dpSetAlias

[jcbaar]

We have an issue which is somewhat difficult to explain but here goes. We use alias filtering on the alert rows of our UI clients. This is working perfectly fine however we notice on larger dist systems with a lot of UI clients with alias filters active on the alert row a significant slowdown (up to the point that the UI is unusable for multiple seconds) on the UI's when changing the alias of a datapoint element using dpSetAlias().

We have refdef panels for configuring symbols that do multiple dpSetAlias() call's for different alerts on that symbol which compounds the issue. We can somewhat speculate what is happening when setting an alias but have no clue what to do to remedy this situation.

So the question is what does dpSetAlias() actually do and what can we do to increase performance?

With kind regards,
Jan

[leoknipp]

Please always add the information which WinCC OA version and patch level you are using.
If you describe that the alias is set, is it a new alias or is an existing alias set again?

For an analysis more detailed information is needed, e.g. knowledge about the query string which is used and the system configuration.
Please get in contact with your common WinCC OA support if you need further assistance.

Best Regards
Leopold Knipp
Senior Support Specialist

[jcbaar]

My apologies for the omission. It is on WinCC OA 3.14, Patch 18. The alias being set are mostly new alias (creation of new symbol dp's with aliasses being set) but we see the same temporary degradation of performance when we edit a symbol (I.E. set the same alias again).

Information about the query string is difficult to provide. The alert row creates the queries, we simply feed the alert row configuration the DP groups to filter on in which the alias filters are defined.

I understand the question is difficult to answer without having a complete picture of the configuration but I am curious as to what dpSetAlias() is triggering in the system as a whole for it to have such an effect.

[leoknipp]

If you are using queries which are filtering for alias information the Event Manager needs to parse the query again if an alias is changed.
While the Event Manager is parsing a query all other tasks in the Event Manager are blocked. Therefore you will possibly see no updates in the UI.

At the moment there is no other solution than disconnecting the queries before importing/changing alias information to avoid a peak in the ressource usage of the Event Manager.

Best Regards
Leopold Knipp
Senior Support Specialist