nd_stats_value_index()

static int nd_stats_value_index ( const ND_STATS *  stats, int *  indexes  )

static

Given a position in the n-d histogram (i,j,k) return the position in the 1-d values array.

Definition at line 436 of file gserialized_estimate.c.

{
        int d;
        int accum = 1, vdx = 0;
 
        /* Calculate the index into the 1-d values array that the (i,j,k,l) */
        /* n-d histogram coordinate implies. */
        /* index = x + y * sizex + z * sizex * sizey + m * sizex * sizey * sizez */
        for ( d = 0; d < (int)(stats->ndims); d++ )
        {
                int size = (int)(stats->size[d]);
                if ( indexes[d] < 0 || indexes[d] >= size )
                {
                        POSTGIS_DEBUGF(3, " bad index at (%d, %d)", indexes[0], indexes[1]);
                        return -1;
                }
                vdx += indexes[d] * accum;
                accum *= size;
        }
        return vdx;
}

References ND_STATS_T::ndims, and ND_STATS_T::size.

Referenced by compute_gserialized_stats_mode(), estimate_join_selectivity(), and estimate_selectivity().

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