Package org.hibernate.dialect

Source Code of org.hibernate.dialect.HSQLDialect$ReadUncommittedLockingStrategy

/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2010, Red Hat Inc. or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors.  All third-party contributions are
* distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA  02110-1301  USA
*/
package org.hibernate.dialect;

import java.sql.SQLException;
import java.sql.Types;
import java.io.Serializable;

import org.hibernate.Hibernate;
import org.hibernate.LockMode;
import org.hibernate.StaleObjectStateException;
import org.hibernate.JDBCException;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.persister.entity.Lockable;
import org.hibernate.cfg.Environment;
import org.hibernate.dialect.function.AvgWithArgumentCastFunction;
import org.hibernate.dialect.function.SQLFunctionTemplate;
import org.hibernate.dialect.function.NoArgSQLFunction;
import org.hibernate.dialect.function.StandardSQLFunction;
import org.hibernate.dialect.function.VarArgsSQLFunction;
import org.hibernate.dialect.lock.*;
import org.hibernate.exception.JDBCExceptionHelper;
import org.hibernate.exception.TemplatedViolatedConstraintNameExtracter;
import org.hibernate.exception.ViolatedConstraintNameExtracter;
import org.hibernate.util.ReflectHelper;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
* An SQL dialect compatible with HSQLDB (HyperSQL).
* <p/>
* Note this version supports HSQLDB version 1.8 and higher, only.
* <p/>
* Enhancements to version 3.5.0 GA to provide basic support for both HSQLDB 1.8.x and 2.0
* Should work with Hibernate 3.2 and later
*
* @author Christoph Sturm
* @author Phillip Baird
* @author Fred Toussi
*/
public class HSQLDialect extends Dialect {


  private static final Logger log = LoggerFactory.getLogger( HSQLDialect.class );

  /**
   * version is 18 for 1.8 or 20 for 2.0
   */
  private int hsqldbVersion = 18;


  public HSQLDialect() {
    super();

    try {
      Class props = ReflectHelper.classForName( "org.hsqldb.persist.HsqlDatabaseProperties" );
      String versionString = (String) props.getDeclaredField( "THIS_VERSION" ).get( null );

      hsqldbVersion = Integer.parseInt( versionString.substring( 0, 1 ) ) * 10;
      hsqldbVersion += Integer.parseInt( versionString.substring( 2, 3 ) );
    }
    catch ( Throwable e ) {
      // must be a very old version
    }

    registerColumnType( Types.BIGINT, "bigint" );
    registerColumnType( Types.BINARY, "binary" );
    registerColumnType( Types.BIT, "bit" );
        registerColumnType( Types.BOOLEAN, "boolean" );
    registerColumnType( Types.CHAR, "char($l)" );
    registerColumnType( Types.DATE, "date" );

    registerColumnType( Types.DECIMAL, "decimal($p,$s)" );
    registerColumnType( Types.DOUBLE, "double" );
    registerColumnType( Types.FLOAT, "float" );
    registerColumnType( Types.INTEGER, "integer" );
    registerColumnType( Types.LONGVARBINARY, "longvarbinary" );
    registerColumnType( Types.LONGVARCHAR, "longvarchar" );
    registerColumnType( Types.SMALLINT, "smallint" );
    registerColumnType( Types.TINYINT, "tinyint" );
    registerColumnType( Types.TIME, "time" );
    registerColumnType( Types.TIMESTAMP, "timestamp" );
    registerColumnType( Types.VARCHAR, "varchar($l)" );
    registerColumnType( Types.VARBINARY, "varbinary($l)" );

    if ( hsqldbVersion < 20 ) {
      registerColumnType( Types.NUMERIC, "numeric" );
    }
    else {
      registerColumnType( Types.NUMERIC, "numeric($p,$s)" );
    }

