Person table have 2 Million rows and 3 Million rows in Finance and on HR schema respectively. Now I'm going to update the Person status on Finance schema with the person_status on the HR schema. Query is running on M3000 Server with 32 GB RAM with Solaris 10 and Oracle 11.2.2. It took 117 hours and still runnning. How can I optimize this query. I have created index on person_no.
DECLARE
CURSOR c IS
SELECT p1.person_no AS "PersonNo1"
, p2.person_no AS "PersonNo2"
, p2.person_status AS "P2_PERSON_STATUS"
FROM person p1
, hr.person p2
WHERE (lower(p1.person_no) = lower(p2.person_no)
OR substr(p1.person_no, instr(p1.person_no, '-') + 1, length(p1.person_no))
= substr(p2.person_no, instr(p2.person_no, '-') + 1, length(p2.person_no)));
BEGIN
FOR i IN c LOOP
UPDATE person
SET person_status_id = decode(lower(i.P2_PERSON_STATUS), 'y', 1, 'n', 2)
WHERE (lower(person_no) = lower(i.PersonNo2)
OR substr(person_no, instr(person_no, '-') + 1, length(person_no))
= substr(i.PersonNo2, instr(i.PersonNo2, '-') + 1, length(i.PersonNo2)));
COMMIT;
END LOOP;
END;
/
There is several things you can do to optimize this. It would be helpful to see a query plan.
You can use a merge statement. Then you have only one statement and you can work optimizing this statement. Something like this
merge into person
using hr.person person_hr
on (person.person_no=person_hr.person_no)
when matched then
update set person_status_id=decode(lower(person_status),'y',1,'n',2);
You have to adjust the on part to match your where statement.
This might then be the source of best optimization. Maybe you have to create an index for lower and also for substr.
Something like
CREATE INDEX person_idx
ON person (lower(person_no))
Also of course for the substrings etc. Hope this helps.
In the code provided as question i can see there are two aspects.
1) Query Optimization
2) ROW BY ROW Update --> Never Recommended for such a huge records count..
Approach to Optmization.
1) Use Merge Statement as it will Bundle up the block into pure SQL thus will enhance your query.
2) Use Function based Index as i can see there are lot of functions like "LOWER" is used in the query "WHERE" conditions.
NOTE : [Over INDEXING may also cause deterioration in the performance}
3) Last but not the least if you have to go by Anonymous block only then avoid using ROW BY ROW Update. Try using Bulk collect Options as illustrated below.
Since i do not have workstation handy with me please bear with any Syntax Errors.
Let me know if this helps.
DECLARE
TYPE p1
IS
TABLE OF <table_name>.<COLUMN_NAME>%TYPE;
PersonNo1 p1;
TYPE p2
IS
TABLE OF <table_name>.<COLUMN_NAME>%TYPE;
PersonNo2 p2;
TYPE status
IS
TABLE OF <table_name>.<COLUMN_NAME>%TYPE;
P2_PERSON_STATUS status;
BEGIN
SELECT p1.person_no AS "PersonNo1" ,
p2.person_no AS "PersonNo2" ,
p2.person_status AS "P2_PERSON_STATUS" BULK COLLECT
INTO PersonNo1,
PersonNo2,
P2_PERSON_STATUS
FROM person p1 ,
hr.person p2
WHERE (lower(p1.person_no) = lower(p2.person_no)
OR SUBSTR(p1.person_no, instr(p1.person_no, '-') + 1, LENGTH(p1.person_no)) = SUBSTR(p2.person_no, instr(p2.person_no, '-') + 1, LENGTH(p2.person_no)));
FORALL I IN PersonNo1.FIRST..PersonNo1.LAST
UPDATE person
SET person_status_id = DECODE(lower(P2_PERSON_STATUS(I)), 'y', 1, 'n', 2)
WHERE (lower(person_no) = lower(PersonNo2(I))
OR SUBSTR(person_no, instr(person_no, '-') + 1, LENGTH(person_no)) = SUBSTR(PersonNo2(I), instr(PersonNo2(I), '-') + 1, LENGTH(PersonNo2(I))));
COMMIT;
END;
Related
I am converting some code in Access over to Oracle, and one of the queries in Access uses a table that I am unable to use in Oracle. I am unable to create new tables, so I am trying to figure out a way to use the logic behind the table in the FOR section of my select.
