Hotfix/match db indices

[judgeaxl]

Improve performance on match queries for a given day by adding an index to start_date and also turn match_statistics and details to JSONB.

[judgeaxl]

This will probably not get merged as:

• Adding an index on start_time doesn't help, it's not used when the query runs on the date part only.
• Adding the index and running the query on the date time range instead slows it down by a factor of 100. (!) Execution planner claims the index is used here, but it finds a lot more rows.
• Removing the index and running on the date time range is similar to using date without an index.
• Switching from json to jsonb and back for 200k rows took a second or so on the analytics DB.
• Using jsonb had no significant effect on query time, although memory usage went down a little bit.

[einarth]

Maybe check if a block range index performs better; dates like these are usually both ordered and clustered, so it's probably worth a shot.