Re: [Sqlalchemy-tickets] [sqlalchemy] #2731: for_update=whatever always creates a "FOR UPDATE" query

[sqlalchemy <mi...@zz...>]

#2731: for_update=whatever always creates a "FOR UPDATE" query
----------------------------------+------------------------------------
      Reporter:  fayaz            |      Owner:  zzzeek
          Type:  defect           |     Status:  closed
      Priority:  medium           |  Milestone:
     Component:  sql              |   Severity:  no triage selected yet
    Resolution:  worksforme       |   Keywords:
Progress State:  awaiting triage  |
----------------------------------+------------------------------------
Changes (by zzzeek):

 * status:  new => closed
 * resolution:   => worksforme


Comment:

 the docs state here that these behaviors are dialect specific:

 http://docs.sqlalchemy.org/en/rel_0_8/core/expression_api.html?highlight=for_update#sqlalchemy.sql.expression.select

    for_update=False –

    when True, applies FOR UPDATE to the end of the resulting statement.

     Certain database dialects also support alternate values for this
 parameter:

         With the MySQL dialect, the value "read" translates to LOCK IN
 SHARE MODE.
         With the Oracle and Postgresql dialects, the value "nowait"
 translates to FOR UPDATE NOWAIT.
         With the Postgresql dialect, the values “read” and "read_nowait"
 translate to FOR SHARE and FOR SHARE NOWAIT, respectively.

 so here the behavior requires a mysql dialect:

 {{{
 #!python
 from sqlalchemy import *
 from sqlalchemy.dialects import mysql

 def test():
     table = Table('user', MetaData(), Column('id', Integer,
 primary_key=True))
     query = table.select(for_update='read')
     assert "LOCK IN SHARE MODE" in
 str(query.compile(dialect=mysql.dialect()))


 if __name__ == '__main__':
     test()
 }}}

--
Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2731#comment:1>
sqlalchemy <http://www.sqlalchemy.org/>
The Database Toolkit for Python