update docs for snuba storage queries

docs/source/language/snql.rst

@@ -45,11 +45,18 @@ MATCH clause that are currently supported:
 
 ``MATCH (<entity> [SAMPLE n])``
 
-This is equivalent to all of our current queries. This is querying data from
-a single entity (Events, Transactions etc.) It is possible to add an optional
+Or for datasets without entities:
+
+``MATCH (STORAGE(<storage>) [SAMPLE n])``
+
+This is equivalent to all of our current queries. This either queries data from
+a single entity or a single storage directly. It is possible to add an optional
 sample to the query by adding it with the entity.
 
-Example ``MATCH (events)``.
+Example::
+
+    MATCH (events) # for entity queries
+    MATCH (STORAGE(profile_chunks)) # for storage queries.
 
 **Subquery:**
 

docs/source/query/overview.rst

@@ -9,7 +9,7 @@ Exploring the Snuba data model
 ==============================
 
 In order to architect a Snuba query, the first step is being able to
-know which Dataset you should query, which Entities you should select
+know which Dataset you should query, which Entities you should select,
 and what the schema of each Entity is.
 
 For an introduction about Datasets and Entities, see the :doc:`/architecture/datamodel`
@@ -99,6 +99,24 @@ The query is represented as a ``Query`` object like::
         granularity=Granularity(3600),
     )
 
+For simpler datasets, there may not exist an entity. In this case, we can
+query the storage directly like::
+
+    query = Query(
+        dataset="profiles",
+        match=Storage("profile_chunks"),
+        select=[
+            Column("chunk_id"),
+        ],
+        where=[
+            Condition(Column("start_timestamp"), Op.GT, datetime.datetime(2021, 1, 1)),
+            Condition(Column("end_timestamp"), Op.LT, datetime.datetime(2021, 1, 2)),
+            Condition(Column("project_id"), Op.IN, Function("tuple", [1, 2, 3])),
+        ],
+        limit=Limit(10),
+        offset=Offset(0),
+    )
+
 More details on how to build a query are in the sdk documentation.
 
 Once the query object is ready it can be sent to Snuba.