Column-oriented and table-oriented zone maps

You can use column-oriented or table-oriented zone maps.

With Netezza Performance Server, you can add the table-oriented zone map feature that organizes the zone maps such that the zone map statistics for all columns from the same table are stored together in the dataslice. Table-oriented zone maps are optimized for improved performance of incremental (or trickle) loads. Table-oriented zone maps also minimize interactions between concurrent loads to a subset of tables in the system, from queries running against a different subset of tables. The zone map data remains the same, so table-oriented zone maps provide the same benefit for query performance.

The zone map format is a system-wide setting. The default is to use table-oriented zone maps for new user tables.

To change column-oriented zone maps to table-oriented zone maps, run the nzzonemapformat -table command. You must pause the system by using the nzsystem pause command, run the conversion command, and then resume the system by using the nzsystem resume command. The conversion process could take from a few minutes to an hour, depending on the amount of data stored on the system. Take that time into account when scheduling the service window to perform the conversion to minimize the impact on database users and applications.

You can convert back to column-oriented zone maps using the command nzzonemapformat -column. You must pause the system to convert back to column-oriented zone maps as well.