SERVER-53484: Allow rewrite to push meta predicates past $unpackBucket

1 files changed, 11 insertions, 0 deletions

diff --git a/src/mongo/db/pipeline/document_source_internal_unpack_bucket.h b/src/mongo/db/pipeline/document_source_internal_unpack_bucket.h
index 50a1513cc51..18316a1a3e9 100644
--- a/src/mongo/db/pipeline/document_source_internal_unpack_bucket.h
+++ b/src/mongo/db/pipeline/document_source_internal_unpack_bucket.h
@@ -32,6 +32,7 @@
 #include <set>
 
 #include "mongo/db/pipeline/document_source.h"
+#include "mongo/db/pipeline/document_source_match.h"
 
 namespace mongo {
 
@@ -206,6 +207,16 @@ public:
         Pipeline::SourceContainer::iterator itr, Pipeline::SourceContainer* container) const;
 
     /**
+     * Attempts to split 'match' into two stages, where the first is dependent only on the metaField
+     * and the second is the remainder, so that applying them in sequence is equivalent to applying
+     * 'match' once. Will return two intrusive_ptrs to new $match stages. Either pointer may be
+     * null. If the first is non-null, it will have the metaField renamed from the user defined name
+     * to 'kBucketMetaFieldName'.
+     */
+    std::pair<boost::intrusive_ptr<DocumentSourceMatch>, boost::intrusive_ptr<DocumentSourceMatch>>
+    splitMatchOnMetaAndRename(boost::intrusive_ptr<DocumentSourceMatch> match);
+
+    /**
      * Takes a predicate after $_internalUnpackBucket on a bucketed field as an argument and
      * attempts to map it to a new predicate on the 'control' field. For example, the predicate
      * {a: {$gt: 5}} will generate the predicate {control.max.a: {$_internalExprGt: 5}}, which will