PostgreSQL在何处处理 sql查询之六十六

继续分析

/*
 * final_cost_hashjoin
 *      Final estimate of the cost and result size of a hashjoin path.
 *
 * Note: the numbatches estimate is also saved into 'path' for use later
 *
 * 'path' is already filled in except for the rows and cost fields and
 *        num_batches
 * 'workspace' is the result from initial_cost_hashjoin
 * 'sjinfo' is extra info about the join for selectivity estimation
 * 'semifactors' contains valid data if path->jointype is SEMI or ANTI
 */
void
final_cost_hashjoin(PlannerInfo *root, HashPath *path,
                    JoinCostWorkspace *workspace,
                    SpecialJoinInfo *sjinfo,
                    SemiAntiJoinFactors *semifactors)
{
    Path       *outer_path = path->jpath.outerjoinpath;
    Path       *inner_path = path->jpath.innerjoinpath;
    double        outer_path_rows = outer_path->rows;
    double        inner_path_rows = inner_path->rows;
    List       *hashclauses = path->path_hashclauses;
    Cost        startup_cost = workspace->startup_cost;
    Cost        run_cost = workspace->run_cost;
    int            numbuckets = workspace->numbuckets;
    int            numbatches = workspace->numbatches;
    Cost        cpu_per_tuple;
    QualCost    hash_qual_cost;
    QualCost    qp_qual_cost;
    double        hashjointuples;
    double        virtualbuckets;
    Selectivity innerbucketsize;
    ListCell   *hcl;

    ...
    qp_qual_cost.startup -= hash_qual_cost.startup;
    qp_qual_cost.per_tuple -= hash_qual_cost.per_tuple;
    ...
}