When I execute a TSQL query or a stored procedure that returns large number of records (1M+) by default it begins to display result while query is still executing.
Is there way to prevent this and postpone returning of the result until the query execution is complete?
If you add a column like the following to the returned dataset, it almost certainly will not be able to do a FAST(N):
.., MAX(prevColumn) OVER(PARTITON BY 1) As Dummy, ...
Where prevColumn is any other column that you are already returning, especially if it's not an indexed column.
You can use ORDER BY or Aggregate function in SELECT will help you.
Related
I have a column workId in my table which has values like :
W1/2009/12345, G2/2018/2345
Now a user want to get this particular id G2/2018/2345. I am using like operator in my query as below:
select * from u_table as s where s.workId like '%2345%' .
It is giving me both above mentioned workids. I tried following query:
select * from u_table as s where s.workId like '%2345%' and s.workId not like '_2345'
This query also giving me same result.
If anyone please provide me with the correct query. Thanks!
Why not use the existing delimiters to match with your criteria?
select *
from u_table
where concat('/', workId, '/') like concat('%/', '2345', '/%');
Ideally of course your 3 separate values would be 3 separate columns; delimiting multiple values in a single column goes against first-normal form and prevents the optimizer from performing an efficient index seek, forcing a scan of all rows every time, hurting performance and concurrency.
I have designed a function that works with an SSRS report. I have a drop down parameter that lists multiple items and only one can be selected. This drop down gets its data from a query/data set, and I added one line of data that says 'All' in it. So the dropdown will look like this:
Item1
Item2
Item3
All
And then in the function, I make one small change in the where clause:
...where (#parameterName = 'All' or table.name = #parameterName)
The problem with this is that table.name has about 50000 rows of data. When the user selects 'All' in the drop down, I would have thought that since the first statement in brackets is true, and that the next statement (after the 'or') should not even be executed. But it causes the query to run for 5-20 minutes and still does not produce any result after that long. If I simply change the where clause to
...where (#parameterName = 'All')
The function runs in less than a second, if the user still selects 'All' from the drop down.
I implement a similar concept with another filter but I guess because the table that that parameter uses is much smaller (about 90 rows), so it doesn't take long.
Is there basically a way to have an optional parameter that is not expensive to calculate?
EDIT: I will add that the parameter is declared as nvarchar(max). Will changing this to something smaller help the query?
What you have there is a catch-all query. Consider adding OPTION (RECOMPILE) to the end of your statement. This'll force the engine to recreate the plan each time it runs the query, meaning it won't use poor choices based on a previous run where your variable has a value like 'Item1'.
In a .CFC file, within a CFfunction and with CFargument tags.
<cfscript>
var sp=new storedproc();
sp.setDatasource(variables.datasource);
sp.setProcedure("storedProcedure_INSERT");
sp.addParam(cfsqltype="cf_sql_integer",type="in",value=arguments.one);
sp.addParam(cfsqltype="cf_sql_integer",type="in",value=arguments.two);
sp.addParam(cfsqltype="cf_sql_integer",type="in",value=arguments.three);
sp.addParam(cfsqltype="cf_sql_integer",type="in",value=arguments.four);
sp.addProcResult(name="results",resultset=1);
//writeDump(sp);break; //This dump is reached
var spObj=sp.execute(); //blows up here; this is never reached
writeDump(spObj);break; //This is never reached, either.
var spResults=spObj.getProcResultSets().results;
A shiny nickle to anyone who can tell me why the sp.execute() is blowing up with message
"Cannot find results key in structure.
The specified key, results, does not exist in the structure."
I've used this psuedo-code many, may times in the past, and never had it do this. I'm connected to a MSSQL Server 2012 DB, everything's cricket in CF Admin, and other SPs are working properly. The stack trace doesn't even include any of MY code at all o_O
The error occurred in C:/ColdFusion10/cfusion/CustomTags/com/adobe/coldfusion/base.cfc: line 491
Called from C:/ColdFusion10/cfusion/CustomTags/com/adobe/coldfusion/storedproc.cfc: line 142
Called from //hq-devfs/development$/websites/myProject/cfc/mySOAPWSDLs.cfc: line 123
And SO is blowing up if I try and paste anymore of that. Google has...not been helpful ._.
Short answer: The error means you are trying to retrieve a resultset from the stored procedure, when it does not actually return one. A simple solution is to add a SELECT to the end of your procedure, so it returns a resultset containing the data you need. Then your original code will work:
SELECT ##ROWCOUNT AS NumOfRowsAffected;
Longer answer:
The method you are using, addProcResult(), is the equivalent of <cfprocresult>. It is intended to capture a resultset returned from a stored procedure. (Due to CF's poor choice of attribute names, a lot of people think "resultset" means the storedproc "result" structure, but they are two totally different things). A "resultset" is a query object", in CF parlance.
While all four (4) of the primary sql statements return some result, not all of them return a "query object"
Only SELECT statements generate a "query object"
INSERT/UPDATE/DELETE statements simply return the number of rows affected. They do not generate a "query object".
Since your stored procedure performs an INSERT, it does not generate a "query object". Hence the error when you try and grab the non-existent query here:
sp.addProcResult(name="results",resultset=1);
The simple solution is to add a SELECT statement to the end of your stored procedure, so that it does return a query object. Then your code will work as expected.
As an aside, I suspect you were actually trying to grab the "result" structure, but used the wrong method. The equivalent of <cfstoredproc result=".."> is getPrefix(). Though that would not work here anyway. According to the docs, it does not contain the number of rows affected. Probably because stored procedures can execute multiple statements, each one potentially returning a row count, so there is not just a single value to return.
What can I do so that EF becomes aware of the output clause in SPs and generates the result object accordingly?
INSERT INTO goodtable
(token,
ip, long_ip,
) OUTPUT INSERTED.*
VALUES
(#token,
#ip, #long_ip,
);
What I currently do to circumvent this is writing a dummy select, generate the objects and the comment out the dummy select leaving the output. This is not a good solution for a long term run.
Please do not suggest changing the SQL.
Have you tried. when importing the stored procedure into EF, using function import, to add the returns a collection of option.
I've never tried it, but can't see a reason for it not to work.
I was just wondering if in SQL Server if in a statement like this:
SELECT A.Field1, dbo.someFunction(A.IdentifierID) As Field
FROM Table A WHERE A.IdentifierID = 1000
Will it call someFunction for all the rows in the table, or will it call it once?
Thanks!
It will be called for every row of result
the count of calls depends on the resulted rows, i.e, if the output of the query 100 row the it will be called 100 times, not for all rows in the table
but if it were in the where clause, the it will evaluated for each row
Will call it for every row, but since you are selecting a specific one (or so it seems), it will be called once on your example.
As vlad commented you should try it and see. There are of course two options:
It could call it just once knowing IdentifierID will always be 1000.
but that might not be the right thing...
It could call it for each row - maybe the function has side-effects?
I strongly suspect #2.
Compliant SQL servers are supposed to appear as if they apply the WHERE clause before they apply the SELECT clause. So it should appear to evaluate the function at most once for each row that satisfies WHERE A.IdentifierID = 1000.
But database engines are free to optimize however they like, as long as they give you the same results the standards require. So in your case, since you're selecting a single ID number, it might only have to evaluate the function once.