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PXFExternalTableandAPIReference.html
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<h3 class="title-container">PXF External Table and API Reference</h3>
<div class="content">
<!-- Python script replaces main content -->
<div id ="main"><div style="visibility:hidden; height:2px;">Pivotal Product Documentation : PXF External Table and API Reference</div><div class="wiki-content group" id="main-content">
<p align="LEFT">You can extend PXF functionality and add new services and formats using the Java API without changing HAWQ. The API includes the four classes Fragmenter, Accessor, Resolver, Analyzer. The Fragmenter, Accessor, and Resolver classes must be implemented to add a new service. The Analyzer class is optional.</p><p align="LEFT"><style type="text/css">/*<![CDATA[*/
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<ul class="toc-indentation">
<li><a href="#PXFExternalTableandAPIReference-CreatinganExternalTable">Creating an External Table</a></li>
<li><a href="#PXFExternalTableandAPIReference-AbouttheJavaClassServicesandFormats">About the Java Class Services and Formats</a>
<ul class="toc-indentation">
<li><a href="#PXFExternalTableandAPIReference-Fragmenter">Fragmenter</a></li>
<li><a href="#PXFExternalTableandAPIReference-Accessor">Accessor</a></li>
<li><a href="#PXFExternalTableandAPIReference-Resolver">Resolver</a></li>
<li><a href="#PXFExternalTableandAPIReference-Analyzer">Analyzer</a></li>
</ul>
</li>
<li><a href="#PXFExternalTableandAPIReference-AboutCustomProfiles">About Custom Profiles</a></li>
<li><a href="#PXFExternalTableandAPIReference-AboutQueryFilterPush-Down">About Query Filter Push-Down</a>
<ul class="toc-indentation">
<li><a href="#PXFExternalTableandAPIReference-FilterAvailabilityandOrdering">Filter Availability and Ordering</a></li>
<li><a href="#PXFExternalTableandAPIReference-CreatingaFilterBuilderClass">Creating a Filter Builder Class</a></li>
<li><a href="#PXFExternalTableandAPIReference-FilterOperations">Filter Operations</a></li>
<li><a href="#PXFExternalTableandAPIReference-SampleImplementation">Sample Implementation</a></li>
<li><a href="#PXFExternalTableandAPIReference-UsingFilters">Using Filters</a></li>
</ul>
</li>
<li><a href="#PXFExternalTableandAPIReference-Reference">Reference</a>
<ul class="toc-indentation">
<li><a href="#PXFExternalTableandAPIReference-ExternalTableExamples">External Table Examples</a></li>
<li><a href="#PXFExternalTableandAPIReference-PluginExamples">Plugin Examples</a></li>
<li><a href="#PXFExternalTableandAPIReference-ConfigurationFiles">Configuration Files</a></li>
</ul>
</li>
<li><a href="#PXFExternalTableandAPIReference-CredentialsforRemoteServices">Credentials for Remote Services</a></li>
<li><a href="#PXFExternalTableandAPIReference-CredentialsforremoteservicesisallowingaPXFplugintoaccessaremoteservicethatrequirescredentials.">Credentials for remote services is allowing a PXF plugin to access a remote service that requires credentials.</a>
<ul class="toc-indentation">
<li><a href="#PXFExternalTableandAPIReference-InHawq">In Hawq</a></li>
<li><a href="#PXFExternalTableandAPIReference-InaPXFPlugin">In a PXF Plugin</a></li>
</ul>
</li>
</ul>
</div></p><h2 id="PXFExternalTableandAPIReference-CreatinganExternalTable">Creating an External Table</h2><p align="LEFT">Syntax for an <em>EXTERNAL TABLE</em> that uses the PXF protocol is as follows:.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: sql; gutter: false" style="font-size:12px;">CREATE EXTERNAL TABLE ext_table <attr list, ...>
