Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/536#discussion_r82495497
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/PlannerSettings.java
---
@@ -46,40 +46,83 @@
// max off heap memory for planning (16G)
private static final long MAX_OFF_HEAP_ALLOCATION_IN_BYTES = 16l * 1024
* 1024 * 1024;
- public static final OptionValidator CONSTANT_FOLDING = new
BooleanValidator("planner.enable_constant_folding", true);
+ public static final OptionValidator CONSTANT_FOLDING = new
BooleanValidator("planner.enable_constant_folding", true,
+ "If one side of a filter condition is a constant expression,
constant folding evaluates the expression in the" +
+ " planning phase and replaces the expression with the constant
value. For example, Drill can rewrite" +
+ " this clause ' WHERE age + 5 < 42 as WHERE age < 37'.");
+
public static final OptionValidator EXCHANGE = new
BooleanValidator("planner.disable_exchanges", false);
+
public static final OptionValidator HASHAGG = new
BooleanValidator("planner.enable_hashagg", true);
+
public static final OptionValidator STREAMAGG = new
BooleanValidator("planner.enable_streamagg", true);
- public static final OptionValidator HASHJOIN = new
BooleanValidator("planner.enable_hashjoin", true);
- public static final OptionValidator MERGEJOIN = new
BooleanValidator("planner.enable_mergejoin", true);
+
+ public static final OptionValidator HASHJOIN = new
BooleanValidator("planner.enable_hashjoin", true,
+ "Enable the memory hungry hash join. Drill assumes that a query with
have adequate memory to complete and" +
--- End diff --
with have --> will have
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