I believe, Oracle provide better performance for single query. Nice articicle, thank you. Would you mind to explain 11 and 12 with one each. I couldnt distinguish. Nice Article. Very useful. Can any one suggest me when we have to use union operator ,any minimum records count is their. If query fetch 50, rows can we use union operator. Suggest me if any record count restrictions. Bitmap gives a lot of flexibility.
In general to get the same performance as the three bitmaps, we need to place all three columns in a single index. From 12c you can benefit from non shared statistics on GTT and temporary undo to achieve really high concurrency and performance.
Hi Ranjan. I wonder if I could authorize me to write this information in Spanish and put in my Spanish Blog. Thanks so much. Save my name, email, and website in this browser for the next time I comment. This is by no means an exhaustive list to get the best tuning results but can serve as a ready reference to avoid the common pitfalls while working with Oracle SQL: 1. If the selective predicate is in the sub query, then use IN. Use equi-joins whenever possible, they improve SQL efficiency Often this results in the entire view being instantiated, and then the query is run against the view data Partitioning strategies.
About the Author: Ranjan Gupta. Related Posts. Tomaz July 21, at pm - Reply. Arjun August 31, at pm - Reply. Very helpful information Ranjan. This saves lot of time for developers by checking these points. If your database load is low in the daylight, you can run it.
Statistic of Database and its objects should be up to date in Oracle database for Oracle optimizer. Because Oracle optimizer uses database statistics to generate lots of execution plans in same time and If statistics are up to date ,then Optimizer decide correct execution plans. If your database statistics are staled out of date , then you should update it. The usage of Index is very common especially in the performance tuning of Oracle Databases.
It is one of the most important objects that are indispensable and proper performance tuning of databases. Too many delete operations cause fragmentation and performance problems. Just use it as a last resort. You should analyze all columns in select or DML clause and if it is unnecessary, you should remove that columns in queries.
I have run several of the examples using MariaDB Thanks a lot for pointing this out. I would not have thought this possible at the time : They even have hash joins now, still hoping for support for heap tables, too. I just have a question though probably a very dumb one but, oh well where can I find the databases to run your SQL code for examples 4 and 5? I really want to be able to follow along those queries but not sure how to get ahold of those databases for this to work.
Thank you very much in advance. Thanks for your nice words! Just make something up. Skip to content Listicles like these do work — not only do they attract attention, if the content is also valuable and in this case it is, trust me , the article format can be extremely entertaining.
This article will bring you 10 SQL tricks that many of you might not have thought were possible. SUM t. Like this: Like Loading Published by lukaseder. Could you suggest me to replicate problem 7 in sybase? Happy now? Ah, I see then. You are right. My solution is incorrect, sorry. I sent a solution by mail datageekery so that I could add a schema… Loading Hi lukaseder, very good presentation for better understanding of this function.
Thank you very much for pointing this out. Challenge accepted : Loading Cheers, Lukas Loading
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