nd_stats_to_json()

static char* nd_stats_to_json ( const ND_STATS *  nd_stats )

static

Convert an ND_STATS to a JSON representation for external use.

Definition at line 493 of file gserialized_estimate.c.

{
        char *json_extent, *str;
        int d;
        stringbuffer_t *sb = stringbuffer_create();
        int ndims = (int)roundf(nd_stats->ndims);
 
        stringbuffer_append(sb, "{");
        stringbuffer_aprintf(sb, "\"ndims\":%d,", ndims);
 
        /* Size */
        stringbuffer_append(sb, "\"size\":[");
        for ( d = 0; d < ndims; d++ )
        {
                if ( d ) stringbuffer_append(sb, ",");
                stringbuffer_aprintf(sb, "%d", (int)roundf(nd_stats->size[d]));
        }
        stringbuffer_append(sb, "],");
 
        /* Extent */
        json_extent = nd_box_to_json(&(nd_stats->extent), ndims);
        stringbuffer_aprintf(sb, "\"extent\":%s,", json_extent);
        pfree(json_extent);
 
        stringbuffer_aprintf(sb, "\"table_features\":%d,", (int)roundf(nd_stats->table_features));
        stringbuffer_aprintf(sb, "\"sample_features\":%d,", (int)roundf(nd_stats->sample_features));
        stringbuffer_aprintf(sb, "\"not_null_features\":%d,", (int)roundf(nd_stats->not_null_features));
        stringbuffer_aprintf(sb, "\"histogram_features\":%d,", (int)roundf(nd_stats->histogram_features));
        stringbuffer_aprintf(sb, "\"histogram_cells\":%d,", (int)roundf(nd_stats->histogram_cells));
        stringbuffer_aprintf(sb, "\"cells_covered\":%d", (int)roundf(nd_stats->cells_covered));
        stringbuffer_append(sb, "}");
 
        str = stringbuffer_getstringcopy(sb);
        stringbuffer_destroy(sb);
        return str;
}

References ND_STATS_T::cells_covered, ND_STATS_T::extent, ND_STATS_T::histogram_cells, ND_STATS_T::histogram_features, nd_box_to_json(), ND_STATS_T::ndims, ND_STATS_T::not_null_features, ND_STATS_T::sample_features, ND_STATS_T::size, str, stringbuffer_append(), stringbuffer_aprintf(), stringbuffer_create(), stringbuffer_destroy(), stringbuffer_getstringcopy(), and ND_STATS_T::table_features.

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

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