Class SelectableScheme
- java.lang.Object
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- com.mckoi.database.SelectableScheme
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- Direct Known Subclasses:
BlindSearch
,CollatedBaseSearch
public abstract class SelectableScheme extends java.lang.Object
Represents a base class for a mechanism to select ranges from a given set. Such schemes could include BinaryTree, Hashtable or just a blind search.A given element in the set is specified through a 'row' integer whose contents can be obtained through the 'table.getCellContents(column, row)'. Every scheme is given a table and column number that the set refers to. While a given set element is refered to as a 'row', the integer is really only a pointer into the set list which can be de-referenced with a call to table.getCellContents(row). Better performance schemes will keep such calls to a minimum.
A scheme may choose to retain knowledge about a given element when it is added or removed from the set, such as a BinaryTree that catalogs all elements with respect to each other.
- Author:
- Tobias Downer
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Field Summary
Fields Modifier and Type Field Description protected static BlockIntegerList
EMPTY_LIST
Some statics.protected static BlockIntegerList
ONE_LIST
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Constructor Summary
Constructors Constructor Description SelectableScheme(TableDataSource table, int column)
The constructor for all schemes.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description abstract SelectableScheme
copy(TableDataSource table, boolean immutable)
Returns an exact copy of this scheme including any optimization information.protected DebugLogger
Debug()
Returns the DebugLogger object to log debug messages to.abstract void
dispose()
Dispose and invalidate this scheme.protected TObject
getCellContents(int row)
Obtains the given cell in the row from the table.protected int
getColumn()
Returns the column this scheme is indexing in the table.SelectableScheme
getSubsetScheme(Table subset_table, int subset_column)
Asks the Scheme for a SelectableScheme abject that describes a sub-set of the set handled by this Scheme.protected TransactionSystem
getSystem()
Returns the global transaction system.protected TableDataSource
getTable()
Returns the Table.BlockIntegerList
internalOrderIndexSet(IntegerVector row_set)
Returns a BlockIntegerList that represents the given row_set sorted in the order of this scheme.boolean
isImmutable()
Returns true if this scheme is immutable.abstract void
readFrom(java.io.InputStream in)
Reads the entire contents of the scheme from a InputStream object.IntegerVector
selectAll()
These are the select operations that are the main purpose of the scheme.IntegerVector
selectAllNonNull()
Selects all values in the column that are not null.IntegerVector
selectBetween(TObject ob1, TObject ob2)
IntegerVector
selectEqual(TObject ob)
IntegerVector
selectFirst()
IntegerVector
selectGreater(TObject ob)
IntegerVector
selectGreaterOrEqual(TObject ob)
IntegerVector
selectLast()
IntegerVector
selectLess(TObject ob)
IntegerVector
selectLessOrEqual(TObject ob)
IntegerVector
selectNotEqual(TObject ob)
IntegerVector
selectNotFirst()
IntegerVector
selectNotLast()
void
setImmutable()
Sets this scheme to immutable.java.lang.String
toString()
Diagnostic information.abstract void
writeTo(java.io.OutputStream out)
Writes the entire contents of the scheme to an OutputStream object.
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Field Detail
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EMPTY_LIST
protected static final BlockIntegerList EMPTY_LIST
Some statics.
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ONE_LIST
protected static final BlockIntegerList ONE_LIST
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Constructor Detail
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SelectableScheme
public SelectableScheme(TableDataSource table, int column)
The constructor for all schemes.
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Method Detail
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getTable
protected final TableDataSource getTable()
Returns the Table.
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getSystem
protected final TransactionSystem getSystem()
Returns the global transaction system.
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Debug
protected final DebugLogger Debug()
Returns the DebugLogger object to log debug messages to.
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getColumn
protected final int getColumn()
Returns the column this scheme is indexing in the table.
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getCellContents
protected final TObject getCellContents(int row)
Obtains the given cell in the row from the table.
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setImmutable
public final void setImmutable()
Sets this scheme to immutable.
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isImmutable
public final boolean isImmutable()
Returns true if this scheme is immutable.
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toString
public java.lang.String toString()
Diagnostic information.- Overrides:
toString
in classjava.lang.Object
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writeTo
public abstract void writeTo(java.io.OutputStream out) throws java.io.IOException
Writes the entire contents of the scheme to an OutputStream object.- Throws:
java.io.IOException
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readFrom
public abstract void readFrom(java.io.InputStream in) throws java.io.IOException
Reads the entire contents of the scheme from a InputStream object. If the scheme is full of any information it throws an exception.- Throws:
java.io.IOException
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copy
public abstract SelectableScheme copy(TableDataSource table, boolean immutable)
Returns an exact copy of this scheme including any optimization information. The copied scheme is identical to the original but does not share any parts. Modifying any part of the copied scheme will have no effect on the original and vice versa.The newly copied scheme can be given a new table source. If 'immutable' is true, then the resultant scheme is an immutable version of the parent. An immutable version may share information with the copied version so can not be changed.
NOTE: Even if the scheme maintains no state you should still be careful to ensure a fresh SelectableScheme object is returned here.
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dispose
public abstract void dispose()
Dispose and invalidate this scheme.
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internalOrderIndexSet
public BlockIntegerList internalOrderIndexSet(IntegerVector row_set)
Returns a BlockIntegerList that represents the given row_set sorted in the order of this scheme. The values in 'row_set' must be references to rows in the domain of the table this scheme represents.The returned set must be stable, meaning if values are equal they keep the same ordering.
Note that the default implementation of this method can often be optimized. For example, InsertSearch uses a secondary RID list to sort items if the given list is over a certain size.
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getSubsetScheme
public SelectableScheme getSubsetScheme(Table subset_table, int subset_column)
Asks the Scheme for a SelectableScheme abject that describes a sub-set of the set handled by this Scheme. Since a Table stores a subset of a given DataTable, we pass this as the argument. It returns a new SelectableScheme that orders the rows in the given columns order. The 'column' variable specifies the column index of this column in the given table.
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selectAll
public IntegerVector selectAll()
These are the select operations that are the main purpose of the scheme. They retrieve the given information from the set. Different schemes will have varying performance on different types of data sets. The select operations must *always* return a resultant row set that is sorted from lowest to highest.
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selectFirst
public IntegerVector selectFirst()
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selectNotFirst
public IntegerVector selectNotFirst()
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selectLast
public IntegerVector selectLast()
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selectNotLast
public IntegerVector selectNotLast()
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selectAllNonNull
public IntegerVector selectAllNonNull()
Selects all values in the column that are not null.
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selectEqual
public IntegerVector selectEqual(TObject ob)
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selectNotEqual
public IntegerVector selectNotEqual(TObject ob)
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selectGreater
public IntegerVector selectGreater(TObject ob)
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selectLess
public IntegerVector selectLess(TObject ob)
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selectGreaterOrEqual
public IntegerVector selectGreaterOrEqual(TObject ob)
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selectLessOrEqual
public IntegerVector selectLessOrEqual(TObject ob)
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selectBetween
public IntegerVector selectBetween(TObject ob1, TObject ob2)
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