dbms_stats.gather_table_stats

Hi everybody:

I am running oracle 10.2.0.1. Once a week we have a analyze process run to gather stats on all the
tables in the schema via commands like this one exec dbms_stats.gather_table_stats( 'schema', 'table', null, 25, degree=>8, cascade=>true );

Some of the tables are partitioned and we have 6 or 7 historical partitions which are not being updated anymore
so I thought I would save time by restricting this command to only last two partitions:

exec dbms_stats.gather_table_stats( 'owner', 'table', 'part1', 25, degree=>8, cascade=>true );
exec dbms_stats.gather_table_stats( 'owner', 'table', 'part2', 25, degree=>8, cascade=>true );

The partitions are roughly the same size. The indices are globally partitioned. The first command (analyze
the whole table) took 25 minutes. Last two command combined - 27 min. Considering that there are 5 more patitions in the table, the math does not add up. What am I missing?

thank you

Gene Gurevich

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