Hi, if you don’t know about flashback data archive you can check this post first: http://mustafakalayci.me/2019/03/02/goodbye-log-triggers-welcome-flashback-data-archive/ I mentioned about flashback data archive (FDA) in that post and really flattered it. Well, maybe I shouldn’t! FDA is really fast dml tracking method but thanks to Peter Schlaeger, I noticed some potential problems and “some” solutions. Few
Administration
Oracle Table Compression Part1
Hi, I have been dealing with table compression a lot during my development period and I still do. I wanted to share some information about table information but I believe this will be a long explanation so I will write them in parts and this is part1. Table compression is a very useful feature of
Redo Log Switch Order
Hi, I always have the impression that redo log switch occurs in group number order but a small test showed me, I was wrong. As you know redo log is one of the most important part of a Oracle database. it almost protect everything! your data in memory, data file, your transaction etc. whenever you
NVME Drives and Oracle Database
Hi There, NVME drives are so hot these days. They have amazing read/write speed. my old samsung ssd drive can read and write around 550/530 MB per second and my even older 2.5inch hdd drive has 45/20 MB per second. Current NVME disc drives has around 3500 read and 3000 MB per second which is
Control File Content and the Limits
Hi, I would like to talk about Control File (CF). One of the most important component of the Oracle Database. It stores many critical data and limits for the database. Last SCN (System Change Number). Last Checkpoint Information. Data file locations. Redo log file locations. RMAN Repository (where the backup related files are). Parameters like
Frequent and Fast Refresh Materialized Views has a Big Problem!
Hi, While I was checking V$SQL_PLAN view for a whole different reason, I realized that some of the cursors has incredibly high child cursors. I started to dig and finally I find the problem. My customer have a few frequently fast refreshed materialized views. One of them is refreshed every 10 seconds (you might say
Is It Possible to Change SQL Statement in the Database?
YES! Hi, today I want to write about something which has been asked for many times to me. Let’s say you have an application and it is running very poorly designed sql statements in your database and you are really bored having fights with development teams to ask a change about the sql. Well, in
V$SqlStats vs V$SqlStats_Plan_Hash, different columns?
Hi there, V$SQLSTATSis a beautiful view for information about sql statements. you might say v$sql has that information too which is correct but V$SQLSTATSis much more faster than v$sql and keeps data about sql statements for a longer time than v$sql. https://docs.oracle.com/en/database/oracle/oracle-database/19/refrn/V-SQLSTATS.html However, the V$SQLSTATS view differs from V$SQL and V$SQLAREA in that it is faster, more scalable, and has a
Native Compilation of a PLSQL Object
Hi, you’ve probably heard about “NATIVE” compilation about plsql objects. I wanted to demonstrate how it is work and whether it really does matter or not. By default Oracle compiles every plsql object as “INTERPRETED” which means, your plsql code transform into a intermediate form which interpreted every time when you run it. This part
What is the Max Size of an Oracle Database?
Hi, sometimes I search for “what is the biggest” or “what is the highest” of things and I just realized that I never checked for the max size of an Oracle Database. so based on the limitations ( https://docs.oracle.com/en/database/oracle/oracle-database/19/refrn/physical-database-limits.html#GUID-939CB455-783E-458A-A2E8-81172B990FE9 ) and using default settings; default tablespace type is “smallfile” which means a datafile can contain