    //HSQL has no Blob/Clob support .... but just put these here for now!
    if ( hsqldbVersion < 20 ) {
      registerColumnType( Types.BLOB, "longvarbinary" );
      registerColumnType( Types.CLOB, "longvarchar" );
    }
    else {
      registerColumnType( Types.BLOB, "blob" );
      registerColumnType( Types.CLOB, "clob" );
    }

    registerFunction( "avg", new AvgWithArgumentCastFunction( "double" ) );

    registerFunction( "ascii", new StandardSQLFunction( "ascii", Hibernate.INTEGER ) );
    registerFunction( "char", new StandardSQLFunction( "char", Hibernate.CHARACTER ) );
    registerFunction( "lower", new StandardSQLFunction( "lower" ) );
    registerFunction( "upper", new StandardSQLFunction( "upper" ) );
    registerFunction( "lcase", new StandardSQLFunction( "lcase" ) );
    registerFunction( "ucase", new StandardSQLFunction( "ucase" ) );
    registerFunction( "soundex", new StandardSQLFunction( "soundex", Hibernate.STRING ) );
    registerFunction( "ltrim", new StandardSQLFunction( "ltrim" ) );
    registerFunction( "rtrim", new StandardSQLFunction( "rtrim" ) );
    registerFunction( "reverse", new StandardSQLFunction( "reverse" ) );
    registerFunction( "space", new StandardSQLFunction( "space", Hibernate.STRING ) );
    registerFunction( "rawtohex", new StandardSQLFunction( "rawtohex" ) );
    registerFunction( "hextoraw", new StandardSQLFunction( "hextoraw" ) );
    registerFunction( "str", new SQLFunctionTemplate( Hibernate.STRING, "cast(?1 as varchar(24))" ) );
    registerFunction( "user", new NoArgSQLFunction( "user", Hibernate.STRING ) );
    registerFunction( "database", new NoArgSQLFunction( "database", Hibernate.STRING ) );

    registerFunction( "sysdate", new NoArgSQLFunction( "sysdate", Hibernate.DATE, false ) );
    registerFunction( "current_date", new NoArgSQLFunction( "current_date", Hibernate.DATE, false ) );
    registerFunction( "curdate", new NoArgSQLFunction( "curdate", Hibernate.DATE ) );
    registerFunction(
        "current_timestamp", new NoArgSQLFunction( "current_timestamp", Hibernate.TIMESTAMP, false )
    );
    registerFunction( "now", new NoArgSQLFunction( "now", Hibernate.TIMESTAMP ) );
    registerFunction( "current_time", new NoArgSQLFunction( "current_time", Hibernate.TIME, false ) );
    registerFunction( "curtime", new NoArgSQLFunction( "curtime", Hibernate.TIME ) );
    registerFunction( "day", new StandardSQLFunction( "day", Hibernate.INTEGER ) );
    registerFunction( "dayofweek", new StandardSQLFunction( "dayofweek", Hibernate.INTEGER ) );
    registerFunction( "dayofyear", new StandardSQLFunction( "dayofyear", Hibernate.INTEGER ) );
    registerFunction( "dayofmonth", new StandardSQLFunction( "dayofmonth", Hibernate.INTEGER ) );
    registerFunction( "month", new StandardSQLFunction( "month", Hibernate.INTEGER ) );
    registerFunction( "year", new StandardSQLFunction( "year", Hibernate.INTEGER ) );
    registerFunction( "week", new StandardSQLFunction( "week", Hibernate.INTEGER ) );
    registerFunction( "quarter", new StandardSQLFunction( "quarter", Hibernate.INTEGER ) );
    registerFunction( "hour", new StandardSQLFunction( "hour", Hibernate.INTEGER ) );
    registerFunction( "minute", new StandardSQLFunction( "minute", Hibernate.INTEGER ) );
    registerFunction( "second", new StandardSQLFunction( "second", Hibernate.INTEGER ) );
    registerFunction( "dayname", new StandardSQLFunction( "dayname", Hibernate.STRING ) );
    registerFunction( "monthname", new StandardSQLFunction( "monthname", Hibernate.STRING ) );