LOCATION('pxf://<namenode>:<port>/path/to/data?FRAGMENTER=package.name.FragmenterForX&ACCESSOR=package.name.AccessorForX&RESOLVER=package.name.ResolverForX&<Other custom user options>=<value>')FORMAT 'custom'(formatter='pxfwritable_import');</pre>
</div></div><p> Where:</p><h5 id="PXFExternalTableandAPIReference-Table:Parametervaluesanddescription">Table: Parameter values and description</h5><div class="table-wrap"><table class="confluenceTable"><tbody><tr><td class="confluenceTd"><p align="LEFT"><strong>Parameter</strong></p></td><td class="confluenceTd"><p align="LEFT"><strong>Value and description</strong></p></td></tr><tr><td class="confluenceTd"><p align="LEFT">namenode</p></td><td class="confluenceTd"><p align="LEFT">The current host of the PXF service is HDFS Namenode port.</p></td></tr><tr><td class="confluenceTd"><p align="LEFT">REST </p></td><td class="confluenceTd"><p align="LEFT">Port for Namenode, 50070 by default.</p></td></tr><tr><td class="confluenceTd" colspan="1"> path/to/data</td><td class="confluenceTd" colspan="1"> A directory, file name, wildcard pattern, table name, etc</td></tr><tr><td class="confluenceTd" colspan="1"> FRAGMENTER</td><td class="confluenceTd" colspan="1"> The plugin (java class) to use for fragmenting data. Used in READABLE external tables only.</td></tr><tr><td class="confluenceTd" colspan="1"> ACCESSOR</td><td class="confluenceTd" colspan="1">The plugin (java class) to use for accessing the data. Used in READABLE and WRITABLE tables.</td></tr><tr><td class="confluenceTd" colspan="1"> RESOLVER</td><td class="confluenceTd" colspan="1">The plugin (java class) to use for serializing and deserializing the data. Used in READABLE and WRITABLE tables.</td></tr><tr><td class="confluenceTd" colspan="1"> Custom Options</td><td class="confluenceTd" colspan="1">Anything else that is desired to add. Will be passed in runtime to the plugins indicated above. </td></tr></tbody></table></div><p align="LEFT">For more information about this example, see <em>"About the Java Class Services and Formats" and the Pivotal Extension Installation and Administrator Guide.</em></p><h2 id="PXFExternalTableandAPIReference-AbouttheJavaClassServicesandFormats">About the Java Class Services and Formats</h2><p>The Java class names you must include in the PXF URI are Fragmenter, Accessor, and Resolver. The Fragmenter class is mandatory for READABLE tables, and not supported for WRITABLE tables. Pivotal recommends that you reuse a previously-defined Accessor or Resolver data format.</p><p>All the attributes are passed from HAWQ as headers to the PXF Java service. The Java service retrieves the source data and converts it to a HAWQ-readable format. You can pass any additional information to the user-implemented services.</p><p>The example in<em> "Creating an External Table"</em> shows the available keys and associated values. The example also contains attributes that are passed in from the HAWQ side. The available keys and associated values are as follows:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">FRAGMENTER: ‘pkg.name.FragmenterForX’
ACCESSOR: ‘pkg.name.AccessorForX’
RESOLVER: ‘pkg.name.ResolverForX’
</pre>
</div></div><p>These three Java plugins and the optional plugin, Analyzer, extend the <em>com.pivotal.pxf.api.utilities.Plugin</em> class.</p><p>The Java classes can be described as follows:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">package com.pivotal.pxf.api.utilities;
/*
* Base class for all plugin types (Accessor, Resolver, Fragmenter, Analyzer)
* Holds InputData as well (the meta data information used by all plugin types)
*/
public class Plugin
{
protected InputData inputData;
/*
* C'tor
*/
public Plugin(InputData input);
/**
* Checks if the plugin is thread safe or not, based on inputData.
