enhance(mysql): add better indexes for posts_gdocs table

[marcelgerber]

This PR does a few things to the posts_gdocs table:

• Add a composite index on type, published, publishedAt
  • These sorts of queries are very common, e.g. WHERE type = "data-insight" AND published = 1 AND publishedAt <= NOW()
  • Also, it can be used on queries that just filter on type
• Add another composite index on published, publishedAt
  • Again, filtering on published is very common
• Convert the computed column type from VIRTUAL to STORED
• Add a computed stored column on content ->> "$.authors"
  • This allows us to filter on them without running out of MySQL sort memory

I tested this a bunch and it works well overall, and the new indexes are used.
The only thing I'm not sure about is the addition of the authors column, which in theory could cause issues because we're not properly removing it someplace before inserting/updating into the DB. But if serializePostsGdocsRow is always used before sending things to the DB, then things will be fine on that end. (Also worth noting that we never had any issues with type, which has been a computed column for a long time now.)

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Edited: 2025-02-17 13:24:02 UTC
Execution time: 1.18 seconds