gserialized_joinsel_internal()

double gserialized_joinsel_internal	(	PlannerInfo *	root,
		List *	args,
		JoinType	jointype,
		int	mode
	)

Definition at line 1121 of file gserialized_estimate.c.

{
        float8 selectivity;
        Oid relid1, relid2;
        ND_STATS *stats1, *stats2;
        Node *arg1 = (Node*) linitial(args);
        Node *arg2 = (Node*) lsecond(args);
        Var *var1 = (Var*) arg1;
        Var *var2 = (Var*) arg2;
 
        POSTGIS_DEBUGF(2, "%s: entered function", __func__);
 
        /* We only do column joins right now, no functional joins */
        /* TODO: handle g1 && ST_Expand(g2) */
        if (!IsA(arg1, Var) || !IsA(arg2, Var))
        {
                POSTGIS_DEBUGF(1, "%s called with arguments that are not column references", __func__);
                return DEFAULT_ND_JOINSEL;
        }
 
        /* What are the Oids of our tables/relations? */
        relid1 = rt_fetch(var1->varno, root->parse->rtable)->relid;
        relid2 = rt_fetch(var2->varno, root->parse->rtable)->relid;
 
        /* Pull the stats from the stats system. */
        stats1 = pg_get_nd_stats(relid1, var1->varattno, mode, false);
        stats2 = pg_get_nd_stats(relid2, var2->varattno, mode, false);
 
        /* If we can't get stats, we have to stop here! */
        if (!stats1)
        {
                POSTGIS_DEBUGF(2, "%s: cannot find stats for \"%s\"",  __func__, get_rel_name(relid2) ? get_rel_name(relid2) : "NULL");
                return DEFAULT_ND_JOINSEL;
        }
        else if (!stats2)
        {
                POSTGIS_DEBUGF(2, "%s: cannot find stats for \"%s\"",  __func__, get_rel_name(relid2) ? get_rel_name(relid2) : "NULL");
                return DEFAULT_ND_JOINSEL;
        }
 
        selectivity = estimate_join_selectivity(stats1, stats2);
        POSTGIS_DEBUGF(2, "got selectivity %g", selectivity);
        pfree(stats1);
        pfree(stats2);
        return selectivity;
}

References DEFAULT_ND_JOINSEL, estimate_join_selectivity(), and pg_get_nd_stats().

Referenced by gserialized_gist_joinsel(), and postgis_index_supportfn().

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