db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2793) Ensure LIKE predicate follows correct rules for determing collation
Date Mon, 09 Jul 2007 23:58:05 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2793?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12511296

Mamta A. Satoor commented on DERBY-2793:

Dan's last comment on July 5th had this question "Wouldn't it be simple to add a check that
at least one of the operands have the derivation IMPLICIT or EXPLICIT (in addition to the
existing tests)? " We have jira entry for this issue DERBY-2725 ( If all the operands involved
in collation operation have a collation derivation of NONE, then Derby should throw an exception
for that as per the SQL standards.) and it was fixed on July 6th. After this fix, now we have
a behavior which is sub-set of the SQL standard.

As for Dan's another remark "I also wonder if fixing the collation determination to be correct
(9.13 based) will affect existing applications/databases, those with collation=UCS_BASIC.
Will there be some comparisons that will (correctly) not be supported anymore? " I haven't
spent enough time to be able to visualize a problem with existing applications/databases.
Dan, do you have some examples in mind which shows how the existing application might get
impacted? The only way one can run into colllation derivation of NONE is if character string
types of different collation types are involved in operations like CONCAT, COALESCE, NULLIF
etc. But since existing applications/databases will all always have the same collation type
which is UCS_BASIC, at this point, I can't see how they might get affected?

> Ensure LIKE predicate follows correct rules for determing collation
> -------------------------------------------------------------------
>                 Key: DERBY-2793
>                 URL: https://issues.apache.org/jira/browse/DERBY-2793
>             Project: Derby
>          Issue Type: Sub-task
>          Components: SQL
>            Reporter: Daniel John Debrunner
>            Assignee: Mamta A. Satoor
>             Fix For:
> The current code in LikeEscapeOperatorNode seems to only check that the collations are
identical. That is not the correct mechanism for determing collation which is based upon SQL
spec Section 9.13 "Collation determination" or item 12 in the DERBY-1478 wiki page.
> http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478
> I think it's also essential that the (somewhat complex) logic to implement collation
determination is in a single method, not repeated multiple times for each collation.
> There is a TODO in LikeEscapeOperatorNode  that might be related to this.

This message is automatically generated by JIRA.
You can reply to this email to add a comment to the issue online.

View raw message