Friday, April 15, 2011

Collaborate 2011 - Day 5 and Wrap Up

The last (half day) of the conference. Makes me wonder why most (if not all) of the conferences add an additional half day after throwing "the" big party. Why not make it a full day and throw the party at that night - or just end with the Wednesday night party. That will keep everyone at the show. Because these last half days are usually not very well attended anymore, which is not very kind to the speakers.
Anyway, the first session of today was Obscure Tools of the Trade for Tuning SQL. The speaker - after handing out, or throwing, candies, discussed tools that are freely available to get insight in how your SQL runs. The first was not that obscure: DBMS_XPLAN. This package can show all kinds of details on your SQL and can even show AWR reports. And if you use it with the gather_plan_statistics hint, you can also show the expected rows vs the actual rows (so your statistics may be wrong). The next one wasTrace Analyzer, a.k.a. TRCA, available via Metalin. It is like TKPROF on steroids. The main advantage is, you can provide your developers access to this information without access to the udump directory or bothering the DBA. It generates nice HTML readable and navigable output.  Another one was SQLT (SQLTXPLAIN), also available from Metalink This tool understands DB-links, while TRCA does not. It has multiple methods, like xtract, xecute etc The output is like the TRCA output, but TRCA needs SQL, this one needs trace files. TRCA gives a broader view, SQLT more detailed. The last one discussed was Oracle Active Report for Real Time SQL Monitoring. You can use this by using the dbms_sqltune (11gr2) package. It returns HTML, containing Flash or not. So it generates very nice, OEM like, output (with or without using OEM).
Then Rich Niemiec did a very nice presentation about Trends in de Database World. Did you know one Oracle Database is capable of storing all, yes all, information on the entire planet if we only had the hardware? So, that's cloud computing to the max! And another remarkable thing (I've heard before, but still): The development of Fusion Applications is the largest project in the world! The three major trends Rich discussed where Consolidation, the lower cost grid using Linux and Globalisation. Of course they all come together at the end. An nice to know : Oracle's original name was SDL.
The last (real) one of the conference was about SQL Anti Patterns. It appeared to be a MySQL focussed session, but still a lot of the common mistakes made in the MySQL world also apply to the Oracle world, like these:
1. Check if a row exists before insert. You can end up with a race condition, two people might try to do the same thing (apart from that, it is an extra database action). So instead of that, just do insert and catch the error.
2. All string columns have the same, to large, size. Might take too much space for tables and indexes and arrays. So right size your strings. Another solution for reducing your indexes: use the first x characters of a column.
3. The assumption that a select without order by returns rows in order of primary key. Not true, not in MySQL, not in Oracle. Can be true if it is an "index only" query. There is no "natural" order. So if you need a specific ordering, specify that.
4. Commit and rollback in lower level functions. These may lead to unexpected results like half transactions. Ue these only on the highest calling level - the service layer, thus in the application itself.
The last session of this Collaborate was Iron Application Throw-down. Two teams had set up a solution for creating a session planner. The most striving thing was, both uses Oracle Application Express as the preferred front-end! I wonder why....

All in all, Collaborate is for 80% an applications event. So most of the session are aimed at EBS, Peoplesoft, JDEdwards etc. The same holds for the exhibitors. There is some DBA stuff going on (around 10% I guess) and the other 10% is Development, split by regular SQL and PL/SQL and APEX. No Forms, Designer and - even more remarkable, hardly no ADF or other Fusion Middleware!  So if you are a developer, the first event I would recommend, is ODTUG's KScope - see you all there!
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