2. Vector Concepts : Table Structures : Raw Table Storage Format
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Raw Table Storage Format
The default storage format for a Vector table (VECTORWISE) is also known as a RAW table. This format stores the data on disk in columns in the order in which it is inserted and the data is compressed.
In addition, for each column the system automatically maintains simple statistics about the data distribution by storing the minimum and maximum value for ranges of tuples. If a query includes a filter on the column data value, the execution engine uses these min-max data values to decide whether to examine the data in a given block. Since min-max information is maintained in memory outside of the data block, this simple form of automatic indexing can dramatically reduce disk I/O and memory usage. You can configure the granularity of the min-max index with the [cbm] minmax_maxsize parameter (see  minmax_maxsize).