All Downloads are FREE. Search and download functionalities are using the official Maven repository.

de.akquinet.jbosscc.guttenbase.statements.SplitByColumnSelectCountStatementCreator Maven / Gradle / Ivy

The newest version!
package de.akquinet.jbosscc.guttenbase.statements;

import de.akquinet.jbosscc.guttenbase.hints.SplitColumnHint;
import de.akquinet.jbosscc.guttenbase.meta.ColumnMetaData;
import de.akquinet.jbosscc.guttenbase.meta.TableMetaData;
import de.akquinet.jbosscc.guttenbase.repository.ConnectorRepository;
import de.akquinet.jbosscc.guttenbase.tools.SplitColumn;

import java.util.List;

/**
 * Sometimes the amount of data in the result set exceeds any buffer. In these cases we need to split the data by some given range, usually
 * the primary key. I.e., the data is read in chunks where these chunks are split using the ID column range of values.
 * 

* With this statement we count the number of rows that actually will be read for the given chunk. * *

* © 2012-2034 akquinet tech@spree *

*

* Hint is used by {@link SplitColumnHint} * * @author M. Dahm */ public class SplitByColumnSelectCountStatementCreator extends AbstractSelectStatementCreator { public SplitByColumnSelectCountStatementCreator(final ConnectorRepository connectorRepository, final String connectorId) { super(connectorRepository, connectorId); } @Override protected String createColumnClause(final List columns) { return "COUNT(*)"; } @Override protected String createWhereClause(final TableMetaData tableMetaData) { final ColumnMetaData splitColumn = _connectorRepository.getConnectorHint(_connectorId, SplitColumn.class).getValue() .getSplitColumn(tableMetaData); return "WHERE " + splitColumn.getColumnName() + " BETWEEN ? AND ?"; } }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy