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 […]

Timestamp Arithmetic and Well Known Mistakes

Hi, Lately, I started to see many developer uses timestamp types (like timestamp or timestamp with time zone) wrong especially in time arithmetic. So as a short reminder, adding and subtracting numbers to/from a DATE value will add/subtract number of days:

Basically that is all if you use add and subtract of course we […]

CSV Data in Clob to Columns Using Select

Hi, Thanks to one of my customers, I am dealing with csv data in clob lately a lot. so they asked me if I can get a csv data in a clob column as separated columns using select statement. They wanted to show this data on their applicaitons. I suggested different methods but they said […]

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 […]

Performance Gain of NOCOPY Parameters

Hi, Almost every Oracle database uses PLSQL codes like packages/procedures/functions etc. Complex systems with complex codes pass many arguments (parameters) many times between plsql objects. Passing parameters might be the most executed operations in a database. So how well do you pass your parameters? I assume you know about types of parameters like IN or […]

Oracle Join Methods

Hi, Actually I won’t explain anything today. I will just share a video by Chris Saxon who is also from askTom team. Great guy, you should also follow him. So he made a great, so simple and explanatory video that I have ever seen. Many thanks to Chris. Please watch.