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Datometry Documentation

Statistics Collection Hints

The following hints allow you to specify how Teradata statistics collection is emulated by Hyper-Q on the destination data warehouse.

Specify Statistics Collection Sampling Percentage You can specify the Teradata statistics collection sampling on Azure Synapse using the Hyper-Q hint default_stats_sample.

Enable or Disable Index Statistics Collection Error Messages On databases that do not support statistics you can specify if Hyper-Q should return an error when attempting to collect or drop statistics, or ignore the error, using the allow_stats_commands configuration parameter.

Enable or Disable Statistics Collection on Temp Tables You can specify whether or not Hyper-Q collects statistics on temporary tables created during nested case emulation. This allows you to determine when statistics are collected, particularly if they are not needed and may impact performance.

Enable Azure Synapse TABLESAMPLE The use_synapse_tablesample_for_sample hint lets you enable the use of the Azure Synapse TABLESAMPLE statistics collection command. Normally, Hyper-Q uses SAMPLE to collect table statistics. However, the use of SAMPLE can be prohibitively slow. For this reason you can enable the use of TABLESAMPLE, which also disables (turns off) SAMPLE when accessing Azure Synapse through Hyper-Q.