As it was mentioned before, CFS always appends updated blocks to the end of the compressed file. So physical size of the file

can be greater than used size in this file. I.e. CFS file is fragmented and defragmentation is periodically performed by CFS

garbage collector. <varname>cfs_fragmentation(relation)</varname> functions returns average fragmentation of relation files.

It is calculated asrum of physical sizes of the files divided by sum ofused size of the files.

It is calculated assum of physical sizes of the filesminus sum of used size of the filesdivided by sum ofphysical sizes of the files.

</para>

<para>

pfree(map_path);

relation_close(rel,AccessShareLock);

}

PG_RETURN_FLOAT8((double)physSize/usedSize);

PG_RETURN_FLOAT8((double)(physSize-usedSize)/physSize);

}

Datumcfs_gc_activity_processed_bytes(PG_FUNCTION_ARGS)