This is likely an issue with MySQL driver caching returned data. The
solution was implemented in Cayenne 3.0 (which is now in beta):
query.setStatementFetchSize(1000);
This propagates the fetch size setting to the JDBC statement, reducing
the driver memory footprint.
Andrus
On Dec 24, 2009, at 9:43 AM, Emanuele Maiarelli wrote:
> im using cayenne 2.0.4, and i need to fetch an huge ammout of data,
> i did that way:
>
>
> public static StringBuffer traceProts;
>
>
> static {
> traceProts = new StringBuffer();
> traceProts.append("SELECT ");
> traceProts.append("PROTOCOLLI.* ");
> traceProts.append("FROM PROTOCOLLI, ");
> traceProts.append("( ");
> traceProts.append(" SELECT ");
> traceProts.append(" FORM_PROT_FK ");
> traceProts.append(" FROM ");
> traceProts.append(" ( ");
> traceProts.append(" SELECT ");
> traceProts.append(" FORM_PROT_FK,SUM(IF(ME_PK is not null,
> 1,0)) AS ESPORTAZIONI ");
> traceProts.append(" FROM FORMULARI ");
> traceProts.append(" LEFT JOIN MOV_EXPORTED ON
> (FORM_PK=ME_FORMULARI_FK) ");
> traceProts.append(" GROUP BY FORM_PROT_FK ");
> traceProts.append(" ) ");
> traceProts.append(" EXPS ");
> traceProts.append(" WHERE ESPORTAZIONI=0 ");
> traceProts.append(") ");
> traceProts.append("UNEXP ");
> traceProts.append("where PROT_PK=UNEXP.FORM_PROT_FK");
> }
>
> this query returns an huge ammont of row,
>
> and im fetching row using IteratedQuery, that's the code im using
>
> StringBuffer mq=new StringBuffer();
> Vector<EXPProtocolli> toRet=new Vector<EXPProtocolli>();
> mq.append(traceProts);
> mq.append(" AND PROT_CHIUSO=true AND PROT_RIPARTITO=true");
> SQLTemplate rawSelect = new SQLTemplate(Protocolli.class,
> mq.toString());
> ResultIterator v=ctx.performIteratedQuery(rawSelect);
> while (v.hasNextRow())
> {
> EXPProtocolli prt=new EXPProtocolli();
> DataRow dataRow = (DataRow) v.nextDataRow();
>
> Protocolli p=(Protocolli)
> ctx.objectFromDataRow(Protocolli.class, dataRow,false);
>
> this.bindEXPProtMsg(p,prt);
> prt.setStato(ProtStato.PROT_CARICO_ESPORTABILE);
> toRet.add(prt);
> }
> return toRet;
>
> when running this method i always get an heap space problem
>
> java.lang.OutOfMemoryError: Java heap space
> at com.mysql.jdbc.MysqlIO.nextRowFast(MysqlIO.java:1621)
> at com.mysql.jdbc.MysqlIO.nextRow(MysqlIO.java:1398)
> at com.mysql.jdbc.MysqlIO.readSingleRowSet(MysqlIO.java:2816)
> at com.mysql.jdbc.MysqlIO.getResultSet(MysqlIO.java:467)
> at
> com.mysql.jdbc.MysqlIO.readResultsForQueryOrUpdate(MysqlIO.java:2510)
> at com.mysql.jdbc.MysqlIO.readAllResults(MysqlIO.java:1746)
> at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2135)
> at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:
> 2542)
> at
> com
> .mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:
> 1734)
> at
> com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:995)
> at
> org
> .apache
> .cayenne
> .access.jdbc.SQLTemplateAction.execute(SQLTemplateAction.java:135)
> at
> org
> .apache
> .cayenne
> .access.jdbc.SQLTemplateAction.performAction(SQLTemplateAction.java:
> 107)
> at
> org
> .apache
> .cayenne
> .access.DataNodeQueryAction.runQuery(DataNodeQueryAction.java:59)
> at
> org.apache.cayenne.access.DataNode.performQueries(DataNode.java:273)
> at
> org
> .apache
> .cayenne
> .access
> .DataDomainLegacyQueryAction
> .execute(DataDomainLegacyQueryAction.java:81)
> at org.apache.cayenne.access.DataDomain
> $1.transform(DataDomain.java:725)
> at
> org
> .apache.cayenne.access.DataDomain.runInTransaction(DataDomain.java:
> 826)
> at
> org.apache.cayenne.access.DataDomain.performQueries(DataDomain.java:
> 722)
> at
> org
> .apache
> .cayenne
> .access.DataContext.internalPerformIteratedQuery(DataContext.java:
> 1329)
> at
> org
> .apache
> .cayenne.access.DataContext.performIteratedQuery(DataContext.java:
> 1295)
> at services.EXP.Factory.getProtocolliCaricoNonEsp(Factory.java:
> 85)
> at services.EXP.EXPServicePBE.getData(EXPServicePBE.java:54)
> at services.EXPExporter.processRequest(EXPExporter.java:52)
> ....
>
> the error is generated by: ResultIterator
> v=ctx.performIteratedQuery(rawSelect);
>
> any hints?
>
>
>
>
>
This archive was generated by hypermail 2.0.0 : Thu Dec 24 2009 - 03:53:27 EST