PostGIS  3.0.6dev-r@@SVN_REVISION@@

◆ _postgis_gserialized_joinsel()

Datum _postgis_gserialized_joinsel ( PG_FUNCTION_ARGS  )

Definition at line 2145 of file gserialized_estimate.c.

2146 {
2147  Oid table_oid1 = PG_GETARG_OID(0);
2148  text *att_text1 = PG_GETARG_TEXT_P(1);
2149  Oid table_oid2 = PG_GETARG_OID(2);
2150  text *att_text2 = PG_GETARG_TEXT_P(3);
2151  ND_STATS *nd_stats1, *nd_stats2;
2152  float8 selectivity = 0;
2153  int mode = 2; /* 2D mode by default */
2154 
2155 
2156  /* Retrieve the stats object */
2157  nd_stats1 = pg_get_nd_stats_by_name(table_oid1, att_text1, mode, false);
2158  nd_stats2 = pg_get_nd_stats_by_name(table_oid2, att_text2, mode, false);
2159 
2160  if ( ! nd_stats1 )
2161  elog(ERROR, "stats for \"%s.%s\" do not exist", get_rel_name(table_oid1), text_to_cstring(att_text1));
2162 
2163  if ( ! nd_stats2 )
2164  elog(ERROR, "stats for \"%s.%s\" do not exist", get_rel_name(table_oid2), text_to_cstring(att_text2));
2165 
2166  /* Check if we've been asked to not use 2d mode */
2167  if ( ! PG_ARGISNULL(4) )
2168  {
2169  text *modetxt = PG_GETARG_TEXT_P(4);
2170  char *modestr = text_to_cstring(modetxt);
2171  if ( modestr[0] == 'N' )
2172  mode = 0;
2173  }
2174 
2175  /* Do the estimation */
2176  selectivity = estimate_join_selectivity(nd_stats1, nd_stats2);
2177 
2178  pfree(nd_stats1);
2179  pfree(nd_stats2);
2180  PG_RETURN_FLOAT8(selectivity);
2181 }
static ND_STATS * pg_get_nd_stats_by_name(const Oid table_oid, const text *att_text, int mode, bool only_parent)
Pull the stats object from the PgSQL system catalogs.
static float8 estimate_join_selectivity(const ND_STATS *s1, const ND_STATS *s2)
Given two statistics histograms, what is the selectivity of a join driven by the && or &&& operator?
char * text_to_cstring(const text *textptr)
N-dimensional statistics structure.

References estimate_join_selectivity(), pg_get_nd_stats_by_name(), and text_to_cstring().

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