TN - 1302 Historian - Disabling Indexing For Debugging Purposes

Description

This article from InSource shows how to disable indexing within the Aveva Historian to validate tag data is making it to the historian.  

• Author: Frank Ross
• Published: 12/09/2022
• Applies to: Aveva Historian 2017 & Newer

Details

Scenario:   Customer has identified specific tags which do not appear to be historizing within the Aveva Historian.  However, other tags are successfully being historized.    The configuration between those that are not and those that are historizing are the same.    Further analysis shows that if new tags are created using the same PLC references, those tags are historizing too.    The root cause could be from an indexing issue, so to prove this theory, the system needs to have indexing disabled.   Once disabled, the Historian client (or by using SQL queries), can be used to verify the tag data is actually making it to the Historian and being stored in the data blocks. 

To disable indexing on the Historian node, you will need to make a change to the Registry.   Before making any changes to the Registry, it is recommended to make a copy of the Registry. 

The Registry setting that needs modified is to add a new entry Dword 32 to HKLM>Software>Archestra>Historian>Programs>aahStorage, name it UseIndexing and set it to 0.  (see example below). 

Once the Registry setting has been modified, you can use either the Query Tool or Trend to verify the "missing" tag data is now appearing within the queries.     

Please note:  This registry change should not be a permanent change because it disables indexing, thus making the queries very ineffecient.    What this essentially proves is that there is a potential indexing issue but the tag data is making it into the Historian data blocks.