The following comment has been added to this issue:
Author: Jeff Lichtman
Created: Tue, 28 Sep 2004 12:39 AM
Body:
I see what you want to do here: you are trying to number the rows in a table
according to an ordering.
Standard SQL doesn't allow the "order by" clause on an insert-select. Normally,
this makes sense because a table (AKA relation) is an unordered set of rows
(AKA tuples). Normally, the order that the rows are inserted would have no
consequence that one should rely on. For example, if you select the rows from
the table you just inserted them into, there is no guarantee that they would
come back in the same order.
In this case, though, you want to rely on a side-effect of inserting (the
generation of indentity values) as the insert happens. This is a valid thing to
want to do - however, it makes me nervous to make a broad extension for such a
specific purpose.
If the Virtual Table Interface (VTI) still existed (it was in Cloudscape 5.1
and earlier versions), I would suggest using that as a workaround. VTIs allowed
the user to write a Java class with methods that returned ResultSets. One could
easily hide the "order by" clause inside the VTI.
I don't think "group by" is a valid workaround. A select statement with a
"group by" and no aggregates in the select list is the same as a "select
distinct." No ordering is guaranteed - for example, a smart optimizer could
avoid a sort if there were a unique index on a subset of the result columns.
---------------------------------------------------------------------
View this comment:
http://issues.apache.org/jira/browse/DERBY-4?page=comments#action_53453
---------------------------------------------------------------------
View the issue:
http://issues.apache.org/jira/browse/DERBY-4
Here is an overview of the issue:
---------------------------------------------------------------------
Key: DERBY-4
Summary: "order by" is not supported for "insert ... select"
Type: New Feature
Status: Unassigned
Priority: Minor
Project: Derby
Assignee:
Reporter: Christian d'Heureuse
Created: Mon, 27 Sep 2004 10:53 AM
Updated: Tue, 28 Sep 2004 12:39 AM
Description:
When filling a table with "insert ... select ...", "order by" cannot be
specified.
There is not method to copy a table sorted into another table (except using
export/import). This would be useful to optimize performance for big tables, or
to create identity values that are ascending (related to another column).
Example:
create table temp1 (
s varchar(10));
insert into temp1 values 'x','a','c','b','a';
create table temp2 (
i integer not null
generated always as identity
primary key,
s varchar(10));
insert into temp2 (s)
select s from temp1 order by s;
--> Error: "order by" is not allowed.
-- trying to use "group by" instead of "oder by":
insert into temp2 (s)
select s from temp1 group by s;
select * from temp2;
--> "group by" did not sort the table.
---------------------------------------------------------------------
JIRA INFORMATION:
This message is automatically generated by JIRA.
If you think it was sent incorrectly contact one of the administrators:
http://issues.apache.org/jira/secure/Administrators.jspa
If you want more information on JIRA, or have a bug to report see:
http://www.atlassian.com/software/jira
