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https://issues.apache.org/jira/browse/DERBY-268?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12907342#action_12907342
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Rick Hillegas commented on DERBY-268:
-------------------------------------
Re-using the import/replace code will allow truncate to succeed in the
following edge case, which currently raises an error:
o The truncated table is referenced by a foreign key
o But there are no rows in the referencing table
It seems to me that the proposal may not be appropriate for an issue flagged
for a newcomer. I recommend one of the following:
o Create a new JIRA for the improvement
o Remove the "newcomer" flag and negotiate with Eranda about who will do the
work
------------------------------
Here is a script which demonstrates the different edge-case behavior of the
truncate and import/replace code:
connect 'jdbc:derby:memory:dummy;create=true';
create table deltriggertest_t1(x int);
create table deltriggertest_t2(y int);
create trigger deltriggertest_tr after delete on deltriggertest_t1 referencing
old as old for each row insert into deltriggertest_t2 values old.x;
create table foreignkey_t1(x int primary key);
create table foreignkey_t2(y int references foreignkey_t1);
insert into deltriggertest_t1( x ) values ( 1 );
insert into foreignkey_t1 values 1,2;
insert into foreignkey_t2 values 2;
call syscs_util.syscs_export_table ( null, 'DELTRIGGERTEST_T1', 'z.dat', null,
null, null );
-- fails because of delete trigger
truncate table deltriggertest_t1;
-- fails because of foreign key
truncate table foreignkey_t1;
-- fails because of delete trigger
call syscs_util.syscs_import_table( null, 'DELTRIGGERTEST_T1', 'z.dat', null,
null, null,1 );
-- fails because foreign key is not satisfied
call syscs_util.syscs_import_table( null, 'FOREIGNKEY_T1', 'z.dat', null, null,
null,1 );
delete from foreignkey_t2;
delete from foreignkey_t1;
delete from deltriggertest_t1;
-- fails because of delete trigger
truncate table deltriggertest_t1;
-- fails because of foreign key
truncate table foreignkey_t1;
-- fails because of delete trigger
call syscs_util.syscs_import_table( null, 'DELTRIGGERTEST_T1', 'z.dat', null,
null, null,1 );
-- succeeds
call syscs_util.syscs_import_table( null, 'FOREIGNKEY_T1', 'z.dat', null, null,
null,1 );
> Add Support for truncate table
> ------------------------------
>
> Key: DERBY-268
> URL: https://issues.apache.org/jira/browse/DERBY-268
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Reporter: Lance Andersen
> Assignee: Eranda Sooriyabandara
> Priority: Minor
> Attachments: derby-268-01-ab-enableForInsaneBuilds.diff,
> Derby-268.diff, tests.diff
>
>
> Adding support for truncate table command will aid to portability
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