Followup Support NULL literals in where clause

datafusion/expr/src/logical_plan/plan.rs

@@ -2091,7 +2091,7 @@ impl Filter {
         // construction (such as with correlated subqueries) so we make a best effort here and
         // ignore errors resolving the expression against the schema.
         if let Ok(predicate_type) = predicate.get_type(input.schema()) {
-            if predicate_type != DataType::Boolean {
+            if predicate_type != DataType::Boolean && predicate_type != DataType::Null {
                 return plan_err!(
                     "Cannot create filter with non-boolean predicate '{predicate}' returning {predicate_type}"
                 );

datafusion/optimizer/src/analyzer/type_coercion.rs

@@ -47,8 +47,9 @@ use datafusion_expr::type_coercion::{is_datetime, is_utf8_or_large_utf8};
 use datafusion_expr::utils::merge_schema;
 use datafusion_expr::{
     is_false, is_not_false, is_not_true, is_not_unknown, is_true, is_unknown, not,
-    type_coercion, AggregateFunction, AggregateUDF, Expr, ExprSchemable, LogicalPlan,
-    Operator, ScalarUDF, Signature, WindowFrame, WindowFrameBound, WindowFrameUnits,
+    type_coercion, AggregateFunction, AggregateUDF, Expr, ExprSchemable, Filter,
+    LogicalPlan, Operator, ScalarUDF, Signature, WindowFrame, WindowFrameBound,
+    WindowFrameUnits,
 };
 
 use crate::analyzer::AnalyzerRule;
@@ -86,6 +87,18 @@ fn analyze_internal(
     external_schema: &DFSchema,
     plan: LogicalPlan,
 ) -> Result<Transformed<LogicalPlan>> {
+    if let LogicalPlan::Filter(Filter {
+        predicate, input, ..
+    }) = &plan
+    {
+        if predicate == &Expr::Literal(ScalarValue::Null) {
+            return Ok(Transformed::yes(LogicalPlan::Filter(Filter::try_new(
+                Expr::Literal(ScalarValue::Boolean(Some(false))),
+                Arc::clone(input),
+            )?)));
+        }
+    }
+
     // get schema representing all available input fields. This is used for data type
     // resolution only, so order does not matter here
     let mut schema = merge_schema(plan.inputs());

datafusion/sqllogictest/test_files/misc.slt

@@ -24,3 +24,16 @@ query TT?
 select 'foo', '', NULL
 ----
 foo (empty) NULL
+
+query I
+select 1 where NULL
+----
+
+query I
+select 1 where NULL and 1 = 1
+----
+
+query I
+select 1 where NULL or 1 = 1
+----
+1