Re: BUG #7604: adding criteria to a query against a view in 9.2 expands the results instead of constraining them

On 10/15/2012 2:29 PM, Tom Lane wrote:
> Bill MacArthur <webmaster(at)dhs-club(dot)com> writes:
>> Tom, in preparation for a test case I created a new schema (testcase) and copied 6 tables to that, including only the columns significant to enable the VIEWs to be created. I took the 3 VIEWs involved and tweaked them into the new schema (just renamed to testcase.viewname and referencing testcase.relation). However, when run from in there, the results are as expected rather than erroneous. The live data and VIEWs still produce erroneous results. Any clues??
>
> Is the query plan the same according to EXPLAIN?
>
> If not, you may have forgotten to vacuum/analyze the new tables, or
> forgotten some relevant index. Or it might be that the total table size
> is affecting the plan choice, in which case you need dummy data in the
> "irrelevant" columns rather than removing them altogether.
>
> regards, tom lane
>
Update, I started placing primary keys on the testcase tables and watched the planner output. Once I put a PK on one of the tables in particular, the planner revised the plan to use the PK. At that point, the results become erroneous as the planner also moves another filter evaluation to an earlier point at which time I don't think it has the data to make the decision.

I can still finish up with the test case if you like, but here is a highlight. The first VIEW, which I did not originally post is this:

CREATE OR REPLACE VIEW testcase.members_cancel_pending AS
SELECT m.id, m.alias, m.emailaddress, m.firstname, m.lastname,
m.mail_option_lvl,
CASE
WHEN c.id IS NULL THEN m.membertype
WHEN c.status = 'tr'::text OR c.status = 'p'::text OR c.status = 'cd'::text OR c.status = 'sp'::text OR c.status = 'sa'::text THEN m.membertype
ELSE 'c'::character varying
END AS membertype
FROM testcase.members m
LEFT JOIN testcase.cancellations c ON c.id = m.id;

The membertype column is actually calculated.
Then I have the two VIEWs I previous posted:

CREATE OR REPLACE VIEW testcase.vip_decline_mailers_base AS
SELECT m.id, m.alias, m.firstname, m.lastname, m.emailaddress,
CASE
WHEN s.void = false THEN s.end_date
ELSE (s.end_date - '1 mon'::interval)::date
END AS paid_thru,
mop.payment_method, m.mail_option_lvl, now()::date AS "current_date"
FROM testcase.nop_seed,
testcase.subscriptions s
JOIN testcase.mop mop ON mop.id = s.member_id
JOIN testcase.members_cancel_pending m ON m.id = s.member_id AND m.membertype::text = 'v'::text
JOIN testcase.subscription_types st ON s.subscription_type = st.subscription_type
WHERE (s.end_date < nop_seed.paid_thru OR s.void = true) AND st.sub_class::text = 'VM'::text;

This should only be looking for membertype='v'

From here another VIEW is built:

CREATE OR REPLACE VIEW testcase.vip_mailer_unpaid_current AS
SELECT vip_decline_mailers_base.id, vip_decline_mailers_base.alias,
vip_decline_mailers_base.firstname, vip_decline_mailers_base.lastname,
vip_decline_mailers_base.emailaddress, vip_decline_mailers_base.paid_thru,
vip_decline_mailers_base.payment_method,
vip_decline_mailers_base.mail_option_lvl,
vip_decline_mailers_base."current_date",
current_month_text(now()) AS current_month_text
FROM testcase.vip_decline_mailers_base vip_decline_mailers_base
WHERE vip_decline_mailers_base.mail_option_lvl > 0 AND vip_decline_mailers_base.paid_thru >= first_of_another_month((now()::date - '1 mon'::interval)::date) AND vip_decline_mailers_base.paid_thru <= (first_of_month() - 1);

It is assuming that there will only be membertype 'v' is the basic results and is only applying date filters.

Here is the planner output before I put a PK on testcase.cancellations

network=# explain select count(*) from testcase.vip_mailer_unpaid_current;
QUERY PLAN

