diff options
Diffstat (limited to 'lib/private/DB/QueryBuilder/Sharded')
9 files changed, 1126 insertions, 0 deletions
diff --git a/lib/private/DB/QueryBuilder/Sharded/AutoIncrementHandler.php b/lib/private/DB/QueryBuilder/Sharded/AutoIncrementHandler.php new file mode 100644 index 00000000000..3a230ea544d --- /dev/null +++ b/lib/private/DB/QueryBuilder/Sharded/AutoIncrementHandler.php @@ -0,0 +1,155 @@ +<?php + +declare(strict_types=1); +/** + * SPDX-FileCopyrightText: 2024 Robin Appelman <robin@icewind.nl> + * SPDX-License-Identifier: AGPL-3.0-or-later + */ + +namespace OC\DB\QueryBuilder\Sharded; + +use OCP\ICacheFactory; +use OCP\IMemcache; +use OCP\IMemcacheTTL; + +/** + * A helper to atomically determine the next auto increment value for a sharded table + * + * Since we can't use the database's auto-increment (since each db doesn't know about the keys in the other shards) + * we need external logic for doing the auto increment + */ +class AutoIncrementHandler { + public const MIN_VALID_KEY = 1000; + public const TTL = 365 * 24 * 60 * 60; + + private ?IMemcache $cache = null; + + public function __construct( + private ICacheFactory $cacheFactory, + private ShardConnectionManager $shardConnectionManager, + ) { + if (PHP_INT_SIZE < 8) { + throw new \Exception('sharding is only supported with 64bit php'); + } + } + + private function getCache(): IMemcache { + if (is_null($this->cache)) { + $cache = $this->cacheFactory->createDistributed('shared_autoincrement'); + if ($cache instanceof IMemcache) { + $this->cache = $cache; + } else { + throw new \Exception('Distributed cache ' . get_class($cache) . ' is not suitable'); + } + } + return $this->cache; + } + + /** + * Get the next value for the given shard definition + * + * The returned key is unique and incrementing, but not sequential. + * The shard id is encoded in the first byte of the returned value + * + * @param ShardDefinition $shardDefinition + * @return int + * @throws \Exception + */ + public function getNextPrimaryKey(ShardDefinition $shardDefinition, int $shard): int { + $retries = 0; + while ($retries < 5) { + $next = $this->getNextInner($shardDefinition); + if ($next !== null) { + if ($next > ShardDefinition::MAX_PRIMARY_KEY) { + throw new \Exception('Max primary key of ' . ShardDefinition::MAX_PRIMARY_KEY . ' exceeded'); + } + // we encode the shard the primary key was originally inserted into to allow guessing the shard by primary key later on + return ($next << 8) | $shard; + } else { + $retries++; + } + } + throw new \Exception('Failed to get next primary key'); + } + + /** + * auto increment logic without retry + * + * @param ShardDefinition $shardDefinition + * @return int|null either the next primary key or null if the call needs to be retried + */ + private function getNextInner(ShardDefinition $shardDefinition): ?int { + $cache = $this->getCache(); + // because this function will likely be called concurrently from different requests + // the implementation needs to ensure that the cached value can be cleared, invalidated or re-calculated at any point between our cache calls + // care must be taken that the logic remains fully resilient against race conditions + + // in the ideal case, the last primary key is stored in the cache and we can just do an `inc` + // if that is not the case we find the highest used id in the database increment it, and save it in the cache + + // prevent inc from returning `1` if the key doesn't exist by setting it to a non-numeric value + $cache->add($shardDefinition->table, 'empty-placeholder', self::TTL); + $next = $cache->inc($shardDefinition->table); + + if ($cache instanceof IMemcacheTTL) { + $cache->setTTL($shardDefinition->table, self::TTL); + } + + // the "add + inc" trick above isn't strictly atomic, so as a safety we reject any result that to small + // to handle the edge case of the stored value disappearing between the add and inc + if (is_int($next) && $next >= self::MIN_VALID_KEY) { + return $next; + } elseif (is_int($next)) { + // we hit the edge case, so invalidate the cached value + if (!