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Leap years in the Oracle database

Leap years in the Oracle database

Leap years have been a headache throughout history. Also for computer systems and databases.
Discover the origin of these problems and let’s take a look at date bugs that are still present in Oracle23c

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A chain of synonyms #JoelKallmanDay

A chain of synonyms #JoelKallmanDay

This one is about bad practices. The use of synonyms. If you have felt a cold sweat, you probably experienced something similar. Many users want to access application tables "transparently." Note that I put it in quotes because calling "transparent" "without prefixing...

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Indexing columns with non pure functions

Indexing columns with non pure functions

When you filter a column using a function, the optimizer does not use the indexes on that particular column because the function "transforms" the values and makes the index non useful to get the proper ROWIDs. To get around that hurdle, Oracle has function-based...

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Unordered sorts

Unordered sorts

For the result of an SQL query to be ordered, the only valid clause is ORDER BY. Oracle only guarantees the ordered return of rows when ORDER BY is set as the sort criteria. I have repeated these two phrases like a mantra thousands of times. Any other way to get the...

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