Below sample query is a part of my main query. I found SORT operator in below query is consuming 30% of the cost.
To avoid SORT, there is need of creation of Indexes. Is there any other way to optimize this code.
SELECT TOP 1 CONVERT( DATE, T_Date) AS T_Date
FROM TableA
WHERE ID = r.ID
AND Status = 3
AND TableA_ID >ISNULL((
SELECT TOP 1 TableA_ID
FROM TableA
WHERE ID = r.ID
AND Status <> 3
ORDER BY T_Date DESC
), 0)
ORDER BY T_Date ASC
Looks like you can use not exists rather than the sorts. I think you'll probably get a better performance boost by use a CTE or derived table instead of the a scalar subquery.
select *
from r ... left outer join
(
select ID, min(t_date) as min_date from TableA t1
where status = 3 and not exists (
select 1 from TableA t2
where t2.ID = t1.ID
and t2.status <> 3 and t2.t_date > t1.t_date
)
group by ID
) as md on md.ID = r.ID ...
or
select *
from r ... left outer join
(
select t1.ID, min(t1.t_date) as min_date
from TableA t1 left outer join TableA t2
on t2.ID = t1.ID and t2.status <> 3
where t1.status = 3 and t1.t_date < t2.t_date
group by t1.ID
having count(t2.ID) = 0
) as md on md.ID = r.ID ...
It also appears that you're relying on an identity column but it's not clear what those values mean. I'm basically ignoring it and using the date column instead.
Try this:
SELECT TOP 1 CONVERT( DATE, T_Date) AS T_Date
FROM TableA a1
LEFT JOIN (
SELECT ID, MAX(TableA_ID) AS MaxAID
FROM TableA
WHERE Status <> 3
GROUP BY ID
) a2 ON a2.ID = a1.ID AND a1.TableA_ID > coalesce(a2.MAXAID,0)
WHERE a1.ID = r.ID AND a1.Status = 3
ORDER BY T_Date ASC
The use of TOP 1 in combination with the unexplained r alias concern me. There's almost certainly a MUCH better way to get this data into your results that doesn't involve doing this in a sub query (unless this is for an APPLY operation).
Related
how to find number of records in both table using join.
i have two tables table1 and table2 with same structure.
table1
id
item
1
A
1
B
1
C
2
A
2
B
table2
id
item
1
A
1
B
2
A
2
B
2
C
2
D
Output should be like this.
id
table1.itemcount
table2.itemcount
1
3
2
2
2
4
SELECT DISTINCT id, (
SELECT COUNT(*) FROM table1 AS table1_2 WHERE table1_2.id=table1.id
) AS "table1.itemcount", (
SELECT COUNT(*) FROM table2 AS table2_2 WHERE table2_2.id=table1.id
) AS "table2.itemcount"
FROM table1;
Assuming that each id is guaranteed to exist in both tables, the following would work
select
t1.id,
count(distinct t1.item) t1count,
count(distinct t2.item) t2count
from t1
join t2 on t1.id = t2.id
group by 1;
But if that is not guaranteed then we'll have to use full outer join to get unique ids from both tables
select
coalesce(t1.id, t2.id) id,
count(distinct t1.item) t1count,
count(distinct t2.item) t2count
from t1
full outer join t2 on t1.id = t2.id
group by 1;
We're using coalesce here as well for id because if it only exists in t2, t1.id would result in null.
#DeeStark's answer also works if ids are guaranteed to be in both tables but it's quite inefficient because count is essentially run twice for every distinct id in the table. Here's the fiddle where you can test out different approaches. I've prefixed each query with explain which shows the cost
Hope this helps
I know that LEAD & LAG functions are there to achieve the task to get previous & next data row. my question is how to achieve the same goal in old sql server where LEAD & LAG not present. please suggest some good approach to retrieve Previous & Next data row with LEAD & LAG function. Thanks
Here i am sharing one example which is working fine.
Create table #test
(
ID int identity(1,1),
Quarter nvarchar(20)
)
insert into #test values
('1Q 2010'),
('2Q 2010'),
('3Q 2010'),
('4Q 2010'),
('FY 2010')
select * from #test
select PrevID,PrevQuarter,CurrID,CurrQuarter
from
(
select Lag(ID,1) over(order by ID)PrevID ,LAG(Quarter,1)over(order by ID)PrevQuarter,
ID as CurrID,Quarter as CurrQuarter
from #test
)t
where CurrID=4
You could use correlated TOP subqueries in lieu of LEAD and LAG:
SELECT PrevID, PrevQuarter, CurrID, CurrQuarter
FROM
(
SELECT
(SELECT TOP 1 ID FROM #test t2
WHERE t2.ID < t1.ID ORDER BY t2.ID DESC) PrevID,
(SELECT TOP 1 Quarter FROM #test t2
WHERE t2.ID < t1.ID ORDER BY t2.ID DESC) PrevQuarter,
ID AS CurrID, Quarter AS CurrQuarter
FROM #test t1
) t
WHERE CurrID = 4;
Here is a working demo.
