How to use SELECT clause using in very slow?
– Stack Overflow SELECT clause using IN … very slow? Could you guys please review the following query to an Oracle DB and point out what’s wrong: Time taken: 10.53 seconds. t2.empno is indexed. t1.id is indexed. t2.id is indexed. The above query was just a sample replica of the query i use. Here below in a more true form
What can I do about Oracle-in clause too slow?
However, when I do first the subquery, I export the results to excel (they are always like between 100 or 400 results) and then I pass ass static values, the query only takes 1 second: I want something like the subquery runs only once, pass the values and then the other query start running. What can I do ?
When to use the with clause in a larger query?
I have identified one particular with clause in a larger query to be really, really slow. Here are three versions of the same query, they all have the same execution plan! Version 1 (takes 30 seconds): Version 2 (takes 50ms): I’d really like to use the with clause to keep the large query tidy. However, the difference in execution time is dramatic.
When to use the with clause in Oracle?
I’d really like to use the with clause to keep the large query tidy. However, the difference in execution time is dramatic. Version 2 and 3 only take a few ms and Version 1 runs for about 30 seconds. What is it that oracle does so that the statement with the with clause is that much slower and how can I get rid of it?
What does an n-prefixed data type mean?
The N-prefixed data types indicate that the resulting string could be comprised of a Unicode character set with variable length where each character occupies 2 bytes.
Can a string be converted without the N prefix?
Without the N prefix, the string could be converted to the default charset of the database but could result in certain special characters not being recognized as part of the International Language Character Set. Today’s development platforms or their operating systems support the Unicode character set.
Why is index not used in varchar query?
Also, this explains the index not being used for this query because the index will not get seek when a column used with any function in Where clause. SQL Server parse and compile time: CPU time = 12 ms, elapsed time = 12 ms. (1 row affected) Table ‘SalesOrderHeader’.