The logic of the table is similar to:
FOR i = 1 To 100
number = number + 1
.AddNew
!tbl_number = number
NEXT i
I'm trying to convert this to oracle, and so far I have:
FOR i in 1 .. 100 LOOP
number := number + 1;
--This is where I am stuck; How do I simulate the table part
END LOOP;
I was thinking a cursor or a record would be the answer, but I can't seem to figure out how to implement that. In the end I basically want to have:
SELECT
table.number
FROM
(
--My for loop logic
) table
EDIT
The calculation is a bit more complicated; that was just an example. They aren't actually sequential, and there isn't really a pattern to rows.
EDIT
Here is a more complicated version of the for loop which is closer to what I'm actually doing:
FOR i in 1 .. 100 LOOP
number1 := number1 + 7;
number2 := (number2 + 8) / number1;
--This is where I am stuck; How do I simulate the table part
END LOOP;
You could use a recursive query (assuming you are on Oralce 11gR2 or later):
with example(idx, number1, number2) as (
-- Anchor Section
select 1
, 1 -- initial value
, 2 -- initial value
from dual
union all
-- Recursive Section
select prev.idx + 1
, prev.number1 + 7
, (prev.number2 + 8) / prev.number1
from example prev
where prev.idx < 100 -- The Guard
)
select * from example;
In the Anchor section set all the values for your first record. Then in the Recursive section setup the logic to determine the next records values as a function of the prior records values.
The Anchor section could select the initial values from some other table rather than being hard coded as in my example.
The recursive section needs to select from the named subquery (in this case example) but may also join to other tables as needed.
You need to generate a set with sequential integer numbers. Maybe you can use this (for Oracle 10g and above):
SELECT
ROWNUM NUM
FROM
DUAL D1,
DUAL D2
CONNECT BY
(D1.DUMMY = D2.DUMMY AND ROWNUM <= 100)
For frequent period of time, i'm doing same process of updating few tables with consecutive values. Hope to make this simple an example below,
UPDATE Table_1 SET vchar_val = REPLACE (vchar_val, '.360/', '.370/'),
WHERE vchar_val LIKE 'http://services%.360/%'
AND c_version IN ('ALL', 'N/A', '37.0');
For 37th version, i'm replacing the places where '36' with '37'. The same i'll do for '38' and it continues...This is making me bore and time consuming process as i've 50 plus records like this for different tables for which i'm manually editing all update queries.
So i planned to write a scheduler which i can trigger for each version by giving input as previous version and current version, in which i'll put all this update queries.
Here comes the place where i struck, if i go by giving version values as input, i'm supposed to introduce local parameter to store. HOW CAN I ASSIGN THAT LOCAL VARIABLE TO MY UPDATE SCRIPT.??????
I go with concatenate the texts like
REPLACE (vchar_val, '.'+ #PrevVersion +'/', '.'+ #CurrentVersion +'/')
PrevVer** & CurrentVer** is my local variable with values .360 & .370 resp.
I think i miss quiet piece of code in this snippet as i'm getting error when running this.
Please help me guys to rearrange this code to automate the query or ur comments to do this job in any alternative way...