$cache->cas($shardDefinition->table, $next, 'empty-placeholder')) { + // someone else is changing the value concurrently, give up and retry + return null; + } + } + + // discard the encoded initial shard + $current = $this->getMaxFromDb($shardDefinition); + $next = max($current, self::MIN_VALID_KEY) + 1; + if ($cache->cas($shardDefinition->table, 'empty-placeholder', $next)) { + return $next; + } + + // another request set the cached value before us, so we should just be able to inc + $next = $cache->inc($shardDefinition->table); + if (is_int($next) && $next >= self::MIN_VALID_KEY) { + return $next; + } elseif (is_int($next)) { + // key got cleared, invalidate and retry + $cache->cas($shardDefinition->table, $next, 'empty-placeholder'); + return null; + } else { + // cleanup any non-numeric value other than the placeholder if that got stored somehow + $cache->ncad($shardDefinition->table, 'empty-placeholder'); + // retry + return null; + } + } + + /** + * Get the maximum primary key value from the shards, note that this has already stripped any embedded shard id + */ + private function getMaxFromDb(ShardDefinition $shardDefinition): int { + $max = $shardDefinition->fromFileId; + $query = $this->shardConnectionManager->getConnection($shardDefinition, 0)->getQueryBuilder(); + $query->select($shardDefinition->primaryKey) + ->from($shardDefinition->table) + ->orderBy($shardDefinition->primaryKey, 'DESC') + ->setMaxResults(1); + foreach ($shardDefinition->getAllShards() as $shard) { + $connection = $this->shardConnectionManager->getConnection($shardDefinition, $shard); + $result = $query->executeQuery($connection)->fetchOne(); + if ($result) { + if ($result > $shardDefinition->fromFileId) { + $result = $result >> 8; + } + $max = max($max, $result); + } + } + return $max; + } +} diff --git a/lib/private/DB/QueryBuilder/Sharded/CrossShardMoveHelper.php b/lib/private/DB/QueryBuilder/Sharded/CrossShardMoveHelper.php new file mode 100644 index 00000000000..81530b56725 --- /dev/null +++ b/lib/private/DB/QueryBuilder/Sharded/CrossShardMoveHelper.php @@ -0,0 +1,162 @@ +<?php + +declare(strict_types=1); +/** + * SPDX-FileCopyrightText: 2024 Robin Appelman <robin@icewind.nl> + * SPDX-License-Identifier: AGPL-3.0-or-later + */ + +namespace OC\DB\QueryBuilder\Sharded; + +use OCP\DB\QueryBuilder\IQueryBuilder; +use OCP\IDBConnection; + +/** + * Utility methods for implementing logic that moves data across shards + */ +class CrossShardMoveHelper { + public function __construct( + private ShardConnectionManager $connectionManager, + ) { + } + + public function getConnection(ShardDefinition $shardDefinition, int $shardKey): IDBConnection { + return $this->connectionManager->getConnection($shardDefinition, $shardDefinition->getShardForKey($shardKey)); + } + + /** + * Update the shard key of a set of rows, moving them to a different shard if needed + * + * @param ShardDefinition $shardDefinition + * @param string $table + * @param string $shardColumn + * @param int $sourceShardKey + * @param int $targetShardKey + * @param string $primaryColumn + * @param int[] $primaryKeys + * @return void + */ + public function moveCrossShards(ShardDefinition $shardDefinition, string $table, string $shardColumn, int $sourceShardKey, int $targetShardKey, string $primaryColumn, array $primaryKeys): void { + $sourceShard = $shardDefinition->getShardForKey($sourceShardKey); + $targetShard = $shardDefinition->getShardForKey($targetShardKey); + $sourceConnection = $this->connectionManager->getConnection($shardDefinition, $sourceShard); + if ($sourceShard === $targetShard) { + $this->updateItems($sourceConnection, $table, $shardColumn, $targetShardKey, $primaryColumn, $primaryKeys); + + return; + } + $targetConnection = $this->connectionManager->getConnection($shardDefinition, $targetShard); + + $sourceItems = $this->loadItems($sourceConnection, $table, $primaryColumn, $primaryKeys); + foreach ($sourceItems as &$sourceItem) { + $sourceItem[$shardColumn] = $targetShardKey; + } + if (!$sourceItems) { + return; + } + + $sourceConnection->beginTransaction(); + $targetConnection->beginTransaction(); + try { + $this->saveItems($targetConnection, $table, $sourceItems); + $this->deleteItems($sourceConnection, $table, $primaryColumn, $primaryKeys); + + $targetConnection->commit(); + $sourceConnection->commit(); + } catch (\Exception $e) { + $sourceConnection->rollback(); + $targetConnection->rollback(); + throw $e; + } + } + + /** + * Load rows from a table to move + * + * @param IDBConnection $connection + * @param string $table + * @param string $primaryColumn + * @param int[] $primaryKeys + * @return array[] + */ + public function loadItems(IDBConnection $connection, string $table, string $primaryColumn, array $primaryKeys): array { + $query = $connection->getQueryBuilder(); + $query->select('*') + ->from($table) + ->where($query->expr()->in($primaryColumn, $query->createParameter('keys'))); + + $chunks = array_chunk($primaryKeys, 1000); + + $results = []; + foreach ($chunks as $chunk) { + $query->setParameter('keys', $chunk, IQueryBuilder::PARAM_INT_ARRAY); + $results = array_merge($results, $query->execute()->fetchAll()); + } + + return $results; + } + + /** + * Save modified rows + * + * @param IDBConnection $connection + * @param string $table + * @param array[] $items + * @return void + */ + public function saveItems(IDBConnection $connection, string $table, array $items): void { + if (count($items) === 