I have been slowly trying to learn MDX coming from a background of using SQL. In DBMSs such as PostgreSQL, one can get a query plan for their query e.g. using EXPLAIN. Is this possible in any version of MDX and if so, how? I have not managed to come across something of this nature.
Not exactly a query plan, but DMVs and profiler will be helpful. The profiler can be launched from management studio, Tools.
Related
In Oracle IDEs, such as Navigator, Toad, Oracle SqlDeveloper how can I get a query execution plan for a query / stored procedure?
I can find some commands for them online, even though I am not able to use them sometimes, but is there any functionality/tools built-in for these IDE's for that purpose?
Here's for TOAD and SQL Developer; don't know about other tools as I don't use them.
Here are the ones I have found.
For navigator:
Or from Tools-Explain Plan Tolls
And I found out another tool for getting SQL Plan too. It has been of great help to me. It's
Dell™ SQL Optimizer for Oracle®
There, you can simply write your query, and it will both find better versions of it and show and compare their plans too.
I am very new to SQL queries and developing a report using the SQL Server 2008. I was trying to find ways to optimize my query and came across something called as SQL Hints. I researched some sites and it said it overwrites the existing optimizing policy which SQL decides for the query.
I would like to know if the same will work for a view? Because I am using views to extract data.
Please guide.
Since view is a saved query, query hints also apply to the query behind view. My humble guess is that you don't have to use hints to optimize your query, look around indexes and ensure your query uses sargs for optimization.
just a question about Neo4j and graph databases: Is there something similar like SQL Server Management Studio from Microsoft?
Background information: I have to compare SQL vs graph databases for study. For the practical section I need to implement a friend structure (of social networks) for sql and (I chosen) Neo4j. I just want to compare the speed of both dbs (performance test). So if I execute a query I need the execution time - and I know SQL Server Management Studio does this.
Or has someone any other solution/idea for comparison? :)
Thanks.
It depends on what you are testing. If you are testing Cypher execution speed (which is not optimized for performance yet), then you get timings with the result set. Otherwise, you could implement an unmanaged extension that measures queries as they come in and get executed, see http://docs.neo4j.org/chunked/milestone/server-unmanaged-extensions.html .
I've seen the sql server execution plan and the mysql explain, which give details about where queries are not performing as well as they might. I think I need to create some indexes, but I'm not sure where.
Is there a tool for sqlite ?
Don't mind if its on the mac or windows.
SQLite has a built-in query explain statement. You probably want EXPLAIN QUERY PLAN.
In the never-ending search for performance (and my own bludgeoning experience), I've learnt a few things that could drag down the performance of a SQL statement.
Obsessive Compulsive Subqueries Disorder
Doing crazy type conversions (and nest those into oblivion)
Group By on aggregate functions of said crazy type conversions
Where fldID in (select EVERYTHING from my 5mil record table)
I typically work with MSSQL. What tools are available to test the performance of a SQL statement? Are these tools built in and specific to each type of DB server? Or are there general tools available?
SQL Profiler (built-in): Monitoring with SQL Profiler
SQL Benchmark Pro (Commercial)
SQL Server 2008 has the new Data Collector
SQL Server 2005 (onwards) has a missing indexes Dynamic Management View (DMV) which can be quite useful (but only for query plans currently in the plan cache): About the Missing Indexes Feature.
There is also the SQL Server Database Engine Tuning Advisor which does a reasonable job (just don't implement everything it suggests!)
I mostly just use Profiler and the execution plan viewer
Execution Plans are one of the first things to look at when debugging query performance problems. An execution plan will tell you how much time is roughly spent in each portion of your query, and can be used to quickly identify if you are missing indexes or have expensive joins or loops.
MSSQL has a database tuning advisor that will often recommend indexes for tables based upon common queries run during the tuning period, however it wo't rewrite a query for you.
In my opinion, experience and experimentation are the best tools for writing good SQL queries.
In mysql (may be in other databases too) you can EXPLAIN your query to see what database server thinks about it. This usually used to deside which indexes should be created. And this one is build-in, so you can use it without installing additional software.
Adam Machanic has a simple tool called SqlQueryStress that might be of use. It is designed to be used to "run a quick performance test against a single query, in order to test ideas or validate changes".