fix: don't needlessly contrain join when the left side is allow to be null

Signed-off-by: Robin Appelman <robin@icewind.nl>

Author: icewind1991

lib/private/DB/QueryBuilder/Partitioned/PartitionQuery.php

@@ -26,6 +26,7 @@ public function __construct(
 		public string $joinFromColumn,
 		public string $joinToColumn,
 		public string $joinMode,
+		public string $joinToTableAlias,
 	) {
 		if ($joinMode !== self::JOIN_MODE_LEFT && $joinMode !== self::JOIN_MODE_INNER) {
 			throw new InvalidPartitionedQueryException("$joinMode joins aren't allowed in partitioned queries");

lib/private/DB/QueryBuilder/Partitioned/PartitionedQueryBuilder.php

@@ -234,7 +234,8 @@ public function join($fromAlias, $join, $alias, $condition = null, $joinMode = P
 				$this->splitQueries[$partition->name] = new PartitionQuery(
 					$this->newQuery(),
 					$joinCondition->fromAlias ?? $joinCondition->fromColumn, $joinCondition->toAlias ?? $joinCondition->toColumn,
-					$joinMode
+					$joinMode,
+					$alias,
 				);
 				$this->splitQueries[$partition->name]->query->from($join, $alias);
 				$this->ensureSelect($joinCondition->fromColumn, $joinCondition->fromAlias);
@@ -269,7 +270,8 @@ public function join($fromAlias, $join, $alias, $condition = null, $joinMode = P
 				$this->splitQueries[$partitionName] = new PartitionQuery(
 					$this->newQuery(),
 					$joinCondition->fromAlias ?? $joinCondition->fromColumn, $joinCondition->toAlias ?? $joinCondition->toColumn,
-					$joinMode
+					$joinMode,
+					$alias,
 				);
 				$this->ensureSelect($joinCondition->fromColumn, $joinCondition->fromAlias);
 				$this->ensureSelect($joinCondition->toColumn, $joinCondition->toAlias);
@@ -349,11 +351,14 @@ public function andWhere(...$where) {
 		if ($where) {
 			foreach ($this->splitPredicatesByParts($where) as $alias => $predicates) {
 				if (isset($this->splitQueries[$alias])) {
+					$mergedPredicate = new CompositeExpression(CompositeExpression::TYPE_AND, $predicates);
 					// when there is a condition on a table being left-joined it starts to behave as if it's an inner join
 					// since any joined column that doesn't have the left part will not match the condition
 					// when there the condition is `$joinToColumn IS NULL` we instead mark the query as excluding the left half
 					if ($this->splitQueries[$alias]->joinMode === PartitionQuery::JOIN_MODE_LEFT) {
-						$this->splitQueries[$alias]->joinMode = PartitionQuery::JOIN_MODE_INNER;
+						if ($this->constraintsTableNotNull($mergedPredicate, $this->splitQueries[$alias]->joinToTableAlias)) {
+							$this->splitQueries[$alias]->joinMode = PartitionQuery::JOIN_MODE_INNER;
+						}
 
 						$column = $this->quoteHelper->quoteColumnName($this->splitQueries[$alias]->joinToColumn);
 						foreach ($predicates as $predicate) {
@@ -374,6 +379,33 @@ public function andWhere(...$where) {
 		return $this;
 	}
 
+	/**
+	 * Check if any part of a predicates constraints any part of a table to be not null
+	 *
+	 * @return bool
+	 */
+	private function constraintsTableNotNull($predicate, string $table): bool {
+		if ($predicate instanceof CompositeExpression) {
+			if ($predicate->getType() === CompositeExpression::TYPE_OR) {
+				$all = true;
+				foreach ($predicate->getParts() as $part) {
+					$all = $all && $this->constraintsTableNotNull($part, $table);
+				}
+				return $all;
+			} else {
+				foreach ($predicate->getParts() as $part) {
+					if ($this->constraintsTableNotNull($part, $table)) {
+						return true;
+					}
+				}
+				return false;
+			}
+		} else {
+			$predicate = (string)$predicate;
+			return str_starts_with($predicate, "`$table`.") && !str_ends_with($predicate, "IS NULL");
+		}
+	}
+
 	private function getPartitionForPredicate(string $predicate): ?PartitionSplit {
 		foreach ($this->partitions as $partition) {