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Re: Large in memory DW table

From: Nigel Thomas <nigel_cl_thomas_at_yahoo.com>
Date: Fri, 16 Nov 2007 08:15:57 -0800 (PST)
Message-ID: <492535.48758.qm@web58808.mail.re1.yahoo.com>


Ric, unless things have changed recently you *always* get at least 2 slots in the ITL, even when you specify just one. See earlier threads eg http://www.freelists.org/archives/oracle-l/03-2005/msg00811.html.

I repeated Mark Powell's test (create table ... initrans 1) on XE 10.2.0.1.0 and my block dump looks like this:

Block header dump: 0x0040da0a
Object id on Block? Y
seg/obj: 0x5fb8 csc: 0x00.63166d itc: 2 flg: - typ: 1 - DATA fsl: 0 fnx: 0x0 ver: 0x01
Itl Xid Uba Flag Lck Scn/Fsc
0x01 0x0009.016.00000c35 0x008002e9.0cf9.03 C--- 0 scn 0x0000.0063166c 0x02 0x0001.010.0000095b 0x00801519.0bbf.0f --U- 25 fsc 0x0000.0063166e

Regards Nigel

<snip>

ITLs are not used for a SELECT, however they are checked by a SELECT (or any other statement that touches a block) to see if there are still valid transactions in the block. The disadvantage to forcing only one ITL slot is that there can never be more then one transaction ever doing DML in the block. I think setting it to at least 2 might be a better idea, just gives you some options for the future.  

<snip>

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Received on Fri Nov 16 2007 - 10:15:57 CST

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