diff options
| -rw-r--r-- | src/mongo/db/pipeline/sharded_agg_helpers.cpp | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/src/mongo/db/pipeline/sharded_agg_helpers.cpp b/src/mongo/db/pipeline/sharded_agg_helpers.cpp index cd5d35f9925..0db983a12d3 100644 --- a/src/mongo/db/pipeline/sharded_agg_helpers.cpp +++ b/src/mongo/db/pipeline/sharded_agg_helpers.cpp @@ -1261,16 +1261,26 @@ std::unique_ptr<Pipeline, PipelineDeleter> attachCursorToPipeline(Pipeline* owne invariant(pipeline->getSources().empty() || !dynamic_cast<DocumentSourceMergeCursors*>(pipeline->getSources().front().get())); + if (expCtx->ns.isConfigDotCacheDotChunks()) { + // We take special care to attach the local cursor stage to 'ownedPipeline' here rather than + // attaching it to a serialized and re-parsed copy of the pipeline to avoid optimizations + // such as the $sequentialCache stage from being lost. This is safe because each shard has + // its own complete copy of any "config.cache.chunks.*" namespace. + return expCtx->mongoProcessInterface->attachCursorSourceToPipelineForLocalRead( + pipeline.release()); + } + auto catalogCache = Grid::get(expCtx->opCtx)->catalogCache(); return shardVersionRetry( expCtx->opCtx, catalogCache, expCtx->ns, "targeting pipeline to attach cursors"_sd, [&]() { auto pipelineToTarget = pipeline->clone(); - if (allowTargetingShards && !expCtx->ns.isConfigDotCacheDotChunks() && - expCtx->ns.db() != "local") { - return targetShardsAndAddMergeCursors(expCtx, std::move(pipelineToTarget)); + if (!allowTargetingShards || expCtx->ns.db() == "local") { + // If the db is local, this may be a change stream examining the oplog. We know the + // oplog (and any other local collections) will not be sharded. + return expCtx->mongoProcessInterface->attachCursorSourceToPipelineForLocalRead( + pipelineToTarget.release()); } - return expCtx->mongoProcessInterface->attachCursorSourceToPipelineForLocalRead( - pipelineToTarget.release()); + return targetShardsAndAddMergeCursors(expCtx, std::move(pipelineToTarget)); }); } |