
This function collects (or updates) values distribution data for a given column.

It splits the sorted column values in n_buckets intervals and collects the last value of each interval.
The values are then inserted into the SYS_COL_HIST table.

If the table in question hasn"t been analyzed, then it calls SYS_STAT_ANALYZE for the table.

The histograms are then used by the Optimized SQL compiler. All the cached compilations are
discarded, because some of them may compile differently in the light of the new data.