    registerFunction( "abs", new StandardSQLFunction( "abs" ) );
    registerFunction( "sign", new StandardSQLFunction( "sign", Hibernate.INTEGER ) );

    registerFunction( "acos", new StandardSQLFunction( "acos", Hibernate.DOUBLE ) );
    registerFunction( "asin", new StandardSQLFunction( "asin", Hibernate.DOUBLE ) );
    registerFunction( "atan", new StandardSQLFunction( "atan", Hibernate.DOUBLE ) );
    registerFunction( "cos", new StandardSQLFunction( "cos", Hibernate.DOUBLE ) );
    registerFunction( "cot", new StandardSQLFunction( "cot", Hibernate.DOUBLE ) );
    registerFunction( "exp", new StandardSQLFunction( "exp", Hibernate.DOUBLE ) );
    registerFunction( "log", new StandardSQLFunction( "log", Hibernate.DOUBLE ) );
    registerFunction( "log10", new StandardSQLFunction( "log10", Hibernate.DOUBLE ) );
    registerFunction( "sin", new StandardSQLFunction( "sin", Hibernate.DOUBLE ) );
    registerFunction( "sqrt", new StandardSQLFunction( "sqrt", Hibernate.DOUBLE ) );
    registerFunction( "tan", new StandardSQLFunction( "tan", Hibernate.DOUBLE ) );
    registerFunction( "pi", new NoArgSQLFunction( "pi", Hibernate.DOUBLE ) );
    registerFunction( "rand", new StandardSQLFunction( "rand", Hibernate.FLOAT ) );

    registerFunction( "radians", new StandardSQLFunction( "radians", Hibernate.DOUBLE ) );
    registerFunction( "degrees", new StandardSQLFunction( "degrees", Hibernate.DOUBLE ) );
    registerFunction( "roundmagic", new StandardSQLFunction( "roundmagic" ) );

    registerFunction( "ceiling", new StandardSQLFunction( "ceiling" ) );
    registerFunction( "floor", new StandardSQLFunction( "floor" ) );

    // Multi-param dialect functions...
    registerFunction( "mod", new StandardSQLFunction( "mod", Hibernate.INTEGER ) );

    // function templates
    registerFunction( "concat", new VarArgsSQLFunction( Hibernate.STRING, "(", "||", ")" ) );

    getDefaultProperties().setProperty( Environment.STATEMENT_BATCH_SIZE, DEFAULT_BATCH_SIZE );
  }

  public String getAddColumnString() {
    return "add column";
  }

  public boolean supportsIdentityColumns() {
    return true;
  }

  public String getIdentityColumnString() {
    return "generated by default as identity (start with 1)"; //not null is implicit
  }

  public String getIdentitySelectString() {
    return "call identity()";
  }

  public String getIdentityInsertString() {
    return hsqldbVersion < 20 ? "null" : "default";
  }

  public boolean supportsLockTimeouts() {
    return false;
  }

  public String getForUpdateString() {
    return "";
  }

  public boolean supportsUnique() {
    return false;
  }

  public boolean supportsLimit() {
    return true;
  }

  public String getLimitString(String sql, boolean hasOffset) {
    if ( hsqldbVersion < 20 ) {
      return new StringBuffer( sql.length() + 10 )
          .append( sql )
          .insert(
              sql.toLowerCase().indexOf( "select" ) + 6,
              hasOffset ? " limit ? ?" : " top ?"
          )
          .toString();
    }
    else {
      return new StringBuffer( sql.length() + 20 )
          .append( sql )
          .append( hasOffset ? " offset ? limit ?" : " limit ?" )
          .toString();
    }
  }

  public boolean bindLimitParametersFirst() {
    return hsqldbVersion < 20;
  }

  public boolean supportsIfExistsAfterTableName() {
    return true;
  }

  public boolean supportsColumnCheck() {
    return hsqldbVersion >= 20;
  }

  public boolean supportsSequences() {
    return true;
  }

  public boolean supportsPooledSequences() {
    return true;
  }

  protected String getCreateSequenceString(String sequenceName) {
    return "create sequence " + sequenceName;
  }