0) { + return; + } + $query = $connection->getQueryBuilder(); + $query->insert($table); + foreach ($items[0] as $column => $value) { + $query->setValue($column, $query->createParameter($column)); + } + + foreach ($items as $item) { + foreach ($item as $column => $value) { + if (is_int($column)) { + $query->setParameter($column, $value, IQueryBuilder::PARAM_INT); + } else { + $query->setParameter($column, $value); + } + } + $query->executeStatement(); + } + } + + /** + * @param IDBConnection $connection + * @param string $table + * @param string $primaryColumn + * @param int[] $primaryKeys + * @return void + */ + public function updateItems(IDBConnection $connection, string $table, string $shardColumn, int $targetShardKey, string $primaryColumn, array $primaryKeys): void { + $query = $connection->getQueryBuilder(); + $query->update($table) + ->set($shardColumn, $query->createNamedParameter($targetShardKey, IQueryBuilder::PARAM_INT)) + ->where($query->expr()->in($primaryColumn, $query->createNamedParameter($primaryKeys, IQueryBuilder::PARAM_INT_ARRAY))); + $query->executeQuery()->fetchAll(); + } + + /** + * @param IDBConnection $connection + * @param string $table + * @param string $primaryColumn + * @param int[] $primaryKeys + * @return void + */ + public function deleteItems(IDBConnection $connection, string $table, string $primaryColumn, array $primaryKeys): void { + $query = $connection->getQueryBuilder(); + $query->delete($table) + ->where($query->expr()->in($primaryColumn, $query->createParameter('keys'))); + $chunks = array_chunk($primaryKeys, 1000); + + foreach ($chunks as $chunk) { + $query->setParameter('keys', $chunk, IQueryBuilder::PARAM_INT_ARRAY); + $query->executeStatement(); + } + } +} diff --git a/lib/private/DB/QueryBuilder/Sharded/HashShardMapper.php b/lib/private/DB/QueryBuilder/Sharded/HashShardMapper.php new file mode 100644 index 00000000000..af778489a2d --- /dev/null +++ b/lib/private/DB/QueryBuilder/Sharded/HashShardMapper.php @@ -0,0 +1,21 @@ +<?php + +declare(strict_types=1); +/** + * SPDX-FileCopyrightText: 2024 Robin Appelman <robin@icewind.nl> + * SPDX-License-Identifier: AGPL-3.0-or-later + */ + +namespace OC\DB\QueryBuilder\Sharded; + +use OCP\DB\QueryBuilder\Sharded\IShardMapper; + +/** + * Map string key to an int-range by hashing the key + */ +class HashShardMapper implements IShardMapper { + public function getShardForKey(int $key, int $count): int { + $int = unpack('L', substr(md5((string)$key, true), 0, 4))[1]; + return $int % $count; + } +} diff --git a/lib/private/DB/QueryBuilder/Sharded/InvalidShardedQueryException.php b/lib/private/DB/QueryBuilder/Sharded/InvalidShardedQueryException.php new file mode 100644 index 00000000000..733a6acaf9d --- /dev/null +++ b/lib/private/DB/QueryBuilder/Sharded/InvalidShardedQueryException.php @@ -0,0 +1,29 @@ +<?php + +declare(strict_types=1); +/** + * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors + * SPDX-License-Identifier: AGPL-3.0-only + */ + +namespace OC\DB\QueryBuilder\Sharded; + +/** + * Queries on sharded table has the following limitations: + * + * 1. Either the shard key (e.g. "storage") or primary key (e.g. "fileid") must be mentioned in the query. + * Or the query must be explicitly marked as running across all shards. + * + * For queries where it isn't possible to set one of these keys in the query normally, you can set it using `hintShardKey` + * + * 2. Insert statements must always explicitly set the shard key + * 3. A query on a sharded table is not allowed to join on the same table + * 4. Right joins are not allowed on sharded tables + * 5. Updating the shard key where the new shard key maps to a different shard is not allowed + * + * Moving rows to a different shard needs to be implemented manually. `CrossShardMoveHelper` provides + * some tools to help make this easier. + */ +class InvalidShardedQueryException extends \Exception { + +} diff --git a/lib/private/DB/QueryBuilder/Sharded/RoundRobinShardMapper.php b/lib/private/DB/QueryBuilder/Sharded/RoundRobinShardMapper.php new file mode 100644 index 00000000000..a5694b06507 --- /dev/null +++ b/lib/private/DB/QueryBuilder/Sharded/RoundRobinShardMapper.php @@ -0,0 +1,20 @@ +<?php + +declare(strict_types=1); +/** + * SPDX-FileCopyrightText: 2024 Robin Appelman <robin@icewind.nl> + * SPDX-License-Identifier: AGPL-3.0-or-later + */ + +namespace OC\DB\QueryBuilder\Sharded; + +use OCP\DB\QueryBuilder\Sharded\IShardMapper; + +/** + * Map string key to an int-range by hashing the key + */ +class RoundRobinShardMapper implements IShardMapper { + public function getShardForKey(int $key, int $count): int { + return $key % $count; + } +} diff --git a/lib/private/DB/QueryBuilder/Sharded/ShardConnectionManager.php b/lib/private/DB/QueryBuilder/Sharded/ShardConnectionManager.php