/**
* Estimate the cardinality of a join. The cardinality of a join is the number of tuples produced
* by the join.
*
* @param j A LogicalJoinNode representing the join operation being performed.
* @param card1 Cardinality of the left-hand table in the join
* @param card2 Cardinality of the right-hand table in the join
* @param t1pkey Is the left-hand table a primary-key table?
* @param t2pkey Is the right-hand table a primary-key table?
* @param stats The table stats, referenced by table names, not alias
* @return The cardinality of the join
*/
public int estimateJoinCardinality(
LogicalJoinNode j,
int card1,
int card2,
boolean t1pkey,
boolean t2pkey,
Map<String, TableStats> stats) {
if (j instanceof LogicalSubplanJoinNode) {
// A LogicalSubplanJoinNode represents a subquery.
// You do not need to implement proper support for these for Project 3.
return card1;
} else {
return estimateTableJoinCardinality(
j.p,
j.t1Alias,
j.t2Alias,
j.f1PureName,
j.f2PureName,
card1,
card2,
t1pkey,
t2pkey,
stats,
p.getTableAliasToIdMapping());
}
}
/**
* Estimate the cardinality of a join. The cardinality of a join is the number of tuples produced
* by the join.
*
* @param j A LogicalJoinNode representing the join operation being performed.
* @param card1 Cardinality of the left-hand table in the join
* @param card2 Cardinality of the right-hand table in the join
* @param t1pkey Is the left-hand table a primary-key table?
* @param t2pkey Is the right-hand table a primary-key table?
* @param stats The table stats, referenced by table names, not alias
* @return The cardinality of the join
*/
public int estimateJoinCardinality(
LogicalJoinNode j,
int card1,
int card2,
boolean t1pkey,
boolean t2pkey,
Map<String, TableStats> stats) {
if (j instanceof LogicalSubplanJoinNode) {
// A LogicalSubplanJoinNode represents a subquery.
// Don't worry about implementing a more sophisticated estimate than the one below.
return card1;
} else {
return estimateTableJoinCardinality(
j.p,
j.t1Alias,
j.t2Alias,
j.f1PureName,
j.f2PureName,
card1,
card2,
t1pkey,
t2pkey,
stats,
p.getTableAliasToIdMapping());
}
}
/** Adds an expression and returns a reference name. */
public String addExpr(Expr expr) throws PlanningException {
if (idToExprBiMap.inverse().containsKey(expr)) {
int refId = idToExprBiMap.inverse().get(expr);
return idToNamesMap.get(refId).get(0);
}
String generatedName = plan.generateUniqueColumnName(expr);
return addExpr(expr, generatedName);
}
/**
* Helper function to display a Swing window with a tree representation of the specified list of
* joins. See {@link #orderJoins}, which may want to call this when the analyze flag is true.
*
* @param js the join plan to visualize
* @param pc the PlanCache accumulated whild building the optimal plan
* @param stats table statistics for base tables
* @param selectivities the selectivities of the filters over each of the tables (where tables are
* indentified by their alias or name if no alias is given)
*/
private void printJoins(
Vector<LogicalJoinNode> js,
PlanCache pc,
HashMap<String, TableStats> stats,
HashMap<String, Double> selectivities) {
JFrame f = new JFrame("Join Plan for " + p.getQuery());
// Set the default close operation for the window,
// or else the program won't exit when clicking close button
f.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
f.setVisible(true);
f.setSize(300, 500);
HashMap<String, DefaultMutableTreeNode> m = new HashMap<String, DefaultMutableTreeNode>();
// int numTabs = 0;
// int k;
DefaultMutableTreeNode root = null, treetop = null;
HashSet<LogicalJoinNode> pathSoFar = new HashSet<LogicalJoinNode>();
boolean neither;
System.out.println(js);
for (LogicalJoinNode j : js) {
pathSoFar.add(j);
System.out.println("PATH SO FAR = " + pathSoFar);
String table1Name = Database.getCatalog().getTableName(this.p.getTableId(j.t1Alias));
String table2Name = Database.getCatalog().getTableName(this.p.getTableId(j.t2Alias));
// Double c = pc.getCost(pathSoFar);
neither = true;
root =
new DefaultMutableTreeNode(
"Join "
+ j
+ " (Cost ="
+ pc.getCost(pathSoFar)
+ ", card = "
+ pc.getCard(pathSoFar)
+ ")");
DefaultMutableTreeNode n = m.get(j.t1Alias);
if (n == null) { // never seen this table before
n =
new DefaultMutableTreeNode(
j.t1Alias
+ " (Cost = "
+ stats.get(table1Name).estimateScanCost()
+ ", card = "
+ stats.get(table1Name).estimateTableCardinality(selectivities.get(j.t1Alias))
+ ")");
root.add(n);
} else {
// make left child root n
root.add(n);
neither = false;
}
m.put(j.t1Alias, root);
n = m.get(j.t2Alias);
if (n == null) { // never seen this table before
n =
new DefaultMutableTreeNode(
j.t2Alias == null
? "Subplan"
: (j.t2Alias
+ " (Cost = "
+ stats.get(table2Name).estimateScanCost()
+ ", card = "
+ stats
.get(table2Name)
.estimateTableCardinality(selectivities.get(j.t2Alias))
+ ")"));
root.add(n);
} else {
// make right child root n
root.add(n);
neither = false;
}
m.put(j.t2Alias, root);
// unless this table doesn't join with other tables,
// all tables are accessed from root
if (!neither) {
for (String key : m.keySet()) {
m.put(key, root);
}
}
treetop = root;
}
JTree tree = new JTree(treetop);
JScrollPane treeView = new JScrollPane(tree);
tree.setShowsRootHandles(true);
// Set the icon for leaf nodes.
ImageIcon leafIcon = new ImageIcon("join.jpg");
DefaultTreeCellRenderer renderer = new DefaultTreeCellRenderer();
renderer.setOpenIcon(leafIcon);
renderer.setClosedIcon(leafIcon);
tree.setCellRenderer(renderer);
f.setSize(300, 500);
f.add(treeView);
for (int i = 0; i < tree.getRowCount(); i++) {
tree.expandRow(i);
}
if (js.size() == 0) {
f.add(new JLabel("No joins in plan."));
}
f.pack();
}
/**
* Return true if field is a primary key of the specified table, false otherwise
*
* @param tableAlias The alias of the table in the query
* @param field The pure name of the field
*/
private boolean isPkey(String tableAlias, String field) {
int tid1 = p.getTableId(tableAlias);
String pkey1 = Database.getCatalog().getPrimaryKey(tid1);
return pkey1.equals(field);
}