PostGIS  2.5.7dev-r@@SVN_REVISION@@

◆ _postgis_gserialized_joinsel()

Datum _postgis_gserialized_joinsel ( PG_FUNCTION_ARGS  )

Definition at line 2133 of file gserialized_estimate.c.

2134 {
2135  Oid table_oid1 = PG_GETARG_OID(0);
2136  text *att_text1 = PG_GETARG_TEXT_P(1);
2137  Oid table_oid2 = PG_GETARG_OID(2);
2138  text *att_text2 = PG_GETARG_TEXT_P(3);
2139  ND_STATS *nd_stats1, *nd_stats2;
2140  float8 selectivity = 0;
2141  int mode = 2; /* 2D mode by default */
2142 
2143 
2144  /* Retrieve the stats object */
2145  nd_stats1 = pg_get_nd_stats_by_name(table_oid1, att_text1, mode, false);
2146  nd_stats2 = pg_get_nd_stats_by_name(table_oid2, att_text2, mode, false);
2147 
2148  if ( ! nd_stats1 )
2149  elog(ERROR, "stats for \"%s.%s\" do not exist", get_rel_name(table_oid1), text_to_cstring(att_text1));
2150 
2151  if ( ! nd_stats2 )
2152  elog(ERROR, "stats for \"%s.%s\" do not exist", get_rel_name(table_oid2), text_to_cstring(att_text2));
2153 
2154  /* Check if we've been asked to not use 2d mode */
2155  if ( ! PG_ARGISNULL(4) )
2156  {
2157  text *modetxt = PG_GETARG_TEXT_P(4);
2158  char *modestr = text_to_cstring(modetxt);
2159  if ( modestr[0] == 'N' )
2160  mode = 0;
2161  }
2162 
2163  /* Do the estimation */
2164  selectivity = estimate_join_selectivity(nd_stats1, nd_stats2);
2165 
2166  pfree(nd_stats1);
2167  pfree(nd_stats2);
2168  PG_RETURN_FLOAT8(selectivity);
2169 }
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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