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https://issues.apache.org/jira/browse/DERBY-3603?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12587239#action_12587239
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A B commented on DERBY-3603:
----------------------------
Thanks for the investigation, Bryan and Thomas! I was hoping to look more into
this last night but was hit by a freak migraine that knocked me out early.
It's great to see that some work is still happening, though.
bryan> The other thing I was thinking about is that if I change the query to
just IN (1) rather
bryan> than IN (1,21), then the problem does not occur.
Just a quick note that when the IN list only has a single value, it is
transformed into a normal equality predicate. See
InListOperatorNode.preprocess(...). So in that case IN-list "multi-probing"
processing, which appears to be where the underlying bug resides, does not come
into play. That could be why things work correctly in that case...
thomas> It is a possibility that in this case we neglect that there is a
equivalent rightOperand
thomas> (it's not simply a true as might be expected)
Without having done any tracing myself, I agree with both of you: this seems
worth pursuing...
> 'IN' clause ignores valid results, incorrect qualifier handling suspected
> -------------------------------------------------------------------------
>
> Key: DERBY-3603
> URL: https://issues.apache.org/jira/browse/DERBY-3603
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.3.2.1, 10.4.1.1
> Reporter: David Butterworth
> Attachments: derbydb.tar.bz2
>
>
> Derbys' 'IN' clause is returning different results depending on which side of
> a joined table
> I am doing my 'IN' comparison against. This only occurs when the number of
> items within the 'IN' clause is greater then 1.
> This behaviour was also confirmed by Bryan Pendleton in this thread:
> http://mail-archives.apache.org/mod_mbox/db-derby-user/200804.mbox/[EMAIL
> PROTECTED]
> Using the test database attatched the following 2 queries produce the issue:
> ij> select count(*) FROM spike.accounts account, spike.admin_units
> admin_unit,
> spike.bookings booking
> WHERE booking.child_id = 2 AND
> admin_unit.admin_unit_id IN (1,21) AND
> booking.booking_date_time_out >= 20080331000000 AND
> booking.booking_date_time_in <= 20080406235900 AND
> account.account_id = booking.account_id AND
> admin_unit.admin_unit_id = account.admin_unit_id;
> 1
> -----------
> 2
> 1 row selected
> ij> select count(*) FROM spike.accounts account, spike.admin_units admin_unit,
> spike.bookings booking
> WHERE booking.child_id = 2 AND
> account.admin_unit_id IN (1,21) AND
> booking.booking_date_time_out >= 20080331000000 AND
> booking.booking_date_time_in <= 20080406235900 AND
> account.account_id = booking.account_id AND
> admin_unit.admin_unit_id = account.admin_unit_id;
> 1
> -----------
> 3
> 1 row selected
> ij>
> The only difference between the 2 statements is which side of a join the 'IN'
> clause is matched against.
> Bryan performed some initial testing and stated the following:
> --------------------- SNIP ------------------------
> Interestingly, although the actual results do NOT contain any values
> for admin_unit_id = 21, if I change the query to:
> admin_unit.admin_unit_id IN (1)
> or
> account.admin_unit_id IN (1)
> then the problem disappears -- I get 3 rows for both queries.
> I also ran query plans for both the queries (in the IN (1,21) case)
> and have pasted the (simplified) query plans at the end of this message.
> I notice that in the case where the query gives 2 rows, which is
> when we specify admin_unit.admin_unit_id in (1,21), the admin_unit_id
> index scan output in the query plan contains:
> qualifiers:
> Column[0][0] Id: 0
> Operator: =
> Ordered nulls: false
> Unknown return value: false
> Negate comparison result: false
> However, in the case where the query gives 3 rows, which is
> when we specify account.admin_unit_id in (1,21), the admin_unit_id
> index scan output in the query plan contains:
> qualifiers:
> None
> I think it is the presence/absence of this qualifier on the query
> scan which is causing the different results in the query, as in
> the first case we see:
> Number of rows qualified=2
> Number of rows visited=3
> but in the second case we see:
> Number of rows qualified=3
> Number of rows visited=3
> I definitely don't have any explanation for why you are getting
> this odd behavior; it certainly seems like a bug to me.
> -------------END SNIP -----------------------
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