  protected String getDropSequenceString(String sequenceName) {
    return "drop sequence " + sequenceName;
  }

  public String getSelectSequenceNextValString(String sequenceName) {
    return "next value for " + sequenceName;
  }

  public String getSequenceNextValString(String sequenceName) {
    return "call next value for " + sequenceName;
  }

  public String getQuerySequencesString() {
    // this assumes schema support, which is present in 1.8.0 and later...
    return "select sequence_name from information_schema.system_sequences";
  }

  public ViolatedConstraintNameExtracter getViolatedConstraintNameExtracter() {
    return hsqldbVersion < 20 ? EXTRACTER_18 : EXTRACTER_20;
  }

  private static ViolatedConstraintNameExtracter EXTRACTER_18 = new TemplatedViolatedConstraintNameExtracter() {

    /**
     * Extract the name of the violated constraint from the given SQLException.
     *
     * @param sqle The exception that was the result of the constraint violation.
     * @return The extracted constraint name.
     */
    public String extractConstraintName(SQLException sqle) {
      String constraintName = null;

      int errorCode = JDBCExceptionHelper.extractErrorCode( sqle );

      if ( errorCode == -8 ) {
        constraintName = extractUsingTemplate(
            "Integrity constraint violation ", " table:", sqle.getMessage()
        );
      }
      else if ( errorCode == -9 ) {
        constraintName = extractUsingTemplate(
            "Violation of unique index: ", " in statement [", sqle.getMessage()
        );
      }
      else if ( errorCode == -104 ) {
        constraintName = extractUsingTemplate(
            "Unique constraint violation: ", " in statement [", sqle.getMessage()
        );
      }
      else if ( errorCode == -177 ) {
        constraintName = extractUsingTemplate(
            "Integrity constraint violation - no parent ", " table:",
            sqle.getMessage()
        );
      }
      return constraintName;
    }

  };

  /**
   * HSQLDB 2.0 messages have changed
   * messages may be localized - therefore use the common, non-locale element " table: "
   */
  private static ViolatedConstraintNameExtracter EXTRACTER_20 = new TemplatedViolatedConstraintNameExtracter() {

    public String extractConstraintName(SQLException sqle) {
      String constraintName = null;

      int errorCode = JDBCExceptionHelper.extractErrorCode( sqle );

      if ( errorCode == -8 ) {
        constraintName = extractUsingTemplate(
            "; ", " table: ", sqle.getMessage()
        );
      }
      else if ( errorCode == -9 ) {
        constraintName = extractUsingTemplate(
            "; ", " table: ", sqle.getMessage()
        );
      }
      else if ( errorCode == -104 ) {
        constraintName = extractUsingTemplate(
            "; ", " table: ", sqle.getMessage()
        );
      }
      else if ( errorCode == -177 ) {
        constraintName = extractUsingTemplate(
            "; ", " table: ", sqle.getMessage()
        );
      }
      return constraintName;
    }
  };

  public String getSelectClauseNullString(int sqlType) {
    String literal;
    switch ( sqlType ) {
      case Types.VARCHAR:
      case Types.CHAR:
        literal = "cast(null as varchar(100))";
        break;
      case Types.DATE:
        literal = "cast(null as date)";
        break;
      case Types.TIMESTAMP:
        literal = "cast(null as timestamp)";
        break;
      case Types.TIME:
        literal = "cast(null as time)";
        break;
      default:
        literal = "cast(null as int)";
    }
    return literal;
  }

    public boolean supportsUnionAll() {
        return true;
    }

  // temporary table support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  // Hibernate uses this information for temporary tables that it uses for its own operations
  // therefore the appropriate strategy is taken with different versions of HSQLDB

  // All versions of HSQLDB support GLOBAL TEMPORARY tables where the table
  // definition is shared by all users but data is private to the session
  // HSQLDB 2.0 also supports session-based LOCAL TEMPORARY tables where
  // the definition and data is private to the session and table declaration
  // can happen in the middle of a transaction