*
* @return if plugin is thread safe or not
*/
public boolean isThreadSafe() {
return true;
}
}</pre>
</div></div><p>Attributes are available through the <em>com.pivotal.pxf.api.utilities.InputData</em> class. The following example shows how <em>inputData.getProperty(‘USERINFO1’)</em> returns <em>optional_info</em>.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">package com.pivotal.pxf.api.utilities;
/*
* Common configuration of all MetaData classes
* Provides read-only access to common parameters supplied using system properties
*/
public class InputData
{
/*
* Constructor of InputData
* Parses X-GP-* configuration variables
*
* @param paramsMap contains all query-specific parameters from Hawq
* @param servletContext Servlet context contains attributes required by SecuredHDFS
*/
public InputData(Map<String, String> paramsMap);
/*
* Expose the parameters map
*/
public Map<String, String> getParametersMap();
/* Copy contructor of InputData
* Used to create from an extending class
*/
public InputData(InputData copy);
/*
* Returns a property as a string type
*/
public String getProperty(String property);
/*
* returns the number of segments in GP
*/
public int totalSegments();
/*
* returns the current segment ID
*/
public int segmentId();
/* returns the current outputFormat
* currently either text or gpdbwritable
*/
public OutputFormat outputFormat();
/*
* returns the server name providing the service
*/
public String serverName();
/*
* returns the server port providing the service
*/
public int serverPort();
/*
* Returns true if there is a filter string to parse
*/
public boolean hasFilter();
/*
* The filter string
*/
public String filterString();
/*
* returns the number of columns in Tuple Description
*/
public int columns();
/*
* returns column index from Tuple Description
*/
public ColumnDescriptor getColumn(int index);
/*
* returns fragment serialized metadata
*/
public byte[] getFragmentMetadata();
/*
* Set fragment serialized metadata
*/
public void setFragmentMetadata(byte[] location);
/*
* returns fragment user data
*/
public byte[] getFragmentUserData();
/*
* returns a data fragment index
*/
public int getDataFragment();
/*
* returns the column descriptor of the recordkey column.
* If the recordkey column was not specified by the user in the create table statement,
* then getRecordkeyColumn will return null.
*/
public ColumnDescriptor getRecordkeyColumn();
/*
* Returns the data source of the required resource (i.e a file path or a table name).
*/
public String dataSource();
/*
* Sets the data source of the required resource (i.e a file path or a table name).
*/
public void setDataSource(String dataSource);
/* returns the path of the schema used for various deserializers
* e.g, Avro file name, Java object file name.
*/
public String srlzSchemaName() throws FileNotFoundException, IllegalArgumentException;
/*
* returns the ClassName for the java class that handles the file access
*/
public String accessor();
/*
* returns the ClassName for the java class that handles the record deserialization
*/
public String resolver();
/*
* The avroSchema fetched by the AvroResolver and used in case of Avro File
* In case of avro records inside a sequence file this variable will be null
* and the AvroResolver will not use it.
*/
public Object getSchema();
/*
* The avroSchema is set from the outside by the AvroFileAccessor
*/
public void setSchema(Object schema);
/*
* Returns the compression codec (can be null - means no compression)
*/
public String compressCodec();
}</pre>
</div></div><h3 id="PXFExternalTableandAPIReference-Fragmenter">Fragmenter</h3> <div class="aui-message hint shadowed information-macro">
<p class="title">Note</p>
<span class="aui-icon icon-hint">Icon</span>
<div class="message-content">
<p>The Fragmenter Plugin reads data into HAWQ. Such tables are called READABLE PXF tables. The Fragmenter Plugin cannot write data out of HAWQ. Such tables are called WRITABLE tables.</p>
</div>
</div>
<p align="LEFT">The Fragmenter is responsible for passing datasource metadata back to HAWQ. It also returns a list of data fragments to the Accessor or Resolver. Each data fragment describes some part of the requested data set. It contains the datasource name, such as the file or table name, including the hostname where it is located. For example, if the source is a HDFS file, the Fragmenter returns a list of data fragments containing a HDFS file block. Each fragment includes the location of the block. If the source data is an HBase table, the Fragmenter returns information about table regions, including their locations.</p><p align="LEFT">The following implementations are shipped with PXF 2.2 and higher:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">com.pivotal.pxf.plugins.hdfs.HdfsDataFragmenter
com.pivotal.pxf.plugins.hbase.HBaseDataFragmenter
com.pivotal.pxf.plugins.hive.HiveDataFragmenter</pre>
</div></div><p>The Fragmenter.getFragments() methods returns a List<Fragment>:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">package com.pivotal.pxf.api;
/*
* Fragment holds a data fragment' information.
