Fix default ad hoc filters

[cwurm]

According to the README, it should be possible to use ad hoc filters without any special configuration:

clickhouse-datasource/README.md

Line 211 in 2573f94

By default, Ad Hoc filters will be populated with all Tables and Columns. If

But that's actually not the case. The current logic sets the target table for the filter to default when $clickhouse_adhoc_query is not set. This then leads to a query with a setting like SETTINGS additional_table_filters = {'default':' field = value } that doesn't work because it's not specifying the correct table.

This fix removes setting the target table to default (which seems weird in any case since there isn't usually a table like that in ClickHouse; there is only a database by that name) and sets it to the table from the query instead if no table has been specified any other way. With that, ad hoc filters work without setting $clickhouse_adhoc_query or a default database in the datasource settings.

Fixes #599.

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[bossinc]

This makes sense but, I am not able to make this work. I am using the default ChickHouse - Query Analysis dashboard with an added a adhoc var.
I set the adhoc var to query_log.query_kind with a value of Create. The query inspector returns additional_table_filters={'query_log' : ' query_kind = \'Create\' '} for the adhoc function. It should be additional_table_filters={'system.query_log' : ' query_kind = \'Create\' '} It is not filtering without the database before the table.

[cwurm]

This makes sense but, I am not able to make this work. I am using the default ChickHouse - Query Analysis dashboard with an added a adhoc var.

@bossinc How are you adding the adhoc var? With that dashboard, I can add it via the Query overview panel: Edit -> Overrides -> Override 20 -> Add override property Standard options -> Ad-hoc filterable and then I can click on table cells in the Type column and it filters the whole dashboard.

[cwurm]

This makes sense but, I am not able to make this work. I am using the default ChickHouse - Query Analysis dashboard with an added a adhoc var. I set the adhoc var to query_log.query_kind with a value of Create. The query inspector returns additional_table_filters={'query_log' : ' query_kind = \'Create\' '} for the adhoc function. It should be additional_table_filters={'system.query_log' : ' query_kind = \'Create\' '} It is not filtering without the database before the table.

@bossinc Ah, I think I know what you mean. You're creating a new variable on the dashboard level, type Ad hoc filters and then setting it to query_log.query_kind and Create while on the dashboard?

Seems that's another case that's not working (and hasn't worked before this PR, either).

I've fixed that as well now. Can you check that it's working for you?

[bossinc]

@cwurm I think we are talking about two difference ad-hoc filters. I did not know that you could make overrides for ad-hoc filters in tables like you described. 😆
I am referring to template variable adhoc filters found in dashboard settings. Here are the grafana docs: adhoc filters
In the CH plugin when filtering with adhoc filters, the data source adds the CH function additional_table_filters. When filtering with overrides it is filtering the response on the frontend instead of CH doing the filtering

[cwurm]

@cwurm I think we are talking about two difference ad-hoc filters. I did not know that you could make overrides for ad-hoc filters in tables like you described. 😆
I am referring to template variable adhoc filters found in dashboard settings. Here are the grafana docs: adhoc filters

Ah, crossed wires! This should be working as well now as per my previous comment.

In the CH plugin when filtering with adhoc filters, the data source adds the CH function additional_table_filters. When filtering with overrides it is filtering the response on the frontend instead of CH doing the filtering

Hm, from what I can see, overrides also change the ClickHouse query.

[bossinc]

Hm, from what I can see, overrides also change the ClickHouse query.
You are right! I am trying to recreate what I thought I saw and the ad-hoc vars seem to be the same. 🤷

This PR looks good.