tabledescriptor.java

derby database source code.good for you.

	 * Sets the constraint descriptor list
	 *
	 * @param newCDL	The new constraint descriptor list for this table descriptor
	 */
	public void setConstraintDescriptorList(ConstraintDescriptorList newCDL)
	{
		constraintDescriptorList = newCDL;
	}

	/**
	 * Empty the constraint descriptor list
	 *
	 * @return Nothing.
	 *
	 * @exception StandardException		Thrown on failure
	 */
	public void emptyConstraintDescriptorList()
		throws StandardException
	{
		// Easier just to get a new CDL then to clean out the current one
		this.constraintDescriptorList = new ConstraintDescriptorList();
	}

	/**
	 * Gets the primary key, may return null if no primary key
	 *
	 * @return	The priamry key or null
	 *
	 * @exception StandardException		Thrown on failure
	 */
	public ReferencedKeyConstraintDescriptor getPrimaryKey() 
		throws StandardException
	{
		ConstraintDescriptorList cdl = getDataDictionary().getConstraintDescriptors(this);
		
		return cdl.getPrimaryKey();
	}

	/**
	 * Gets the trigger descriptor list
	 *
	 * @return	The trigger descriptor list for this table descriptor
	 *
	 * @exception StandardException		Thrown on failure
	 */
	public GenericDescriptorList getTriggerDescriptorList()
		throws StandardException
	{
		return triggerDescriptorList;
	}

	/**
	 * Sets the trigger descriptor list
	 *
	 * @param newCDL	The new trigger descriptor list for this table descriptor
	 */
	public void setTriggerDescriptorList(GenericDescriptorList newCDL)
	{
		triggerDescriptorList = newCDL;
	}

	/**
	 * Empty the trigger descriptor list
	 *
	 * @return Nothing.
	 *
	 * @exception StandardException		Thrown on failure
	 */
	public void emptyTriggerDescriptorList()
		throws StandardException
	{
		// Easier just to get a new CDL then to clean out the current one
		this.triggerDescriptorList = new GenericDescriptorList();
	}

	
	/**
	 * Compare the tables descriptors based on the names.
	 * Null schema names match.
	 *
	 * @param otherTableName	the other table name
	 * @param otherSchemaName	the other schema name
	 *
	 * @return boolean		Whether or not the 2 TableNames are equal.
	 */
	public boolean tableNameEquals(String otherTableName, String otherSchemaName)
	{
		String schemaName = getSchemaName();

		if ((schemaName == null) || 
				 (otherSchemaName == null))
		{
			return tableName.equals(otherTableName);
		}
		else
		{
			return	schemaName.equals(otherSchemaName) &&
					tableName.equals(otherTableName);
		}
	}

	/**
	 * Remove this descriptor
	 *
	 * @param	The conglomerate descriptor 
	 *
	 * @exception StandardException on error
	 */
	public void removeConglomerateDescriptor(ConglomerateDescriptor cd)
		throws StandardException
	{
		conglomerateDescriptorList.dropConglomerateDescriptor(getUUID(), cd);
	}

	/**
	 * Remove this descriptor.  Warning, removes by using object
	 * reference, not uuid.
	 *
	 * @param	The constraint descriptor 
	 *
	 * @exception StandardException on error
	 */
	public void removeConstraintDescriptor(ConstraintDescriptor cd)
		throws StandardException
	{
		constraintDescriptorList.remove(cd);
	}

	/**
	 * Get the descriptor for a column in the table,
	 * either by the column name or by its ordinal position (column number).
	 * Returns NULL for columns that do not exist.
	 *
	 * @param columnName	A String containing the name of the column
	 *
	 * @return	A ColumnDescriptor describing the column
	 */
	public ColumnDescriptor	getColumnDescriptor(String columnName)
	{
		return columnDescriptorList.getColumnDescriptor(oid, columnName);
	}

	/**
	 * @param columnNumber	The ordinal position of the column in the table
	 *
	 * @return	A ColumnDescriptor describing the column
	 */
	public ColumnDescriptor	getColumnDescriptor(int columnNumber)
	{
		return columnDescriptorList.getColumnDescriptor(oid, columnNumber);
	}

