gserialized_gist_penalty()

Datum gserialized_gist_penalty

(

PG_FUNCTION_ARGS

)

Definition at line 1175 of file gserialized_gist_nd.c.

{
        GISTENTRY *origentry = (GISTENTRY *)PG_GETARG_POINTER(0);
        GISTENTRY *newentry = (GISTENTRY *)PG_GETARG_POINTER(1);
        float *result = (float *)PG_GETARG_POINTER(2);
        GIDX *gbox_index_orig, *gbox_index_new;
 
        gbox_index_orig = (GIDX *)DatumGetPointer(origentry->key);
        gbox_index_new = (GIDX *)DatumGetPointer(newentry->key);
 
        /* Penalty value of 0 has special code path in Postgres's gistchoose.
         * It is used as an early exit condition in subtree loop, allowing faster tree descend.
         * For multi-column index, it lets next column break the tie, possibly more confidently.
         */
        *result = 0.0;
 
        /* Drop out if we're dealing with null inputs. Shouldn't happen. */
        if (gbox_index_orig && gbox_index_new)
        {
                /* Calculate the size difference of the boxes (volume difference in this case). */
                float size_union = gidx_union_volume(gbox_index_orig, gbox_index_new);
                float size_orig = gidx_volume(gbox_index_orig);
                float volume_extension = size_union - size_orig;
 
                /* REALM 1: Area extension is nonzero, return it */
                if (volume_extension > FLT_EPSILON)
                        *result = pack_float(volume_extension, 1);
                else
                {
                        /* REALM 0: Area extension is zero, return nonzero edge extension */
                        float edge_union = gidx_union_edge(gbox_index_orig, gbox_index_new);
                        float edge_orig = gidx_edge(gbox_index_orig);
                        float edge_extension = edge_union - edge_orig;
                        if (edge_extension > FLT_EPSILON)
                                *result = pack_float(edge_extension, 0);
                }
        }
        PG_RETURN_POINTER(result);
}

References gidx_edge(), gidx_union_edge(), gidx_union_volume(), gidx_volume(), and pack_float().

Referenced by gserialized_gist_picksplit_constructsplit().

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