Fragmentation catalogue

This is a list of all articles I’ve written that discuss “fragmentation”, space wastage and rebuilds. Each entry has a date stamp and a short note of the contents. The articles are (may be / will be) grouped in a couple of different categories, but otherwise are generally listed most-recent first.

I am currently working backwards through my entire blog adding articles to catalogues as I go, so any individual catalogue may grow very slowly.

• Quiz – what’s the row length (May 2022): avg_row_len * num_rows isn’t always a good approximation to the total space your data needs – even when it’s simple Oracle types.
• Reclaiming SYSAUX space (Mar 2022): notes on shrinking the size of SYSAUX, and the special case for handling PDBs.
• Free space performance threat (Aug 2019): if you have things in your recyclebin then querying dba_free_space may be very slow – unless you gather some x$ stats.
• Quantum Space (May 2017): why some space can be both free and not free.
• Tablespace HWM (March 2015): some comments about finding the tablespace highwaterr mark.
• Fragmentation (getting started) (July 2013): a list with a definitive starting point for the discussions.
• Shrinking a tablespace (Feb 2010): comments on a common problem with shrinking the files in a tablespace.