PostGIS  3.4.0dev-r@@SVN_REVISION@@

◆ _postgis_gserialized_joinsel()

Datum _postgis_gserialized_joinsel ( PG_FUNCTION_ARGS  )

Definition at line 2135 of file gserialized_estimate.c.

2136 {
2137  Oid table_oid1 = PG_GETARG_OID(0);
2138  text *att_text1 = PG_GETARG_TEXT_P(1);
2139  Oid table_oid2 = PG_GETARG_OID(2);
2140  text *att_text2 = PG_GETARG_TEXT_P(3);
2141  ND_STATS *nd_stats1, *nd_stats2;
2142  float8 selectivity = 0;
2143  int mode = 2; /* 2D mode by default */
2144 
2145 
2146  /* Retrieve the stats object */
2147  nd_stats1 = pg_get_nd_stats_by_name(table_oid1, att_text1, mode, false);
2148  nd_stats2 = pg_get_nd_stats_by_name(table_oid2, att_text2, mode, false);
2149 
2150  if ( ! nd_stats1 )
2151  elog(ERROR, "stats for \"%s.%s\" do not exist", get_rel_name(table_oid1), text_to_cstring(att_text1));
2152 
2153  if ( ! nd_stats2 )
2154  elog(ERROR, "stats for \"%s.%s\" do not exist", get_rel_name(table_oid2), text_to_cstring(att_text2));
2155 
2156  /* Check if we've been asked to not use 2d mode */
2157  if ( ! PG_ARGISNULL(4) )
2158  {
2159  text *modetxt = PG_GETARG_TEXT_P(4);
2160  char *modestr = text_to_cstring(modetxt);
2161  if ( modestr[0] == 'N' )
2162  mode = 0;
2163  }
2164 
2165  /* Do the estimation */
2166  selectivity = estimate_join_selectivity(nd_stats1, nd_stats2);
2167 
2168  pfree(nd_stats1);
2169  pfree(nd_stats2);
2170  PG_RETURN_FLOAT8(selectivity);
2171 }
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?
N-dimensional statistics structure.

References estimate_join_selectivity(), and pg_get_nd_stats_by_name().

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