Merge pull request !2775 from rhodecode-enterprise-ce feature/RCCE-217_optimize_migration

feature: adds validation that column does not exist before adding it

rhodecode/lib/dbmigrate/versions/116_version_5_7_0.py

@@ -1,5 +1,7 @@
 import json
 import logging
+
+from psycopg2.errorcodes import DUPLICATE_COLUMN
 from sqlalchemy import *
 from sqlalchemy.engine import reflection
 
@@ -24,18 +26,22 @@ def upgrade(migrate_engine):
 
     context = MigrationContext.configure(migrate_engine.connect())
     op = Operations(context)
+    inspector = inspect(migrate_engine)
 
     pr_tables = [db.PullRequest.__table__, db.PullRequestVersion.__table__]
     for pr_table in pr_tables:
-        with op.batch_alter_table(pr_table.name) as batch_op:
-            new_column = Column(
-                "settings_json",
-                MutationObj.as_mutable(
-                    JsonType(dialect_map=dict(mysql=UnicodeText(16384))),
-                ),
-                default=dict,
-            )
-            batch_op.add_column(new_column)
+        existing_columns = [col["name"] for col in inspector.get_columns(pr_table.name)]
+        new_column_name = "settings_json"
+        if new_column_name not in existing_columns:
+            with op.batch_alter_table(pr_table.name) as batch_op:
+                new_column = Column(
+                    new_column_name,
+                    MutationObj.as_mutable(
+                        JsonType(dialect_map=dict(mysql=UnicodeText(16384))),
+                    ),
+                    default=dict,
+                )
+                batch_op.add_column(new_column)
 
     _inherit_settings(db, meta.Session, op)