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org/hibernate/hql/ast/exec/MultiTableDeleteExecutor.java
// $Id: MultiTableDeleteExecutor.java 11287 2007-03-15 11:38:25Z [email protected] $
package org.hibernate.hql.ast.exec;

import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.Iterator;

import org.hibernate.HibernateException;
import org.hibernate.engine.QueryParameters;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.exception.JDBCExceptionHelper;
import org.hibernate.hql.ast.HqlSqlWalker;
import org.hibernate.hql.ast.tree.DeleteStatement;
import org.hibernate.hql.ast.tree.FromElement;
import org.hibernate.param.ParameterSpecification;
import org.hibernate.persister.entity.Queryable;
import org.hibernate.sql.Delete;
import org.hibernate.util.StringHelper;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Implementation of MultiTableDeleteExecutor.
 *
 @author Steve Ebersole
 */
public class MultiTableDeleteExecutor extends AbstractStatementExecutor {
  private static final Log log = LogFactory.getLogMultiTableDeleteExecutor.class );

  private final Queryable persister;
  private final String idInsertSelect;
  private final String[] deletes;

  public MultiTableDeleteExecutor(HqlSqlWalker walker) {
    superwalker, log );

    if !walker.getSessionFactoryHelper().getFactory().getDialect().supportsTemporaryTables() ) {
      throw new HibernateException"cannot perform multi-table deletes using dialect not supporting temp tables" );
    }

    DeleteStatement deleteStatement = DeleteStatement walker.getAST();
    FromElement fromElement = deleteStatement.getFromClause().getFromElement();
    String bulkTargetAlias = fromElement.getTableAlias();
    this.persister = fromElement.getQueryable();

    this.idInsertSelect = generateIdInsertSelectpersister, bulkTargetAlias, deleteStatement.getWhereClause() );
    log.trace"Generated ID-INSERT-SELECT SQL (multi-table delete) : " +  idInsertSelect );

    String[] tableNames = persister.getConstraintOrderedTableNameClosure();
    String[][] columnNames = persister.getContraintOrderedTableKeyColumnClosure();
    String idSubselect = generateIdSubselectpersister );

    deletes = new String[tableNames.length];
    for int i = tableNames.length - 1; i >= 0; i-- ) {
      // TODO : an optimization here would be to consider cascade deletes and not gen those delete statements;
      //      the difficulty is the ordering of the tables here vs the cascade attributes on the persisters ->
      //          the table info gotten here should really be self-contained (i.e., a class representation
      //          defining all the needed attributes), then we could then get an array of those
      final Delete delete = new Delete()
          .setTableNametableNames[i] )
          .setWhere"(" + StringHelper.join", ", columnNames[i] ) ") IN (" + idSubselect + ")" );
      if getFactory().getSettings().isCommentsEnabled() ) {
        delete.setComment"bulk delete" );
      }

      deletes[i= delete.toStatementString();
    }
  }

  public String[] getSqlStatements() {
    return deletes;
  }

  public int execute(QueryParameters parameters, SessionImplementor sessionthrows HibernateException {
    coordinateSharedCacheCleanupsession );

    createTemporaryTableIfNecessarypersister, session );

    try {
      // First, save off the pertinent ids, saving the number of pertinent ids for return
      PreparedStatement ps = null;
      int resultCount = 0;
      try {
        try {
          ps = session.getBatcher().prepareStatementidInsertSelect );
          Iterator paramSpecifications = getWalker().getParameters().iterator();
          int pos = 1;
          while paramSpecifications.hasNext() ) {
            final ParameterSpecification paramSpec = ParameterSpecification paramSpecifications.next();
            pos += paramSpec.bindps, parameters, session, pos );
          }
          resultCount = ps.executeUpdate();
        }
        finally {
          if ps != null ) {
            session.getBatcher().closeStatementps );
          }
        }
      }
      catchSQLException e ) {
        throw JDBCExceptionHelper.convert(
            getFactory().getSQLExceptionConverter(),
                e,
                "could not insert/select ids for bulk delete",
                idInsertSelect
          );
      }

      // Start performing the deletes
      for int i = 0; i < deletes.length; i++ ) {
        try {
          try {
            ps = session.getBatcher().prepareStatementdeletes[i] );
            ps.executeUpdate();
          }
          finally {
            if ps != null ) {
              session.getBatcher().closeStatementps );
            }
          }
        }
        catchSQLException e ) {
          throw JDBCExceptionHelper.convert(
              getFactory().getSQLExceptionConverter(),
                  e,
                  "error performing bulk delete",
                  deletes[i]
            );
        }
      }

      return resultCount;
    }
    finally {
      dropTemporaryTableIfNecessarypersister, session );
    }
  }

  protected Queryable[] getAffectedQueryables() {
    return new Queryable[] { persister };
  }
}