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Query Plan References

MongoDB states the operations that can be performed in a list.

Operation Category Reference Description
AND_HASH Combinator Link It performs a hash-based intersection of two or more sets of documents.
AND_SORTED Combinator Link It performs an intersection of two or more sets of documents in order.
BATCHED_DELETE Consumer Link Delete documents in batches.
CACHED_PLAN Executor Link It evaluates the cost of a cached plan
COLLSCAN Producer Link It scans over a collection.
COLUMN_IXSCAN Producer Link  An index scan operation that returns only the indexed field values for a given collection.
COUNT Folder Link “COUNT” refers to the stage in the query execution plan that performs a count operation. The count operation counts the number of documents in a collection that match a specified filter.
COUNT_SCAN Producer Link Used by the count command. Scans an index from a start key to an end key.
DELETE Consumer Link Delete a document.
DISTINCT_SCAN Producer Link Used by the distinct command.  Executes a mutated index scan over the provided bounds.
EOF Executor Link EOF” represents no data is read and output.
EQ_LOOKUP Producer Link Represents a lookup from a foreign collection by equality match on foreign and local fields.
FETCH Executor Link This stage turns a Record Id into a BSONObj.
GEO_NEAR_2D Folder Link Outputs documents in order of nearest to farthest from a specified point.
GEO_NEAR_2DSPHERE Folder Link It finds the documents that are near a given geographic location with the 2d spherical index.
GROUP Folder Link Group data.
IDHACK Producer Link A standalone stage implementing the fast path for key-value retrievals via the _id index.
IXSCAN Producer Link Stage scans over an index from startKey to endKey, returning results that pass the provided filter.
LIMIT Combinator Link Limit the number of returned rows.
MOCK Executor Link “MOCK” refers to a stage that is used for testing purposes, and is not part of the actual query execution plan.
MULTI_ITERATOR Producer Link “MULT_ITERATOR” refers to a stage that is used when multiple indexes are used to retrieve the documents in a query.
MULTI_PLAN Executor Link MULTI_PLAN” refers to a stage that is used when multiple query plans are generated and evaluated by the query optimizer.
OR Combinator Link This stage outputs the union of its children. It optionally deduplicates on RecordId.
PROJECTION_COVERED Projector Link An explicit projection which is supported by an index scan (eg, for a “covered” index query).
PROJECTION_DEFAULT Projector Link A “default” projection, where no explicit projection is requested.
PROJECTION_SIMPLE Projector Link An explicit projection which is supported by a collection access – usually preceded by a FETCH or COLLSCAN step.
QUEUED_DATA Producer Link “QUEUED_DATA” is a stage that is used to retrieve documents from a queue that were added to it by a preceding stage.
RECORD_STORE_FAST_COUNT Folder Link “RECORD_STORE_FAST_COUNT” is an operation in MongoDB query plans that counts the number of documents in a collection using a fast count operation. This operation uses a metadata field called “ns” in the collection to count the number of documents without scanning the actual documents.
RETURN_KEY Producer Link the RETURN_KEY stage indicates that the query is a covered query, and the results can be fetched directly from the index keys without actually retrieving the full documents from the collection.
SAMPLE_FROM_TIMESERIES_BUCKET Producer Link the SAMPLE_FROM_TIMESERIES_BUCKET stage is specific to the MongoDB Time Series collections and is used to retrieve a random sample of documents from the specified time-series bucket.
SENTINEL Executor Link a stage that acts as a placeholder for a query plan stage that has been pruned during optimization
SHARDING_FILTER   Link The “SHARDING_FILTER” stage in MongoDB query plans refers to the filtering of data based on the shard key. We mapped it into the property filter.
SKIP Executor Link an operation that skips the specified number of documents from the beginning of the result set. It is commonly used with “LIMIT” to implement pagination in queries.
SORT_DEFAULT Combinator Link Sort data
SORT_KEY_GENERATOR Combinator Link an operator that generates keys for sorting a set of documents based on the values of the specified fields.
SORT_MERGE Combinator Link an operation that sorts the results of two or more sub-plans and then merges them together.
SORT_SIMPLE Combinator Link Sort data.
SUBPLAN Executor Link It plans each clause of the $or individually and then creates an overall query plan based on the winning plan from each clause.
TEXT_MATCH Producer Link A stage that returns every document in the child that satisfies the FTS text matcher built with the query parameter.
TEXT_OR Combinator Link A blocking stage that returns the set of WSMs with RecordIDs of all of the documents that contain the positive terms in the search query, as well as their scores.
TRIAL Executor Link TrialStage runs a specified ‘trial’ plan for a given number of iterations, tracking the number of times the plan advanced over that duration. If the ratio of advances to works falls below a given threshold, then the trial results are discarded and the backup plan is adopted. Otherwise, we consider the trial a success and return the cached results of the trial phase followed by any further results that the plan produces.
UNKNOWN Executor Link An operation for testing that always throws exceptions.
UNPACK_TIMESERIES_BUCKET Producer Link It unpacks data from time series buckets.
UPDATE Consumer Link Update data.
VIRTUAL_SCAN Producer Link A VirtualScanNode is similar to a collection or an index scan except that it doesn’t depend on an underlying storage implementation. It can be used to represent a virtual collection or an index scan in memory by using a backing vector of BSONArray.

References