PostGIS  2.5.7dev-r@@SVN_REVISION@@

◆ _postgis_gserialized_sel()

Datum _postgis_gserialized_sel ( PG_FUNCTION_ARGS  )

Definition at line 2094 of file gserialized_estimate.c.

2095 {
2096  Oid table_oid = PG_GETARG_OID(0);
2097  text *att_text = PG_GETARG_TEXT_P(1);
2098  Datum geom_datum = PG_GETARG_DATUM(2);
2099  GBOX gbox; /* search box read from gserialized datum */
2100  float8 selectivity = 0;
2101  ND_STATS *nd_stats;
2102  int mode = 2; /* 2D mode by default */
2103 
2104  /* Check if we've been asked to not use 2d mode */
2105  if ( ! PG_ARGISNULL(3) )
2106  mode = text_p_get_mode(PG_GETARG_TEXT_P(3));
2107 
2108  /* Retrieve the stats object */
2109  nd_stats = pg_get_nd_stats_by_name(table_oid, att_text, mode, false);
2110 
2111  if ( ! nd_stats )
2112  elog(ERROR, "stats for \"%s.%s\" do not exist", get_rel_name(table_oid), text_to_cstring(att_text));
2113 
2114  /* Calculate the gbox */
2115  if ( ! gserialized_datum_get_gbox_p(geom_datum, &gbox) )
2116  elog(ERROR, "unable to calculate bounding box from geometry");
2117 
2118  POSTGIS_DEBUGF(3, " %s", gbox_to_string(&gbox));
2119 
2120  /* Do the estimation */
2121  selectivity = estimate_selectivity(&gbox, nd_stats, mode);
2122 
2123  pfree(nd_stats);
2124  PG_RETURN_FLOAT8(selectivity);
2125 }
char * gbox_to_string(const GBOX *gbox)
Allocate a string representation of the GBOX, based on dimensionality of flags.
Definition: g_box.c:399
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_selectivity(const GBOX *box, const ND_STATS *nd_stats, int mode)
This function returns an estimate of the selectivity of a search GBOX by looking at data in the ND_ST...
static int text_p_get_mode(const text *txt)
Utility function to see if the first letter of the mode argument is 'N'.
char * text_to_cstring(const text *textptr)
N-dimensional statistics structure.

References estimate_selectivity(), gbox_to_string(), pg_get_nd_stats_by_name(), text_p_get_mode(), and text_to_cstring().

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