Warn when selection only includes static data

[jleibs]

What

Based on top of:

• Include a view.schema() API and improved support for static data #7754
• Will need rebase after merging ^

This tries to alleviates a possible footgun where a user creates what appears to be a valid view expression but it only includes static data. In these cases the results of .select() won't produce any data since there are no row-providing columns.

There are many possible ways to end up in this state but the logic here should not be too likely for false-warnings while producing a reasonable degree of user safety.

If the user:

• Writes a content expression that only matches static content
• AND writes a select statement that queries static data
• AND does not call using_index_values(...)

Then we will produce a warning.

The most likely false positive where this would introduce a spurious warning would be a user wanting to query for a mixture of static and non-static data in a circumstance where sometimes none of the non-static data is logged and the user expects to (correctly) get no rows in this case. However, these circumstances generally imply a more advanced user that could then work around then with a mixed query + join anyways.

Future work:

• Configurable warning policy for Dataframe APIs #7759

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