there are many ways to do it. Here are 2
Self Join:
If ID is not continuous, use row_number() to generate one
select p.ID as PrevID, p.Quarter as PrevQuarter,
c.ID as CurrID, c.Quarter as CurrQuarter
from #test c
left join #test p on c.ID = p.ID + 1
where c.ID = 4
using APPLY():
select p.ID as PrevID, p.Quarter as PrevQuarter,
c.ID as CurrID, c.Quarter as CurrQuarter
from #test c
outer apply
(
select top 1 ID, Quarter
from #test x
where x.ID < c.ID
order by x.ID desc
) p
where c.ID = 4
Lets assume we have the following table1:
1 2 3
a x m
a y m
b z m
I want to do an inner join on the table
INNER JOIN tabel2 ON table1.2 = table2.2
Somehow like this, but additional a condition that the value of table1.1 not unique. Thus on table1.1 = b no inner join will occure in this example.
What is the best way to achieve this?
Using a an aggregate in a sub query is how I would do it
SELECT *
FROM table1
JOIN table2
ON table1."2" = table2."2"
JOIN (
SELECT "1"
FROM table1
GROUP BY "1"
HAVING COUNT(*) > 1
) AS sub_q
ON sub_q."1" = table1."1";
Another option might be a cte or temporary table to hold the rows you're joining on
WITH _cte AS
(
SELECT "1"
FROM table1
GROUP BY "1"
HAVING COUNT(*) > 1
)
SELECT *
FROM table1
JOIN table2
ON table1."2" = table2."2"
JOIN _cte AS cte
ON cte."1" = table1."1";
temp table:
CREATE TEMPORARY TABLE _tab
(
"1" varchar
);
INSERT INTO _tab
SELECT "1"
FROM table1
GROUP BY "1"
HAVING COUNT(*) > 1;
SELECT *
FROM table1
JOIN table2
ON table1."2" = table2."2"
JOIN _tab AS tab
ON tab."1" = table1."1";
We created a view in Postgres and I am getting strange result.
View Name: event_puchase_product_overview
When I try to get records with *, I get the correct result. but when I try to get specific fields, I get wrong values.
I hope the screens attached here can explain the problem well.
select *
from event_purchase_product_overview
where id = 15065;
select id, departure_id
from event_puchase_product_overview
where id = 15065;
VIEW definition:
CREATE OR REPLACE VIEW public.event_puchase_product_overview AS
SELECT row_number() OVER () AS id,
e.id AS departure_id,
e.type AS event_type,
e.name,
p.id AS product_id,
pc.name AS product_type,
product_date.attribute AS option,
p.upcomming_date AS supply_date,
pr.date_end AS bid_deadline,
CASE
WHEN (pt.categ_id IN ( SELECT unnest(tt.category_ids) AS unnest
FROM ( SELECT string_to_array(btrim(ir_config_parameter.value, '[]'::text), ', '::text)::integer[] AS category_ids
FROM ir_config_parameter
WHERE ir_config_parameter.key::text = 'trip_product_flight.product_category_hotel'::text) tt)) THEN e.maximum_rooms
WHEN (pt.categ_id IN ( SELECT unnest(tt.category_ids) AS unnest
FROM ( SELECT string_to_array(btrim(ir_config_parameter.value, '[]'::text), ', '::text)::integer[] AS category_ids
FROM ir_config_parameter
WHERE ir_config_parameter.key::text = 'trip_product_flight.product_category_flight'::text) tt)) THEN e.maximum_seats
WHEN (pt.categ_id IN ( SELECT unnest(tt.category_ids) AS unnest
FROM ( SELECT string_to_array(btrim(ir_config_parameter.value, '[]'::text), ', '::text)::integer[] AS category_ids
FROM ir_config_parameter
WHERE ir_config_parameter.key::text = 'trip_product_flight.product_category_bike'::text) tt)) THEN e.maximum_bikes
ELSE e.maximum_seats
END AS departure_qty,
CASE
WHEN now()::date > pr.date_end AND po.state::text = 'draft'::text THEN true
ELSE false
END AS is_deadline,
pl.product_qty::integer AS purchased_qty,
pl.comments,
pl.price_unit AS unit_price,
rp.id AS supplier,
po.id AS po_ref,
po.state AS po_state,
po.date_order AS po_date,
po.user_id AS operator,
pl.po_state_line AS line_status
FROM event_event e
LEFT JOIN product_product p ON p.related_departure = e.id
LEFT JOIN product_template pt ON pt.id = p.product_tmpl_id
LEFT JOIN product_category pc ON pc.id = pt.categ_id
LEFT JOIN purchase_order_line pl ON pl.product_id = p.id
LEFT JOIN purchase_order po ON po.id = pl.order_id
LEFT JOIN purchase_order_purchase_requisition_rel prr ON prr.purchase_order_id = po.id
LEFT JOIN purchase_requisition pr ON pr.id = prr.purchase_requisition_id
LEFT JOIN res_partner rp ON rp.id = po.partner_id
LEFT JOIN ( SELECT p_1.id AS product_id,
pav.name AS attribute
FROM product_product p_1
LEFT JOIN product_attribute_value_product_product_rel pa ON pa.prod_id = p_1.id
LEFT JOIN product_attribute_value pav ON pav.id = pa.att_id
LEFT JOIN product_attribute pat ON pat.id = pav.attribute_id
WHERE pat.name::text <> ALL (ARRAY['Date'::character varying, 'Departure'::character varying]::text[])) product_date ON product_date.product_id = p.id
WHERE (p.id IN ( SELECT DISTINCT mrp_bom_line.product_id
FROM mrp_bom_line)) AND p.active
ORDER BY e.id, pt.categ_id, p.id;
If I add new event_event or new product_product I'll get a new definition of row_number in my view, then the column ID of my view is not stable.
