Oracle: Statistics
- Statistics is the data distribution and storage characteristics of tables, columns, indexes and partitions.- Selectctivity is the fraction of rows in a table that sql statement's predicate chooses.
- Statistics generated include the following:
- Table statistics
- Number of rows
- Number of blocks
- Average row length
- Column statistics
- Number of distinct values in column
- Number of nulls in column
- Data distribution (histogram)
- Index statistics
- Number of leaf blocks
- Levels
- Clustering factor
- System statistics
- I/O performance and utilization
- CPU performance and utilization
posted by James Pei @ 2:35 PM
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