Count user's votes by subquery

[dartcafe]

The current approach to count a user's votes by a join statement returns a by the count of options multiplied result

• Replace join by a subquery
• correctly count votes of a user and count via subquery
• count user's yes votes via subquery

This replaces selects on the votes table for every poll

to dos

• Count orphaned votes via subquery

[dartcafe]

OK. The IParam has to be defined outside of the subquery method.

[dartcafe]

@come-nc Do you think it is a little bit overengeneered?
Are subqueries a good idea regarding performance?

[come-nc]

Hello,

We looked into it and I think it would be best to avoid subqueries and limit ourselves to counts, sums and joins.
Do you think it would be possible to remove the orphan count information from the polls list? It’s the hardest to get without subquery or sidequery, and it does not look like something which should always be computed for all votes.

Couldn’t the orphaned votes simply be cleared at option deletion, or by a background job?

[dartcafe]

Couldn’t the orphaned votes simply be cleared at option deletion, or by a background job?

This is the problem. Deleted options are kept by intention, in case an option is deleted accitentially or is to be added again after deletion. User's votes should be kept in these cases.

This is why I think a subquery is better than running recursively over the result list.

The other problem is that vote counts get multiplied by the avialable options before changing to the subquery. Sure, this could be solved in a join as well, but for me it works.

Please take also a look into #3479. I tried to solve the frontend rendering problems by chunking the polls list and by reducing the polls in the navigation to a maximum of 6 entries.

Chunking the polls list works by only rendering 20 items and add 20 more by reaching the list bottom by scrolling.

[come-nc]

Works and is better than previous state.
Having two separate subqueries for vote count and yes vote count seems suboptimal but let’s merge that for now it’s better anyway.
Maybe squash commits to help with backporting?

[dartcafe]

Having two separate subqueries for vote count and yes vote count seems suboptimal but let’s merge that for now it’s better anyway.

:-) I went the lazy way, and avoided figuring out how to selct two results from the subquery. Any hint for improvement is welcome.

[dartcafe]

Ah damn, I forgot to squash. @come-nc