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Add support for a USING clause when altering a column's type in PostgreSQL #292

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sqlalchemy-bot opened this Issue Apr 13, 2015 · 5 comments

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sqlalchemy-bot commented Apr 13, 2015

Migrated issue, originally created by Wouter Bolsterlee (@wbolster)

When changing a column's type, it is sometimes necessary to specify how to convert the existing value into a value of the new type. This is done using the USING clause of the SET DATA TYPE clause of the ALTER TABLE statement. See http://www.postgresql.org/docs/9.4/static/sql-altertable.html for details.

Currently it seems impossible to specify the USING clause using Alembic's op. alter_column(). It would be great if something like alter_column(using="convert_from(data, 'utf-8')::jsonb") would work.

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sqlalchemy-bot commented Apr 13, 2015

Changes by Wouter Bolsterlee (@wbolster):

  • changed title from "Add support for a ALTER COLUMN USING ... in Postgr" to "Add support for a USING clause when altering a col"
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sqlalchemy-bot commented Apr 13, 2015

Michael Bayer (@zzzeek) wrote:

it would be called postgresql_using. I can accept this as a PR which would alter the alembic/ddl/postgresql.py dialect to support this flag, in a similar way as something like "mssql_drop_foreign" in alembic/ddl/mssql.py.

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sqlalchemy-bot commented Aug 22, 2016

Michael Bayer (@zzzeek) wrote:

Support USING for Postgresql ALTER COLUMN.

Added support for the USING clause to the ALTER COLUMN operation
for Postgresql. Support is via the
:paramref:.op.alter_column.postgresql_using
parameter.

Fixes: #292
Change-Id: I8b1d418df0b6b731a68614dbffd7a9fb13de4de5
Pull-request: zzzeek/alembic#27

84b9298

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sqlalchemy-bot commented Aug 22, 2016

Changes by Michael Bayer (@zzzeek):

  • changed status to closed
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sqlalchemy-bot commented Sep 15, 2016

Michael Bayer (@zzzeek) wrote:

Issue #39 was marked as a duplicate of this issue.

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