Karl Reitschuster's Tech Space

Do you remember?

About 10 years ago OODBMS (Poet, Gemstone, Versant, ...) seemed to be starting to replace RDBMS; The idea for using OODBMS was simple - if the programming model is OOP why not persist Objects with an OODBMS directly instead of populating it's properties and class hierarchy into a couple of tables? It was the reason Oracle 8 came with object relational features; But they (OODBMS) failed for following reason:

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Tanel Poder holds a 2 day session in Düsseldorf last week; This was not my first Tuning/Troubleshooting training. But it was extraordinary what Tanel showed us when usual ways would not work

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Now living in a time of financial crisis and a growing gap of natural resources
a new paradigma - a new database paragdima is needed.

For Oracle 12 i think this could be Oracle 12 Eco;

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Hi Reader,
with Oracle 10g all default parameters of the DBMS_STATS package are defined as default in the data dictionary accessible with the DBMS_STATS GET_PARAM Method :

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Hi reader,

usually queries using LIKE and leading '%' cannot be indexed. So an idea would be to mirror the string content with the string reverse function to be able to put the '%' operator at the end :

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Dear reader,

pipelined functions are very comfortable to process incoming data and to return it as structured result set. For this reason they are frequently used in SQL; But be carefully if you join result sets from pipelined function with other tables.

The Oracle optimizer usually uses gathered table statistics to calculate the cardinality of a join operation; For a result set  originated in a pipeline function it has no statistics to evaluate and hence could try to get another path to the data. 

Following SQL retrieves internal employee GUID's from external Id's passed as comma delimited string.

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Hello reader,

Last week we faced performance problems also shown on the Oracle 10g Db-Console as 'SQL found consuming ...'; The users of the application mourned everything is going slow. Hm ...

The strange thing was that the same kind of SQL run without problems before. I started to monitor I/O with iostat on the Sun  Solaris Database Server. The Storage was based on SAN. The I/O rates were from 5m/s - 10m/s. The devices were about 95%-100% busy and this with an I/O rate with only about 10M/second? Usually 100m/s and more were possible.

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With Oracle 10g Oracle introduced a new key column spread over the dynamic performance views - the SQL_ID; The SQL_ID identified a SQL statement. The SQL_ID was needed to persist all performance metrics of a specific SQL statement in a repository. With Oracle 11g the granularity even gets deeper. With the new columns SQL_EXEC_ID and SQL_EXEX_START performance data could be collected of a specific execution of a specific SQL statement! What a quantum leap in monitoring!

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A really new step in real-time Oracle Performance Monitoring was the Database Control introduced with Oracle RDBMS 10.1; With Oracle 11.1 the concept was improved and more detailed metrics could be viewed via Database Control. The Performance page has now 4 Tabs : * Throughput * I/O * Parallel Execution * Services

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Intro

Examples
* Mathematics with Account numbers
* Timestamp as order citeria, unique history sequence
* The ultimate is_number - function

Impact of choosing the wrong datatype
* Optimizer miss-assumptions
* Breakdown of data interfaces
* Loss of service

Conclusion

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