- Fixed bug where column names added to ``mysql_length`` parameter

on an index needed to have the same quoting for quoted names in
order to be recognized.  The fix makes the quotes optional but
also provides the old behavior for backwards compatibility with those
using the workaround.
fixes #3085

1 files changed, 7 insertions, 3 deletions

diff --git a/lib/sqlalchemy/dialects/mysql/base.py b/lib/sqlalchemy/dialects/mysql/base.py
index 40715cc31..6d8b6a07c 100644
--- a/lib/sqlalchemy/dialects/mysql/base.py
+++ b/lib/sqlalchemy/dialects/mysql/base.py
@@ -1725,9 +1725,13 @@ class MySQLDDLCompiler(compiler.DDLCompiler):
                 # length value can be a (column_name --> integer value) mapping
                 # specifying the prefix length for each column of the index
                 columns = ', '.join(
-                    ('%s(%d)' % (col, length[col])
-                     if col in length else '%s' % col)
-                    for col in columns
+                    '%s(%d)' % (expr, length[col.name]) if col.name in length
+                    else
+                    (
+                        '%s(%d)' % (expr, length[expr]) if expr in length
+                        else '%s' % expr
+                    )
+                    for col, expr in zip(index.expressions, columns)
                 )
             else:
                 # or can be an integer value specifying the same