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    <div class="moz-cite-prefix">On 6/17/15 12:40 PM, Ihar Hrachyshka
      wrote:<br>
    </div>
    <blockquote cite="mid:5581A2F8.9090509@redhat.com" type="cite">
      <pre wrap="">-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

On 06/17/2015 11:27 AM, Anna Kamyshnikova wrote:
</pre>
      <blockquote type="cite">
        <pre wrap="">Ihar, thanks for bringing this up!

This is very interesting and I think it worth trying. I'm +1 on
that and want to participate in this work.

</pre>
      </blockquote>
      <pre wrap="">
Awesome.

</pre>
      <blockquote type="cite">
        <pre wrap="">In fact a lot *not strict* migrations are removed with
juno_initial, so I hope it won't be so hard for now to apply
stricter rules for migration. But what is the plan for those
migrations that are *not strict* now?
</pre>
      </blockquote>
      <pre wrap="">
Still, we have several live data migrations from Juno to Kilo:

- - 14be42f3d0a5_default_sec_group_table.py: populates db with default
security groups;

- - 16cdf118d31d_extra_dhcp_options_ipv6_support.py: populates
extraqdhcpopts with default ip_version = 4;

- - 2d2a8a565438_hierarchical_binding.py: populates db with
port_binding_levels objects, then drops old tables;

- - 35a0f3365720_add_port_security_in_ml2.py: port security field is
populated with True for ports and networks;

- - 034883111f_remove_subnetpool_allow_overlap.py: drops allow_overlap
column from subnetpools: probably unused so we can be ok with it?..

In any case, the plan for existing migration rules is: don't touch
them. Their presence in N release just indicates that we cannot get
online db migration in N+1. That's why we should adopt strict rules
the earlier the better, so that opportunity does not slip to N+X where
X is too far.

The patches currently in review that look suspicious in this regard are:
- - I4ff7db0f5fa12b0fd1c6b10318e9177fde0210d7: moves data from one table
into another;
- - Iecb3e168a805fc5f3d59d894c3f0d9298505e872: fills new columns with
default server values (why is it even needed?..);
- - Icde55742aa78ed995bac0896c01c80c9d28aa0cf: alter_column(). Not sure
we are ok with it;
- - I66b3ee8c2f9fa6f04b9e89dc49d1a3d277d63191: probably not an issue
though since it touches existing live data impact rule?</pre>
    </blockquote>
    <br>
    I made a list of migrations from juno-> kilo that are non
    expansive or do data migrations:<br>
    <br>
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    <div class="" id="magicdomid6"><span class="b"><b>these contain
          "drop column":</b></span></div>
    <div class="" id="magicdomid7"><br>
    </div>
    <div class="" id="magicdomid8"><span class="">034883111f_remove_subnetpool_allow_overlap.py</span></div>
    <div class="" id="magicdomid9"><span class="">2d2a8a565438_hierarchical_binding.py</span></div>
    <div class="" id="magicdomid10"><br>
    </div>
    <div class="" id="magicdomid11"><span class="b"><b>these contain
          "drop table":</b></span></div>
    <div class="" id="magicdomid12"><br>
    </div>
    <div class="" id="magicdomid13"><span class="">28c0ffb8ebbd_remove_mlnx_plugin.py</span></div>
    <div class="" id="magicdomid14"><span class="">2b801560a332_remove_hypervneutronplugin_tables.py</span></div>
    <div class="" id="magicdomid15"><span class="">408cfbf6923c_remove_ryu_plugin.py</span></div>
    <div class="" id="magicdomid16"><span class="">57086602ca0a_scrap_nsx_adv_svcs_models.py</span></div>
    <div class="" id="magicdomid17"><br>
    </div>
    <div class="" id="magicdomid18"><span class="b"><b>these contain
          data migrations:</b></span></div>
    <div class="" id="magicdomid19"><br>
    </div>
    <div class="" id="magicdomid20"><span class="">14be42f3d0a5_default_sec_group_table.py</span></div>
    <div class="" id="magicdomid21"><span class="">16cdf118d31d_extra_dhcp_options_ipv6_support.py</span></div>
    <div class="" id="magicdomid22"><span class="">2b801560a332_remove_hypervneutronplugin_tables.py</span></div>
    <div class="" id="magicdomid23"><span class="">2d2a8a565438_hierarchical_binding.py</span></div>
    <div class="" id="magicdomid24"><span class="">35a0f3365720_add_port_security_in_ml2.py</span></div>
    <div class="" id="magicdomid25"><br>
    </div>
    <div class="" id="magicdomid26"><span class="b"><b>Example of
          failure:</b></span></div>
    <div class="" id="magicdomid27"><br>
    </div>
    <div class="" id="magicdomid28"><span class="">neutron/db/migration/alembic_migrations/versions/2d2a8a565438_hierarchical_binding.py
        - drops the following columns:</span></div>
    <div class="" id="magicdomid29"><br>
    </div>
    <div class="" id="magicdomid30"><span class="">   
        op.drop_constraint(fk_name_dvr[0], 'ml2_dvr_port_bindings',
        'foreignkey')</span></div>
    <div class="" id="magicdomid31"><span class="">   
        op.drop_column('ml2_dvr_port_bindings', 'cap_port_filter')</span></div>
    <div class="" id="magicdomid32"><span class="">   
        op.drop_column('ml2_dvr_port_bindings', 'segment')</span></div>
    <div class="" id="magicdomid33"><span class="">   
        op.drop_column('ml2_dvr_port_bindings', 'driver')</span></div>
    <div class="" id="magicdomid34"><br>
    </div>
    <div class="" id="magicdomid35"><span class="">   
        op.drop_constraint(fk_name[0], 'ml2_port_bindings',
        'foreignkey')</span></div>
    <div class="" id="magicdomid36"><span class="">   
        op.drop_column('ml2_port_bindings', 'driver')</span></div>
    <div class="" id="magicdomid37"><span class="">   
        op.drop_column('ml2_port_bindings', 'segment')</span></div>
    <div class="" id="magicdomid38"><span class="">    </span></div>
    <div class="" id="magicdomid39"><span class="">    which then causes
        a failure in Juno:</span></div>
    <div class="" id="magicdomid40"><span class="">    </span></div>
    <div class="" id="magicdomid41"><span class="">    OperationalError:
        (OperationalError) (1054, "Unknown column</span></div>
    <div class="" id="magicdomid42"><span class="">'ml2_port_bindings_1.driver'
        in 'field list'") </span></div>
    <div class="" id="magicdomid43"><br>
    </div>
    <br>
    <br>
    <br>
    <blockquote cite="mid:5581A2F8.9090509@redhat.com" type="cite">
      <pre wrap="">

(the list can be incomplete)

</pre>
      <blockquote type="cite">
        <pre wrap="">
I think that we should try to use Alembic as much we could as Mike
is going to support us in that and we have time to make some change
in Alembic directly.
</pre>
      </blockquote>
      <pre wrap="">
Yes, sure, I'm looking forward to see Mike's proposal in public.

</pre>
      <blockquote type="cite">
        <pre wrap="">
We should undoubtedly plan this work for M release because there
will be some issues that will appear in the process.

</pre>
      </blockquote>
      <pre wrap="">
Sure.

Ihar
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</pre>
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