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Check MySQL foreign keys explicitly; keep index prefix lengths and foreign keys of created tables

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Switching FOREIGN_KEY_CHECKS back on does not check the rows loaded
meanwhile, and DDL would commit halfway, so on MySQL every foreign key is
checked with a query for rows that point at nothing, before the commit.

The recorded table structure now keeps index options (the prefix lengths
MySQL needs for long text columns) and foreign keys; tables the restore
creates get their foreign keys after the commit.

The full-restore test also runs on MariaDB.
This commit is contained in:
Dillard Blom
2026-10-18 02:09:00 +02:00
parent 7b735ea941
commit 4f6a2e5b70
5 changed files with 90 additions and 15 deletions
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lib/Db/DbDumper.php
+64 -6
View File
@@ -214,6 +214,21 @@ final class DbDumper {
$this->restoreSequences($manifest['sequences'] ?? []);
$this->resumeForeignKeys($foreignKeys);
$this->db->commit();
// Foreign keys of the tables created above, now their rows are in. Not inside the
// transaction: MySQL commits on DDL. A failure is reported, not fatal: the data is
// restored either way.
foreach ($report['created'] as $table) {
$structure = $manifest['tables'][$table]['schema'] ?? [];
foreach ($structure['foreignKeys'] ?? [] as $fk) {
try {
$this->db->createSchemaManager()->createForeignKey(
new \Doctrine\DBAL\Schema\ForeignKeyConstraint($fk['columns'], $fk['table'], $fk['foreign'], $fk['name'], $fk['options'] ?? []),
$table);
} catch (\Throwable $e) {
$report['foreignKeyErrors'][] = $table . '.' . $fk['name'] . ': ' . $e->getMessage();
}
}
}
} catch (\Throwable $e) {
$this->db->rollBack();
// PostgreSQL rolls the dropped foreign keys back with the transaction; MySQL's session
@@ -268,10 +283,18 @@ final class DbDumper {
$indexes = [];
foreach ($table->getIndexes() as $i) {
if (!$i->isPrimary()) {
$indexes[] = ['name' => $i->getName(), 'columns' => array_values($i->getColumns()), 'unique' => $i->isUnique()];
// options holds the prefix lengths MySQL needs for indexes on long text columns
$indexes[] = ['name' => $i->getName(), 'columns' => array_values($i->getColumns()), 'unique' => $i->isUnique(),
'flags' => array_values($i->getFlags()), 'options' => $i->getOptions()];
}
}
return ['columns' => $columns, 'pk' => array_values($table->getPrimaryKey()?->getColumns() ?? []), 'indexes' => $indexes];
$foreignKeys = [];
foreach ($table->getForeignKeys() as $fk) {
$foreignKeys[] = ['name' => $fk->getName(), 'columns' => array_values($fk->getLocalColumns()),
'table' => $fk->getForeignTableName(), 'foreign' => array_values($fk->getForeignColumns()), 'options' => $fk->getOptions()];
}
return ['columns' => $columns, 'pk' => array_values($table->getPrimaryKey()?->getColumns() ?? []), 'indexes' => $indexes,
'foreignKeys' => $foreignKeys];
}
private static function tableFromStructure(string $name, array $structure): \Doctrine\DBAL\Schema\Table {
@@ -287,7 +310,9 @@ final class DbDumper {
$table->setPrimaryKey($structure['pk']);
}
foreach ($structure['indexes'] as $i) {
$i['unique'] ? $table->addUniqueIndex($i['columns'], $i['name']) : $table->addIndex($i['columns'], $i['name']);
$i['unique']
? $table->addUniqueIndex($i['columns'], $i['name'], $i['options'] ?? [])
: $table->addIndex($i['columns'], $i['name'], $i['flags'] ?? [], $i['options'] ?? []);
}
return $table;
}
@@ -316,8 +341,30 @@ final class DbDumper {
return $restore;
}
if ($platform instanceof \Doctrine\DBAL\Platforms\AbstractMySQLPlatform) {
// MySQL does not check rows again when FOREIGN_KEY_CHECKS goes back to 1, and its DDL
// would commit the transaction halfway. So every foreign key is checked explicitly,
// with a query that finds rows pointing at nothing (resumeForeignKeys()).
$rows = $this->db->fetchAllAssociative(
'SELECT TABLE_NAME AS tbl, CONSTRAINT_NAME AS name, COLUMN_NAME AS col, REFERENCED_TABLE_NAME AS rtbl, REFERENCED_COLUMN_NAME AS rcol
FROM information_schema.KEY_COLUMN_USAGE
WHERE TABLE_SCHEMA = DATABASE() AND REFERENCED_TABLE_NAME IS NOT NULL
ORDER BY TABLE_NAME, CONSTRAINT_NAME, ORDINAL_POSITION');
$keys = [];
foreach ($rows as $r) {
if (str_starts_with((string)$r['tbl'], $this->prefix)) {
$keys[$r['tbl'] . "\0" . $r['name']][] = $r;
}
}
$q = fn (string $i): string => $this->db->quoteIdentifier($i);
$checks = ['SET FOREIGN_KEY_CHECKS = 1'];
foreach ($keys as $parts) {
$join = implode(' AND ', array_map(fn (array $r): string => 'c.' . $q($r['col']) . ' = p.' . $q($r['rcol']), $parts));
$set = implode(' AND ', array_map(fn (array $r): string => 'c.' . $q($r['col']) . ' IS NOT NULL', $parts));
$checks[] = sprintf('SELECT COUNT(*) FROM %s c LEFT JOIN %s p ON %s WHERE %s AND p.%s IS NULL /* %s */',
$q($parts[0]['tbl']), $q($parts[0]['rtbl']), $join, $set, $q($parts[0]['rcol']), $parts[0]['name']);
}
$this->db->executeStatement('SET FOREIGN_KEY_CHECKS = 0');
return ['SET FOREIGN_KEY_CHECKS = 1'];
return $checks;
}
if ($platform instanceof \Doctrine\DBAL\Platforms\SqlitePlatform) {
$this->db->executeStatement('PRAGMA defer_foreign_keys = ON'); // checked at commit
@@ -325,11 +372,22 @@ final class DbDumper {
return [];
}
/** Add the foreign keys back; a row that breaks one fails the restore here, before it commits. */
/**
* Check the foreign keys again; a row that breaks one fails the restore here, before it commits.
* Statements add them back (PostgreSQL) or switch the checks on (MySQL); queries count the rows
* that point at nothing (MySQL) and must find none.
*/
private function resumeForeignKeys(array $statements): void {
foreach ($statements as $sql) {
try {
$this->db->executeStatement($sql);
if (str_starts_with($sql, 'SELECT ')) {
$orphans = (int)$this->db->fetchOne($sql);
if ($orphans > 0) {
throw new \RuntimeException("$orphans rows point at nothing");
}
} else {
$this->db->executeStatement($sql);
}
} catch (\Throwable $e) {
throw new \RuntimeException('The restored data breaks a foreign key (' . $sql . '): ' . $e->getMessage(), 0, $e);
}