How often is a tag saved to a database?

What is the database save rate for an analog tag or digital? Is this set in ignition?

Examples:
If I have an analog “SQL Data Tag” based on temperature, do I set in Ignition that is in a .1 deg format and is it saved whenever it changes by .1 degree or is the save time based or both?
As far as a digital “SQL Data Tag” is that only saved when it changes or re-saved over time?

IS a message tag saved the same as a digital tag?

Is this any different for MYSQL or MSSQL?
This related as to how big a database will grow over time…

Your SQL tags aren’t saved to the database unless you either
A. enable historical function for them
B. put them into a transaction group
C. write them via a query

In all of the above situations you can specify the frequency of the tag writes!

[quote=“Dravik”]Your SQL tags aren’t saved to the database unless you either
A. enable historical function for them
B. put them into a transaction group
C. write them via a query

In all of the above situations you can specify the frequency of the tag writes![/quote]

As I understand…there are two types of tags…in regards as to how they are handled.
I thought “SQL Data Tags” was the reference to tags saved to the database and “SQLtags” were not saved to the database. Did I use the wrong reference to the tag types in my original post?

Since I am asking questions pre-development… Referring to my original post…what is the frequency for analog and discrete tags, Is it based on change and/or time.?

It would appear that a query ©, those on written on action of the query.
How about historical function (A)?

Hi,

Perhaps the rather unfortunate name “SQLTags” is adding confusion. They have that name because some time ago, they only existed in an external database. Now there are two options, “internal” and “external”. And then there is the idea for history, which can be used for both.

So now, are you asking about history, or realtime? That is, do you want to store the current values of tags externally to a database? This is done with an “external sqltags driving provider”. In this case, the values are stored according to the tags’ scan class, but only if the values have changed. The deadband on the tag can be used to reduce the number of changes. Analog and digitals work the same.

For history, values are also stored according to a scan class, though it doesn’t have to be the same scan class that drives the realtime value (for example, the current value could be updated at a 500ms scan class, but history stored only every 10 seconds). Again, it only stores when the value has changed, but in this case, it’s a little trickier. There is a historical deadband, but it functions differently for tags marked as analog than for digitals. This difference is explained more in depth in the user manual, here.

Hope this helps,

Excellent answer…
Thank you.