de.julielab.xmlData.dataBase

Class ThreadedColumnsToRetrieveIterator

java.lang.Object

de.julielab.xmlData.dataBase.DBCIterator<E>

de.julielab.xmlData.dataBase.DBCThreadedIterator<byte[][]>

de.julielab.xmlData.dataBase.ThreadedColumnsToRetrieveIterator

All Implemented Interfaces:

Iterator<byte[][]>

public class ThreadedColumnsToRetrieveIterator
extends DBCThreadedIterator<byte[][]>

An iterator that returns documents stored in the database identified by the primary keys delivered in a list upon creation of the iterator. The returned data corresponds to the columns marked to be retrieved in the table schema also given at iterator creation.
The iterator employs two threads to retrieve new documents from the database while other documents, fetched before, can be processed concurrently. The idea is that the database can work in parallel to the program working with the retrieved documents.

Author:

hellrich

Field Summary

Fields inherited from class de.julielab.xmlData.dataBase.DBCThreadedIterator

backgroundThread, listExchanger

Constructor Summary

Constructors

Constructor and Description
ThreadedColumnsToRetrieveIterator(DataBaseConnector dbc, Connection conn, List<Object[]> ids, String[] tables, String[] schemaNames) Retrieves data from the database over multiple tables.
ThreadedColumnsToRetrieveIterator(DataBaseConnector dbc, Connection conn, List<Object[]> ids, String table, String schemaName)
ThreadedColumnsToRetrieveIterator(DataBaseConnector dbc, Connection conn, List<Object[]> ids, String table, String whereClause, String schemaName)
ThreadedColumnsToRetrieveIterator(DataBaseConnector dbc, List<Object[]> ids, String[] tables, String[] schemaNames)
ThreadedColumnsToRetrieveIterator(DataBaseConnector dbc, List<Object[]> ids, String table, String schemaName)
ThreadedColumnsToRetrieveIterator(DataBaseConnector dbc, List<Object[]> ids, String table, String whereClause, String schemaName)

Method Summary

Modifier and Type	Method and Description
void	close() Frees resources occupied by this iterator (e.g.

Methods inherited from class de.julielab.xmlData.dataBase.DBCThreadedIterator

hasNext, next, remove, update

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Iterator

forEachRemaining

Constructor Detail

ThreadedColumnsToRetrieveIterator

public ThreadedColumnsToRetrieveIterator(DataBaseConnector dbc,
                                         Connection conn,
                                         List<Object[]> ids,
                                         String table,
                                         String schemaName)

ThreadedColumnsToRetrieveIterator

public ThreadedColumnsToRetrieveIterator(DataBaseConnector dbc,
                                         List<Object[]> ids,
                                         String table,
                                         String schemaName)

ThreadedColumnsToRetrieveIterator

public ThreadedColumnsToRetrieveIterator(DataBaseConnector dbc,
                                         List<Object[]> ids,
                                         String table,
                                         String whereClause,
                                         String schemaName)

ThreadedColumnsToRetrieveIterator

public ThreadedColumnsToRetrieveIterator(DataBaseConnector dbc,
                                         Connection conn,
                                         List<Object[]> ids,
                                         String table,
                                         String whereClause,
                                         String schemaName)

ThreadedColumnsToRetrieveIterator

public ThreadedColumnsToRetrieveIterator(DataBaseConnector dbc,
                                         Connection conn,
                                         List<Object[]> ids,
                                         String[] tables,
                                         String[] schemaNames)

Retrieves data from the database over multiple tables. All tables will be joined on the given IDs. The columns to be retrieved for each table is determined by its table schema. For this purpose, the tables and schemaName arrays are required to be parallel.

Parameters:

dbc - A DataBaseConnector instance

conn - An active database connection

ids - A list of primary keys identifying the items to retrieve.

tables - The tables from which the items should be retrieved that are identified by ids.

schemaNames - A parallel array to tables thas specifies the table schema name of each table.

ThreadedColumnsToRetrieveIterator

public ThreadedColumnsToRetrieveIterator(DataBaseConnector dbc,
                                         List<Object[]> ids,
                                         String[] tables,
                                         String[] schemaNames)

Method Detail

close

public void close()

Description copied from class: DBCIterator

Frees resources occupied by this iterator (e.g. database connections).

Overrides:

close in class DBCThreadedIterator<byte[][]>