[FAB-13161] Tips and tricks for couchdb

Change-Id: I16a1cbff60637f1f610463a84f04514f614ac94c
Signed-off-by: joe-alewine <Joe.Alewine@ibm.com>

Author: joe-alewine

docs/source/couchdb_as_state_database.rst

@@ -137,7 +137,7 @@ index is getting initialized. During transaction processing, the indexes will au
 as blocks are committed to the ledger.
 
 CouchDB Configuration
-----------------------
+---------------------
 
 CouchDB is enabled as the state database by changing the ``stateDatabase`` configuration option from
 goleveldb to CouchDB. Additionally, the ``couchDBAddress`` needs to configured to point to the
@@ -212,5 +212,35 @@ is to be changed after creation of the container.
 
 .. note:: CouchDB peer options are read on each peer startup.
 
+Good practices for queries
+--------------------------
+
+Avoid using chaincode for queries that will result in a scan of the entire
+CouchDB database. Full length database scans will result in long response
+times and will degrade the performance of your network. You can take some of
+the following steps to avoid long queries:
+
+- When using JSON queries:
+
+    * Be sure to create indexes in the chaincode package.
+    * Avoid query operators such as ``$or``, ``$in`` and ``$regex``, which lead
+      to full database scans.
+
+- For range queries, composite key queries, and JSON queries:
+
+    * Utilize paging support (as of v1.3) instead of one large result set.
+
+- If you want to build a dashboard or collect aggregate data as part of your
+  application, you can query an off-chain database that replicates the data
+  from your blockchain network. This will allow you to query and analyze the
+  blockchain data in a data store optimized for your needs, without degrading
+  the performance of your network or disrupting transactions. To achieve this,
+  applications may use block or chaincode events to write transaction data
+  to an off-chain database or analytics engine. For each block received, the block
+  listener application would iterate through the block transactions and build a
+  data store using the key/value writes from each valid transaction's ``rwset``.
+  The :doc:`peer_event_services` provide replayable events to ensure the
+  integrity of downstream data stores.
+
 .. Licensed under Creative Commons Attribution 4.0 International License
-   https://creativecommons.org/licenses/by/4.0/
+   https://creativecommons.org/licenses/by/4.0/