Create and Run Atlas Search Queries
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Atlas Search queries take the form of an aggregation pipeline stage. Atlas Search provides $search
and
$searchMeta
stages, both of which must be the first stage
in any query pipeline, including the $lookup
and
$unionWith
sub-pipelines. These stages can be used in
conjunction with other aggregation pipeline stages in your query pipeline. To learn more about these
pipeline stages, see Choose the Aggregation Pipeline Stage.
Atlas Search also provides query operators and
collectors that you can use inside the
$search
and $searchMeta
aggregation
pipeline stages. The Atlas Search operators allow you to
locate and retrieve relevant data from the collection on your Atlas
cluster. The collector returns a document representing the search
metadata results.
You can use Atlas Search operators to query terms, phrases, geographic shapes
and points, numeric values, similar documents, synonymous terms, and more.
You can also search using regex and wildcard expressions. The Atlas Search
compound operator allows you to combine multiple operators
inside your $search
stage to perform a complex search and
filter of data based on what must, must not, or should be present
in the documents returned by Atlas Search. You can use the compound
operator to also match or filter documents in the $search
stage itself. Running $match
after $search
is
less performant than running $search
with the
compound operator.
To learn more about the syntax, options, and usage of the Atlas Search operators, see Use Operators and Collectors in Atlas Search Queries.
mongod
andmongot
on the Same NodeWhen you run a query, Atlas Search uses the configured read preference to identify the node on which to run the query. The query first goes to the MongoDB process, which is
mongod
for a replica set cluster ormongos
for a sharded cluster.For a replica set cluster, the MongoDB process routes the query to the
mongot
on the same node. For sharded clusters, your cluster data is partitioned acrossmongod
instances and eachmongot
knows about the data on themongod
on the same node only. Therefore, you can't run Atlas Search queries that target a particular shard.mongos
directs the queries to all shards, making these scatter gather queries. If you use zones to distribute a sharded collection over a subset of the shards in the cluster, Atlas Search routes the query to the zone that contains the shards for the collection that you are querying and runs your$search
queries on just the shards where the collection is located.Atlas Search performs the search and scoring and returns the document IDs and other search metadata for the matching results to
mongod
. Themongod
then performs a full document lookup implicitly for the matching results and returns the results to the client. If you use the$search
concurrent option in your query, Atlas Search enables intra-query parallelism. To learn more, see Parallelize Query Execution Across Segments.mongod
andmongot
on Different NodesWhen you run a query, the query first goes to the
mongod
based on the configured read preference. Themongod
process routes the search query through a load balancer on the same node, which distributes the requests across all of themongot
processes.The Atlas Search
mongot
process performs the search and scoring and returns the document IDs and metadata for the matching results tomongod
. Themongod
then performs a full document lookup for the matching results and returns the results to the client. If you use the$search
concurrent option in your query, Atlas Search enables intra-query parallelism. To learn more, see Parallelize Query Execution Across Segments.
Atlas Search associates a relevance-based score with every document in the result set. The relevance-based scoring allows Atlas Search to return documents in the order from the highest score to the lowest. Atlas Search scores documents higher if the query term appears frequently in a document and lower if the query term appears across many documents in the collection. Atlas Search also supports customizing the relevance-based default score by boosting, decaying, or other modifying options. To learn more about customizing the resulting scores, see Score the Documents in the Results.
Tip
See also: Learn by Watching
Supported Clients
You can create and run Atlas Search queries using the following:
MongoDB Compass
Atlas CLI
Next Steps
To learn how to create and run a query, see Create a Query. For hands-on experience creating Atlas Search indexes and running Atlas Search queries against the sample datasets, try the tutorials in the following pages: