Select object_name, edition_name, object_type, namespace, editionable, status If we want to reorder columns physically, maybe to improve data compression, then this is not the way to do it. Important to understand is that the table is not physically changed, only the data dictionary entry is manipulated.
This can be used to reorder columns in the column list. We can change the logical column order by setting them invisible and making them visible again. So loosing the sequence cache looks like the default behaviour, although it is not. The problem is that most DBAs seem way too keen on doing a shutdown abort. All other “organized” shutdowns will keep the cache intact. So a shutdown abort will loose the sequence cache. See Oracle Database Utilities for details. The database might also skip cached sequence numbers after an export and import. Also, sequence numbers that have been used but not saved are lost as well. For example, when an instance abnormally shuts down (for example, when an instance failure occurs or a SHUTDOWN ABORT statement is issued), sequence numbers that have been cached but not used are lost. The database might skip sequence numbers if you choose to cache a set of sequence numbers. There is an indirect mention of the behaviour in the 11g admin guide. It will probably not work in the same way on a RAC – because there is a separate cache for each instance. it might be that only older versions of the oracle docs still have this information.
This was documented somewhere but I am not able to find it anymore. Only a shutdown abort will loose the cache. Instead the next value will be used and set as last_number. Shutdown normal|immediate|transactional will not loose the sequence cache. Using this parameter we can test some of the newest options which are available only on exadata/cloud, like automated indexing.ĥ – sequence cache is not lost during graceful database shutdown alter system set "_exadata_feature_on"=true scope=spfile Warning! This is only for testing purposes! It can potentially destroy your database.
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