https://community.databricks.com/t5/data-engineering/what-fields-should-i-zorder-by-does-the-order-of-zorder-matter/m-p/22304#M15261 Fri, 18 Jun 2021 21:18:04 GMT Anonymous 2021-06-18T21:18:04Z https://community.databricks.com/t5/data-engineering/what-fields-should-i-zorder-by-does-the-order-of-zorder-matter/m-p/22304#M15261 Fri, 18 Jun 2021 21:18:04 GMT https://community.databricks.com/t5/data-engineering/what-fields-should-i-zorder-by-does-the-order-of-zorder-matter/m-p/22304#M15261 Anonymous 2021-06-18T21:18:04Z https://community.databricks.com/t5/data-engineering/what-fields-should-i-zorder-by-does-the-order-of-zorder-matter/m-p/22305#M15262 <P>If you expect a column to be commonly used in query predicates and if that column has high cardinality (that is, a large number of distinct values), then use&nbsp;</P><P>ZORDER&nbsp;BY</P><P>.</P><P>You can specify multiple columns for&nbsp;</P><P>ZORDER&nbsp;BY</P><P></P><P>&nbsp;as a comma-separated list. However, the effectiveness of the locality drops with each additional column. Z-Ordering on columns that do not have statistics collected on them would be ineffective and a waste of resources as data skipping requires column-local stats such as min, max, and count. You can configure statistics collection on certain columns by re-ordering columns in the schema or increasing the number of columns to collect statistics on. See the section&nbsp;<A href="https://docs.databricks.com/delta/optimizations/file-mgmt.html#delta-data-skipping" alt="https://docs.databricks.com/delta/optimizations/file-mgmt.html#delta-data-skipping" target="_blank">Data skipping</A>&nbsp;for more details.</P> Mon, 21 Jun 2021 12:51:45 GMT https://community.databricks.com/t5/data-engineering/what-fields-should-i-zorder-by-does-the-order-of-zorder-matter/m-p/22305#M15262 User16826994223 2021-06-21T12:51:45Z