Clik here to view.
ORA-06502: PL/SQL: numeric or value error: Bulk Bind: Truncated Bind
Have you ever been faced to the above error? I mean this bizarre Bulk Bind: Truncated Bind? This is a strange and unclear error message. Let me put you in the context that gave me this error. I am...
View ArticleClik here to view.
Intelligent CBO
Just a small note to show you a situation I’ve recently encountered which shows how the CBO is intelligent. I have the following two pieces of SQL UPDATE t1 a SET a.padding = 'yyyyyyyy' WHERE a.id1 in...
View ArticleClik here to view.
On how to enforce uniqueness when unique constraint is not possible
The following select gives a list of existing table that do not possess a unique constraint select table_name from user_tables u1 where not exists (select null from user_constraints u2 where...
View ArticleClik here to view.
You want a bridge from single instance to RAC? this book is for you
When Syed Jaafar Oracle ACE Director and one of the world RAC experts asked me to review the new book Oracle Expert Oracle RAC 12c he has coauthored with 3 other Oracle ACE Directors, my first thought...
View ArticleClik here to view.
CBO and unusable unique index
Very recently a question came up on oracle-list where the original poster was wondering about two things (a) how could a refresh on materialized view allows duplicate key to be possible in the presence...
View ArticleClik here to view.
Index on a virtual column: would it help others?
Is it possible to create an index on a column a and use it for column b? In certain situations yes. Let’s first build the model and explore those situations (in 11.2.0.3) create table t1 as...
View ArticleClik here to view.
Partitioned Index: Global or local?
Recently I was investigating a performance problem using the SQL Monitoring feature looking for SQLs taking more than 5 seconds, when one query retained my attention. I drilled down to its...
View ArticleClik here to view.
Cost-Based Oracle Fundamentals: a magic book
It was back in late 2005 or early 2006 when I was prompted by an Oracle magazine issue to buy the then best Oracle seller book of the year: Oracle Cost Based Fundamentals. When Amazon shipped me this...
View ArticleClik here to view.
Interval Partitioning and PSTOP in execution plan
The last release of the Northern California Oracle Users Group Journal published a Tom Kyte article entitled Advice for an Oracle Beginner? In which the author wrote the following phrase...
View ArticleClik here to view.
Log file sync and user commits
This is a brief note to demonstrate from where a difference between the number of log file sync wait event and user commits might come. Very recently I have been pointed out in an otn thread that my...
View ArticleClik here to view.
Expert Oracle Database Architecture: buy your Oracle job insurance
In the process of reviewing books I have bought almost a decade ago (first edition), today is the turn of Tom Kyte Expert Oracle Database Architecture. The review of this book, and a couple of others...
View ArticleClik here to view.
SQLTXPLAIN under Oracle 12c
I like very much Tanel Poder snapper and Carlos Sierra SQLTXPLAIN . They represent valuable performance diagnostic tools. Unfortunately I am still waiting to find a customer site where I will be...
View ArticleClik here to view.
On how important is collecting statistics adequately
Very recently I have been handled the following sub-optimal execution plan of a classical MERGE statement between two tables, t1 and t2...
View ArticleClik here to view.
Why?
Why? This is a fundamental question. And in the context of my work (or actually my hobby to say so) I often say ”Why”. Yesterday I have been handled a query to tune. This query is honored with the...
View ArticleClik here to view.
Dynamic Partition Pruning
A recent question on otn forum prompted me to write few words about dynamic pruning. Dynamic pruning occurs when Oracle knows that it will accomplish a partition pruning (elimination) but is unable to...
View ArticleClik here to view.
Partition pruning with hash partitioned tables
This is a simple reminder on how partition pruning with hash partitioned table could be different from range partitioned ones. If you have a range partitioned table, a query using a partition key in...
View ArticleClik here to view.
Tuning via row source execution plan
Browsing over draft blogs I have not finished and forget to come back to, I found one article about a sub optimal execution plan of a query suffering terrible performance problem. If my memory is still...
View ArticleClik here to view.
Partition range operation: how many times it has been started
It is well known that when reading row source execution plan in order to states about the accuracy of the estimations done by the CBO based on the available table and index statistics, we should use...
View ArticleClik here to view.
2013 in review
I would like to share with you a summary of my annual blogging stuff. My 2013 blogging activity was more accurate than it was the last year. I have published 33 new posts growing the total archive to...
View ArticleClik here to view.
SQL Plan Management: what’s new in 12c
Don’t be disappointed by the title. This is a simple note to show one difference I have noticed in how a stored SPM execution plan is managed when a dependent object is dropped or renamed. To keep it...
View Article