1 files changed, 61 insertions, 0 deletions
diff --git a/lib/private/Files/Search/QueryOptimizer/PathPrefixOptimizer.php b/lib/private/Files/Search/QueryOptimizer/PathPrefixOptimizer.php
new file mode 100644
index 00000000000..2994a9365a7
--- /dev/null
+++ b/lib/private/Files/Search/QueryOptimizer/PathPrefixOptimizer.php
@@ -0,0 +1,61 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2021 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OC\Files\Search\QueryOptimizer;
+
+use OC\Files\Search\SearchComparison;
+use OCP\Files\Search\ISearchBinaryOperator;
+use OCP\Files\Search\ISearchComparison;
+use OCP\Files\Search\ISearchOperator;
+
+class PathPrefixOptimizer extends QueryOptimizerStep {
+	private bool $useHashEq = true;
+
+	public function inspectOperator(ISearchOperator $operator): void {
+		// normally any `path = "$path"` search filter would be generated as an `path_hash = md5($path)` sql query
+		// since the `path_hash` sql column usually provides much faster querying that selecting on the `path` sql column
+		//
+		// however, if we're already doing a filter on the `path` column in the form of `path LIKE "$prefix/%"`
+		// generating a `path = "$prefix"` sql query lets the database handle use the same column for both expressions and potentially use the same index
+		//
+		// If there is any operator in the query that matches this pattern, we change all `path = "$path"` instances to not the `path_hash` equality,
+		// otherwise mariadb has a tendency of ignoring the path_prefix index
+		if ($this->useHashEq && $this->isPathPrefixOperator($operator)) {
+			$this->useHashEq = false;
+		}
+
+		parent::inspectOperator($operator);
+	}
+
+	public function processOperator(ISearchOperator &$operator) {
+		if (!$this->useHashEq && $operator instanceof ISearchComparison && !$operator->getExtra() && $operator->getField() === 'path' && $operator->getType() === ISearchComparison::COMPARE_EQUAL) {
+			$operator->setQueryHint(ISearchComparison::HINT_PATH_EQ_HASH, false);
+		}
+
+		parent::processOperator($operator);
+	}
+
+	private function isPathPrefixOperator(ISearchOperator $operator): bool {
+		if ($operator instanceof ISearchBinaryOperator && $operator->getType() === ISearchBinaryOperator::OPERATOR_OR && count($operator->getArguments()) == 2) {
+			$a = $operator->getArguments()[0];
+			$b = $operator->getArguments()[1];
+			if ($this->operatorPairIsPathPrefix($a, $b) || $this->operatorPairIsPathPrefix($b, $a)) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	private function operatorPairIsPathPrefix(ISearchOperator $like, ISearchOperator $equal): bool {
+		return (
+			$like instanceof ISearchComparison && $equal instanceof ISearchComparison
+			&& !$like->getExtra() && !$equal->getExtra() && $like->getField() === 'path' && $equal->getField() === 'path'
+			&& $like->getType() === ISearchComparison::COMPARE_LIKE_CASE_SENSITIVE && $equal->getType() === ISearchComparison::COMPARE_EQUAL
+			&& $like->getValue() === SearchComparison::escapeLikeParameter($equal->getValue()) . '/%'
+		);
+	}
+}