new file mode 100644 index 00000000000..74358e3ca96 --- /dev/null +++ b/lib/private/DB/QueryBuilder/Sharded/ShardConnectionManager.php @@ -0,0 +1,52 @@ +<?php + +declare(strict_types=1); +/** + * SPDX-FileCopyrightText: 2024 Robin Appelman <robin@icewind.nl> + * SPDX-License-Identifier: AGPL-3.0-or-later + */ + +namespace OC\DB\QueryBuilder\Sharded; + +use OC\DB\ConnectionAdapter; +use OC\DB\ConnectionFactory; +use OC\SystemConfig; +use OCP\IDBConnection; + +/** + * Keeps track of the db connections to the various shards + */ +class ShardConnectionManager { + /** @var array<string, IDBConnection> */ + private array $connections = []; + + public function __construct( + private SystemConfig $config, + private ConnectionFactory $factory, + ) { + } + + public function getConnection(ShardDefinition $shardDefinition, int $shard): IDBConnection { + $connectionKey = $shardDefinition->table . '_' . $shard; + + if (isset($this->connections[$connectionKey])) { + return $this->connections[$connectionKey]; + } + + if ($shard === ShardDefinition::MIGRATION_SHARD) { + $this->connections[$connectionKey] = \OC::$server->get(IDBConnection::class); + } elseif (isset($shardDefinition->shards[$shard])) { + $this->connections[$connectionKey] = $this->createConnection($shardDefinition->shards[$shard]); + } else { + throw new \InvalidArgumentException("invalid shard key $shard only " . count($shardDefinition->shards) . ' configured'); + } + + return $this->connections[$connectionKey]; + } + + private function createConnection(array $shardConfig): IDBConnection { + $shardConfig['sharding'] = []; + $type = $this->config->getValue('dbtype', 'sqlite'); + return new ConnectionAdapter($this->factory->getConnection($type, $shardConfig)); + } +} diff --git a/lib/private/DB/QueryBuilder/Sharded/ShardDefinition.php b/lib/private/DB/QueryBuilder/Sharded/ShardDefinition.php new file mode 100644 index 00000000000..4f98079d92d --- /dev/null +++ b/lib/private/DB/QueryBuilder/Sharded/ShardDefinition.php @@ -0,0 +1,80 @@ +<?php + +declare(strict_types=1); +/** + * SPDX-FileCopyrightText: 2024 Robin Appelman <robin@icewind.nl> + * SPDX-License-Identifier: AGPL-3.0-or-later + */ + +namespace OC\DB\QueryBuilder\Sharded; + +use OCP\DB\QueryBuilder\Sharded\IShardMapper; + +/** + * Configuration for a shard setup + */ +class ShardDefinition { + // we reserve the bottom byte of the primary key for the initial shard, so the total shard count is limited to what we can fit there + // additionally, shard id 255 is reserved for migration purposes + public const MAX_SHARDS = 255; + public const MIGRATION_SHARD = 255; + + public const PRIMARY_KEY_MASK = 0x7F_FF_FF_FF_FF_FF_FF_00; + public const PRIMARY_KEY_SHARD_MASK = 0x00_00_00_00_00_00_00_FF; + // since we reserve 1 byte for the shard index, we only have 56 bits of primary key space + public const MAX_PRIMARY_KEY = PHP_INT_MAX >> 8; + + /** + * @param string $table + * @param string $primaryKey + * @param string $shardKey + * @param string[] $companionKeys + * @param IShardMapper $shardMapper + * @param string[] $companionTables + * @param array $shards + */ + public function __construct( + public string $table, + public string $primaryKey, + public array $companionKeys, + public string $shardKey, + public IShardMapper $shardMapper, + public array $companionTables, + public array $shards, + public int $fromFileId, + public int $fromStorageId, + ) { + if (count($this->shards) >= self::MAX_SHARDS) { + throw new \Exception('Only allowed maximum of ' . self::MAX_SHARDS . ' shards allowed'); + } + } + + public function hasTable(string $table): bool { + if ($this->table === $table) { + return true; + } + return in_array($table, $this->companionTables); + } + + public function getShardForKey(int $key): int { + if ($key < $this->fromStorageId) { + return self::MIGRATION_SHARD; + } + return $this->shardMapper->getShardForKey($key, count($this->shards)); + } + + /** + * @return list<int> + */ + public function getAllShards(): array { + if ($this->fromStorageId !== 0) { + return array_merge(array_keys($this->shards), [self::MIGRATION_SHARD]); + } else { + return array_keys($this->shards); + } + } + + public function isKey(string $column): bool { + return $column === $this->primaryKey || in_array($column, $this->companionKeys); + } +} diff --git a/lib/private/DB/QueryBuilder/Sharded/ShardQueryRunner.php b/lib/private/DB/QueryBuilder/Sharded/ShardQueryRunner.php new file mode 100644 index 00000000000..25e2a3d5f2d --- /dev/null +++ b/lib/private/DB/QueryBuilder/Sharded/ShardQueryRunner.php @@ -0,0 +1,200 @@ +<?php + +declare(strict_types=1); +/** + * SPDX-FileCopyrightText: 2024 Robin Appelman <robin@icewind.nl> + * SPDX-License-Identifier: AGPL-3.0-or-later + */ + +namespace OC\DB\QueryBuilder\Sharded; + +use OC\DB\ArrayResult; +use OCP\DB\IResult; +use OCP\DB\QueryBuilder\IQueryBuilder; + +/** + * Logic for running a query across a number of shards, combining the results + */ +class ShardQueryRunner { + public function __construct( + private ShardConnectionManager $shardConnectionManager, + private ShardDefinition $shardDefinition, + ) { + } + + /** + * Get the shards for a specific query or null if the shards aren't known in advance + * + * @param bool $allShards + * @param int[] $shardKeys + * @return null|int[] + */ + public function getShards(bool $allShards, array $shardKeys): ?array { + if ($allShards) { + return $this->shardDefinition->getAllShards(); + } + $allConfiguredShards = $this->shardDefinition->getAllShards(); + if (count($allConfiguredShards) === 1) { + return $allConfiguredShards; + } + if (empty($shardKeys)) { + return null; + } + $shards = array_map(function ($shardKey) { + return $this->shardDefinition->getShardForKey((int)$shardKey); + }, $shardKeys); + return array_values(array_unique($shards)); + } + + /** + * Try to get the shards that the keys are likely to be in, based on the shard the row was created + * + * @param int[] $primaryKeys + * @return int[] + */ + private function getLikelyShards(array $primaryKeys): array { + $shards = []; + foreach ($primaryKeys as $primaryKey) { + if ($primaryKey < $this->shardDefinition->fromFileId && !in_array(ShardDefinition::MIGRATION_SHARD, $shards)) { + $shards[] = ShardDefinition::MIGRATION_SHARD; + } + $encodedShard = $primaryKey & ShardDefinition::PRIMARY_KEY_SHARD_MASK; + if ($encodedShard < count($this->shardDefinition->shards) && !in_array($encodedShard, $shards)) { + $shards[] = $encodedShard; + } + } + return $shards; + } + + /** + * Execute a SELECT statement across the configured shards + * + * @param IQueryBuilder $query + * @param bool $allShards + * @param int[] $shardKeys + * @param int[] $primaryKeys + * @param array{column: string, order: string}[] $sortList + * @param int|null $limit + * @param int|null $offset + * @return IResult + */ + public function executeQuery( + IQueryBuilder $query, + bool $allShards, + array $shardKeys, + array $primaryKeys, + ?array $sortList = null, + ?int $limit = null, + ?int $offset = null, + ): IResult { + $shards = $this->getShards($allShards, $shardKeys); + $results = []; + if ($shards && count($shards) === 1) { + // trivial case + return $query->executeQuery($this->shardConnectionManager->getConnection($this->shardDefinition, $shards[0])); + } + // we have to emulate limit and offset, so we select offset+limit from all shards to ensure we have enough rows + // and then filter them down after we merged the results + if ($limit !== null && $offset !== null) { + $query->setMaxResults($limit + $offset); + } + + if ($shards) { + // we know exactly what shards we need to query + foreach ($shards as $shard) { + $shardConnection = $this->shardConnectionManager->getConnection($this->shardDefinition, $shard); + $subResult = $query->executeQuery($shardConnection); + $results = array_merge($results, $subResult->fetchAll()); + $subResult->closeCursor(); + } + } else { + // we don't know for sure what shards we need to query, + // we first try the shards that are "likely" to have the rows we want, based on the shard that the row was + // originally created in. If we then still haven't found all rows we try the rest of the shards + $likelyShards = $this->getLikelyShards($primaryKeys); + $unlikelyShards = array_diff($this->shardDefinition->getAllShards(), $likelyShards); + $shards = array_merge($likelyShards, $unlikelyShards); + + foreach ($shards as $shard) { + $shardConnection = $this->shardConnectionManager->getConnection($this->shardDefinition, $shard); + $subResult = $query->executeQuery($shardConnection); + $rows = $subResult->fetchAll(); + $results = array_merge($results, $rows); + $subResult->closeCursor(); + + if (count($rows) >= count($primaryKeys)) { + // we have all the rows we're looking for + break; + } + } + } + + if ($sortList) { + usort($results, function ($a, $b) use ($sortList) { + foreach ($sortList as $sort) { + $valueA = $a[$sort['column']] ?? null; + $valueB = $b[$sort['column']] ?? null; + $cmp = $valueA <=> $valueB; + if ($cmp === 0) { + continue; + } + if ($sort['order'] === 'DESC') { + $cmp = -$cmp; + } + return $cmp; + } + }); + } + + if ($limit !== null && $offset !== null) { + $results = array_slice($results, $offset, $limit); + } elseif ($limit !== null) { + $results = array_slice($results, 0, $limit); + } elseif ($offset !