Collecting Statistics When No COLUMN or INDEX Clause Is Specified
If you do not specify a COLUMN or INDEX clause, a COLLECT STATISTICS request updates the statistics for all columns and indexes for which statistics had previously been collected. This is called recollecting statistics.
The exceptions are as follows.
To replace deleted statistics, specify the appropriate set of column or index names in a COLLECT STATISTICS request.
This limit can be lower than 512 columns subject to limits on the other resources such as the number of available spools and plastic or concrete step segment sizes.
A cylinder index scan performs up to n-1 data block reads, where n is the number of partitions, when collecting statistics on the system‑derived PARTITION column of a table.
If the original statistics were collected using sampling, then the recollected statistics are sampled as well. Otherwise, the system recollects full statistics for the specified table.
You can, however, collect sampled statistics on an INDEX set that contains partitioning columns.