Performance issue with SQL server due to sql query - sql

Question

Need some help to solve this error:
The query processor ran out of internal resources and could not
produce a query plan. This is a rare event and only expected for
extremely complex queries or queries that reference a very large
number of tables or partitions. Please simplify the query. If you
believe you have received this message in error, contact Customer
Support Services for more information.
SQL query: (I am just putting one of the query. I got 9 such queries running)
var query1 = from article in _db.Articles
from scl in article.Scls
where article.publishDate < DateTime.Now
&& article.removalDate > DateTime.Now
&& article.finished == true
&& article.flagged== true
&& listOfScl.Contains(scl.id)
select article;
var query2 = from article in _db.Articles
from com in article.Coms
where article.publishDate < DateTime.Now
&& article.removalDate > DateTime.Now
&& article.finished == true
&& article.flagged== true
&& listOfCom.Contains(com.id)
select article;
query = (query1.Union(query2)).Distinct();
Don't know what is wrong with query its working fine but giving some performance issue on SQL Server.
I need some help to avoid such error and re-write this SQL query without using UNION.
Thanks in advance.

Answer 1

Also note that by default LINQ does UNION, which will eliminate duplicates, therefore there is no need for Distinct, which will likely improve performance.
"re-write this SQL query without using UNION.". How is this?
var query1 = from article in _db.Articles
from scl in article.Scls
where article.publishDate < DateTime.Now
&& article.removalDate > DateTime.Now
&& article.finished == true
&& article.flagged== true
&& (
listOfScl.Contains(scl.id)
|| listOfCom.Contains(com.id)
)
select article;
You could try the performance of this, so that you don't need a distinct. It will involve a subquery though, so it's hard to say what will perform better without testing:
var query1 = _db.Articles.Where(article => article.publishDate < DateTime.Now
&& article.removalDate > DateTime.Now
&& article.finished == true
&& article.flagged== true
&& ( article.Scls.Any(s=> listOfScl.Contains(s.id))
|| article.Coms.Any(c=> listOfCom.Contains(c.id))
)
);