at least you can't use row_number as Id of the view,
If you insist to use row_number, you can use the Order By "creation DATE" by this way all new records will be as last lines in the view and this will not change the correspondency between ID (row_number) and other columns.
Hope that helps !
Very likely the execution plan of your query depends on the columns you select. Compare the execution plans!
Your id is generated using the row_number window function. Now window functions are executed before the ORDER BY clause, so the order will depend on the execution plan and hence on the columns you select.
Using row_number without an explicit ordering doesn't make any sense.
To fix that, don't use
row_number() OVER ()
but
row_number() OVER (ORDER BY e.id, pt.categ_id, p.id)
so that you have a reliable ordering.
In addition, you should omit the ORDER BY clause at the end.
I am trying to use a correlated subquery, but I am trying to limit it to the "best" record. When I use SQL very similiar to what follows, I get two rows per BigTable.identifier, and I wish to have only one. In the 'UNION' statement, the second half is more desirable than the first half. However, sometimes the first half will be needed. Any ideas? Here's the code:
select
BigTable.identifier,
Correlated.ID,
Correlated.Effective_Date,
Correlated.Period_Number
from
BigTable
inner join
(
select
TOP 2147483647
Table3.identifier,
Table4.Effective_Date,
Table4.Period_Number
from
Table3
inner join Table4 on Table3.matching_key = Table4.matching_key
where
Table4.Period_Number = 0
order by Table4.Effective_Date desc
UNION
select
TOP 2147483647
Table3.Identifer,
Table4.Effective_Date,
Table4.Period_Number
from
Table3
inner join Table5 on Table3.matching-key = Table5.matching-key
inner join Table4 on Table5.key1 = Table4.key1 and
Table5.key2 = Table4.key2
where
Table4.period_number = 1
order by Table4.Effective_Date desc
) as Correlated
on BigTable.identifier = Correlated.identifier
If each sub-query in that UNION had some condition which EXCLUDED the row if it was less-preferred, you would never see the less-preferred rows in the UNION.
So, if each were to have a NOT EXISTS (.... a better row in the other side of the union ....), you would eliminate less-preferred rows at the root.
I'm not clear on how you want to use effective date. Assuming you mean that you prefer Period=1 but if the Effective date is less you prefer Period=0, then something like this might work.
select
BigTable.identifier,
Correlated.ID,
Correlated.Effective_Date,
Correlated.Period_Number
from
BigTable
inner join
(
select
TOP 2147483647
Table3.identifier,
Table4.Effective_Date,
Table4.Period_Number
from
Table3
inner join Table4 on Table3.matching_key = Table4.matching_key
where
Table4.Period_Number = 0
AND NOT EXISTS
(select 1
from Table5 T5 inner join Table4 T4
on T5.key1 = T4.key1 and T5.key2 = T4.key2
where Table3.matching-key = T5.matching-key
and (T4.Effective_Date >= Table4.Effective_Date and T4.Period_Number = 1)
)
order by Table4.Effective_Date desc
UNION
select
TOP 2147483647
Table3.Identifer,
Table4.Effective_Date,
Table4.Period_Number
from
Table3
inner join Table5 on Table3.matching-key = Table5.matching-key
inner join Table4 on Table5.key1 = Table4.key1 and
Table5.key2 = Table4.key2
where
Table4.period_number = 1
AND NOT EXISTS
(select 1
from Table4 T4
where Table3.matching-key = T4.matching-key
and (T4.Period_Number > 0)
and (T4.Effective_Date > Table4.Effective_Date and T4.Period_Number = 0)
)
order by Table4.Effective_Date desc
) as Correlated
on BigTable.identifier = Correlated.identifier