Before discussing the Exadata-specific feature, let’s review what the database engine can do independently of whether Exadata is used. To execute queries containing the min or max functions efficiently, two specific operations are available with B-tree indexes defined on the column referenced in the min or max function. The first, INDEX FULL SCAN (MIN/MAX), is […]
With the INMEMORY clause you can specify 4 sub-clauses: The MEMCOMPRESS clause specifies whether and how compression is used The PRIORITY clause specifies the priority (“order”) in which the segments are loaded when the IMCS is populated The DISTRIBUTE clause specifies how data is distributed across RAC instances The DUPLICATE clause specifies whether and how […]
The aim of this post is not to explain how the APPROX_COUNT_DISTINCT function works (you find basic information in the documentation and in this post written by Luca Canali), but to show you the results of a test case I run to assess how well it works. Here’s what I did… I created a table […]