com.mckoi.database

Class JoinedTable

java.lang.Object

com.mckoi.database.Table

com.mckoi.database.JoinedTable

All Implemented Interfaces:

TableDataSource

Direct Known Subclasses:

NaturallyJoinedTable, VirtualTable

public abstract class JoinedTable
extends Table

A Table that represents the result of one or more other tables joined together. VirtualTable and NaturallyJoinedTable are derived from this class.

Author:

Tobias Downer

Field Summary

Fields

Modifier and Type	Field and Description
protected int[]	column_filter Gives a column filter to the given column to route correctly to the ancestor.
protected SelectableScheme[]	column_scheme The schemes to describe the entity relation in the given column.
protected int[]	column_table Maps the column number in this table to the reference_list array to route to.
protected Table[]	reference_list The list of tables that make up the join.

Fields inherited from class com.mckoi.database.Table

DEBUG_QUERY

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	JoinedTable() Protected constructor.

Method Summary

Modifier and Type	Method and Description
int	findFieldName(Variable v) Given a fully qualified variable field name, ie.
TObject	getCellContents(int column, int row) Returns an object that represents the information in the given cell in the table.
int	getColumnCount() Returns the number of columns in the table.
Database	getDatabase() We simply pick the first table to resolve the Database object.
DataTableDef	getDataTableDef() Returns the DataTableDef object that describes the columns in this table.
protected Table[]	getReferenceTables() Returns the list of Table objects that represent this VirtualTable.
Variable	getResolvedVariable(int column) Returns a fully qualified Variable object that represents the name of the column at the given index.
boolean	hasRootsLocked() Returns true if the table has its row roots locked (via the lockRoot(int) method.
protected void	init(Table[] tables) Helper function for initializing the variables in the joined table.
void	lockRoot(int lock_key) Locks the root table(s) of this table so that it is impossible to overwrite the underlying rows that may appear in this table.
void	printGraph(PrintStream out, int indent) Prints a graph of the table hierarchy to the stream.
protected abstract void	resolveAllRowsForTableAt(IntegerVector row_set, int table_num) Given an IntegerVector that represents a list of pointers to rows in this table, this resolves the rows to row indexes in the given parent table.
protected abstract int	resolveRowForTableAt(int row_number, int table_num) Given a row and a table index (to a parent reference table), this will return the row index in the given parent table for the given row.
RowEnumeration	rowEnumeration() Returns an Enumeration of the rows in this table.
void	unlockRoot(int lock_key) Unlocks the root tables so that the underlying rows may once again be used if they are not locked and have been removed.

Methods inherited from class com.mckoi.database.Table

all, allColumnMatchesValue, any, columnContainsCell, columnContainsValue, columnMatchesValue, columnMerge, compareCells, Debug, distinct, distinct, dumpTo, emptySelect, exhaustiveSelect, fastFindFieldName, getColumnDefAt, getColumnScheme, getFirstCellContent, getFirstCellContent, getLastCellContent, getLastCellContent, getRowCount, getSingleCellContent, getSingleCellContent, getSystem, getTableAccessState, getTTypeForColumn, getTTypeForColumn, join, orderByColumn, orderByColumn, orderByColumn, orderByColumns, orderedRowList, outside, rangeSelect, selectAll, selectAll, selectFirst, selectLast, selectRange, selectRest, simpleJoin, simpleSelect, singleRowSelect, toMap, toString, union

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

reference_list

protected Table[] reference_list

The list of tables that make up the join.

column_scheme

protected SelectableScheme[] column_scheme

The schemes to describe the entity relation in the given column.

column_table

protected int[] column_table

Maps the column number in this table to the reference_list array to route to.

column_filter

protected int[] column_filter

Gives a column filter to the given column to route correctly to the ancestor.

Constructor Detail

JoinedTable

protected JoinedTable()

Protected constructor.

Method Detail

init

protected void init(Table[] tables)

Helper function for initializing the variables in the joined table.

getDatabase

public Database getDatabase()

We simply pick the first table to resolve the Database object.

Specified by:

getDatabase in class Table

getColumnCount

public int getColumnCount()

Returns the number of columns in the table. This simply returns the column counts in the parent table(s).

Specified by:

getColumnCount in class Table

findFieldName

public int findFieldName(Variable v)

Given a fully qualified variable field name, ie. 'APP.CUSTOMER.CUSTOMERID' this will return the column number the field is at. Returns -1 if the field does not exist in the table.

Specified by:

findFieldName in class Table

getResolvedVariable

public final Variable getResolvedVariable(int column)

Returns a fully qualified Variable object that represents the name of the column at the given index. For example, new Variable(new TableName("APP", "CUSTOMER"), "ID")

Specified by:

getResolvedVariable in class Table

getReferenceTables

protected final Table[] getReferenceTables()

Returns the list of Table objects that represent this VirtualTable.

getDataTableDef

public DataTableDef getDataTableDef()

Returns the DataTableDef object that describes the columns in this table. For a VirtualTable, this object contains the union of all the columns in the children in the order set. The name of a virtual table is the concat of all the parent table names. The schema is set to null.

Specified by:

getDataTableDef in interface TableDataSource

Specified by:

getDataTableDef in class Table

getCellContents

public TObject getCellContents(int column,
                               int row)

Returns an object that represents the information in the given cell in the table.

Specified by:

getCellContents in interface TableDataSource

Specified by:

getCellContents in class Table

rowEnumeration

public RowEnumeration rowEnumeration()

Returns an Enumeration of the rows in this table. The Enumeration is a fast way of retrieving consequtive rows in the table.

Specified by:

rowEnumeration in interface TableDataSource

Specified by:

rowEnumeration in class Table

lockRoot

public void lockRoot(int lock_key)

Locks the root table(s) of this table so that it is impossible to overwrite the underlying rows that may appear in this table. This is used when cells in the table need to be accessed 'outside' the lock. So we may have late access to cells in the table. 'lock_key' is a given key that will also unlock the root table(s). NOTE: This is nothing to do with the 'LockingMechanism' object.

Specified by:

lockRoot in class Table

unlockRoot

public void unlockRoot(int lock_key)

Unlocks the root tables so that the underlying rows may once again be used if they are not locked and have been removed. This should be called some time after the rows have been locked.

Specified by:

unlockRoot in class Table

hasRootsLocked

public boolean hasRootsLocked()

Returns true if the table has its row roots locked (via the lockRoot(int) method.

Specified by:

hasRootsLocked in class Table

printGraph

public void printGraph(PrintStream out,
                       int indent)

Prints a graph of the table hierarchy to the stream.

Overrides:

printGraph in class Table

resolveRowForTableAt

protected abstract int resolveRowForTableAt(int row_number,
                                            int table_num)

Given a row and a table index (to a parent reference table), this will return the row index in the given parent table for the given row.

resolveAllRowsForTableAt

protected abstract void resolveAllRowsForTableAt(IntegerVector row_set,
                                                 int table_num)

Given an IntegerVector that represents a list of pointers to rows in this table, this resolves the rows to row indexes in the given parent table. This method changes the 'row_set' IntegerVector object.