PostGIS  2.2.8dev-r@@SVN_REVISION@@

◆ _postgis_gserialized_joinsel()

Datum _postgis_gserialized_joinsel ( PG_FUNCTION_ARGS  )

Definition at line 1996 of file gserialized_estimate.c.

References estimate_join_selectivity(), gserialized_gist_sel_2d(), PG_FUNCTION_INFO_V1(), pg_get_nd_stats_by_name(), and text2cstring().

Referenced by _postgis_gserialized_sel().

1997 {
1998  Oid table_oid1 = PG_GETARG_OID(0);
1999  text *att_text1 = PG_GETARG_TEXT_P(1);
2000  Oid table_oid2 = PG_GETARG_OID(2);
2001  text *att_text2 = PG_GETARG_TEXT_P(3);
2002  ND_STATS *nd_stats1, *nd_stats2;
2003  float8 selectivity = 0;
2004  int mode = 2; /* 2D mode by default */
2005 
2006 
2007  /* Retrieve the stats object */
2008  nd_stats1 = pg_get_nd_stats_by_name(table_oid1, att_text1, mode);
2009  nd_stats2 = pg_get_nd_stats_by_name(table_oid2, att_text2, mode);
2010 
2011  if ( ! nd_stats1 )
2012  elog(ERROR, "stats for \"%s.%s\" do not exist", get_rel_name(table_oid1), text2cstring(att_text1));
2013 
2014  if ( ! nd_stats2 )
2015  elog(ERROR, "stats for \"%s.%s\" do not exist", get_rel_name(table_oid2), text2cstring(att_text2));
2016 
2017  /* Check if we've been asked to not use 2d mode */
2018  if ( ! PG_ARGISNULL(4) )
2019  {
2020  text *modetxt = PG_GETARG_TEXT_P(4);
2021  char *modestr = text2cstring(modetxt);
2022  if ( modestr[0] == 'N' )
2023  mode = 0;
2024  }
2025 
2026  /* Do the estimation */
2027  selectivity = estimate_join_selectivity(nd_stats1, nd_stats2);
2028 
2029  pfree(nd_stats1);
2030  pfree(nd_stats2);
2031  PG_RETURN_FLOAT8(selectivity);
2032 }
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...
static ND_STATS * pg_get_nd_stats_by_name(const Oid table_oid, const text *att_text, int mode)
Pull the stats object from the PgSQL system catalogs.
N-dimensional statistics structure.
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