Commit and Moveout

NarayanV

Hi Team,

 

   Would like to know , whether COMMIT statment will invoke moveout process, so that the data in WOS (Memory) moves to ROS (Disk). Please explain.

Gayatri_R

Hi,

 

Issuing a COMMIT will not trigger a moveout. By default, TM Moveout runs every 300 seconds (this is governed by the configuration parameter 'MoveOutInterval'  - default is 300 seconds). Data will remain in WOS even after a  COMMIT until the next moveout run.

 

Thanks

Gayatri

NarayanV

Hi,

 

   Thanks for getting back to me. So my understanding , is that there is slight possiblity of lossing the data even after commiting the data, like all nodes going down together in a cluster before the moveout happens.

 

    The real  safe point  as for us the data is concerned is that "The checkpoint epoch", which is the latest epoch for which there is no data in the WOS.  Please correct me , if my udnerstanding is wrong.

eli_revach

Hi , Correct you still have a chance for data lost if all your nodes are failed (in case of clean showdown Vertica will make sure your WOS is clean before finish ) . The real safe point for you to recover is LGE ( last good epoch ) I hope you will find it useful Thanks

NarayanV

Thanks, Now I am clear