  /**
   * Does this dialect support temporary tables?
   *
   * @return True if temp tables are supported; false otherwise.
   */
  public boolean supportsTemporaryTables() {
    return true;
  }

  /**
   * With HSQLDB 2.0, the table name is qualified with MODULE to assist the drop
   * statement (in-case there is a global name beginning with HT_)
   *
   * @param baseTableName The table name from which to base the temp table name.
   *
   * @return The generated temp table name.
   */
  public String generateTemporaryTableName(String baseTableName) {
    if ( hsqldbVersion < 20 ) {
      return "HT_" + baseTableName;
    }
    else {
      return "MODULE.HT_" + baseTableName;
    }
  }

  /**
   * Command used to create a temporary table.
   *
   * @return The command used to create a temporary table.
   */
  public String getCreateTemporaryTableString() {
    if ( hsqldbVersion < 20 ) {
      return "create global temporary table";
    }
    else {
      return "declare local temporary table";
    }
  }

  /**
   * No fragment is needed if data is not needed beyond commit, otherwise
   * should add "on commit preserve rows"
   *
   * @return Any required postfix.
   */
  public String getCreateTemporaryTablePostfix() {
    return "";
  }

  /**
   * Command used to drop a temporary table.
   *
   * @return The command used to drop a temporary table.
   */
  public String getDropTemporaryTableString() {
    return "drop table";
  }

  /**
   * Different behaviour for GLOBAL TEMPORARY (1.8) and LOCAL TEMPORARY (2.0)
   * <p/>
   * Possible return values and their meanings:<ul>
   * <li>{@link Boolean#TRUE} - Unequivocally, perform the temporary table DDL
   * in isolation.</li>
   * <li>{@link Boolean#FALSE} - Unequivocally, do <b>not</b> perform the
   * temporary table DDL in isolation.</li>
   * <li><i>null</i> - defer to the JDBC driver response in regards to
   * {@link java.sql.DatabaseMetaData#dataDefinitionCausesTransactionCommit()}</li>
   * </ul>
   *
   * @return see the result matrix above.
   */
  public Boolean performTemporaryTableDDLInIsolation() {
    if ( hsqldbVersion < 20 ) {
      return Boolean.TRUE;
    }
    else {
      return Boolean.FALSE;
    }
  }

  /**
   * Do we need to drop the temporary table after use?
   *
   * todo - clarify usage by Hibernate
   * Version 1.8 GLOBAL TEMPORARY table definitions persist beyond the end
   * of the session (data is cleared). If there are not too many such tables,
   * perhaps we can avoid dropping them and reuse the table next time?
   *
   * @return True if the table should be dropped.
   */
  public boolean dropTemporaryTableAfterUse() {
    return true;
  }

  // current timestamp support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  /**
   * HSQLDB 1.8.x requires CALL CURRENT_TIMESTAMP but this should not
   * be treated as a callable statement. It is equivalent to
   * "select current_timestamp from dual" in some databases.
   * HSQLDB 2.0 also supports VALUES CURRENT_TIMESTAMP
   *
   * @return True if the current timestamp can be retrieved; false otherwise.
   */
  public boolean supportsCurrentTimestampSelection() {
    return true;
  }

  /**
   * Should the value returned by {@link #getCurrentTimestampSelectString}
   * be treated as callable.  Typically this indicates that JDBC escape
   * syntax is being used...
   *
   * @return True if the {@link #getCurrentTimestampSelectString} return
   *         is callable; false otherwise.
   */
  public boolean isCurrentTimestampSelectStringCallable() {
    return false;
  }

  /**
   * Retrieve the command used to retrieve the current timestamp from the
   * database.
   *
   * @return The command.
   */
  public String getCurrentTimestampSelectString() {
    return "call current_timestamp";
  }

