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/**
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* '$RCSfile$'
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* Purpose: An adapter class for PostgreSQL RDBMS.
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* Copyright: 2000 Regents of the University of California and the
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* National Center for Ecological Analysis and Synthesis
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* Authors: Jivka Bojilova
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* Release: @release@
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*
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* '$Author: sgarg $'
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* '$Date: 2005-11-10 13:22:57 -0800 (Thu, 10 Nov 2005) $'
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* '$Revision: 2728 $'
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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package edu.ucsb.nceas.dbadapter;
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import java.sql.*;
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import edu.ucsb.nceas.metacat.*;
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/**
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* The PostgreSQL db adapter implementation.
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*/
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public class PostgresqlAdapter extends AbstractDatabase {
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/**
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* The PostgreSQL unique ID /sequence generator
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* The name of the sequence used to generate the unique id
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* is made from the name of the table that uses the id by
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* appending "_id_seq" to it.
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* When record is inserted in the table and insert trigger gets
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* a nextval from that sequence, select currval of that sequence
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* can return the generated key in the same db connection.
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*
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* @param conn db connection in which the unique id was generated
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* @param tableName the name of table which unique id was generate
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* @exception SQLException any SQLException that can be thrown
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* during the db operation
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* @return return the generated unique id as a long type
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*/
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public long getUniqueID(Connection conn, String tableName)
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throws SQLException {
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long uniqueid = 0;
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Statement stmt = null;
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stmt = conn.createStatement();
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stmt.execute("SELECT currval('" + tableName + "_id_seq')");
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ResultSet rs = stmt.getResultSet();
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if ( rs.next() )
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{
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uniqueid = rs.getLong(1);
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}
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stmt.close();
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return uniqueid;
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}
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/**
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* The PostgreSQL function name that gets the current date
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* and time from the database server
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*
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* @return return the current date and time function name: "now()"
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*/
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public String getDateTimeFunction() {
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//System.out.println("The date and time function: " + "now()");
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//to return just the date use now()::date
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//and for the time use now()::time
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return "now()";
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}
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/**
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* The PostgreSQL function name that is used to return non-NULL value
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*
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* @return return the non-NULL function name: "coalesce"
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*/
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public String getIsNULLFunction() {
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return "coalesce";
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}
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/**
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* PostgreSQL's string delimiter character: single quote (')
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*
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* @return return the string delimiter: single quote (')
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*/
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public String getStringDelimiter() {
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return "\"";
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}
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/**
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* PostgreSQL's syntax for doing a left join
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* Add 'a.' in front of the fields for first table and
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* 'b.' in front of the fields for the second table
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*
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* @param selectFields fields that you want to be selected
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* @param tableA first table in the join
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* @param tableB second table in the join
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* @param joinCriteria the criteria based on which the join will be made
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* @param nonJoinCriteria all other criterias
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* @return return the string for teh select query
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*/
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public String getLeftJoinQuery(String selectFields, String tableA,
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String tableB, String joinCriteria, String nonJoinCriteria){
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return "SELECT " + selectFields + " FROM " + tableA + " a LEFT JOIN "
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+ tableB + " b ON " + joinCriteria + " WHERE ("
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+ nonJoinCriteria +")";
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}
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/**
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* Return a hard code string to get xml_document list in timed replcation
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*/
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public String getReplicationDocumentListSQL()
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{
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String sql ="select a.docid, a.rev, a.doctype from ( xml_documents as a left outer join xml_revisions as b on (a.docid=b.docid and a.rev<=b.rev)) where b.docid is null ";
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return sql;
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}
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}
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