Wednesday, April 24, 2019

Chinar Aliyev's Blog

Chinar Aliyev has recently started to pick up on several of my blog posts regarding Parallel Execution and the corresponding new features introduced in Oracle 12c.

It is good to see that obviously Oracle has since then improved some of these and added new ones as well.

Here are some links to the corresponding posts:

New automatic Parallel Outer Join Null Handling in 18c

Improvements regarding automatic parallel distribution skew handling in 18c

Chinar has also put some more thoughts on the HASH JOIN BUFFERED operation:

New thoughts about the HASH JOIN BUFFERED operation

There are also a number of posts on his blog regarding histograms and in particular how to properly calculate the join cardinality in the presence of additional filters and resulting skew, which is a very interesting topic and yet to be handled properly by the optimizer even in the latest versions.