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Hi


One of my table has got 3lakhs rows affected by row chaining.I have browsed net for the steps that involes to remove the row chaining.They have advised to move the table to the new segment.

alter table move;


After that its showing no rows affected by row chaining.I have tested this on the Test DB.

Consider the live database,every time we cant move the table to remove the row chaining ,its not advisable also.Because one cant permanently avoid RM/RC issues.If this is the case,how could I remove the row chaining? Also if we move the table from one segment to an another new segment,it will create more undo data and more archive logs(Since its recreating the table in the new segment).

I had run the DB health check report on my live DB,it shows the Buffer Cache Hit Rate as 55% . Iam suspecting the row chaining issues for this low Buffer Cache Hit Rate,am I right ?please clear my doubt. If row chaining is not the reason for low Buffer Cache Hit Rate,how do I increase the Buffer Cache Hit Rate? Help needed.

Thanks

Hello, and thank you for your note.

I can appreciate that you are very concerned about the row chaining and buffer cache hit ratio that you observe in your environment.

You have to determine if either of these two effects is causing a problem as far as the application is concerned.  For example, do you have proof by tracing an important "read" task of your application, that the read is slower because of the extra read events caused by the row chaining?  If yes, then you should invest the time and energy required to fix the row chaining.  If the answer is no, then it is hard to justify going through the work to fix the row chaining, only because you observe that there is some row chaining.

We always suggest that you use the Hotsos Method R to understand to what degree business tasks suffer from performance problems, then to understand what are the right corrective actions to take that would be relevant and helpful.

Regards...