On 2017/08/15 08:05, Tim Gorman wrote:
Not sure if your table of 268 columns might be sparsely-populated or not, but
if the possibility exists, you might be interested in verifying using the
"carl.sql" procedure from this page HERE [1] and referencing this
presentation HERE [2] and this white paper HERE [3]. CARL (calculate average
row length) will attempt to recalculate how you can optimize your AVG_ROW_LEN
by re-organizing the table so that all non-null columns are first in each
row, leaving any null columns to trail. Along the way, it will also attempt
to calculate AVG_ROW_LEN for the present organization. In order for CARL to
work properly, it is best to have analyzed the table for column-level
statistics. The presentation and white paper will also have passing mention
of intra-block chaining, as well as other types of chaining/row-migration.
With more than 255 columns, you can't take advantage of BASIC or OLTP
compression, but any version of Oracle and any wide table can take advantage
of "trailing NULLCOLS" compression.
Hope this helps...
