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new 5036af6fb34 Doc fixes for query from deep storage and MSQ (#15313)
5036af6fb34 is described below
commit 5036af6fb3433ab98ce965c064184168fb28436b
Author: Karan Kumar <[email protected]>
AuthorDate: Fri Nov 3 10:52:20 2023 +0530
Doc fixes for query from deep storage and MSQ (#15313)
Minor updates to the documentation.
Added prerequisites.
Removed a known issue in MSQ since its no longer valid.
---------
Co-authored-by: 317brian <[email protected]>
---
docs/multi-stage-query/known-issues.md | 4 ----
docs/querying/query-from-deep-storage.md | 4 ++++
docs/tutorials/tutorial-query-deep-storage.md | 2 ++
3 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/docs/multi-stage-query/known-issues.md
b/docs/multi-stage-query/known-issues.md
index 570a7f58fa4..f4e97dc23da 100644
--- a/docs/multi-stage-query/known-issues.md
+++ b/docs/multi-stage-query/known-issues.md
@@ -42,10 +42,6 @@ an [UnknownError](./reference.md#error_UnknownError) with a
message including "N
- `GROUPING SETS` are not implemented. Queries using these features return a
[QueryNotSupported](reference.md#error_QueryNotSupported) error.
-- For some `COUNT DISTINCT` queries, you'll encounter a
[QueryNotSupported](reference.md#error_QueryNotSupported) error
- that includes `Must not have 'subtotalsSpec'` as one of its causes. This is
caused by the planner attempting to use
- `GROUPING SET`s, which are not implemented.
-
- The numeric varieties of the `EARLIEST` and `LATEST` aggregators do not work
properly. Attempting to use the numeric
varieties of these aggregators lead to an error like
`java.lang.ClassCastException: class java.lang.Double cannot be cast to
class org.apache.druid.collections.SerializablePair`.
diff --git a/docs/querying/query-from-deep-storage.md
b/docs/querying/query-from-deep-storage.md
index fba131eba31..c9c97f780dd 100644
--- a/docs/querying/query-from-deep-storage.md
+++ b/docs/querying/query-from-deep-storage.md
@@ -24,6 +24,10 @@ title: "Query from deep storage"
Druid can query segments that are only stored in deep storage. Running a query
from deep storage is slower than running queries from segments that are loaded
on Historical processes, but it's a great tool for data that you either access
infrequently or where the low latency results that typical Druid queries
provide is not necessary. Queries from deep storage can increase the surface
area of data available to query without requiring you to scale your Historical
processes to accommodate m [...]
+## Prerequisites
+
+Query from deep storage requires the Multi-stage query (MSQ) task engine. Load
the extension for it if you don't already have it enabled before you begin. See
[enable MSQ](../multi-stage-query/index.md#load-the-extension) for more
information.
+
## Keep segments in deep storage only
Any data you ingest into Druid is already stored in deep storage, so you don't
need to perform any additional configuration from that perspective. However, to
take advantage of the cost savings that querying from deep storage provides,
make sure not all your segments get loaded onto Historical processes.
diff --git a/docs/tutorials/tutorial-query-deep-storage.md
b/docs/tutorials/tutorial-query-deep-storage.md
index d4dfe5e6998..dfb4de22eb0 100644
--- a/docs/tutorials/tutorial-query-deep-storage.md
+++ b/docs/tutorials/tutorial-query-deep-storage.md
@@ -31,6 +31,8 @@ To run the queries in this tutorial, replace `ROUTER:PORT`
with the location of
For more general information, see [Query from deep
storage](../querying/query-from-deep-storage.md).
+If you are trying this feature on an existing cluster, make sure query from
deep storage
[prerequisites](../querying/query-from-deep-storage.md#prerequisites) are met.
+
## Load example data
Use the **Load data** wizard or the following SQL query to ingest the
`wikipedia` sample datasource bundled with Druid. If you use the wizard, make
sure you change the partitioning to be by hour.
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