Thanks
-VIno
begin
for i in 36 .. 50 loop
UPDATE Table_1
SET vchar_val = REPLACE (vchar_val, '.'|| i ||'0/', '.'|| i+1 ||'0/')
WHERE vchar_val LIKE 'http://services%.'|| i ||'0/%'
AND c_version IN ('ALL', 'N/A', i+1 ||'.0');
end loop;
end;
Of course you could do that in one single update with some fancy reg_exp, but I leave that exercice to another fellow stackoverflower :)
Local variable:
declare
my_local_valiable number;
begin
update my_table ... ;
commit;
end;
Autoincrement: sequence
update table_1 set my_field = '.' || my_sequence.nextval where ...;
UPD
Number always in the same position (for example, 2 digits, 10th and 11th symbols in the string):
update table_1 set my_field = substr(my_field, 1, 9) || to_char(to_number(substr(my_field, 10, 2)) + 1) || substr(my_field, 12);
This converts string 'abracadab29ra' to 'abracadab30ra'.
The same with replace:
update table_1 set my_field = replace(my_field, substr(my_field, 10, 2), to_char(to_number(substr(my_field, 10, 2)) + 1));
Number always follows after a string 'value = ' and has two digits:
update table_1 set my_field = replace(my_field, substr(my_field, instr(my_field, 'value = ', 1) + 8, 2), to_char(to_number(substr(my_field, instr(my_field, 'value = ', 1) + 8, 2)) + 1))
This converts string 'my value = 33' to 'my value = 34'.
I had written a cursor in a pl/sql block. This block taking lot of time if it has more records.
How to write this without a cursor or Is there any other alternative way that will reduce the time?
Is there any alternative query to perform insert into one table and delete from another table using a single query?
DECLARE
MDLCursor SYS_REFCURSOR;
BEGIN
open MDLCursor for
select dc.dest_id, dc.digits, dc.Effectivedate, dc.expirydate
from DialCodes dc
INNER JOIN MDL d
ON dc.Dest_ID = d.Dest_ID
AND d.PriceEntity = 1
join sysmdl_calltypes s
on s.call_type_id = v_CallType_ID
and s.dest_id = dc.Dest_ID
and s.call_type_id not in
(select calltype_id from ignore_calltype_for_routing)
order by length(dc.digits) desc, dc.digits desc;
loop
fetch MDLCursor
into v_mdldest_id, v_mdldigits, v_mdlEffectiveDate, v_mdlExpDate;
insert into tt_pendingcost_temp
(Dest_ID,
Digits,
CCASDigits,
Destination,
tariff_id,
NewCost,
Effectivedate,
ExpiryDate,
previous,
Currency)
select v_mdldest_id,
Digits,
v_mdldigits,
Destination,
tariff_id,
NewCost,
Effectivedate,
ExpiryDate,
previous,
Currency
FROM tt_PendingCost
where substr(Digits, 1, 2) = substr(v_MDLDigits, 1, 2)
and instr(Digits, v_MDLDigits) = 1
and v_mdlEffectiveDate <= effectivedate
and (v_mdlExpDate > effectivedate or v_mdlExpDate is null);
if SQL%ROWCOUNT > 0 then
delete FROM tt_PendingCost
where substr(Digits, 1, 2) = substr(v_MDLDigits, 1, 2)
and instr(Digits, v_MDLDigits) = 1
and v_mdlEffectiveDate <= effectivedate
and (v_mdlExpDate > effectivedate or v_mdlExpDate is null);
end if;
exit when MDLCursor%NOTFOUND;
end loop;
close MDLCursor;
END;
I don't have your tables and your data so I can only guess at a couple of things that would be slowing you down.
Firstly, the query used in your cursor has an ORDER BY clause in it. If this query returns a lot of rows, Oracle has to fetch them all and sort them all before it can return the first row. If this query typically returns a lot of results, and you don't particularly need it to return sorted results, you may find your PL/SQL block speeds up a bit if you drop the ORDER BY. That way, you can start getting results out of the cursor without needing to fetch all the results, store them somewhere and sort them first.
