reduce cost of various SQL queries #382
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This is one of the last holdouts of a task clock field that refers to the last run instead of the next run, so this is a neat little win for the consistency department. The main impetus of this change, though, is that the discovering queries for these tasks rank #3 and #8 on our list of most expensive statements (i.e. the pg_stat_statements view, ranked by total_exec_time). The rephrasing from `validated_at` into `next_validation_at` simplifies these queries considerably. The actual implementation is sort of a case of "it can't be this hard... oh no". Most of the diff is in test fixtures, though. The only significant reworking that was required is in package processor, where validateAndStoreManifestCommon() needed to be extended to explicitly be told if the manifest is new or existing, since checking `PushedAt == ValidatedAt` was not feasible anymore.
The INSERT-first approach with ON CONFLICT DO NOTHING is often neat, but in this case, it does not even save queries. And what's worse, the INSERT always advances repo_id_seq even if no record ends up being inserted, so this always incurs a write in the DB even if we only read an existing repo.
majewsky
requested review from
SuperSandro2000,
VoigtS and
Nuckal777
as code owners
SuperSandro2000
approved these changes
May 13, 2024
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