PostGIS  2.5.0dev-r@@SVN_REVISION@@
Datum _postgis_gserialized_joinsel ( PG_FUNCTION_ARGS  )

Definition at line 2110 of file gserialized_estimate.c.

References estimate_join_selectivity(), pg_get_nd_stats_by_name(), and text2cstring().

2111 {
2112  Oid table_oid1 = PG_GETARG_OID(0);
2113  text *att_text1 = PG_GETARG_TEXT_P(1);
2114  Oid table_oid2 = PG_GETARG_OID(2);
2115  text *att_text2 = PG_GETARG_TEXT_P(3);
2116  ND_STATS *nd_stats1, *nd_stats2;
2117  float8 selectivity = 0;
2118  int mode = 2; /* 2D mode by default */
2119 
2120 
2121  /* Retrieve the stats object */
2122  nd_stats1 = pg_get_nd_stats_by_name(table_oid1, att_text1, mode, false);
2123  nd_stats2 = pg_get_nd_stats_by_name(table_oid2, att_text2, mode, false);
2124 
2125  if ( ! nd_stats1 )
2126  elog(ERROR, "stats for \"%s.%s\" do not exist", get_rel_name(table_oid1), text2cstring(att_text1));
2127 
2128  if ( ! nd_stats2 )
2129  elog(ERROR, "stats for \"%s.%s\" do not exist", get_rel_name(table_oid2), text2cstring(att_text2));
2130 
2131  /* Check if we've been asked to not use 2d mode */
2132  if ( ! PG_ARGISNULL(4) )
2133  {
2134  text *modetxt = PG_GETARG_TEXT_P(4);
2135  char *modestr = text2cstring(modetxt);
2136  if ( modestr[0] == 'N' )
2137  mode = 0;
2138  }
2139 
2140  /* Do the estimation */
2141  selectivity = estimate_join_selectivity(nd_stats1, nd_stats2);
2142 
2143  pfree(nd_stats1);
2144  pfree(nd_stats2);
2145  PG_RETURN_FLOAT8(selectivity);
2146 }
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.
char * text2cstring(const text *textptr)
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.

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