  /**
   * The name of the database-specific SQL function for retrieving the
   * current timestamp.
   *
   * @return The function name.
   */
  public String getCurrentTimestampSQLFunctionName() {
    // the standard SQL function name is current_timestamp...
    return "current_timestamp";
  }

  /**
   * For HSQLDB 2.0, this is a copy of the base class implementation.
   * For HSQLDB 1.8, only READ_UNCOMMITTED is supported.
   *
   * @param lockable The persister for the entity to be locked.
   * @param lockMode The type of lock to be acquired.
   *
   * @return The appropriate locking strategy.
   *
   * @since 3.2
   */
  public LockingStrategy getLockingStrategy(Lockable lockable, LockMode lockMode) {
    if ( lockMode == LockMode.PESSIMISTIC_FORCE_INCREMENT ) {
      return new PessimisticForceIncrementLockingStrategy( lockable, lockMode );
    }
    else if ( lockMode == LockMode.PESSIMISTIC_WRITE ) {
      return new PessimisticWriteSelectLockingStrategy( lockable, lockMode );
    }
    else if ( lockMode == LockMode.PESSIMISTIC_READ ) {
      return new PessimisticReadSelectLockingStrategy( lockable, lockMode );
    }
    else if ( lockMode == LockMode.OPTIMISTIC ) {
      return new OptimisticLockingStrategy( lockable, lockMode );
    }
    else if ( lockMode == LockMode.OPTIMISTIC_FORCE_INCREMENT ) {
      return new OptimisticForceIncrementLockingStrategy( lockable, lockMode );
    }

    if ( hsqldbVersion < 20 ) {
      return new ReadUncommittedLockingStrategy( lockable, lockMode );
    }
    else {
      return new SelectLockingStrategy( lockable, lockMode );
    }
  }

  public static class ReadUncommittedLockingStrategy extends SelectLockingStrategy {
    public ReadUncommittedLockingStrategy(Lockable lockable, LockMode lockMode) {
      super( lockable, lockMode );
    }

    public void lock(Serializable id, Object version, Object object, int timeout, SessionImplementor session)
        throws StaleObjectStateException, JDBCException {
      if ( getLockMode().greaterThan( LockMode.READ ) ) {
        log.warn( "HSQLDB supports only READ_UNCOMMITTED isolation" );
      }
      super.lock( id, version, object, timeout, session );
    }
  }

  public boolean supportsCommentOn() {
    return true;
  }

  // Overridden informational metadata ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  @Override
  public boolean supportsEmptyInList() {
    return false;
  }

  /**
   * todo - needs usage clarification
   *
   * If the SELECT statement is always part of a UNION, then the type of
   * parameter is resolved by v. 2.0, but not v. 1.8 (assuming the other
   * SELECT in the UNION has a column reference in the same position and
   * can be type-resolved).
   *
   * On the other hand if the SELECT statement is isolated, all versions of
   * HSQLDB require casting for "select ? from .." to work.
   *
   * @return True if select clause parameter must be cast()ed
   *
   * @since 3.2
   */
  public boolean requiresCastingOfParametersInSelectClause() {
    return true;
  }

  /**
   * For the underlying database, is READ_COMMITTED isolation implemented by
   * forcing readers to wait for write locks to be released?
   *
   * @return True if writers block readers to achieve READ_COMMITTED; false otherwise.
   */
  public boolean doesReadCommittedCauseWritersToBlockReaders() {
    return hsqldbVersion >= 20;
  }

  /**
   * For the underlying database, is REPEATABLE_READ isolation implemented by
   * forcing writers to wait for read locks to be released?
   *
   * @return True if readers block writers to achieve REPEATABLE_READ; false otherwise.
   */
  public boolean doesRepeatableReadCauseReadersToBlockWriters() {
    return hsqldbVersion >= 20;
  }


  public boolean supportsLobValueChangePropogation() {
    return false;
  }

    public String toBooleanValueString(boolean bool) {
        return bool ? "true" : "false";
    }

  public boolean supportsTupleDistinctCounts() {
    return false;
  }
}
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