* Fragmenter.getFragments() returns a list of fragments.
*/
public class Fragment
{
private String sourceName; // File path+name, table name, etc.
private int index; // Fragment index (incremented per sourceName)
private String[] replicas; // Fragment replicas (1 or more)
private byte[] metadata; // Fragment metadata information (starting point + length, region location, etc.)
private byte[] userData; // ThirdParty data added to a fragment. Ignored if null
...
}</pre>
</div></div><p>Any Fragmenter class needs to extend <em>com.pivotal.pxf.api.Fragmenter</em>:</p><h4 id="PXFExternalTableandAPIReference-com.pivotal.pxf.api.Fragmenter">com.pivotal.pxf.api.Fragmenter</h4><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">package com.pivotal.pxf.api;
/*
* Interface that defines the splitting of a data resource into fragments that can be processed in parallel
* GetFragments returns the fragments information of a given path (source name and location of each fragment).
* Used to get fragments of data that could be read in parallel from the different segments.
*/
public abstract class Fragmenter extends Plugin {
protected List<Fragment> fragments;
public Fragmenter(InputData metaData) {
super(metaData);
fragments = new LinkedList<Fragment>();
}
/*
* path is a data source URI that can appear as a file name, a directory name or a wildcard
* returns the data fragments
*/
public abstract List<Fragment> getFragments() throws Exception;
} </pre>
</div></div><h4 id="PXFExternalTableandAPIReference-ClassDescription">Class Description</h4><p><em>getFragments()</em> returns a string in a JSON format of the retrieved fragment. For example, if the input path is a HDFS directory, the source name for each fragment should include the file name including the path for the fragment. </p><h3 id="PXFExternalTableandAPIReference-Accessor"><a name="RTF37363238383a204865616432" rel="nofollow"></a>Accessor</h3><p>The Accessor retrieves specific fragments and passes records back to the Resolver. For example, the Accessor creates a <em>FileInputFormat</em> and a Record Reader for an HDFS file and sends this to the Resolver. In the case of HBase or Hive files, the Accessor returns single rows from an HBase or Hive table. PXF 1.x or higher contains the following implementations:</p><h5 id="PXFExternalTableandAPIReference-Table:Accessorbaseclasses">Table: Accessor base classes<span lang="EN"> </span></h5><div class="table-wrap"><table class="confluenceTable"><tbody><tr><td class="confluenceTd"><p align="LEFT"><strong>Accessor class</strong></p></td><td class="confluenceTd"><p align="LEFT"><strong>Description</strong></p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>com.pivotal.pxf.plugins.hdfs.HdfsAtomicDataAccessor</em></p></td><td class="confluenceTd"><p align="LEFT">Base class for accessing datasources which cannot be split. These will be accessed by a single HAWQ segment.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: plain; gutter: false" style="font-size:12px;">QuotedLineBreakAccessor - Accessor for TEXT files that has records with embedded linebreaks</pre>
</div></div></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>com.pivotal.pxf.plugins.hdfs.HdfsSplittableDataAccessor</em></p><p align="LEFT"> </p><p align="LEFT"> </p></td><td class="confluenceTd"><p align="LEFT">Base class for accessing HDFS files using <em>RecordReaders</em>:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: plain; gutter: false" style="font-size:12px;">LineBreakAccessor - Accessor for TEXT files (replaced the deprecated TextFileAccessor, LineReaderAccessor)
AvroFileAccessor - Accessor for Avro files
</pre>
</div></div><p><span style="font-size: xx-small;"> </span></p></td></tr><tr><td class="confluenceTd" colspan="1"> com.pivotal.pxf.plugins.hive.HiveAccessor</td><td class="confluenceTd" colspan="1">Accessor for Hive tables </td></tr><tr><td class="confluenceTd" colspan="1">com.pivotal.pxf.plugins.hbase.HBaseAccessor </td><td class="confluenceTd" colspan="1">Accessor for HBase tables </td></tr></tbody></table></div><p align="LEFT">The class needs to extend the <em>com.pivotal.pxf.Plugin class,</em> and implement one or both interface<em>s: </em></p><ul><li><em>com.pivotal.pxf.api.ReadAccessor</em></li><li><em>com.pivotal.pxf.api.WriteAccessor</em></li></ul><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">package com.pivotal.pxf.api;
/*
* Internal interface that defines the access to data on the source
* data store (e.g, a file on HDFS, a region of an HBase table, etc).
