On 10/29/2015 12:56 PM, Dane Foster wrote:
On Thu, Oct 29, 2015 at 3:30 PM, Adrian Klaver
<adrian.klaver@xxxxxxxxxxx <mailto:adrian.klaver@xxxxxxxxxxx>> wrote:
On 10/29/2015 12:10 PM, Dane Foster wrote:
On Thu, Oct 29, 2015 at 3:01 PM, John R Pierce
<pierce@xxxxxxxxxxxx <mailto:pierce@xxxxxxxxxxxx>
<mailto:pierce@xxxxxxxxxxxx <mailto:pierce@xxxxxxxxxxxx>>> wrote:
On 10/29/2015 11:20 AM, Dane Foster wrote:
I think you are correct about mysql_fdw "... sending
the trim()
checks for remote execution" because according to the docs:
"The latest version will push-down the foreign table
where clause
to the foreign server. The where condition on the
foreign table
will be executed on the foreign server hence there will
be fewer
rows to to bring across to PostgreSQL. This is a
performance feature."
the alternative would be to fetch the whole table across
the FDW
interface, then run the where locally, for a large table where
you're only selecting a few rows, this would be very painful.
I guess using mysql_fdw is a no-go for my data
migration needs.
or, rewrite that WHERE clause to be mysql compatible.
Easier said than done because the LENGTH and TRIM functions
both exist
in MySQL but I guess under the covers in PostgreSQL btrim is being
invoked when TRIM is called therefore that is what is being "pushed
down" to the MySQL and there is nothing I can do about that.
I guess I could leave out the call to trim, and copy the data into a
temp table on the PostgreSQL side, and blah blah blah. My point
being
why should I have to jump through hoops because mysql_fdw is broken?
I'll just go back to writing the migration script as a PHP program
because if mysql_fdw didn't exist that's what I would have to do
anyway.
Remember you are using a Beta version of Postgres, so it is not
entirely unexpected that things might be broken, especially when
working with non-core extensions. In the spirit of testing, that
Beta implies, why not help fix mysql_fdw by filing an issue? If you
already have, my apologies.
I'm fully aware of that fact and gladly accept my responsibility which
is why I have opened an
issue:https://github.com/EnterpriseDB/mysql_fdw/issues/70
Great and thanks.
For me reporting the issue in the hopes that they will fix it is a
separate issue from expending energy working around the bug because the
great thing about the procedural code is that it's littered w/ the same
SQL that a pure SQL migration script would contain. So if they fix it in
reasonable amount of time then all that's required to create a pure SQL
migration script is copy/paste.
Dane
--
john r pierce, recycling bits in santa cruz
Dane
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Adrian Klaver
adrian.klaver@xxxxxxxxxxx <mailto:adrian.klaver@xxxxxxxxxxx>
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Adrian Klaver
adrian.klaver@xxxxxxxxxxx
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