On 02/01/2016 11:18 AM, Rick Otten wrote:
When I used "aliased" with query.delete(), the fetch query seems to get
confused.
* I'm using SQLAlchemy 1.0.11, which 'pip' tells me is the latest version.
* My backend database is PostgreSQL 9.5
Code snippet:
|
fromsqlalchemy.orm importaliased
myTable =aliased(some_table,name='t')
purgeQuery =dbSession.query(myTable).filter(myTable.some_column ==someValue)
queryString
=str(purgeQuery.statement.compile(compile_kwargs={"literal_binds":True}))
purgeQuery.delete(synchronize_session='fetch')
|
*queryString* shows the expected query. Something like:
select t.id, t.some_column, t.some_other_column from some_table as
*t* where t.some_column = /someValue
/
However, when the fetch query actually runs, it includes the non aliased
table name as well as the aliased table name in the from statement:
select t.idfrom *some_table, some_table as t* where t.some_column =
/someValue/
well that's not a DELETE statement. query.delete() emits a DELETE
statement and you'd have to look in the SQL logs to see it.
There's no "bug" here as DELETE does not support deleting directly from
an alias of a table; it's likely emitting DELETE .. FROM and assuming
you want to do some kind of join against the aliased form of your table.
Otherwise what SQL are you looking for this to produce that has DELETE
but also an aliased form of the table?
This was a surprise to notice in the database logs. This query seems to
get stuck on my database anyway, actually.
For now, I'll work around it by not aliasing my table name when I use a
query.delete(). I thought I'd mention it in case I'm doing something
wrong by using aliased() this way, or in case it was a bug ...
Thanks in advance for your attention to this matter!
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