* All classes that implement actual access to such data sources must
* respect this interface
*/
public interface ReadAccessor {
public boolean openForRead() throws Exception;
public OneRow readNextObject() throws Exception;
public void closeForRead() throws Exception;
}</pre>
</div></div><p><span style="font-size: medium;"> </span></p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">package com.pivotal.pxf.api;
/*
* An interface for writing data into a data store
* (e.g, a sequence file on HDFS).
* All classes that implement actual access to such data sources must
* respect this interface
*/
public interface WriteAccessor {
public boolean openForWrite() throws Exception;
public OneRow writeNextObject(OneRow onerow) throws Exception;
public void closeForWrite() throws Exception;
}</pre>
</div></div><p><span style="font-size: medium;"> </span></p><p align="LEFT">The Accessor calls o<em>penForRead() to read existing data</em>. After reading the data, it calls c<em>loseForRead()</em>. <em>readNextObject()</em> and returns one of the following:</p><ul><li>a single record, encapsulated in a OneRow object</li><li>null if it reaches <em>EOF</em></li></ul><p align="LEFT">The Accessor calls<em> openForWrite() </em>to write data out.<em> </em>After writing the data, it writes a <em>OneRow</em> object with <em>writeNextObject()</em>, and when done calls <em>closeForWrite()</em>. <em>OneRow</em> represents a key-value item.</p><h4 id="PXFExternalTableandAPIReference-com.pivotal.pxf.api.OneRow:">com.pivotal.pxf.api.OneRow:</h4><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">package com.pivotal.pxf.api;
/*
* Represents one row in the external system data store. Supports
* the general case where one row contains both a record and a
* separate key like in the HDFS key/value model for MapReduce
* (Example: HDFS sequence file)
*/
public class OneRow {
/*
* Default constructor
*/
public OneRow()
/*
* Constructor sets key and data
*/
public OneRow(Object inKey, Object inData)
/*
* Copy constructor
*/
public OneRow(OneRow copy)
/*
* Setter for key
*/
public void setKey(Object inKey)
/*
* Setter for data
*/
public void setData(Object inData)
/*
* Accessor for key
*/
public Object getKey()
/*
* Accessor for data
*/
public Object getData()
/*
* Show content
*/
public String toString()
}</pre>
</div></div><h3 id="PXFExternalTableandAPIReference-Resolver">Resolver</h3><p>The Resolver deserializes records in the <em>OneRow</em> format and serializes them to a list of <em>OneField</em> objects. PXF converts a <em>OneField</em> object to a HAWQ-readable <em>GPDBWritable</em> format. PXF 1.x or higher contains the following implementations:</p><h5 id="PXFExternalTableandAPIReference-Table:Resolverbaseclasses">Table: Resolver base classes<span lang="EN"> </span></h5><div class="table-wrap"><table class="confluenceTable"><tbody><tr><td class="confluenceTd"><p align="LEFT"><strong>Resolver class</strong></p></td><td class="confluenceTd"><p align="LEFT"><strong>Description</strong></p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>com.pivotal.pxf.plugins.hdfs.StringPassResolver</em></p><p align="LEFT"> </p><p align="LEFT"> </p></td><td class="confluenceTd"><p align="LEFT">Supports:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">GPBWritable VARCHAR</pre>
</div></div><p><em>StringPassResolver </em>replaced the deprecated <em>TextResolver. </em>It passes whole records (composed of any data types) as strings without parsing them</p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>com.pivotal.pxf.plugins.hdfs.WritableResolver</em></p></td><td class="confluenceTd"><p align="LEFT">Resolver for custom Hadoop Writable implementations. Custom class can be specified with the schema<em> {{,}}</em> and supports the following:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">DataType.BOOLEAN
DataType.INTEGER
DataType.BIGINT
DataType.REAL
DataType.FLOAT8
DataType.VARCHAR
DataType.BYTEA</pre>