Secondly, the following is the WHERE clause used in your INSERT INTO ... SELECT ... and DELETE FROM ... statements:
where substr(Digits, 1, 2) = substr(v_MDLDigits, 1, 2)
and instr(Digits, v_MDLDigits) = 1
and v_mdlEffectiveDate <= effectivedate
and (v_mdlExpDate > effectivedate or v_mdlExpDate is null);
I don't see how Oracle can make effective use of indexes with any of these conditions. It would therefore have to do a full table scan each time.
The last two conditions seem reasonable and there doesn't seem a lot that can be done with them. I'd like to focus on the first two conditions as I think there's more scope for improvement with them.
The second of the four conditions is
instr(Digits, v_MDLDigits) = 1
This condition holds if and only if Digits starts with the contents of v_MDLDigits. A better way of writing this would be
Digits LIKE v_MDLDigits || '%'
The advantage of using LIKE in this situation instead of INSTR is that Oracle can make use of indexes when using LIKE. If you have an index on the Digits column, Oracle will be able to use it with this query. Oracle would then be able to focus in on those rows that start with the digits in v_MDLDigits instead of doing a full table scan.
The first of the four conditions is:
substr(Digits, 1, 2) = substr(v_MDLDigits, 1, 2)
If v_MDLDigits has length at least 2, and all entries in the Digits columns also have length at least 2, then this condition is redundant since it is implied by the previous one we looked at.
I'm not sure why you would have a condition like this. The only reason I can think why you might have this condition is if you have a functional index on substr(Digits, 1, 2). If not, I would be tempted to remove this substr condition altogether.
I don't think the cursor is what is making this procedure run slowly, and there's no single statement I know of that can insert into one table and delete from another. To make this procedure speed up I think you just need to tune the queries a bit.
I have a simple INSERT query where I need to use UPDATE instead when the primary key is a duplicate. In MySQL this seems easier, in Oracle it seems I need to use MERGE.
All examples I could find of MERGE had some sort of "source" and "target" tables, in my case, the source and target is the same table. I was not able to make sense of the examples to create my own query.
Is MERGE the only way or maybe there's a better solution?
INSERT INTO movie_ratings
VALUES (1, 3, 5)
It's basically this and the primary key is the first 2 values, so an update would be like this:
UPDATE movie_ratings
SET rating = 8
WHERE mid = 1 AND aid = 3
I thought of using a trigger that would automatically execute the UPDATE statement when the INSERT was called but only if the primary key is a duplicate. Is there any problem doing it this way? I need some help with triggers though as I'm having some difficulty trying to understand them and doing my own.
MERGE is the 'do INSERT or UPDATE as appropriate' statement in Standard SQL, and probably therefore in Oracle SQL too.
Yes, you need a 'table' to merge from, but you can almost certainly create that table on the fly:
MERGE INTO Movie_Ratings M
USING (SELECT 1 AS mid, 3 AS aid, 8 AS rating FROM dual) N
ON (M.mid = N.mid AND M.aid = N.aid)
WHEN MATCHED THEN UPDATE SET M.rating = N.rating
WHEN NOT MATCHED THEN INSERT( mid, aid, rating)
VALUES(N.mid, N.aid, N.rating);
(Syntax not verified.)
A typical way of doing this is
performing the INSERT and catch a DUP_VAL_ON_INDEX and then perform an UPDATE instead
performing the UPDATE first and if SQL%Rows = 0 perform an INSERT
You can't write a trigger on a table that does another operation on the same table. That's causing an Oracle error (mutating tables).
I'm a T-SQL guy but a trigger in this case is not a good solution. Most triggers are not good solutions. In T-SQL, I would simply perform an IF EXISTS (SELECT * FROM dbo.Table WHERE ...) but in Oracle, you have to select the count...
DECLARE
cnt NUMBER;
BEGIN
SELECT COUNT(*)
INTO cnt
FROM mytable
WHERE id = 12345;
IF( cnt = 0 )
THEN
...
ELSE
...
