diff options
Diffstat (limited to 'src/mongo/db/pipeline/document_source.h')
| -rw-r--r-- | src/mongo/db/pipeline/document_source.h | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/src/mongo/db/pipeline/document_source.h b/src/mongo/db/pipeline/document_source.h index 8f1c2fef4a0..134a8a86e3d 100644 --- a/src/mongo/db/pipeline/document_source.h +++ b/src/mongo/db/pipeline/document_source.h @@ -529,14 +529,18 @@ public: /** * Returns a source to be run on the shards, or NULL if no work should be done on the shards for * this stage. Must not mutate the existing source object; if different behaviour is required in - * the split-pipeline case, a new source should be created and configured appropriately. + * the split-pipeline case, a new source should be created and configured appropriately. It is + * an error for getShardSource() to return a pointer to the same object as getMergeSource(), + * since this can result in the source being stitched into both the shard and merge pipelines + * when the latter is executed on mongoS. */ virtual boost::intrusive_ptr<DocumentSource> getShardSource() = 0; /** * Returns a source that combines results from the shards, or NULL if no work should be done in * the merge pipeline for this stage. Must not mutate the existing source object; if different - * behaviour is required, a new source should be created and configured appropriately. + * behaviour is required, a new source should be created and configured appropriately. It is an + * error for getMergeSource() to return a pointer to the same object as getShardSource(). */ virtual boost::intrusive_ptr<DocumentSource> getMergeSource() = 0; |