Apache Derby Database Engine and Embedded JDBC Driver 10.17.1.0 · org.apache.derby.impl.store.access.btree.BTreeRowPosition

Field Summary

Modifier and Type	Field and Description
public LeafControlRow	current_leaf
public RowLocation	current_lock_row_loc
public DataValueDescriptor[]	current_lock_template
public DataValueDescriptor[]	current_positionKey Fields of the class
protected LeafControlRow	next_leaf
private final BTreeScan	parent The scan that owns this position object.
private DataValueDescriptor[]	positionKey_template Cached template for saving this position by key.
private FetchDescriptor	savedFetchDescriptor Cached fetch descriptor that can be used to fetch the key columns that are not already fetched by the scan.
pack-priv long	versionWhenSaved The version number of the leaf page when this position was saved by key.

Inherited from org.apache.derby.impl.store.access.conglomerate.RowPosition:: current_page current_pageno current_rh current_rh_qualified current_slot

Constructor Summary

Access	Constructor and Description
public	BTreeRowPosition(BTreeScan parent) Constructors for This class:

Method Summary

Modifier and Type	Method and Description
pack-priv FetchDescriptor	Returns: a fetch descriptor getFetchDescriptorForSaveKey(int[] an array which tells which columns the partial key contains (valid columns have non-zero values in the array) vcols, int the length of the full key to create a fetch descriptor for (may be greater than `vcols.length`) fullLength) Get a fetch descriptor that can be used to fetch the missing columns in a partial key.
pack-priv DataValueDescriptor[]	Returns: an array into which the position key can be copied getKeyTemplate() Get a template into which the position key can be copied.
public void	init() Overrides org.apache.derby.impl.store.access.conglomerate.RowPosition.init. Public Methods of This class:
public void	saveMeAndReleasePage() Save this position by key and release the latch on the current leaf.
public final String	toString() Overrides org.apache.derby.impl.store.access.conglomerate.RowPosition.toString. Returns a string representation of the object.
public final void	unlatch() Overrides org.apache.derby.impl.store.access.conglomerate.RowPosition.unlatch.

Inherited from org.apache.derby.impl.store.access.conglomerate.RowPosition:: positionAtNextSlot positionAtPrevSlot

Field Detail

current_leaf	back to summary
public LeafControlRow current_leaf

current_lock_row_loc	back to summary
public RowLocation current_lock_row_loc

current_lock_template	back to summary
public DataValueDescriptor[] current_lock_template

current_positionKey	back to summary
public DataValueDescriptor[] current_positionKey Fields of the class

next_leaf	back to summary
protected LeafControlRow next_leaf

parent	back to summary
private final BTreeScan parent The scan that owns this position object.

positionKey_template	back to summary
private DataValueDescriptor[] positionKey_template Cached template for saving this position by key.

savedFetchDescriptor	back to summary
private FetchDescriptor savedFetchDescriptor Cached fetch descriptor that can be used to fetch the key columns that are not already fetched by the scan. The fetch descriptor is used when this position is about to be saved by its full key.

versionWhenSaved	back to summary
pack-priv long versionWhenSaved The version number of the leaf page when this position was saved by key. Only valid if `current_positionKey` is non-null. This value is used to decide whether repositioning should be performed by using the key, or if `current_rh` could be used directly.

Constructor Detail

BTreeRowPosition	back to summary
public BTreeRowPosition(BTreeScan parent) Constructors for This class:

Method Detail

getFetchDescriptorForSaveKey back to summary

getFetchDescriptorForSaveKey	back to summary
pack-priv FetchDescriptor getFetchDescriptorForSaveKey(int[] vcols, int fullLength) Get a fetch descriptor that can be used to fetch the missing columns in a partial key. The fetch descriptor is only created on the first call to this method. The returned descriptor will be cached, so subsequent calls will return the same descriptor and the arguments to this method should be the same between invokations. Parameters vcols:int[] an array which tells which columns the partial key contains (valid columns have non-zero values in the array) fullLength:int the length of the full key to create a fetch descriptor for (may be greater than `vcols.length`) Returns:FetchDescriptor a fetch descriptor

pack-priv FetchDescriptor getFetchDescriptorForSaveKey(int[] vcols, int fullLength)

Get a fetch descriptor that can be used to fetch the missing columns in a partial key. The fetch descriptor is only created on the first call to this method. The returned descriptor will be cached, so subsequent calls will return the same descriptor and the arguments to this method should be the same between invokations.

Parameters

vcols:int[]: an array which tells which columns the partial key contains (valid columns have non-zero values in the array)
fullLength:int: the length of the full key to create a fetch descriptor for (may be greater than vcols.length)

Returns:FetchDescriptor

a fetch descriptor

getKeyTemplate	back to summary
pack-priv DataValueDescriptor[] getKeyTemplate() throws StandardException Get a template into which the position key can be copied. The value is cached, so two calls to this method on the same object will return the same object. Returns:DataValueDescriptor[] an array into which the position key can be copied Exceptions StandardException: if an error occurs while allocating the template array

getKeyTemplate

back to summary

pack-priv DataValueDescriptor[] getKeyTemplate() throws StandardException

Get a template into which the position key can be copied. The value is cached, so two calls to this method on the same object will return the same object.

Returns:DataValueDescriptor[]

an array into which the position key can be copied

Exceptions

StandardException:: if an error occurs while allocating the template array

init	back to summary
public void init() Overrides org.apache.derby.impl.store.access.conglomerate.RowPosition.init. Public Methods of This class:

init

back to summary

public void init()

Overrides org.apache.derby.impl.store.access.conglomerate.RowPosition.init.

Public Methods of This class:

saveMeAndReleasePage back to summary

saveMeAndReleasePage	back to summary
public void saveMeAndReleasePage() throws StandardException Save this position by key and release the latch on the current leaf. Exceptions StandardException: if an error occurs while saving the position See Also `BTreeScan#savePositionAndReleasePage()`

public void saveMeAndReleasePage() throws StandardException

Save this position by key and release the latch on the current leaf.

Exceptions

StandardException:: if an error occurs while saving the position

toString back to summary

toString	back to summary
public final String toString() Overrides org.apache.derby.impl.store.access.conglomerate.RowPosition.toString. Doc from java.lang.Object.toString. Returns a string representation of the object. Satisfying this method's contract implies a non-`null` result must be returned. Returns:String a string representation of the object

public final String toString()

Overrides org.apache.derby.impl.store.access.conglomerate.RowPosition.toString.

Doc from java.lang.Object.toString.

Returns a string representation of the object. Satisfying this method's contract implies a non-null result must be returned.

Returns:String: a string representation of the object