These key optimizer statistics are maintained in Adaptive Server:
Statistics per partition – table row count; table page count. An unpartitioned table is considered to have one partition for the purposes of the systabstats catalog. Statistics per partition can be found in systabstats.
Statistics per index: index row count – index height; index leaf page count. A local index has a separate systabstats row for each index partition. A global index, which is considered a partitioned index with one partition, has one systabstats row. Statistics per index: index row count can be found in systabstats.
Statistics per column: data distribution. Statistics per column be found in sysstatistics.
Statistics per group of column – density information. Statistics per group of column can be found in sysstatistics.
Statistics per partition –
Column statistics – data distribution per column; density per group of columns. Column statistics can be found in sysstatistics.
Throughout this chapter, density is a statistical measurement of the uniqueness of a given column’s values, and a histogram is a statistical representation of the distribution of values of a given column of the relation.
