private void ConstructSelectGraph()
{
QueryGraph = GraphViewDocDBCommand.DocDB_ConstructGraph(SelectQueryBlock);
NodeTable = QueryGraph.ConnectedSubGraphs[0].Nodes;
var AttachPredicateVisitor = new AttachWhereClauseVisitor();
var TableContext = new WSqlTableContext();
var GraphMeta = new GraphMetaData();
var columnTableMapping = TableContext.GetColumnToAliasMapping(GraphMeta.ColumnsOfNodeTables);
if (SelectQueryBlock != null)
{
AttachPredicateVisitor.Invoke(SelectQueryBlock.WhereClause, QueryGraph, columnTableMapping);
}
int GroupNumber = 0;
foreach (var node in NodeTable)
{
GraphViewDocDBCommand.GetQuery(node.Value);
if (!GraphDescription.ContainsKey(node.Value.NodeAlias))
{
GraphDescription[node.Value.NodeAlias] = ++GroupNumber;
}
}
}
private void AttachPredicates(WWhereClause whereClause, MatchGraph graph)
{
// Attaches proper parts of the where clause into the Estimiation Query
var attachPredicateVisitor = new AttachWhereClauseVisitor();
var columnTableMapping = _context.GetColumnToAliasMapping(_graphMetaData.ColumnsOfNodeTables);
attachPredicateVisitor.Invoke(whereClause, graph, columnTableMapping);
}
/// <summary>
/// Estimate number of rows of node table in graph.
/// </summary>
/// <param name="graph">Constructed node graph</param>
private void EstimateRows(WSelectQueryBlock query, MatchGraph graph)
{
var declareParameter = "";
if (_variables != null)
{
foreach (var parameter in _variables)
{
declareParameter += "DECLARE " + parameter.VariableName.Value + " " +
TsqlFragmentToString.DataType(parameter.DataType) + "\r\n";
}
}
var estimator = new TableSizeEstimator(Conn);
bool first = true;
var fromQuerySb = new StringBuilder(1024);
foreach (var subGraph in graph.ConnectedSubGraphs)
{
foreach (var node in subGraph.Nodes)
{
if (first)
first = false;
else
fromQuerySb.Append(", ");
var currentNode = node.Value;
fromQuerySb.AppendFormat("{0} AS [{1}] WITH (ForceScan)", currentNode.TableObjectName,
currentNode.NodeAlias);
}
}
// Attach proper parts of the where clause into the Estimiation Query
var columnTableMapping = _context.GetColumnTableMapping(_columnsOfNodeTables);
var attachWhereClauseVisiter = new AttachNodeEdgePredictesVisitor();
var nodeEstimationWhereClause = attachWhereClauseVisiter.Invoke(query.WhereClause, graph, columnTableMapping);
string nodeEstimationQuery = string.Format("{0}\r\n SELECT * FROM {1}\r\n", declareParameter,
fromQuerySb);
if (nodeEstimationWhereClause.SearchCondition != null)
nodeEstimationQuery += nodeEstimationWhereClause.ToString();
var estimateRows = estimator.GetQueryTableEstimatedRows(nodeEstimationQuery);
foreach (var subGraph in graph.ConnectedSubGraphs)
{
// Update Row Estimation for nodes
foreach (var node in subGraph.Nodes)
{
var currentNode = node.Value;
currentNode.EstimatedRows = estimateRows[node.Key];
var tableSchema = currentNode.TableObjectName.SchemaIdentifier.Value;
var tableName = currentNode.TableObjectName.BaseIdentifier.Value;
currentNode.TableRowCount = estimator.GetTableRowCount(tableSchema, tableName);
}
}
// Attach predicates to nodes and edges
var attachPredicateVisitor = new AttachWhereClauseVisitor();
attachPredicateVisitor.Invoke(query.WhereClause, graph, columnTableMapping);
}