How is same query, different servers, different performance?

How is same query, different servers, different performance?

On each database you run, as far as you know, the exact same query (whether a straight up ad hoc query, stored procedure, parameterized query, whatever). On your production server, let’s call it PROD, the query runs for 3 hours before it returns, but on the test server, let’s call it TEST, it returns in about 3 seconds.

Can a same database result in different execution times?

Let’s assume that, probably, the databases are the same, as is the data and the statistics, but the problem is a system or database setting. These differences can result in different execution plans and therefore different execution times.

How does prod keep track of different queries?

However, you’re on top of things. You capture the query metrics so you know exactly the amount of time and the reads or writes from each query and you even do this using extended events so you’re minimizing observer effects. You also have monitoring in place, so you know that there is no blocking in PROD.

What are the different types of query performance issues?

Beyond the database compatibility level, a disabled or enabled trace flag 4199 or a changed state of the database-scoped configuration QUERY_OPTIMIZER_HOTFIXES can also influence query execution plan choices at compile time. Trace flags 9481 (force legacy CE) and 2312 (force default CE) also affect the plan.

Why does one SQL query take longer than the other?

I have a SQL database server and 2 databases under it with the same structure and data. I run the same sql query in the 2 databases, one of them takes longer while the other completes in less than 50% of the time. They both have different execution plans.

What happens if you have two databases on the same server?

The fact that you have two databases on same server and with same data set (as you said) does not ensure same execution plan. mdf and ldf files (for each database) are on different drives. If one drives is faster, that database will run the query faster too. stalled statistics.

What can I do to make SQL query run faster?

They both have different execution plans. The things i have already tried are – rebuild & reorganize index on the table (tblRRMHistSimShifts – this table has over 2 million records), checked for locks or other background processes or errors on server, Max degree of parallelism for the server is 0.

What’s the difference between prod and test server?

On your production server, let’s call it PROD, the query runs for 3 hours before it returns, but on the test server, let’s call it TEST, it returns in about 3 seconds. What. The. Hell. This is especially troubling because PROD has 8 processors that are much more powerful than TEST, which has only 2 (either can go parallel, so this is the same).

Why does SQL Server Proc take so long?

Changing the parameter data type to DATETIME or masking the parameter as mentioned above resolves the issue. Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question.

What happens when you have two different servers?

These differences can result in different execution plans and therefore different execution times. If we are dealing with two different servers and we are fairly sure the data, structure and the statistics are the same, the properties of the first operator are a great starting point for understanding what went wrong.

Why do you get different query plans for different executions?

Are you getting different query plans for different executions (you may need to capture a query plan from your initial benchmarks and compare it to the current plan or you may need to increase your AWR retention to retain query plans for a few months in order to see this).

What happens if all queries come from stored procedures?

If you simply make a mandate that “all queries come from stored procedures,” but you don’t give your staff the training necessary to write fast, scalable stored procedures, then the result won’t perform.

How are stored procedures and executesqlthe plans compiled?

For both stored procedures and sp_executesqlthe plan is compiled according to the value of the first set of parameters it sees.

Is the execution plan the same as the SQL query?

Totally understand that, but an execution plan is a combination of queries, each with its own step. The problem is that Query 4, which is exactly the same query text between the two, is radically different between the sp_executeSQL call and the adhoc query run from sql management studio– Nathan TregillusMar 30 ’11 at 16:46

Which is better not exists or SQL joins?

EXISTS is often better than either of these two and when you are talking left joins where you want to all records not in the left join table, then NOT EXISTS is often a much better choice. Performance is based on the amount of data you are executing on… If it is less data around 20k. JOIN works better.

Which is better inner join or where in SQL?

Query is written in two ways: (1)using the join condition inside where part of the statement. (2) using Inner Join. Inner Join (V2) is slightly better than Where (V1). This might indicate that MySQL could use better optimization technique (s) in the case of Inner Join.

When to use joins instead of subqueries in SQL?

You can also use Profiler to actually run the queries multiple times and get the differnce. I would not expect these to be so horribly different, where you can get get real, large performance gains in using joins instead of subqueries is when you use correlated subqueries.

How to improve query performance in Azure SQL?

You can also disable automatic statistics updates to reduce the chances that the good plan will be evicted and a new bad plan will be compiled. Force the plan by explicitly using the USE PLAN query hint by rewriting the query and adding the hint in the query text.

How can you tell the difference between two different servers?

You have two different servers that, as far as you know, are identical in terms of their options and setup (although not necessarily in terms of power, think a test or pre-production system versus production).

How to monitor the performance of SQL Server?

Monitoring performance by using the Query Store 1 Information in the Query Store. Execution plans for any specific query in SQL Server typically evolve over time due to a number of different reasons such as statistics changes, schema 2 Use the Regressed Queries feature. 3 Finding waiting queries. 4 Key Usage Scenarios.

Is the SQL Server 2005 / 2008 query plan the same?

Interesting thing I noted after reviewing these explain plans was that the SQL Server 2005/2008 version generates the exact same query plan for both the CTE and Derived table version.

How to monitor performance by using the query store?

Monitoring performance by using the Query Store. The SQL Server Query Store feature provides you with insight on query plan choice and performance. It simplifies performance troubleshooting by helping you quickly find performance differences caused by query plan changes.

Is it better to separate a big query into multiple smaller query?

In these cases, you can indeed get faster results breaking one extremely complex query into two less complex queries. That said, it’s rare, and I’ll generally write the complex query and find out if there’s a problem rather than breaking the query into smaller chunks pre-emptively.

How to design SQL queries with better performance?

Hence, 0 rows and a constant scan which means that SQL Server has not touched big table also. This is the place where the cost based optimizer comes to the help and does the optimizations for you rather than us doing it based on a NOT EXISTS or NOT IN clauses.

Can a table UDT be used in more than one database?

Table UDTs are only valid for stored procs within the same database. So yes you would have to create the type on each server and reference it in the stored procs – e.g. just run the first part of this example in both DBs http://msdn.microsoft.com/en-us/library/bb510489.aspx.

Why does data move from one table to another in SQL Server?

Here the partition is not allocated, which means the data moves across the tables. First, this ensures the table definitions are the same before applying the SWITCH TO command.