</div></div></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>com.pivotal.pxf.plugins.hdfs.AvroResolver</em></p></td><td class="confluenceTd"><p align="LEFT">Supports the same field objects as <em>WritableResolver</em>. </p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>com.pivotal.pxf.plugins.hbase.HBaseResolver</em></p></td><td class="confluenceTd"><p align="LEFT">Supports the same field objects as <em>WritableResolver</em> and also supports the following:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">DataType.SMALLINT
DataType.NUMERIC
DataType.TEXT
DataType.BPCHAR
DataType.TIMESTAMP</pre>
</div></div></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>com.pivotal.pxf.plugins.hive.HiveResolver</em></p><p align="LEFT"> </p><p align="LEFT"> </p></td><td class="confluenceTd"><p align="LEFT">Supports the same field objects as <em>WritableResolver</em> and also supports the following:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">DataType.SMALLINT
DataType.TEXT
DataType.TIMESTAMP</pre>
</div></div></td></tr></tbody></table></div><p>The class needs to extend the <em>com.pivotal.pxf.resolvers.Plugin class </em>, and implement one or both interface<em>s: </em></p><ul><li><em>com.pivotal.pxf.api.ReadResolver</em></li><li><em>com.pivotal.pxf.api.WriteResolver</em></li></ul><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">package com.pivotal.pxf.api;
/*
* Interface that defines the deserialization of one record brought from
* the data Accessor. Every implementation of a deserialization method
* (e.g, Writable, Avro, ...) must implement this interface.
*/
public interface ReadResolver {
public List<OneField> getFields(OneRow row) throws Exception;
}</pre>
</div></div><p><em><br/></em></p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">package com.pivotal.pxf.api;
/*
* Interface that defines the serialization of data read from the DB
* into a OneRow object.
* Every implementation of a serialization method
* (e.g, Writable, Avro, ...) must implement this interface.
*/
public interface WriteResolver {
public OneRow setFields(List<OneField> record) throws Exception;
}</pre>
</div></div> <div class="aui-message hint shadowed information-macro">
<p class="title">Notes</p>
<span class="aui-icon icon-hint">Icon</span>
<div class="message-content">
<ul><li>getFields should return a List<OneField>, each OneField representing a single field.</li><li><em>setFields </em>should return a single <em>OneRow </em>object, given a List<OneField>.</li></ul>
</div>
</div>
<p> </p><h4 id="PXFExternalTableandAPIReference-com.pivotal.pxf.api.OneField">com.pivotal.pxf.api.OneField</h4><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">package com.pivotal.pxf.api;
/*
* Defines one field on a deserialized record.
* 'type' is in OID values recognized by GPDBWritable
* 'val' is the actual field value
*/
public class OneField {
public OneField() {}
public OneField(int type, Object val) {
this.type = type;
this.val = val;
}
public int type;
public Object val;
}</pre>
</div></div><p> </p><p>The value of t<em>ype</em> should follow the com.pivotal.pxf.api.io.DataType <em>enums</em>. v<em>al</em> is the appropriate Java class. Supported types are as follows:</p><h4 id="PXFExternalTableandAPIReference-Table:Resolversupportedtypes">Table: Resolver supported types</h4><div class="table-wrap"><table class="confluenceTable"><tbody><tr><td class="confluenceTd"><p align="LEFT"><strong>DataType recognized OID</strong></p></td><td class="confluenceTd"><p align="LEFT"><strong>Field value</strong></p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>DataType.SMALLINT</em></p></td><td class="confluenceTd"><p align="LEFT"><em>Short</em></p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>DataType.INTEGER</em></p></td><td class="confluenceTd"><p align="LEFT"><em>Integer</em></p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>DataType.BIGINT</em></p></td><td class="confluenceTd"><p align="LEFT"><em>Long</em></p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>DataType.REAL </em></p></td><td class="confluenceTd"><p align="LEFT"><em>Float</em></p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>DataType.FLOAT8</em></p></td><td