Types and Levels of Statistics Collected
When optimizing a database, you can create several types and levels of statistics by specifying options.
First, you can specify what set of data the statistics are gathered on:
• Non-sampled statistics--all rows in the selected tables are retrieved
• Sampled statistics--a subset of rows from the selected tables is retrieved
Next, either of the following can be created, based on the selected data set. This division determines how much information about the distribution of data the statistics can hold:
• Full statistics--a histogram for the whole range of column values is created
• Minmax statistics--a histogram showing only minimum and maximum values is created