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80 lines
3.3 KiB
PHP
80 lines
3.3 KiB
PHP
<?php
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declare(strict_types=1);
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/**
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* SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
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* SPDX-License-Identifier: AGPL-3.0-only
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*/
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namespace OC\DB\QueryBuilder\Partitioned;
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/**
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* Partitioned queries impose limitations that queries have to follow:
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*
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* 1. Any reference to columns not in the "main table" (the table referenced by "FROM"), needs to explicitly include the
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* table or alias the column belongs to.
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*
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* For example:
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* ```
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* $query->select("mount_point", "mimetype")
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* ->from("mounts", "m")
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* ->innerJoin("m", "filecache", "f", $query->expr()->eq("root_id", "fileid"));
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* ```
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* will not work, as the query builder doesn't know that the `mimetype` column belongs to the "filecache partition".
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* Instead, you need to do
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* ```
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* $query->select("mount_point", "f.mimetype")
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* ->from("mounts", "m")
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* ->innerJoin("m", "filecache", "f", $query->expr()->eq("m.root_id", "f.fileid"));
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* ```
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*
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* 2. The "ON" condition for the join can only perform a comparison between both sides of the join once.
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*
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* For example:
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* ```
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* $query->select("mount_point", "mimetype")
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* ->from("mounts", "m")
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* ->innerJoin("m", "filecache", "f", $query->expr()->andX($query->expr()->eq("m.root_id", "f.fileid"), $query->expr()->eq("m.storage_id", "f.storage")));
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* ```
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* will not work.
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*
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* 3. An "OR" expression in the "WHERE" cannot mention both sides of the join, this does not apply to "AND" expressions.
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*
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* For example:
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* ```
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* $query->select("mount_point", "mimetype")
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* ->from("mounts", "m")
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* ->innerJoin("m", "filecache", "f", $query->expr()->eq("m.root_id", "f.fileid")))
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* ->where($query->expr()->orX(
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* $query->expr()-eq("m.user_id", $query->createNamedParameter("test"))),
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* $query->expr()-eq("f.name", $query->createNamedParameter("test"))),
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* ));
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* ```
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* will not work, but.
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* ```
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* $query->select("mount_point", "mimetype")
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* ->from("mounts", "m")
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* ->innerJoin("m", "filecache", "f", $query->expr()->eq("m.root_id", "f.fileid")))
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* ->where($query->expr()->andX(
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* $query->expr()-eq("m.user_id", $query->createNamedParameter("test"))),
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* $query->expr()-eq("f.name", $query->createNamedParameter("test"))),
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* ));
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* ```
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* will.
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*
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* 4. Queries that join cross-partition cannot use position parameters, only named parameters are allowed
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* 5. The "ON" condition of a join cannot contain and "OR" expression.
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* 6. Right-joins are not allowed.
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* 7. Update, delete and insert statements aren't allowed to contain cross-partition joins.
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* 8. Queries that "GROUP BY" a column from the joined partition are not allowed.
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* 9. Any `join` call needs to be made before any `where` call.
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* 10. Queries that join cross-partition with an "INNER JOIN" or "LEFT JOIN" with a condition on the left side
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* cannot use "LIMIT" or "OFFSET" in queries.
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*
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* The part of the query running on the sharded table has some additional limitations,
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* see the `InvalidShardedQueryException` documentation for more information.
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*/
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class InvalidPartitionedQueryException extends \Exception {
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}
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