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
Aggregate (cost=29784.07..29784.08 rows=1 width=0)
-> Nested Loop (cost=25947.06..29783.08 rows=395 width=0)
Join Filter: ((s.end_date < nop_seed.paid_thru) OR s.void)
-> Hash Right Join (cost=25947.06..29720.65 rows=1 width=5)
Hash Cond: (c.id = m.id)
Filter: ((CASE WHEN (c.id IS NULL) THEN m.membertype WHEN ((c.status = 'tr'::text) OR (c.status = 'p'::text) OR (c.status = 'cd'::text) OR (c.status = 'sp'::text) OR (c.status = 'sa'::text)) THEN m.membertype ELSE 'c'::char
acter varying END)::text = 'v'::text)
-> Seq Scan on cancellations c (cost=0.00..3324.41 rows=119741 width=6)
-> Hash (cost=25946.03..25946.03 rows=83 width=11)
-> Nested Loop (cost=0.00..25946.03 rows=83 width=11)
-> Nested Loop (cost=0.00..25315.99 rows=115 width=13)
-> Nested Loop (cost=0.00..25053.20 rows=115 width=9)
Join Filter: (s.subscription_type = st.subscription_type)
-> Seq Scan on subscriptions s (cost=0.00..24979.10 rows=403 width=11)
Filter: ((CASE WHEN (NOT void) THEN end_date ELSE ((end_date - '1 mon'::interval))::date END <= ((date_trunc('month'::text, now()))::date - 1)) AND (CASE WHEN (NOT void) THEN end_date ELSE ((en
d_date - '1 mon'::interval))::date END >= first_of_another_month((((now())::date - '1 mon'::interval))::date)))
-> Materialize (cost=0.00..1.58 rows=12 width=2)
-> Seq Scan on subscription_types st (cost=0.00..1.52 rows=12 width=2)
Filter: ((sub_class)::text = 'VM'::text)
-> Index Only Scan using tcmopid on mop (cost=0.00..2.28 rows=1 width=4)
Index Cond: (id = s.member_id)
-> Index Scan using tcmembersid on members m (cost=0.00..5.47 rows=1 width=6)
Index Cond: (id = mop.id)
Filter: (mail_option_lvl > 0)
-> Seq Scan on nop_seed (cost=0.00..33.30 rows=2330 width=4)
(23 rows)

network=# select count(*) from testcase.vip_mailer_unpaid_current;
count
-------
331
(1 row)

Here is the output after putting a PK on testcase.cancellations:
ALTER TABLE testcase.cancellations
ADD CONSTRAINT cancellations_pkey PRIMARY KEY(id);

network=# explain select count(*) from testcase.vip_mailer_unpaid_current;
QUERY PLAN

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------
Aggregate (cost=26233.61..26233.62 rows=1 width=0)
-> Nested Loop (cost=0.00..26232.63 rows=395 width=0)
Join Filter: ((s.end_date < nop_seed.paid_thru) OR s.void)
-> Nested Loop Left Join (cost=0.00..26170.20 rows=1 width=5)
-> Nested Loop (cost=0.00..25946.03 rows=83 width=11)
-> Nested Loop (cost=0.00..25315.99 rows=115 width=13)
-> Nested Loop (cost=0.00..25053.20 rows=115 width=9)
Join Filter: (s.subscription_type = st.subscription_type)
-> Seq Scan on subscriptions s (cost=0.00..24979.10 rows=403 width=11)
Filter: ((CASE WHEN (NOT void) THEN end_date ELSE ((end_date - '1 mon'::interval))::date END <= ((date_trunc('month'::text, now()))::date - 1)) AND (CASE WHEN (NOT void) THEN end_date ELSE ((end_date
- '1 mon'::interval))::date END >= first_of_another_month((((now())::date - '1 mon'::interval))::date)))
-> Materialize (cost=0.00..1.58 rows=12 width=2)
-> Seq Scan on subscription_types st (cost=0.00..1.52 rows=12 width=2)
Filter: ((sub_class)::text = 'VM'::text)
-> Index Only Scan using tcmopid on mop (cost=0.00..2.28 rows=1 width=4)
Index Cond: (id = s.member_id)
-> Index Scan using tcmembersid on members m (cost=0.00..5.47 rows=1 width=6)
Index Cond: (id = mop.id)
Filter: (mail_option_lvl > 0)
-> Index Scan using cancellations_pkey on cancellations c (cost=0.00..2.69 rows=1 width=6)
Index Cond: (id = m.id)
Filter: ((CASE WHEN (id IS NULL) THEN m.membertype WHEN ((status = 'tr'::text) OR (status = 'p'::text) OR (status = 'cd'::text) OR (status = 'sp'::text) OR (status = 'sa'::text)) THEN m.membertype ELSE 'c'::character
varying END)::text = 'v'::text)
-> Seq Scan on nop_seed (cost=0.00..33.30 rows=2330 width=4)
(22 rows)

network=# select count(*) from testcase.vip_mailer_unpaid_current;
count
-------
390
(1 row)

Would you still like a test case to run?