Raito Bezarius
64a2f038b1
Sometimes, a path can disappear from the `ValidPaths` table (I have 23 such cases on my 1.4TB Nix store). When this occurs and you try to run a garbage collection, `queryReferrers` will report no referrer because it's performing a *RIGHT JOIN* between `Refs` and `ValidPaths`, finally, when you issue the deletion SQL statement, this will throw an uncaught exception from SQLite side regarding a foreign key violation because `reference` in `Refs` is a foreign key to `ValidPaths` (which we are trying to delete). Why can this happen? Two reasons: * `PRAGMA foreign_keys=off;` will disable deletion on cascade. * Trigger recursion *limits*, a deletion on cascade is a *trigger*, when a delete is issued and it triggers a bunch of deletion on cascade, there's a documented limit by SQLite: https://www.sqlite.org/limits.html#max_trigger_depth > Recursion limit on foreign key actions. The SQLITE_MAX_TRIGGER_DEPTH > and SQLITE_LIMIT_TRIGGER_DEPTH settings determine the maximum > allowable depth of trigger program recursion. For the purposes of > these limits, foreign key actions are considered trigger programs. The > PRAGMA recursive_triggers setting does not affect the operation of > foreign key actions. It is not possible to disable recursive foreign > key actions. As I do not see easy ways to solve the root cause, garbage collection should be self-healing in that regards, so I propose to invalidate phantom referrers as we go. As part of a work improving the consistency of the SQLite database, it would make sense to count how many times this happen and try to find ways to reproduce this issue. Change-Id: I055a8a1d8c0e44d4388a411abe8e5a5e385f7b55 Signed-off-by: Raito Bezarius <raito@lix.systems>
Lix
Lix is an implementation of Nix, a powerful package management system for Linux and other Unix systems that makes package management reliable and reproducible.
Read more about us at https://lix.systems.
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On Linux and macOS the easiest way to install Lix is to run the following shell command (as a user other than root):
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