Pragma value (pragmavalue)
Creates a column to extract the pragma values from a given query. Pragmas are components added to queries to modulate how certain pieces of information are processed without substantially altering the content (for example, locales or time zones).
How does it work in the search window?
Select Create column in the search window toolbar, then select the Pragma value operation. You need to specify three arguments:
|Language (mandatory)||string||The programming language used to specify the query (for example, LINQ).|
|query (mandatory)||string||The full query you want to analyze.|
|pragma key (mandatory)||string||The section of the query where the desired pragma is located and thus the values to extract.|
The data type of the values in the new column is string.
Pragmas are not used on a general basis so we must artificially generate an example to see how this operation works. Let's say we want to extract the pragma values from the following query:
from demo.ecommerce.data group every 5m by method
pragma tz:\"Europe/Madrid\" pragma locale:\"es\"
Be aware that there are differences in syntax when you introduce the query using the interface or the Free Text Query. In this case, the backslashes "\" need to be removed when using the interface and kept when using the Free Text Query.
To do that, we will create two columns using the Pragma value operation and call them time_zone and locale.
The arguments needed to create the new column are:
- Language - Click the pencil icon and introduce linq
- query - Click the pencil icon and introduce from demo.ecommerce.data group every 5m by method pragma tz:"Europe/Madrid" pragma locale:"es"
- pragma key - Click the pencil and introduce tz/locale
Click Create column and you will see the following result:
How does it work in LINQ?
Use the operator
as... and add the operation syntax to create the new column. This is the syntax for the Pragma value operation:
pragmavalue(language_string, query_string, pragma_key_string)
You can copy the following LINQ script and try the example above on the
from demo.ecommerce.data group every 5m by method select pragmavalue ("linq", "from demo.ecommerce.data pragma tz:\"Europe/Madrid\" pragma locale:\"es\"", "tz") as time_zone select pragmavalue ("linq", "from demo.ecommerce.data pragma tz:\"Europe/Madrid\" pragma locale:\"es\"", "locale") as locale