END IF;
END;
It would appear that MERGE is what you need in this case:
MERGE INTO movie_ratings mr
USING (
SELECT rating, mid, aid
WHERE mid = 1 AND aid = 3) mri
ON (mr.movie_ratings_id = mri.movie_ratings_id)
WHEN MATCHED THEN
UPDATE SET mr.rating = 8 WHERE mr.mid = 1 AND mr.aid = 3
WHEN NOT MATCHED THEN
INSERT (mr.rating, mr.mid, mr.aid)
VALUES (1, 3, 8)
Like I said, I'm a T-SQL guy but the basic idea here is to "join" the movie_rating table against itself. If there's no performance hit on using the "if exists" example, I'd use it for readability.
This question already has answers here:
SQL IN Clause 1000 item limit
(5 answers)
Closed 8 years ago.
Is there any way to get around the Oracle 10g limitation of 1000 items in a static IN clause? I have a comma delimited list of many of IDs that I want to use in an IN clause, Sometimes this list can exceed 1000 items, at which point Oracle throws an error. The query is similar to this...
select * from table1 where ID in (1,2,3,4,...,1001,1002,...)
Put the values in a temporary table and then do a select where id in (select id from temptable)
select column_X, ... from my_table
where ('magic', column_X ) in (
('magic', 1),
('magic', 2),
('magic', 3),
('magic', 4),
...
('magic', 99999)
) ...
I am almost sure you can split values across multiple INs using OR:
select * from table1 where ID in (1,2,3,4,...,1000) or
ID in (1001,1002,...,2000)
You may try to use the following form:
select * from table1 where ID in (1,2,3,4,...,1000)
union all
select * from table1 where ID in (1001,1002,...)
Where do you get the list of ids from in the first place? Since they are IDs in your database, did they come from some previous query?
When I have seen this in the past it has been because:-
a reference table is missing and the correct way would be to add the new table, put an attribute on that table and join to it
a list of ids is extracted from the database, and then used in a subsequent SQL statement (perhaps later or on another server or whatever). In this case, the answer is to never extract it from the database. Either store in a temporary table or just write one query.
I think there may be better ways to rework this code that just getting this SQL statement to work. If you provide more details you might get some ideas.
Use ...from table(... :
create or replace type numbertype
as object
(nr number(20,10) )
/
create or replace type number_table
as table of numbertype
/
create or replace procedure tableselect
( p_numbers in number_table
, p_ref_result out sys_refcursor)
is
begin
open p_ref_result for
select *
from employees , (select /*+ cardinality(tab 10) */ tab.nr from table(p_numbers) tab) tbnrs
where id = tbnrs.nr;
end;
/
This is one of the rare cases where you need a hint, else Oracle will not use the index on column id. One of the advantages of this approach is that Oracle doesn't need to hard parse the query again and again. Using a temporary table is most of the times slower.
edit 1 simplified the procedure (thanks to jimmyorr) + example
create or replace procedure tableselect
( p_numbers in number_table
, p_ref_result out sys_refcursor)
is
begin
open p_ref_result for
select /*+ cardinality(tab 10) */ emp.*
from employees emp
, table(p_numbers) tab
where tab.nr = id;
end;
/
Example:
set serveroutput on
create table employees ( id number(10),name varchar2(100));
insert into employees values (3,'Raymond');
insert into employees values (4,'Hans');
commit;
declare
l_number number_table := number_table();
l_sys_refcursor sys_refcursor;
l_employee employees%rowtype;
begin
l_number.extend;
l_number(1) := numbertype(3);
l_number.extend;
l_number(2) := numbertype(4);
tableselect(l_number, l_sys_refcursor);
loop
fetch l_sys_refcursor into l_employee;
exit when l_sys_refcursor%notfound;
dbms_output.put_line(l_employee.name);
end loop;
close l_sys_refcursor;
end;
/
This will output:
Raymond
Hans
I wound up here looking for a solution as well.