== null) { + $results = array_slice($results, $offset); + } + + return new ArrayResult($results); + } + + /** + * Execute an UPDATE or DELETE statement + * + * @param IQueryBuilder $query + * @param bool $allShards + * @param int[] $shardKeys + * @param int[] $primaryKeys + * @return int + * @throws \OCP\DB\Exception + */ + public function executeStatement(IQueryBuilder $query, bool $allShards, array $shardKeys, array $primaryKeys): int { + if ($query->getType() === \Doctrine\DBAL\Query\QueryBuilder::INSERT) { + throw new \Exception('insert queries need special handling'); + } + + $shards = $this->getShards($allShards, $shardKeys); + $maxCount = count($primaryKeys); + if ($shards && count($shards) === 1) { + return $query->executeStatement($this->shardConnectionManager->getConnection($this->shardDefinition, $shards[0])); + } elseif ($shards) { + $maxCount = PHP_INT_MAX; + } else { + // sort the likely shards before the rest, similar logic to `self::executeQuery` + $likelyShards = $this->getLikelyShards($primaryKeys); + $unlikelyShards = array_diff($this->shardDefinition->getAllShards(), $likelyShards); + $shards = array_merge($likelyShards, $unlikelyShards); + } + + $count = 0; + + foreach ($shards as $shard) { + $shardConnection = $this->shardConnectionManager->getConnection($this->shardDefinition, $shard); + $count += $query->executeStatement($shardConnection); + + if ($count >= $maxCount) { + break; + } + } + return $count; + } +} diff --git a/lib/private/DB/QueryBuilder/Sharded/ShardedQueryBuilder.php b/lib/private/DB/QueryBuilder/Sharded/ShardedQueryBuilder.php new file mode 100644 index 00000000000..04082f76ae8 --- /dev/null +++ b/lib/private/DB/QueryBuilder/Sharded/ShardedQueryBuilder.php @@ -0,0 +1,407 @@ +<?php + +declare(strict_types=1); +/** + * SPDX-FileCopyrightText: 2024 Robin Appelman <robin@icewind.nl> + * SPDX-License-Identifier: AGPL-3.0-or-later + */ + +namespace OC\DB\QueryBuilder\Sharded; + +use OC\DB\QueryBuilder\CompositeExpression; +use OC\DB\QueryBuilder\ExtendedQueryBuilder; +use OC\DB\QueryBuilder\Parameter; +use OCP\DB\IResult; +use OCP\DB\QueryBuilder\IQueryBuilder; +use OCP\IDBConnection; + +/** + * A special query builder that automatically distributes queries over multiple database shards. + * + * This relies on `PartitionedQueryBuilder` to handle splitting of parts of the query that touch the sharded tables + * from the non-sharded tables. So the query build here should only either touch only sharded table or only non-sharded tables. + * + * Most of the logic in this class is concerned with extracting either the shard key (e.g. "storage") or primary key (e.g. "fileid") + * from the query. The logic for actually running the query across the shards is mostly delegated to `ShardQueryRunner`. + */ +class ShardedQueryBuilder extends ExtendedQueryBuilder { + private array $shardKeys = []; + private array $primaryKeys = []; + private ?ShardDefinition $shardDefinition = null; + /** @var bool Run the query across all shards */ + private bool $allShards = false; + private ?string $insertTable = null; + private mixed $lastInsertId = null; + private ?IDBConnection $lastInsertConnection = null; + private ?int $updateShardKey = null; + private ?int $limit = null; + private ?int $offset = null; + /** @var array{column: string, order: string}[] */ + private array $sortList = []; + private string $mainTable = ''; + + public function __construct( + IQueryBuilder $builder, + protected array $shardDefinitions, + protected ShardConnectionManager $shardConnectionManager, + protected AutoIncrementHandler $autoIncrementHandler, + ) { + parent::__construct($builder); + } + + public function getShardKeys(): array { + return $this->getKeyValues($this->shardKeys); + } + + public function getPrimaryKeys(): array { + return $this->getKeyValues($this->primaryKeys); + } + + private function getKeyValues(array $keys): array { + $values = []; + foreach ($keys as $key) { + $values = array_merge($values, $this->getKeyValue($key)); + } + return array_values(array_unique($values)); + } + + private function getKeyValue($value): array { + if ($value instanceof Parameter) { + $value = (string)$value; + } + if (is_string($value) && str_starts_with($value, ':')) { + $param = $this->getParameter(substr($value, 1)); + if (is_array($param)) { + return $param; + } else { + return [$param]; + } + } elseif ($value !== null) { + return [$value]; + } else { + return []; + } + } + + public function where(...$predicates) { + return $this->andWhere(...$predicates); + } + + public function andWhere(...$where) { + if ($where) { + foreach ($where as $predicate) { + $this->tryLoadShardKey($predicate); + } + parent::andWhere(...$where); + } + return $this; + } + + private function tryLoadShardKey($predicate): void { + if (!