Re: X$BH.TCH What does it means ?

TCH is the Touch Count Value. From 8i Onwards... The LRU Mechanism is modified to include a Touchcount Algorithm.

In previous rel whenever a Block is read into Memory the Block is placed in the MRU End of the LRU List but from 8i onwards the the Block is Placed in the Middle of the LRU List and the Touch Count Value is Updated when ever the Block is accessed. In This way Oracle Make sure that the MRU End of the List id ot filled with blocks that are used for single row Updates..and Not Touched afterwards.

When this Block comes to the LRU End and the touchcount is pretty high the Block is Placed in the MRU End.

So u need not worry abiyt the TCH Column.

-- 
HTH

Regards,
Ganesh R
"Miguel Zunda" <mzunda_at_polar.es> wrote in message
news:3EE5AF58.9010003_at_polar.es...


> Hello.

>

> When I look at my x$bh I see hundreds of rows with a tch higher than

> 150.  Loads of them are blocks of the same index or of the same table.

>

> 1/What does it mean?.

> 2/What can I do to minimize this value?.

>

> Thanks

>