42 lines
2.9 KiB
PHP
42 lines
2.9 KiB
PHP
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<?php
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require_once(__DIR__
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. DIRECTORY_SEPARATOR . '..'
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. DIRECTORY_SEPARATOR . 'src'
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. DIRECTORY_SEPARATOR . 'Bootstrap.php');
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// Why this exists:
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// 1. Some entities store a few basic stats in special columns for performance reasons. The benefit of such
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// denormalization is vast.
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// 2. The maintenance of the stats is implemented using triggers - when users tags a post, tag usage increases.
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// 3. This mostly works.
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// 4. Meanwhile, in order not to leave any orphans upon row deletions (e.g. have dangling postTags row after specific
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// post removal), the database schema uses foreign keys with CASCADE option. This option recursively removes
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// everything that would have missing references. This is good.
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// 5. Here's the thing: row removals caused by CASCADE foreign key checks don't execute triggers. So if user removes a
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// post, then although corresponding postTags entries will get deleted, ON postTags AFTER DELETE trigger will not
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// execute, leaving the tags with invalid usage count.
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//
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// There are three possible solutions to this problem:
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// 1. Implement all that logic in the appplication layer. I don't feel like doing this at all, it causes more havoc in
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// the code and possibly adds even more holes to the whole denormalization maintenance process.
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// 2. Convert CASCADE foreign checks to another set of triggers. This won't work for MySQL because of its limitations:
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// >Can't update table 'comments' in stored function/trigger because it is already used by statement which invoked
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// >this stored function/trigger
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// Creating complex triggers will result very quickly in this error message (I tested it on postTags and posts, it
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// did). I strongly believe the reason behind the error above is linked directly into the discussed MySQL's
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// limitation.
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// 3. Make a scripts like this. This is the easiest option out. The downside is that changes will be seen not
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// immediately, but except for heavy tag maintenance, I don't see where such a delay in stat synchronization might
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// really hurt.
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use Szurubooru\DatabaseConnection;
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$databaseConnection = Szurubooru\Injector::get(DatabaseConnection::class);
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$pdo = $databaseConnection->getPDO();
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$pdo->exec('UPDATE tags SET usages = (SELECT COUNT(1) FROM postTags WHERE tagId = tags.id)');
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$pdo->exec('UPDATE posts SET tagCount = (SELECT COUNT(1) FROM postTags WHERE postId = posts.id)');
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$pdo->exec('UPDATE posts SET score = (SELECT SUM(score) FROM scores WHERE postId = posts.id)');
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$pdo->exec('UPDATE posts SET favCount = (SELECT COUNT(1) FROM favorites WHERE postId = posts.id)');
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$pdo->exec('UPDATE posts SET lastFavTime = (SELECT MAX(time) FROM favorites WHERE postId = posts.id)');
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$pdo->exec('UPDATE posts SET commentCount = (SELECT COUNT(1) FROM comments WHERE postId = posts.id)');
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$pdo->exec('UPDATE posts SET lastCommentTime = (SELECT MAX(lastEditTime) FROM comments WHERE postId = posts.id)');
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