ITL mechanism
From: vsevolod afanassiev <vsevolod.afanassiev_at_gmail.com>
Date: Thu, 11 Aug 2011 16:48:44 -0700 (PDT)
Message-ID: <e6e3c67b-89e9-4126-9333-cc09aa20006b_at_m5g2000prh.googlegroups.com>
I was reading about ITL mechanism and it was mentioned that Oracle creates ITL entry for *every* updated row in a block. So if one transaction updates 10 rows in the same block Oracle will create 10 transaction entries (ITL entries). Is it really true? Let's say we have a table with very short row, just one column CHAR(1). In this case there could be more than 1000 rows in 8K block. So to update all rows in this block Oracle will need to create more than 1000 transaction entries in the same block. As each entry is 24 bytes there won'be be enough space to do that. However test shows that update works just fine. Received on Thu Aug 11 2011 - 18:48:44 CDT
Date: Thu, 11 Aug 2011 16:48:44 -0700 (PDT)
Message-ID: <e6e3c67b-89e9-4126-9333-cc09aa20006b_at_m5g2000prh.googlegroups.com>
I was reading about ITL mechanism and it was mentioned that Oracle creates ITL entry for *every* updated row in a block. So if one transaction updates 10 rows in the same block Oracle will create 10 transaction entries (ITL entries). Is it really true? Let's say we have a table with very short row, just one column CHAR(1). In this case there could be more than 1000 rows in 8K block. So to update all rows in this block Oracle will need to create more than 1000 transaction entries in the same block. As each entry is 24 bytes there won'be be enough space to do that. However test shows that update works just fine. Received on Thu Aug 11 2011 - 18:48:44 CDT