Depending on the high-end number of items you need to query against, and assuming your items are unique, you could split your query into batches queries of 1000 items, and combine the results on your end instead (pseudocode here):
//remove dupes
items = items.RemoveDuplicates();
//how to break the items into 1000 item batches
batches = new batch list;
batch = new batch;
for (int i = 0; i < items.Count; i++)
{
if (batch.Count == 1000)
{
batches.Add(batch);
batch.Clear()
}
batch.Add(items[i]);
if (i == items.Count - 1)
{
//add the final batch (it has < 1000 items).
batches.Add(batch);
}
}
// now go query the db for each batch
results = new results;
foreach(batch in batches)
{
results.Add(query(batch));
}
This may be a good trade-off in the scenario where you don't typically have over 1000 items - as having over 1000 items would be your "high end" edge-case scenario. For example, in the event that you have 1500 items, two queries of (1000, 500) wouldn't be so bad. This also assumes that each query isn't particularly expensive in of its own right.
This wouldn't be appropriate if your typical number of expected items got to be much larger - say, in the 100000 range - requiring 100 queries. If so, then you should probably look more seriously into using the global temporary tables solution provided above as the most "correct" solution. Furthermore, if your items are not unique, you would need to resolve duplicate results in your batches as well.
Yes, very weird situation for oracle.
if you specify 2000 ids inside the IN clause, it will fail.
this fails:
select ...
where id in (1,2,....2000)
but if you simply put the 2000 ids in another table (temp table for example), it will works
below query:
select ...
where id in (select userId
from temptable_with_2000_ids )
what you can do, actually could split the records into a lot of 1000 records and execute them group by group.
Here is some Perl code that tries to work around the limit by creating an inline view and then selecting from it. The statement text is compressed by using rows of twelve items each instead of selecting each item from DUAL individually, then uncompressed by unioning together all columns. UNION or UNION ALL in decompression should make no difference here as it all goes inside an IN which will impose uniqueness before joining against it anyway, but in the compression, UNION ALL is used to prevent a lot of unnecessary comparing. As the data I'm filtering on are all whole numbers, quoting is not an issue.
#
# generate the innards of an IN expression with more than a thousand items
#
use English '-no_match_vars';
sub big_IN_list{
#_ < 13 and return join ', ',#_;
my $padding_required = (12 - (#_ % 12)) % 12;
# get first dozen and make length of #_ an even multiple of 12
my ($a,$b,$c,$d,$e,$f,$g,$h,$i,$j,$k,$l) = splice #_,0,12, ( ('NULL') x $padding_required );
my #dozens;
local $LIST_SEPARATOR = ', '; # how to join elements within each dozen
while(#_){
push #dozens, "SELECT #{[ splice #_,0,12 ]} FROM DUAL"
};
$LIST_SEPARATOR = "\n union all\n "; # how to join #dozens
return <<"EXP";
WITH t AS (
select $a A, $b B, $c C, $d D, $e E, $f F, $g G, $h H, $i I, $j J, $k K, $l L FROM DUAL
union all
#dozens
)
select A from t union select B from t union select C from t union
select D from t union select E from t union select F from t union
select G from t union select H from t union select I from t union
select J from t union select K from t union select L from t
EXP
}
One would use that like so:
my $bases_list_expr = big_IN_list(list_your_bases());
$dbh->do(<<"UPDATE");
update bases_table set belong_to = 'us'
where id in ($bases_list_expr)
UPDATE
Instead of using IN clause, can you try using JOIN with the other table, which is fetching the id. that way we don't need to worry about limit. just a thought from my side.
Instead of SELECT * FROM table1 WHERE ID IN (1,2,3,4,...,1000);
Use this :
SELECT * FROM table1 WHERE ID IN (SELECT rownum AS ID FROM dual connect BY level <= 1000);
*Note that you need to be sure the ID does not refer any other foreign IDS if this is a dependency. To ensure only existing ids are available then :
SELECT * FROM table1 WHERE ID IN (SELECT distinct(ID) FROM tablewhereidsareavailable);
Cheers