Bypassing schema lock for a join on a feature class published to service?

Question

I would like to programmatically join a table to a feature class that is published as a service on ArcGIS Server 10.4.1. The problem is that the schema is locked. How can I bypass this error? When schema locking is disabled in the server manager, the error still appears.

It is not an option to programatically turn the service off while geoprocessing tasks are executed on the service.

The code below outlines where I would like to execute my join; the schema lock error is thrown at the join line.

def calculate_overdue_tickets(self):

    self.logger.info("calculating overdue days for feature classes '{0}' and '{1}'".format(self.line_ticket_feature_class, self.poly_ticket_feature_class))

    expression = "getDaysOverdue(!{0}!)".format(self.begin_date_field)
    code_block = """def getDaysOverdue(begindate):
import datetime
if begindate is not None:
    begin = datetime.datetime.strptime(begindate, '%m/%d/%Y').date()
    return (datetime.date.today() - begin).days
else:
    return None"""
    arcpy.management.CalculateField(in_table=self.line_ticket_feature_class, field=self.days_overdue_field, expression=expression, expression_type='PYTHON_9.3', code_block=code_block)
    arcpy.management.CalculateField(in_table=self.poly_ticket_feature_class, field=self.days_overdue_field, expression=expression, expression_type='PYTHON_9.3', code_block=code_block)

    self.logger.info("calculating overdue status for feature classes '{0}' and '{1}'".format(self.line_ticket_feature_class, self.poly_ticket_feature_class))

    expression = "getOverdueStatus(!{0}!, !{1}!, !{2}!, !{3}!)".format(self.work_status_field, self.days_overdue_field, self.origpriority_field, self.nextjobid_field)
    code_block = """def getOverdueStatus(workstatus, days, origpriority, nextjobid):
if days is None:
    return '{5}'
elif days < 0:
    return '{0}'
elif days == 0:
    return '{1}'
else:
    if origpriority == '{2}':
        return '{3}'
    elif workstatus in ('N','P','S','A','H') and (nextjobid is not None):
        return '{3}'
    elif workstatus in ('N') and (nextjobid is None):
        return '{4}'
    else:
        return '{5}'
""".format(self.status_upcoming, self.status_today, self.origpriority_value, self.status_inprogress, self.status_overdue, self.status_none)
    arcpy.management.CalculateField(in_table=self.line_ticket_feature_class, field=self.overdue_status_field, expression=expression, expression_type='PYTHON_9.3', code_block=code_block)
    arcpy.management.CalculateField(in_table=self.poly_ticket_feature_class, field=self.overdue_status_field, expression=expression, expression_type='PYTHON_9.3', code_block=code_block)
    arcpy.JoinField_management(in_data=self.line_ticket_feature_class, in_field=self.poly_line_mobile_id, join_table= self.mobile_info_table, join_field=self.mobile_table_id)

Error:

EDIT: After a bit of testing, the join was executed correctly with the schema locking disabled in Server Manager.

Answer 1

The Join Field tool modifies the existing feature class by adding the joined fields to it. This is why you get a schema lock error. Only use this tool if you actually want to permanently modify your feature class.

A typical join (similar to if you right-click a layer in ArcMap) is performed in arcpy by using the Add Join tool. This performs the join in memory.

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If you are trying to update the schema with schema locking disabled, there may be something else locking your feature class. See the note on Disabling schema locking on a map service which says:

Even when you disable schema locking in a map service, other ArcGIS applications and services may still be able to obtain exclusive locks to the schema. If you are unable to update the schema of the dataset after disabling schema locking, see Schema locking. This topic contains information that can help you understand how locks may be preventing you from updating the schema.