database/versions: Add new semver_no_prerelease column

[Turbo87]

This PR is an alternative to:

• database/versions: Add generated version_no_prerelease column #3992 and
• Replace to_semver_no_prerelease() with semver_no_prerelease column #4016

Instead of using our custom semver_triple database type (which caused issues with diesel) we will use an array (NUMERIC[3]). This provides the same sorting and filtering functionality, but is easier to deal with in diesel.

This PR only adds the new column and adjusts the code to fill it for new crate versions, but it does not backfill it for old versions. Neither does it adjust the reverse dependencies SQL query to use the new column, as that requires the old versions to be backfilled first. This will be changed in a future PR.

A SQL script to backfill the column for old versions is:

-- add temporary function that returns an array instead of `semver_triple`

CREATE FUNCTION to_semver_no_prerelease_array(TEXT) RETURNS NUMERIC[3]
    IMMUTABLE
    LANGUAGE sql
AS
$$
SELECT ARRAY [
           split_part($1, '.', 1)::numeric,
           split_part($1, '.', 2)::numeric,
           split_part(split_part($1, '+', 1), '.', 3)::numeric
           ]
WHERE strpos($1, '-') = 0
$$;

-- fill the new column with data incrementally to avoid table locking for
-- extended time periods.

UPDATE versions
SET semver_no_prerelease = to_semver_no_prerelease_array(num)
WHERE semver_no_prerelease IS NULL
  AND created_at < '2016-01-01';

UPDATE versions
SET semver_no_prerelease = to_semver_no_prerelease_array(num)
WHERE semver_no_prerelease IS NULL
  AND created_at < '2016-02-01';

UPDATE versions
SET semver_no_prerelease = to_semver_no_prerelease_array(num)
WHERE semver_no_prerelease IS NULL
  AND created_at < '2016-03-01';

-- ...

UPDATE versions
SET semver_no_prerelease = to_semver_no_prerelease_array(num)
WHERE semver_no_prerelease IS NULL
  AND created_at < '2021-12-01';

-- drop temporary function again

DROP FUNCTION to_semver_no_prerelease_array(TEXT);

[bors]

☔ The latest upstream changes (presumably #4034) made this pull request unmergeable. Please resolve the merge conflicts.

[jtgeibel]

The PR itself looks good to me. For the SQL script, my understanding is that UPDATE queries will run for every version WHERE semver_no_prerelease IS NULL and will simply reassign NULL to semver_no_prerelease if the version is a pre-release. I have just 2 comments on the update script:

• Any prerelease versions meeting created_at < '...' will be processed again for all subsequent queries because semver_no_prerelease will still be NULL. So later queries will lock more rows and for longer than expected.
• I was initially worried that this would cause the updated_at column to be updated for all versions, but it looks like the trigger_versions_set_updated_at trigger has been updated to only run on updates to the yanked column.

[Turbo87]

setting this PR to draft mode for now, until we've decided wether or not #4106 is a better way

[bors]

☔ The latest upstream changes (presumably #4108) made this pull request unmergeable. Please resolve the merge conflicts.

[Turbo87]

closing in favor of #4106