$this->shardDefinition) { + return; + } + if ($keys = $this->tryExtractShardKeys($predicate, $this->shardDefinition->shardKey)) { + $this->shardKeys += $keys; + } + if ($keys = $this->tryExtractShardKeys($predicate, $this->shardDefinition->primaryKey)) { + $this->primaryKeys += $keys; + } + foreach ($this->shardDefinition->companionKeys as $companionKey) { + if ($keys = $this->tryExtractShardKeys($predicate, $companionKey)) { + $this->primaryKeys += $keys; + } + } + } + + /** + * @param $predicate + * @param string $column + * @return string[] + */ + private function tryExtractShardKeys($predicate, string $column): array { + if ($predicate instanceof CompositeExpression) { + $values = []; + foreach ($predicate->getParts() as $part) { + $partValues = $this->tryExtractShardKeys($part, $column); + // for OR expressions, we can only rely on the predicate if all parts contain the comparison + if ($predicate->getType() === CompositeExpression::TYPE_OR && !$partValues) { + return []; + } + $values = array_merge($values, $partValues); + } + return $values; + } + $predicate = (string)$predicate; + // expect a condition in the form of 'alias1.column1 = placeholder' or 'alias1.column1 in placeholder' + if (substr_count($predicate, ' ') > 2) { + return []; + } + if (str_contains($predicate, ' = ')) { + $parts = explode(' = ', $predicate); + if ($parts[0] === "`{$column}`" || str_ends_with($parts[0], "`.`{$column}`")) { + return [$parts[1]]; + } else { + return []; + } + } + + if (str_contains($predicate, ' IN ')) { + $parts = explode(' IN ', $predicate); + if ($parts[0] === "`{$column}`" || str_ends_with($parts[0], "`.`{$column}`")) { + return [trim(trim($parts[1], '('), ')')]; + } else { + return []; + } + } + + return []; + } + + public function set($key, $value) { + if ($this->shardDefinition && $key === $this->shardDefinition->shardKey) { + $updateShardKey = $value; + } + return parent::set($key, $value); + } + + public function setValue($column, $value) { + if ($this->shardDefinition) { + if ($this->shardDefinition->isKey($column)) { + $this->primaryKeys[] = $value; + } + if ($column === $this->shardDefinition->shardKey) { + $this->shardKeys[] = $value; + } + } + return parent::setValue($column, $value); + } + + public function values(array $values) { + foreach ($values as $column => $value) { + $this->setValue($column, $value); + } + return $this; + } + + private function actOnTable(string $table): void { + $this->mainTable = $table; + foreach ($this->shardDefinitions as $shardDefinition) { + if ($shardDefinition->hasTable($table)) { + $this->shardDefinition = $shardDefinition; + } + } + } + + public function from($from, $alias = null) { + if (is_string($from) && $from) { + $this->actOnTable($from); + } + return parent::from($from, $alias); + } + + public function update($update = null, $alias = null) { + if (is_string($update) && $update) { + $this->actOnTable($update); + } + return parent::update($update, $alias); + } + + public function insert($insert = null) { + if (is_string($insert) && $insert) { + $this->insertTable = $insert; + $this->actOnTable($insert); + } + return parent::insert($insert); + } + + public function delete($delete = null, $alias = null) { + if (is_string($delete) && $delete) { + $this->actOnTable($delete); + } + return parent::delete($delete, $alias); + } + + private function checkJoin(string $table): void { + if ($this->shardDefinition) { + if ($table === $this->mainTable) { + throw new InvalidShardedQueryException("Sharded query on {$this->mainTable} isn't allowed to join on itself"); + } + if (!$this->shardDefinition->hasTable($table)) { + // this generally shouldn't happen as the partitioning logic should prevent this + // but the check is here just in case + throw new InvalidShardedQueryException("Sharded query on {$this->shardDefinition->table} isn't allowed to join on $table"); + } + } + } + + public function innerJoin($fromAlias, $join, $alias, $condition = null) { + $this->checkJoin($join); + return parent::innerJoin($fromAlias, $join, $alias, $condition); + } + + public function leftJoin($fromAlias, $join, $alias, $condition = null) { + $this->checkJoin($join); + return parent::leftJoin($fromAlias, $join, $alias, $condition); + } + + public function rightJoin($fromAlias, $join, $alias, $condition = null) { + if ($this->shardDefinition) { + throw new InvalidShardedQueryException("Sharded query on {$this->shardDefinition->table} isn't allowed to right join"); + } + return parent::rightJoin($fromAlias, $join, $alias, $condition); + } + + public function join($fromAlias, $join, $alias, $condition = null) { + return $this->innerJoin($fromAlias, $join, $alias, $condition); + } + + public function setMaxResults($maxResults) { + if ($maxResults > 0) { + $this->limit = (int)$maxResults; + } + return parent::setMaxResults($maxResults); + } + + public function setFirstResult($firstResult) { + if ($firstResult > 0) { + $this->offset = (int)$firstResult; + } + if ($this->shardDefinition && count($this->shardDefinition->shards) > 1) { + // we have to emulate offset + return $this; + } else { + return parent::setFirstResult($firstResult); + } + } + + public function addOrderBy($sort, $order = null) { + $this->registerOrder((string)$sort, (string)$order ?? 