After an intermezzo in Munich that left me with no time for posting, I am now in Bucharest (Romania) for an 11g Data Warehouse Administration course. The students are all Oracle Internals, which is almost a guarantee for fun and a nice atmosphere. The most difficult thing about this course was to get into the Oracle building in Bucharest at all – the security staff is very sharp here…
To get technical: Did you know that if you are doing a parallel query, it is processed with direct reads under circumvention of the Database Buffer Cache? Here is how you can investigate this:
sqlplus sh/sh SQL> select /*+ parallel (sales,2) */ sum(amount_sold) from sales;
SQL> select name,sum(value) from v$sesstat natural join v$statname natural join v$session where username='SH' and name like '%physical reads%' group by name;