mirror of
https://github.com/ZoneMinder/zoneminder.git
synced 2026-11-08 05:33:03 -05:00
Isaac Connor
f3658e6673
Nothing enforced uniqueness, but every reader already assumed one row per name: User::Preferences() hashes the rows by Name, montagereview.php and User_Preference::find_one() take the first match, and TagOrder::load() reads a single Value. With duplicates present those pick an arbitrary row, so a write could land on one row while reads returned another -- the tag order would appear to stop updating. Replace the UserId-only index with UNIQUE (UserId, Name) and make Name NOT NULL. The unique index still serves UserId-only lookups and the UserId foreign key as a leftmost prefix, so the old index is redundant and is dropped. Name has to be NOT NULL for the constraint to mean anything, since a unique index permits any number of NULLs; a NULL-named row is unreachable regardless, as a preference is only ever looked up by name. zm_update-1.39.19.sql discards NULL-named rows, makes the column NOT NULL, collapses existing duplicates keeping the highest Id (the most recently inserted), adds the unique index, then drops the old one. The index is added before the old one is dropped so the foreign key is never left without a usable index. Each schema change is guarded against INFORMATION_SCHEMA so re-running is a no-op. db/User_Preferences.sql gets the same shape for fresh installs. With the constraint in place, TagOrder::recordUsage() replaces its SELECT-then-INSERT-or-UPDATE with a single INSERT ... ON DUPLICATE KEY UPDATE. That drops a query and closes the race where two concurrent tag additions by the same user both see no row and both insert. Verified on MariaDB 11.8.8 against a seeded table: duplicate rows collapse to the expected survivors, NULL-named rows are removed, a second run is a clean no-op, NULL/duplicate/bad-UserId inserts are rejected (1048/1062/1452, so the foreign key survives losing its index), and mysqldump of a fresh install matches a migrated database exactly. Bump version.txt and the redhat spec Version to 1.39.19.
78 lines
2.8 KiB
SQL
78 lines
2.8 KiB
SQL
--
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-- Make User_Preferences unique per (UserId, Name).
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--
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-- Nothing enforced this, but every reader already assumes one row per name:
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-- User::Preferences() hashes the rows by Name, montagereview.php and
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-- User_Preference::find_one() take the first match, and TagOrder::load()
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-- reads a single Value. With duplicates present those pick an arbitrary row,
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-- so a write could land on one row while reads returned another.
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--
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-- Make Name NOT NULL, collapse any existing duplicates keeping the highest Id
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-- (the most recently inserted), then replace the UserId-only index with a
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-- UNIQUE (UserId, Name) index. The unique index still serves UserId-only
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-- lookups and the UserId foreign key as a leftmost prefix, so the old one is
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-- redundant.
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--
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-- A preference is only ever reached by name, so a NULL-named row is
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-- unreachable: User::Preferences() can't hash it and find_one(['Name'=>...])
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-- can't match it. Discard them rather than folding them into '', which would
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-- just manufacture duplicates. NULLs must go before the unique index is added
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-- anyway -- a unique index permits any number of NULLs, so it would not
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-- actually constrain them.
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DELETE FROM User_Preferences WHERE Name IS NULL;
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SET @s = (SELECT IF(
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(SELECT COUNT(*)
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FROM INFORMATION_SCHEMA.COLUMNS
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WHERE table_name = 'User_Preferences'
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AND table_schema = DATABASE()
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AND column_name = 'Name'
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AND is_nullable = 'YES'
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) > 0,
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"ALTER TABLE `User_Preferences` MODIFY `Name` varchar(64) NOT NULL",
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"SELECT 'User_Preferences.Name is already NOT NULL'"
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));
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PREPARE stmt FROM @s;
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EXECUTE stmt;
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DEALLOCATE PREPARE stmt;
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DELETE up FROM User_Preferences AS up
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INNER JOIN (
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SELECT UserId, Name, MAX(Id) AS KeepId
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FROM User_Preferences
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GROUP BY UserId, Name
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) AS keep
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ON up.UserId = keep.UserId AND up.Name = keep.Name
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WHERE up.Id <> keep.KeepId;
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-- Add the unique index before dropping the old one, so the UserId foreign key
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-- always has an index it can use.
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SET @s = (SELECT IF(
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(SELECT COUNT(*)
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FROM INFORMATION_SCHEMA.STATISTICS
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WHERE table_name = 'User_Preferences'
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AND table_schema = DATABASE()
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AND index_name = 'User_Preferences_UserId_Name_idx'
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) > 0,
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"SELECT 'User_Preferences_UserId_Name_idx already exists on User_Preferences table'",
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"ALTER TABLE `User_Preferences` ADD UNIQUE INDEX `User_Preferences_UserId_Name_idx` (`UserId`, `Name`)"
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));
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PREPARE stmt FROM @s;
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EXECUTE stmt;
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DEALLOCATE PREPARE stmt;
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SET @s = (SELECT IF(
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(SELECT COUNT(*)
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FROM INFORMATION_SCHEMA.STATISTICS
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WHERE table_name = 'User_Preferences'
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AND table_schema = DATABASE()
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AND index_name = 'User_Preferences_UserID_idx'
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) > 0,
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"ALTER TABLE `User_Preferences` DROP INDEX `User_Preferences_UserID_idx`",
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"SELECT 'User_Preferences_UserID_idx already removed from User_Preferences table'"
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));
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PREPARE stmt FROM @s;
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EXECUTE stmt;
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DEALLOCATE PREPARE stmt;
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