Database migration to grow mysql blobs.

Should address the following issues

https://trello.com/c/RbW6pOd2
https://trello.com/c/lvz4OQR1
https://trello.com/c/Hv5iIweU

lib/galaxy/model/migrate/versions/0122_grow_mysql_blobs.py

@@ -0,0 +1,58 @@
+"""
+Migration script to grow MySQL blobs.
+"""
+
+from sqlalchemy import MetaData
+
+import datetime
+now = datetime.datetime.utcnow
+
+import logging
+log = logging.getLogger( __name__ )
+
+metadata = MetaData()
+
+BLOB_COLUMNS = [
+    ("deferred_job", "params"),
+    ("extended_metadata", "data"),
+    ("form_definition", "fields"),
+    ("form_definition", "layout"),
+    ("form_values", "content"),
+    ("history_dataset_association", "metadata"),
+    ("job", "destination_params"),
+    ("library_dataset_dataset_association", "metadata"),
+    ("post_job_action", "action_arguments"),
+    ("request", "notification"),
+    ("sample", "workflow"),
+    ("transfer_job", "params"),
+    ("workflow_step", "tool_inputs"),
+    ("workflow_step", "tool_errors"),
+    ("workflow_step", "position"),
+    ("workflow_step", "config"),
+    ("tool_shed_repository", "metadata"),
+    ("tool_shed_repository", "tool_shed_status"),
+]
+
+
+def upgrade(migrate_engine):
+    metadata.bind = migrate_engine
+    print __doc__
+    metadata.reflect()
+
+    if migrate_engine.name != "mysql":
+        return
+
+    for (table, column) in BLOB_COLUMNS:
+        cmd = "ALTER TABLE %s MODIFY COLUMN %s MEDIUMBLOB;" % (table, column)
+        try:
+            migrate_engine.execute( cmd )
+        except Exception as e:
+            print "Failed to grow column %s.%s" % (table, column)
+            print str( e )
+
+
+def downgrade(migrate_engine):
+    metadata.bind = migrate_engine
+    metadata.reflect()
+    # Ignoring..., changed the datatype so no guarantee these columns weren't
+    # MEDIUMBLOBs before.