Merging upstream version 18.2.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 20 insertions, 16 deletions

diff --git a/sqlglot/optimizer/simplify.py b/sqlglot/optimizer/simplify.py
index e550603..3974ea4 100644
--- a/sqlglot/optimizer/simplify.py
+++ b/sqlglot/optimizer/simplify.py
@@ -69,10 +69,10 @@ def simplify(expression):
         node = flatten(node)
         node = simplify_connectors(node, root)
         node = remove_compliments(node, root)
+        node = simplify_coalesce(node)
         node.parent = expression.parent
         node = simplify_literals(node, root)
         node = simplify_parens(node)
-        node = simplify_coalesce(node)
 
         if root:
             expression.replace(node)
@@ -350,7 +350,8 @@ def absorb_and_eliminate(expression, root=True):
 def simplify_literals(expression, root=True):
     if isinstance(expression, exp.Binary) and not isinstance(expression, exp.Connector):
         return _flat_simplify(expression, _simplify_binary, root)
-    elif isinstance(expression, exp.Neg):
+
+    if isinstance(expression, exp.Neg):
         this = expression.this
         if this.is_number:
             value = this.name
@@ -430,13 +431,14 @@ def simplify_parens(expression):
 
     if not isinstance(this, exp.Select) and (
         not isinstance(parent, (exp.Condition, exp.Binary))
-        or isinstance(this, exp.Predicate)
+        or isinstance(parent, exp.Paren)
         or not isinstance(this, exp.Binary)
+        or (isinstance(this, exp.Predicate) and not isinstance(parent, exp.Predicate))
         or (isinstance(this, exp.Add) and isinstance(parent, exp.Add))
         or (isinstance(this, exp.Mul) and isinstance(parent, exp.Mul))
         or (isinstance(this, exp.Mul) and isinstance(parent, (exp.Add, exp.Sub)))
     ):
-        return expression.this
+        return this
     return expression
 
 
@@ -488,18 +490,20 @@ def simplify_coalesce(expression):
     coalesce = coalesce if coalesce.expressions else coalesce.this
 
     # This expression is more complex than when we started, but it will get simplified further
-    return exp.or_(
-        exp.and_(
-            coalesce.is_(exp.null()).not_(copy=False),
-            expression.copy(),
-            copy=False,
-        ),
-        exp.and_(
-            coalesce.is_(exp.null()),
-            type(expression)(this=arg.copy(), expression=other.copy()),
+    return exp.paren(
+        exp.or_(
+            exp.and_(
+                coalesce.is_(exp.null()).not_(copy=False),
+                expression.copy(),
+                copy=False,
+            ),
+            exp.and_(
+                coalesce.is_(exp.null()),
+                type(expression)(this=arg.copy(), expression=other.copy()),
+                copy=False,
+            ),
             copy=False,
-        ),
-        copy=False,
+        )
     )
 
 
@@ -642,7 +646,7 @@ def _flat_simplify(expression, simplifier, root=True):
             for b in queue:
                 result = simplifier(expression, a, b)
 
-                if result:
+                if result and result is not expression:
                     queue.remove(b)
                     queue.appendleft(result)
                     break