标签归档:ora-01555

ORA-01555和延迟块清除

01555, 00000, "snapshot too old: rollback segment number %s
with name \"%s\" too small"
// *Cause: rollback records needed by a reader for consistent read
//         are overwritten by other writers
// *Action: If in Automatic Undo Management mode, increase
//	undo_retention setting. Otherwise, use larger rollback segments

出现ORA-01555直接的原因是一致读所需的undo records被覆盖, 一致读失败有两种情况:
1. 数据块中ITL结构对应的undo block被覆盖, 无法构造一致读.
2. transaction table in undo segment header: 延迟块清除发生时, 如果Oracle需要回滚对应的transaction table, 找到事务确切提交的时间. 而且所需的undo record被覆盖, ORA-01555也会发生.
继续阅读

reading of this two week

Oracle automatic segment space management: ASSM internal structures
http://www.dba-oracle.com/art_builder_assm.htm

Not KEEPing
http://jonathanlewis.wordpress.com/2010/03/20/not-keeping/

Row Directory
http://jonathanlewis.wordpress.com/2009/05/21/row-directory/

Index too big
http://jonathanlewis.wordpress.com/2010/03/25/index-too-big/

heap block compress
http://jonathanlewis.wordpress.com/2010/03/30/heap-block-compress/

Failed Login
http://jonathanlewis.wordpress.com/2010/04/05/failed-login/

Daylight Saving Time Causes Performance Issues!
http://prodlife.wordpress.com/2010/04/02/daylight-saving-time-causes-performance-issues/

Block cleanout – fast or delayed.
http://www.jlcomp.demon.co.uk/cleanout.html

Snapshot too old and delayed block cleanout
http://www.ixora.com.au/q+a/0103/24224451.htm

Parse Calls
http://jonathanlewis.wordpress.com/2007/07/03/parse-calls/

Nutshell – 1
http://jonathanlewis.wordpress.com/2009/10/14/nutshell-1/