java.lang.Object
- org.apache.derby.impl.sql.execute.xplain.XPLAINSystemTableVisitor

All Implemented Interfaces:

XPLAINVisitor
```
public class XPLAINSystemTableVisitor
extends java.lang.Object
implements XPLAINVisitor
```
This is the Visitor, which explains the information and stores the statistics in the system catalogs. It traverses the result set statistics tree and extracts the information.

Field Summary

Fields
Modifier and Type	Field	Description
`private Activation`	`activation`
`private boolean`	`considerTimingInformation`
`private DataDictionary`	`dd`
`private LanguageConnectionContext`	`lcc`
`private boolean`	`no_call_stmts`
`private int`	`noChildren`
`private java.util.List<XPLAINResultSetDescriptor>`	`rsets`
`private java.util.List<java.lang.Object>`	`rsetsTimings`
`private java.util.List<XPLAINScanPropsDescriptor>`	`scanrsets`
`private java.util.List<XPLAINSortPropsDescriptor>`	`sortrsets`
`private XPLAINStatementDescriptor`	`stmt`
`private XPLAINStatementTimingsDescriptor`	`stmtTimings`
`private UUID`	`stmtUUID`
`private java.util.Stack<UUID>`	`UUIDStack`

Constructor Summary

Constructors
Constructor Description

XPLAINSystemTableVisitor()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`private void`	`addArraysToSystemCatalogs()`	This method writes the created descriptor arrays to the cooresponding system catalogs.
`private void`	`addStmtDescriptorsToSystemCatalog()`	This method writes only the stmt and its timing descriptor to the dataDictionary
`private void`	`clean()`	This method cleans up things after explanation.
`void`	`doXPLAIN(RunTimeStatistics rss, Activation activation)`	the interface method, which gets called by the Top-ResultSet, which starts the tree traversal.
`private java.sql.Connection`	`getDefaultConn()`	Open a nested Connection with which to execute INSERT statements.
`private void`	`pushUUIDnoChildren(UUID uuid)`	helper method, which pushes the UUID, "number of Children" times onto the UUIDStack.
`void`	`reset()`	This method resets the visitor.
`void`	`setNumberOfChildren(int noChildren)`	this method only stores the current number of children of the current explained node.
`void`	`visit(ResultSetStatistics statistics)`	Visit this node, calling back to it to get details.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - no_call_stmts
```
private boolean no_call_stmts
```
  - lcc
```
private LanguageConnectionContext lcc
```
  - dd
```
private DataDictionary dd
```
  - activation
```
private Activation activation
```
  - considerTimingInformation
```
private boolean considerTimingInformation
```
  - stmt
```
private XPLAINStatementDescriptor stmt
```
  - stmtTimings
```
private XPLAINStatementTimingsDescriptor stmtTimings
```
  - stmtUUID
```
private UUID stmtUUID
```
  - rsets
```
private java.util.List<XPLAINResultSetDescriptor> rsets
```
  - rsetsTimings
```
private java.util.List<java.lang.Object> rsetsTimings
```
  - sortrsets
```
private java.util.List<XPLAINSortPropsDescriptor> sortrsets
```
  - scanrsets
```
private java.util.List<XPLAINScanPropsDescriptor> scanrsets
```
  - noChildren
```
private int noChildren
```
  - UUIDStack
```
private java.util.Stack<UUID> UUIDStack
```
- Constructor Detail
  - XPLAINSystemTableVisitor
```
public XPLAINSystemTableVisitor()
```
- Method Detail
  - pushUUIDnoChildren
```
private void pushUUIDnoChildren(UUID uuid)
```
    helper method, which pushes the UUID, "number of Children" times onto the UUIDStack.
    
    Parameters:
    
    uuid - the UUID to push
  - setNumberOfChildren
```
public void setNumberOfChildren(int noChildren)
```
    this method only stores the current number of children of the current explained node. The child nodes then can re-use this information.
    
    Specified by:
    
    setNumberOfChildren in interface XPLAINVisitor
    
    Parameters:
    
    noChildren - the number of children of the current explained node.
  - visit
```
public void visit(ResultSetStatistics statistics)
```
    Visit this node, calling back to it to get details. This method visits the RS Statisitcs node, calling back to the node to get detailed descriptor information about it.
    
    Specified by:
    
    visit in interface XPLAINVisitor
    
    Parameters:
    
    statistics - the statistics, which want to get explained.
  - reset
```
public void reset()
```
    This method resets the visitor. Gets called right before explanation to make sure all needed objects exist and are up to date and the lists are cleared
    
    Specified by:
    
    reset in interface XPLAINVisitor
  - doXPLAIN
```
public void doXPLAIN(RunTimeStatistics rss,
                     Activation activation)
              throws StandardException
```
    the interface method, which gets called by the Top-ResultSet, which starts the tree traversal.
    
    Specified by:
    
    doXPLAIN in interface XPLAINVisitor
    
    Throws:
    
    StandardException
  - clean
```
private void clean()
```
    This method cleans up things after explanation. It frees kept resources and still holded references.
  - getDefaultConn
```
private java.sql.Connection getDefaultConn()
                                    throws java.sql.SQLException
```
    Open a nested Connection with which to execute INSERT statements.
    
    Throws:
    
    java.sql.SQLException
  - addStmtDescriptorsToSystemCatalog
```
private void addStmtDescriptorsToSystemCatalog()
                                        throws StandardException,
                                               java.sql.SQLException
```
    This method writes only the stmt and its timing descriptor to the dataDictionary
    
    Throws:
    
    StandardException
    
    java.sql.SQLException
  - addArraysToSystemCatalogs
```
private void addArraysToSystemCatalogs()
                                throws StandardException,
                                       java.sql.SQLException
```
    This method writes the created descriptor arrays to the cooresponding system catalogs.
    
    Throws:
    
    StandardException
    
    java.sql.SQLException

Class XPLAINSystemTableVisitor

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

no_call_stmts

lcc

dd

activation

considerTimingInformation

stmt

stmtTimings

stmtUUID

rsets

rsetsTimings

sortrsets

scanrsets

noChildren

UUIDStack

Constructor Detail

XPLAINSystemTableVisitor

Method Detail

pushUUIDnoChildren

setNumberOfChildren

visit

reset

doXPLAIN

clean

getDefaultConn

addStmtDescriptorsToSystemCatalog

addArraysToSystemCatalogs