHonored = honored;
+ }
+ }
+
+
+}
\ No newline at end of file
