[GitHub] [ignite-3] korlov42 commented on a diff in pull request #821: IGNITE-15475 Describe SQL threading model in the module documentation

[GitBox <gi...@apache.org>]

korlov42 commented on code in PR #821:
URL: https://github.com/apache/ignite-3/pull/821#discussion_r881953922


##########
modules/sql-engine/README.md:
##########
@@ -1,4 +1,67 @@
-#Apache Ignite SQL Engine Module
---------------------------
+# Apache Ignite SQL Engine
 
-Apache Ignite SQL Engine module provides Apache Calcite based query engine.
+## Threading Model
+
+Every Ignite node uses two thread pools for query processing.
+
+### Planning pool
+
+This pool is used to optimize queries and DML statements.
+
+The unit of work for this pool is a query that should be optimized. An optimization task is compute-heavy. Besides, the planning cycle is not optimized well enough, hence some tasks might require unreasonable amounts of time to complete, thus should be killed by a timeout.
+
+The size of this pool was chosen by a dice roll and hardcoded to 4, and should be moved to configuration in the future. The pool is named ‘sql-planning-pool’.

Review Comment:
   fair enough. fixed



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