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3ad727ba78
Summary: Ref T12987. I was focused on the RefCursor table and overlooked that we need some care on this key. It's currently possible to run `bin/storage upgrade --no-adjust`, then start Phabricator, and end up with duplicate records in this table. If you try to run `bin/storage adjust` later, it will try to add the unique key but fail. This is unusual for normal installs (they usually do not use `--no-adjust`) but we do it in the cluster and I did this exact thing on `secure`. Normally, to avoid this, when a new table with a unique key is introduced, we also add a migration to explicitly add that key. This is mostly harmless in this case. Fix this mistake (force the table to contain only unique rows; add the key) and try using `LOCK TABLES` to make this atomic. If this doesn't cause problems we can use this in similar situations in the future. The "alter table may unlock things" warning comes from here: https://dev.mysql.com/doc/refman/5.7/en/lock-tables.html It seems like it's fine to issue `UNLOCK TABLES` even if you don't have any locks, so I think this script should always do the right thing now, regardless of ALTER TABLE unlocking or not unlocking tables. Test Plan: Ran `bin/storage upgrade -f`, saw table end up in the right state. I'll also check this on `secure`, where the starting state is a little messier. Reviewers: amckinley Reviewed By: amckinley Maniphest Tasks: T12987 Differential Revision: https://secure.phabricator.com/D18623
52 lines
1.3 KiB
PHP
52 lines
1.3 KiB
PHP
<?php
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$table = new PhabricatorRepositoryRefPosition();
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$conn = $table->establishConnection('w');
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$key_name = 'key_position';
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try {
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queryfx(
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$conn,
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'ALTER TABLE %T DROP KEY %T',
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$table->getTableName(),
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$key_name);
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} catch (AphrontQueryException $ex) {
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// This key may or may not exist, depending on exactly when the install
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// ran previous migrations and adjustments. We're just dropping it if it
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// does exist.
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// We're doing this first (outside of the lock) because the MySQL
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// documentation says "if you ALTER TABLE a locked table, it may become
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// unlocked".
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}
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queryfx(
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$conn,
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'LOCK TABLES %T WRITE',
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$table->getTableName());
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$seen = array();
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foreach (new LiskMigrationIterator($table) as $position) {
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$cursor_id = $position->getCursorID();
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$hash = $position->getCommitIdentifier();
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// If this is the first copy of this row we've seen, mark it as seen and
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// move on.
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if (empty($seen[$cursor_id][$hash])) {
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$seen[$cursor_id][$hash] = true;
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continue;
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}
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// Otherwise, get rid of this row as it duplicates a row we saw previously.
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$position->delete();
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}
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queryfx(
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$conn,
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'ALTER TABLE %T ADD UNIQUE KEY %T (cursorID, commitIdentifier)',
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$table->getTableName(),
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$key_name);
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queryfx(
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$conn,
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'UNLOCK TABLES');
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