/**
* 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());
}
}