org.apache.derby.impl.store.access.btree

Class BranchControlRow

java.lang.Object

org.apache.derby.impl.store.access.btree.ControlRow

org.apache.derby.impl.store.access.btree.BranchControlRow

All Implemented Interfaces:

TypedFormat, AuxObject

public class BranchControlRow
extends ControlRow

A branch row contains key fields and the pointer to the child page.

Field Summary

Fields inherited from class org.apache.derby.impl.store.access.btree.ControlRow

SPLIT_FLAG_FIRST_IN_TABLE, SPLIT_FLAG_FIRST_ON_PAGE, SPLIT_FLAG_LAST_IN_TABLE, SPLIT_FLAG_LAST_ON_PAGE

Constructor Summary

Constructors

Constructor and Description
BranchControlRow() No arg constructor.
BranchControlRow(OpenBTree open_btree, Page page, int level, ControlRow parent, boolean isRoot, long left_child)

Method Summary

Modifier and Type	Method and Description
int	checkConsistency(OpenBTree btree, ControlRow parent, boolean check_other_pages) Perform consistency checks for a branch page.
ControlRow	getLeftChild(OpenBTree open_btree) Return the left child pointer for the page.
DataValueDescriptor[]	getRowTemplate(OpenBTree open_btree) Return a new template for reading a data row from the current page.
int	getTypeFormatId() Return my format identifier.
boolean	isLeftmostLeaf() Is the current page the leftmost leaf of tree?
boolean	isRightmostLeaf() Is the current page the rightmost leaf of tree?
void	printTree(OpenBTree btree) Recursively print the tree starting at current node in tree.
static long	restartSplitFor(OpenBTree open_btree, DataValueDescriptor[] template, BranchControlRow parent, ControlRow child, DataValueDescriptor[] newbranchrow, DataValueDescriptor[] splitrow, int flag)
ControlRow	search(SearchParameters sp) Perform a recursive search, ultimately returning the latched leaf page and row slot after which the given key belongs.
java.lang.String	toString() The standard toString.

Methods inherited from class org.apache.derby.impl.store.access.btree.ControlRow

auxObjectInvalidated, compareIndexRowFromPageToKey, compareIndexRowToKey, debugPage, get, get, getConglom, getLeftSibling, getleftSiblingPageNumber, getNoWait, getPage, release

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

BranchControlRow

public BranchControlRow()

No arg constructor.

Public no arg constructor is for the monitor to call for format id implementation, it should not be called for any other reason.

BranchControlRow

public BranchControlRow(OpenBTree open_btree,
                        Page page,
                        int level,
                        ControlRow parent,
                        boolean isRoot,
                        long left_child)
                 throws StandardException

Throws:

StandardException

Method Detail

isLeftmostLeaf

public boolean isLeftmostLeaf()
                       throws StandardException

Is the current page the leftmost leaf of tree?

Specified by:

isLeftmostLeaf in class ControlRow

Returns:

true if the current page is the leftmost leaf of the tree, else return false.

Throws:

StandardException - Standard exception policy.

isRightmostLeaf

public boolean isRightmostLeaf()
                        throws StandardException

Is the current page the rightmost leaf of tree?

Specified by:

isRightmostLeaf in class ControlRow

Returns:

true if the current page is the rightmost leaf of the tree, else return false.

Throws:

StandardException - Standard exception policy.

restartSplitFor

public static long restartSplitFor(OpenBTree open_btree,
                                   DataValueDescriptor[] template,
                                   BranchControlRow parent,
                                   ControlRow child,
                                   DataValueDescriptor[] newbranchrow,
                                   DataValueDescriptor[] splitrow,
                                   int flag)
                            throws StandardException

Throws:

StandardException

search

public ControlRow search(SearchParameters sp)
                  throws StandardException

Perform a recursive search, ultimately returning the latched leaf page and row slot after which the given key belongs. The slot is returned in the result structure. If the key exists on the page, the result.exact will be true. Otherwise, result.exact will be false, and the row slot returned will be the one immediately preceding the position at which the key belongs.

Specified by:

search in class ControlRow

Throws:

StandardException - Standard exception policy.

checkConsistency

public int checkConsistency(OpenBTree btree,
                            ControlRow parent,
                            boolean check_other_pages)
                     throws StandardException

Perform consistency checks for a branch page. The checks specific to a branch page are:

The rows on the page are indeed branch rows, and they all have the correct number of fields (which is the b-tree's key fields plus one for the child page number.

The child pages pointed to by the left child pointer and the index rows are linked together in the same order that they appear on the page.

The child pages themselves are all consistent.

This method also performs the consistency checks that are common to both leaf and branch pages (see ControlRow.checkGeneric).

Parameters:

btree - The open btree to associate latches/locks with.

parent - The parent page of this page, "null" if this page is root or if not maintaining parent links.

check_other_pages - Should the consistency check go to other pages (this option breaks the latch protocol).

Returns:

The identifier to be used to open the conglomerate later.

Throws:

StandardException - Standard exception policy.

printTree

public void printTree(OpenBTree btree)
               throws StandardException

Recursively print the tree starting at current node in tree.

Specified by:

printTree in class ControlRow

Parameters:

btree - the open btree to print.

Throws:

StandardException - Standard exception policy.

getLeftChild

public ControlRow getLeftChild(OpenBTree open_btree)
                        throws StandardException

Return the left child pointer for the page.

Leaf pages don't have children, so they override this and return null.

Parameters:

open_btree - The open btree to associate latches/locks with.

Returns:

The page which is the leftmost child of this page.

Throws:

StandardException - Standard exception policy.

getTypeFormatId

public int getTypeFormatId()

Return my format identifier.

Returns:

The identifier. (A UUID stuffed in an array of 16 bytes).

See Also:

TypedFormat.getTypeFormatId()

getRowTemplate

public DataValueDescriptor[] getRowTemplate(OpenBTree open_btree)
                                     throws StandardException

Return a new template for reading a data row from the current page.

Default implementation for rows which are the same as the conglomerates template, sub-classes can alter if underlying template is different (for instance branch rows add an extra field at the end).

Overrides:

getRowTemplate in class ControlRow

Returns:

Newly allocated template.

Throws:

StandardException - Standard exception policy.

toString

public java.lang.String toString()

The standard toString.

Overrides:

toString in class ControlRow