Re: how does expdp use undospace
From: David Fitzjarrell <oratune_at_yahoo.com>
Date: Thu, 29 May 2014 07:35:22 -0700 (PDT)
Message-ID: <1401374122.67802.YahooMailNeo_at_web124704.mail.ne1.yahoo.com>
It uses it the same way any query would use it when reconstructing the data 'image' at the time the query started. expdp creates a consistent 'image' of the table data for each table exported; as such it's subject to the availability of the redo/undo going back to the time the query/export started for a given table. I blogged on that here: The Dreaded ORA-01555 The Dreaded ORA-01555 After looking more closely at the blog I mentioned in my last entry I'm finding more and more that this poor soul has offered in the way of advice that is either incomplete or wrong. One of the mor... View on dfitzjarrell.wordpress.com Preview by Yahoo which explains the conditions causing the 'dreaded' ORA-01555, including delayed block cleanout which may be affecting your exports. David Fitzjarrell Principal author, "Oracle Exadata Survival Guide" On Thursday, May 29, 2014 8:20 AM, David Yu <mr.fishyu_at_gmail.com> wrote: Hi List, I am using expdp to dump two schemas in two sessions with parallel3,but I have Ora-01555 error. My understanding for the undo space usage by expdp is for the consistent read for those blocks which are changed by the transactions after starting expdp. I'd like to understand how dose expdp use the undo space? Rgds David-- http://www.freelists.org/webpage/oracle-l
Date: Thu, 29 May 2014 07:35:22 -0700 (PDT)
Message-ID: <1401374122.67802.YahooMailNeo_at_web124704.mail.ne1.yahoo.com>
It uses it the same way any query would use it when reconstructing the data 'image' at the time the query started. expdp creates a consistent 'image' of the table data for each table exported; as such it's subject to the availability of the redo/undo going back to the time the query/export started for a given table. I blogged on that here: The Dreaded ORA-01555 The Dreaded ORA-01555 After looking more closely at the blog I mentioned in my last entry I'm finding more and more that this poor soul has offered in the way of advice that is either incomplete or wrong. One of the mor... View on dfitzjarrell.wordpress.com Preview by Yahoo which explains the conditions causing the 'dreaded' ORA-01555, including delayed block cleanout which may be affecting your exports. David Fitzjarrell Principal author, "Oracle Exadata Survival Guide" On Thursday, May 29, 2014 8:20 AM, David Yu <mr.fishyu_at_gmail.com> wrote: Hi List, I am using expdp to dump two schemas in two sessions with parallel3,but I have Ora-01555 error. My understanding for the undo space usage by expdp is for the consistent read for those blocks which are changed by the transactions after starting expdp. I'd like to understand how dose expdp use the undo space? Rgds David-- http://www.freelists.org/webpage/oracle-l
-- http://www.freelists.org/webpage/oracle-lReceived on Thu May 29 2014 - 16:35:22 CEST