class="confluenceTd"><p align="LEFT"><em>Double</em></p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>DataType.NUMERIC</em></p></td><td class="confluenceTd"><p align="LEFT"><em>String ( "651687465135468432168421") </em></p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>DataType.BOOLEAN</em></p></td><td class="confluenceTd"><p align="LEFT">Boolean</p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>DataType.VARCHAR</em><em style="line-height: 1.4285;background-color: transparent;"> </em></p></td><td class="confluenceTd"> </td></tr><tr><td class="confluenceTd" colspan="1"><em>DataType.BPCHAR</em></td><td class="confluenceTd" colspan="1"> </td></tr><tr><td class="confluenceTd" colspan="1"><em>DataType.TEXT</em></td><td class="confluenceTd" colspan="1"><em>String</em></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>DataType.BYTEA</em></p></td><td class="confluenceTd"><p align="LEFT"><em>byte [] </em></p></td></tr><tr><td class="confluenceTd"><p align="LEFT"><em>DataType.TIMESTAMP</em></p></td><td class="confluenceTd"><p align="LEFT"><em>Timestamp</em></p></td></tr></tbody></table></div><h3 id="PXFExternalTableandAPIReference-Analyzer">Analyzer</h3><p align="LEFT">The Analyzer provides PXF statistical data for the HAWQ query optimizer. For a detailed explanation about HAWQ statistical data gathering, see <em>ANALYZE</em> in the <em>Pivotal ADS Administrator Guide</em>. Implement the PXF Analyzer for the HDFS text, sequence, and AVRO files. For HBase tables and Hive tables, the Analyzer returns default values.</p><p align="LEFT"><strong>Notes</strong>:</p><ul><li>The new <em>boolean guc pxf_enable_stat_collection</em> requests statistics. The default value is <em>on</em>. When you turn it off, the statistics collected reflect default values.</li><li>Pivotal recommends that you implement the Analyzer to return an estimated result as fast as possible.</li></ul><p align="LEFT">The class needs to extend <em>com.pivotal.pxf.api.Analyzer</em>.</p><h4 id="PXFExternalTableandAPIReference-com.pivotal.pxf.analyzers.Analyzer">com.pivotal.pxf.analyzers.Analyzer</h4><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">package com.pivotal.pxf.api;
import com.pivotal.pxf.api.utilities.InputData;
import com.pivotal.pxf.api.utilities.Plugin;
/*
* Abstract class that defines getting statistics for ANALYZE.
* getEstimatedStats returns statistics for a given path
* (block size, number of blocks, number of tuples).
* Used when calling ANALYZE on a PXF external table, to get
* table's statistics that are used by the optimizer to plan queries.
*/
public abstract class Analyzer extends Plugin
{
public Analyzer(InputData inputData)
{
super(inputData);
}
/*
* 'path' is the data source name (e.g, file, dir, wildcard, table name).
* returns the data statistics in json format.
*
* NOTE: It is highly recommended to implement an extremely fast logic
* that returns *estimated* statistics. Scanning all the data for exact
* statistics is considered bad practice.
*/
public AnalyzerStats getEstimatedStats(String data) throws Exception
{
/* Return default values */
return new AnalyzerStats();
}
}</pre>
</div></div><p align="LEFT"><em>getEstimatedStats</em> creates a<em>n AnalyzerStats</em> , and returns the result <em>AnalyzerStats</em><em>.dataToJSON</em>.</p><h4 id="PXFExternalTableandAPIReference-com.pivotal.pxf.api.AnalyzerStats">com.pivotal.pxf.api.<em>AnalyzerStats</em></h4><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="theme: Confluence; brush: java; gutter: false" style="font-size:12px;">package com.pivotal.pxf.api;
import java.io.IOException;
import org.codehaus.jackson.map.ObjectMapper;
/*
* AnalyzerStats is a public class that represents the size
* information of given path.
*/
public class AnalyzerStats {
private static final long DEFAULT_BLOCK_SIZE = 67108864L; // 64MB (in bytes)
private static final long DEFAULT_NUMBER_OF_BLOCKS = 1L;
private static final long DEFAULT_NUMBER_OF_TUPLES = 1000000L;
private long blockSize; // block size (in bytes)
private long numberOfBlocks; // number of blocks