Under which conditions is it safe to disable coalescing of free extents ?

I am setting up my first Oracle database.

In one of the setups I though of, all tables in a given tablespace have the same INITIAL = NEXT = X and PCTINCREASE = 0. Therefore, all extents of that tablespace which were once allocated and happen to be now free have the same size X, which is the size the next allocation of an extent will request.

Hence, I though of using PCTINCREASE = 0 for the tablespace in order to avoid having SMON coalesce the free extents. Indeed, I do not see the point to merge these properly sized extents just to break again the result later. I hope to save some I/O that way.

Am I correct in thinking this ? In which (other ?) cases is it safe to disable defragmentation ?

Thanks to all of you

• Raoul