Database management

Flame Graph for quick identification of Oracle bug

By Franck Pachot . Most of my performance stores start with a screenshot of Orachrome Lighty my preferred tool to have a graphical view of the database performance, in Standard and Enterprise Edition without any options:(…)

SQL Server 2016: Live query statistics

During my tests of the SQL Server 20126 CTP2, I noticed an additional icon on SQL Server Management studio which is close to the Actual Execution Plan button as shown below: I decided to take a look at the(…)

Testing postgresql development snapshots

If you want to test some of the features that will be coming with the next postgresql release even before an official beta version is released you can use the daily(…)

An alternative to DBA_EXTENTS optimized for LMT

By Franck Pachot . This is a script I have for several years, when tablespaces became locally managed. When we want to know to which segment a block (identified by file id, block id) belongs to, the DBA_EXTENTS view(…)

Oracle memory advisors: how relevant ?

By Franck Pachot . Do you look at memory advisors? I usually don’t but I still show them during the performance tuning workshop because there is no easy way to get an idea about memory sizing. This morning, while(…)

How to disable a SQL Plan Directive permanently

By Franck Pachot . In 12c you will see a lot of SQL Plan Directives. Some are useful to get better execution plans, but some will trigger too much Adaptive Dynamic Sampling and that can become a big overhead,(…)

Convert a snapshot standby to a new database

By Franck Pachot . A snapshot standby database is a nice solution when you want a temporary copy of the primary where you can do whatever you want (test a bug fix for example) and then convert it back(…)

12c Dynamic Sampling and Standard Edition

By Franck Pachot . 12c is coming with more dynamic sampling, now called dynamic statistics and using the new Adaptive Dynamic Sampling algorithm. The goal is to have better estimations and better estimations gives better execution plans. However, this(…)

How to import SQL Plan Directives

By Franck Pachot . Today I’ve presented SQL Plan Directives at the SOUG Romandie event. I had a question about the import/export of directives by Data Pump. The idea is that a lot of testing has been done on(…)

DBA_SQL_PLAN_DIRECTIVE.LAST_USED

By Franck Pachot . If you have read Matching SQL Plan Directives and queries using it then you know how to use the ‘+metrics’ format of dbms_xplan. 21:49:54 SQL> explain plan for select distinct * from DEMO_TABLE where a=0(…)