'ASC'); + return parent::addOrderBy($sort, $order); + } + + public function orderBy($sort, $order = null) { + $this->sortList = []; + $this->registerOrder((string)$sort, (string)$order ?? 'ASC'); + return parent::orderBy($sort, $order); + } + + private function registerOrder(string $column, string $order): void { + // handle `mime + 0` and similar by just sorting on the first part of the expression + [$column] = explode(' ', $column); + $column = trim($column, '`'); + $this->sortList[] = [ + 'column' => $column, + 'order' => strtoupper($order), + ]; + } + + public function hintShardKey(string $column, mixed $value, bool $overwrite = false): self { + if ($overwrite) { + $this->primaryKeys = []; + $this->shardKeys = []; + } + if ($this->shardDefinition?->isKey($column)) { + $this->primaryKeys[] = $value; + } + if ($column === $this->shardDefinition?->shardKey) { + $this->shardKeys[] = $value; + } + return $this; + } + + public function runAcrossAllShards(): self { + $this->allShards = true; + return $this; + } + + /** + * @throws InvalidShardedQueryException + */ + public function validate(): void { + if ($this->shardDefinition && $this->insertTable) { + if ($this->allShards) { + throw new InvalidShardedQueryException("Can't insert across all shards"); + } + if (empty($this->getShardKeys())) { + throw new InvalidShardedQueryException("Can't insert without shard key"); + } + } + if ($this->shardDefinition && !$this->allShards) { + if (empty($this->getShardKeys()) && empty($this->getPrimaryKeys())) { + throw new InvalidShardedQueryException('No shard key or primary key set for query'); + } + } + if ($this->shardDefinition && $this->updateShardKey) { + $newShardKey = $this->getKeyValue($this->updateShardKey); + $oldShardKeys = $this->getShardKeys(); + if (count($newShardKey) !== 1) { + throw new InvalidShardedQueryException("Can't set shard key to an array"); + } + $newShardKey = current($newShardKey); + if (empty($oldShardKeys)) { + throw new InvalidShardedQueryException("Can't update without shard key"); + } + $oldShards = array_values(array_unique(array_map(function ($shardKey) { + return $this->shardDefinition->getShardForKey((int)$shardKey); + }, $oldShardKeys))); + $newShard = $this->shardDefinition->getShardForKey((int)$newShardKey); + if ($oldShards === [$newShard]) { + throw new InvalidShardedQueryException('Update statement would move rows to a different shard'); + } + } + } + + public function executeQuery(?IDBConnection $connection = null): IResult { + $this->validate(); + if ($this->shardDefinition) { + $runner = new ShardQueryRunner($this->shardConnectionManager, $this->shardDefinition); + return $runner->executeQuery($this->builder, $this->allShards, $this->getShardKeys(), $this->getPrimaryKeys(), $this->sortList, $this->limit, $this->offset); + } + return parent::executeQuery($connection); + } + + public function executeStatement(?IDBConnection $connection = null): int { + $this->validate(); + if ($this->shardDefinition) { + $runner = new ShardQueryRunner($this->shardConnectionManager, $this->shardDefinition); + if ($this->insertTable) { + $shards = $runner->getShards($this->allShards, $this->getShardKeys()); + if (!$shards) { + throw new InvalidShardedQueryException("Can't insert without shard key"); + } + $count = 0; + foreach ($shards as $shard) { + $shardConnection = $this->shardConnectionManager->getConnection($this->shardDefinition, $shard); + if (!$this->primaryKeys && $this->shardDefinition->table === $this->insertTable) { + $id = $this->autoIncrementHandler->getNextPrimaryKey($this->shardDefinition, $shard); + parent::setValue($this->shardDefinition->primaryKey, $this->createParameter('__generated_primary_key')); + $this->setParameter('__generated_primary_key', $id, self::PARAM_INT); + $this->lastInsertId = $id; + } + $count += parent::executeStatement($shardConnection); + + $this->lastInsertConnection = $shardConnection; + } + return $count; + } else { + return $runner->executeStatement($this->builder, $this->allShards, $this->getShardKeys(), $this->getPrimaryKeys()); + } + } + return parent::executeStatement($connection); + } + + public function getLastInsertId(): int { + if ($this->lastInsertId) { + return $this->lastInsertId; + } + if ($this->lastInsertConnection) { + $table = $this->builder->prefixTableName($this->insertTable); + return $this->lastInsertConnection->lastInsertId($table); + } else { + return parent::getLastInsertId(); + } + } + + +} |