class RelQueryEngine

The query engine is a repository for views, and also performs semantic checking for queries before optimization

Inheritance:

Public Methods

XxxErrCode	CheckOpDag (RelQueryNode *Root, const XxxArgEnv* Env, RelQueryClass*& Query) Creates an operator DAG for a query view
XxxErrCode	CheckQuery (RelViewClass* View, RelQueryClass*& Query, const XxxArgEnv* Env = NULL) Takes a view and produces a query from it
XxxErrCode	DropView (const char* ViewName) Deletes a view in this query engine
XxxErrCode	PrintViews (ostream& OStr) Prints all views stored in this query engine
	RelQueryEngine (XxxRelationEngine* SrcEng) Constructor
XxxErrCode	RetrieveView (const char* ViewName, RelViewClass*& View, XxxBool& Found) Retrieves a view from this query engine
XxxErrCode	StoreView (const char* ViewName, RelViewClass* View) Stores a view in this query engine
XxxErrCode	ViewToOpDag (RelViewClass *View, RelQueryNode *&Root) Creates an operator DAG for a query view
	~RelQueryEngine () Destructor

Private Fields

XxxRelationEngine*

RelEng a handle on the relation engine

XxxRelationEngine* RelEng

a handle on the relation engine

RelQueryEngine(XxxRelationEngine* SrcEng)

Constructor

Parameters:

SrcEng - The Relation engine to which this engine belongs

~RelQueryEngine()

Destructor

XxxErrCode StoreView(const char* ViewName, RelViewClass* View)

Stores a view in this query engine

Returns:

XXX_OK if no errors occured

Parameters:

ViewName - The name of the view to store
View - The View data structure to store

XxxErrCode DropView(const char* ViewName)

Deletes a view in this query engine

Returns:

XXX_OK if no errors occured

Parameters:

ViewName - The name of the view to store

XxxErrCode RetrieveView(const char* ViewName, RelViewClass*& View, XxxBool& Found)

Retrieves a view from this query engine

Returns:

XXX_OK if no errors occured

Parameters:

ViewName - The name of the view to retrieve
View - The View data structure retrieved

XxxErrCode CheckQuery(RelViewClass* View, RelQueryClass*& Query, const XxxArgEnv* Env = NULL)

Takes a view and produces a query from it. This function transforms the view into a DAG, performs semantic checking, propagates all meta info, performed heuristic rewrite, etc.

Returns:

XXX_OK if no errors occured

Parameters:

View - The view to transform
Query - (output) the query generated
Env - The query environment (optional)

XxxErrCode ViewToOpDag(RelViewClass *View, RelQueryNode *&Root)

Creates an operator DAG for a query view. Uses a RelOpDagBuilder which actually performs the translation.

Parameters:

View - The view to be transformed into a tree
Root - The root of the newly contructed tree

XxxErrCode CheckOpDag(RelQueryNode *Root, const XxxArgEnv* Env, RelQueryClass*& Query)

Creates an operator DAG for a query view. Uses a RelOpDagBuilder which actually performs the translation.

Parameters:

View - The view to be transformed into a tree
Root - The root of the newly contructed tree

XxxErrCode PrintViews(ostream& OStr)

Prints all views stored in this query engine

Parameters:

OStr - The stream to which the views should be printed

alphabetic index hierarchy of classes

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(c)opyright by Malte Zöckler, Roland Wunderling
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