Merging upstream version 18.11.2.

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

1 files changed, 17 insertions, 1 deletions

diff --git a/sqlglot/optimizer/normalize_identifiers.py b/sqlglot/optimizer/normalize_identifiers.py
index 54cf02b..32f3a92 100644
--- a/sqlglot/optimizer/normalize_identifiers.py
+++ b/sqlglot/optimizer/normalize_identifiers.py
@@ -22,6 +22,13 @@ def normalize_identifiers(expression, dialect=None):
     Normalize all unquoted identifiers to either lower or upper case, depending
     on the dialect. This essentially makes those identifiers case-insensitive.
 
+    It's possible to make this a no-op by adding a special comment next to the
+    identifier of interest:
+
+        SELECT a /* sqlglot.meta case_sensitive */ FROM table
+
+    In this example, the identifier `a` will not be normalized.
+
     Note:
         Some dialects (e.g. BigQuery) treat identifiers as case-insensitive even
         when they're quoted, so in these cases all identifiers are normalized.
@@ -43,4 +50,13 @@ def normalize_identifiers(expression, dialect=None):
     """
     if isinstance(expression, str):
         expression = exp.to_identifier(expression)
-    return expression.transform(Dialect.get_or_raise(dialect).normalize_identifier, copy=False)
+
+    dialect = Dialect.get_or_raise(dialect)
+
+    def _normalize(node: E) -> E:
+        if not node.meta.get("case_sensitive"):
+            exp.replace_children(node, _normalize)
+            node = dialect.normalize_identifier(node)
+        return node
+
+    return _normalize(expression)