	/**
	 * Gets a ConglomerateDescriptor[] to loop through all the conglomerate descriptors
	 * for the table.
	 *
	 * @return	A ConglomerateDescriptor[] for looping through the table's conglomerates
	 *
	 * @exception StandardException		Thrown on failure
	 */
	public ConglomerateDescriptor[]	getConglomerateDescriptors()
	{

		int size = conglomerateDescriptorList.size();
		ConglomerateDescriptor[] cdls = new ConglomerateDescriptor[size];
		conglomerateDescriptorList.toArray(cdls);
		return cdls;
	}

	/**
	 * Gets a conglomerate descriptor for the given table and conglomerate number.
	 *
	 * @param conglomerateNumber	The conglomerate number
	 *				we're interested in
	 *
	 * @return	A ConglomerateDescriptor describing the requested
	 *		conglomerate. Returns NULL if no such conglomerate.
	 *
	 * @exception StandardException		Thrown on failure
	 */
	public ConglomerateDescriptor	getConglomerateDescriptor(
						long conglomerateNumber)
						throws StandardException
	{
		return conglomerateDescriptorList.getConglomerateDescriptor(conglomerateNumber);
	}

	/**
	 * Gets array of conglomerate descriptors for the given table and
	 * conglomerate number.  More than one descriptors if duplicate indexes
	 * share one conglomerate.
	 *
	 * @param conglomerateNumber	The conglomerate number
	 *				we're interested in
	 *
	 * @return	Array of ConglomerateDescriptors with the requested
	 *		conglomerate number. Returns size 0 array if no such conglomerate.
	 *
	 * @exception StandardException		Thrown on failure
	 */
	public ConglomerateDescriptor[]	getConglomerateDescriptors(
						long conglomerateNumber)
						throws StandardException
	{
		return conglomerateDescriptorList.getConglomerateDescriptors(conglomerateNumber);
	}


	/**
	 * Gets a conglomerate descriptor for the given table and conglomerate UUID String.
	 *
	 * @param conglomerateUUID	The UUID  for the conglomerate
	 *				we're interested in
	 *
	 * @return	A ConglomerateDescriptor describing the requested
	 *		conglomerate. Returns NULL if no such conglomerate.
	 *
	 * @exception StandardException		Thrown on failure
	 */
	public ConglomerateDescriptor	getConglomerateDescriptor(
						UUID conglomerateUUID)
						throws StandardException
	{
		return conglomerateDescriptorList.getConglomerateDescriptor(conglomerateUUID);
	}

	/**
	 * Gets array of conglomerate descriptors for the given table and
	 * conglomerate UUID.  More than one descriptors if duplicate indexes
	 * share one conglomerate.
	 *
	 * @param conglomerateUUID	The conglomerate UUID
	 *				we're interested in
	 *
	 * @return	Array of ConglomerateDescriptors with the requested
	 *		conglomerate UUID. Returns size 0 array if no such conglomerate.
	 *
	 * @exception StandardException		Thrown on failure
	 */
	public ConglomerateDescriptor[]	getConglomerateDescriptors(
						UUID conglomerateUUID)
						throws StandardException
	{
		return conglomerateDescriptorList.getConglomerateDescriptors(conglomerateUUID);
	}

	/**
	 * Gets an object which lists out all the index row generators on a table together
	 * with their conglomerate ids.
	 *
	 * @return	An object to list out the index row generators.
	 *
	 * @exception StandardException		Thrown on failure
	 */
	public	IndexLister	getIndexLister()
						throws StandardException
	{
		return new IndexLister( this );
	}

	/**
	 * Does the table have an autoincrement column or not?
	 * 
	 * @return TRUE if the table has atleast one autoincrement column, false
	 * otherwise 
	 */
	public boolean tableHasAutoincrement()
	{
		int cdlSize = getColumnDescriptorList().size();
		for (int index = 0; index < cdlSize; index++)
		{
			ColumnDescriptor cd = 
				(ColumnDescriptor) columnDescriptorList.elementAt(index);
			if (cd.isAutoincrement())
				return true;
		}
		return false;
	}
	
