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DB2 for i statistics

Trying to gather statistics for a table in DB2 for i, and Denodo 8 is telling me "It is not possible to gather statistics from the system tables of the data source: Gathering statistics from system tables is not supported for this database". Has anyone else ran into this issue, and how did you get around it? When I click on the gather statistics in the VDP Admin tool, I get the following; Some errors have occurred during the statistics gathering process: Error executing query. Total time 1.664 seconds. QUERY [PROJECTION] [ERROR] GET_STATS_FOR_FIELDS [STORED_PROCEDURE] [ERROR] GET_STATS_FOR_FIELDS [STORED PROCEDURE] [ERROR] Received exception with message 'Error gathering the statistics of the view: Wrong stats query resultset'
DB2
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25-05-2021 13:39:57 -0400
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1 Answer

Hi, Both of these error messages can be returned when gathering statistics isn’t fully supported for the underlying data source. When it comes to gathering statistics, I suggest referring to this documentation to understand what exact [limitations](https://community.denodo.com/docs/html/browse/8.0/en/vdp/administration/optimizing_queries/cost-based_optimization/gathering_the_statistics_of_views#limitations-of-the-gathering-statistics-process) there are, and what the [different capabilities](https://community.denodo.com/docs/html/browse/8.0/en/vdp/administration/optimizing_queries/cost-based_optimization/gathering_the_statistics_of_views#statistics-that-are-gathered-from-the-system-tables-of-each-vendor) are between different databases/vendors. With regards to IBM DB2 in particular, it seems there are limitations in gathering statistics for fields of LONGVARCHAR and LONGVARGRAPHIC, so I would also see if your underlying data source is using any of those. Hope this helps!
Denodo Team
25-05-2021 17:27:52 -0400
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