	/**
	 * Gets an array of column names.
	 *
	 * @return An array, filled with the column names in the table.
	 *
	 */
	public String[] getColumnNamesArray()
	{
		int size = getNumberOfColumns();
		String[] s = new String[size];

		for (int i = 0; i < size; i++)
			s[i] = getColumnDescriptor(i+1).getColumnName();
		
		return s;
	}

	/**
	 * gets an array of increment values for autoincrement columns in the target
	 * table. If column is not an autoincrement column, then increment value is
	 * 0. If table has no autoincrement columns, returns NULL.
	 *
	 * @return		array containing the increment values of autoincrement
	 * columns.
	 *
	 */
	public long[]   getAutoincIncrementArray()
	{
		if (!tableHasAutoincrement())
			return null;

		int size = getNumberOfColumns();
		long[] inc = new long[size];

		for (int i = 0; i < size; i++)
		{
			ColumnDescriptor cd = getColumnDescriptor(i + 1);
			if (cd.isAutoincrement())
				inc[i] = cd.getAutoincInc();
		}

		return inc;
	}

	
	/** Returns a list of statistics for this table.
	 */
	private synchronized List getStatistics() throws StandardException
	{
		// if table already has the statistics descriptors initialized
		// no need to do anything
		if (statisticsDescriptorList != null)
			return statisticsDescriptorList;

		DataDictionary dd = getDataDictionary();
		return statisticsDescriptorList = dd.getStatisticsDescriptors(this);
	}

	/** 
	 * Are there statistics for this particular conglomerate.
	 *
	 * @param cd	Conglomerate/Index for which we want to check if statistics
	 * exist. cd can be null in which case user wants to know if there are any
	 * statistics at all on the table.
	 */
	public boolean statisticsExist(ConglomerateDescriptor cd)
		throws StandardException
	{
		List sdl = getStatistics();

		if (cd == null)
			return (sdl.size() > 0);

		UUID cdUUID = cd.getUUID();

		for (Iterator li = sdl.iterator(); li.hasNext(); )
		{
			StatisticsDescriptor statDesc = (StatisticsDescriptor) li.next();
			if (cdUUID.equals(statDesc.getReferenceID()))
				return true;

		}

		return false;
	}

	/**
	 * For this conglomerate (index), return the selectivity of the first
	 * numKeys. This basically returns the reciprocal of the number of unique
	 * values in the leading numKey columns of the index. It is assumed that
	 * statistics exist for the conglomerate if this function is called.
	 *
	 * @param cd		ConglomerateDescriptor (Index) whose
	 * cardinality we are interested in.
	 * @param numKeys	Number of leading columns of the index for which
	 * cardinality is desired.

	 */
	public double selectivityForConglomerate(ConglomerateDescriptor cd,
											 int numKeys) 
		throws StandardException
	{
		if (!statisticsExist(cd))
		{
			if (SanityManager.DEBUG)
			{
				SanityManager.THROWASSERT("no statistics exist for conglomerate"
										  + cd);
			}
			else 
			{
				double selectivity = 0.1;
				for (int i = 0; i < numKeys; i++)
					selectivity *= 0.1;
				return selectivity;
			}
		}
		
		UUID referenceUUID = cd.getUUID();

		List sdl = getStatistics();
		for (Iterator li = sdl.iterator(); li.hasNext(); )
		{
			StatisticsDescriptor statDesc = (StatisticsDescriptor) li.next();

			if (!referenceUUID.equals(statDesc.getReferenceID()))
				continue;
			
			if (statDesc.getColumnCount() != numKeys)
				continue;
			
			return statDesc.getStatistic().selectivity((Object[])null);
		}
		
		if (SanityManager.DEBUG)
			SanityManager.THROWASSERT("Internal Error-- statistics not found in selectivityForConglomerate.\n cd = " + cd + "\nnumKeys = " + numKeys);
		return 0.1;				// shouldn't come here.
	}

	/** @see TupleDescriptor#getDescriptorName */
	public String getDescriptorName() { return tableName; }

	/** @see TupleDescriptor#getDescriptorType */
	public String getDescriptorType() 
	{
		return (tableType == TableDescriptor.SYNONYM_TYPE) ? "Synonym" : "Table/View";
	}
}