AW: enq: CR - block range reuse ckpt [mode=6]

I observe the same thing when I overwrite tables via datapump.  

Was just experimenting
1- Import tables using datapump (Table_exists_action = replace)  

2- After 2 hours. Import the same tables using the same dump but in other tablespaces (remap_tablespce)  

The first call takes ca. 1 hours, the second one takes more than 5 hours. In the ASH I see the same wait event.
Database 12.1.0.2, rac, 2 nodes.  

Best regards
Ahmed Fikri      

-----Original-Nachricht-----
Betreff: Re: enq: CR - block range reuse ckpt [mode=6] Datum: 2021-04-16T16:32:50+0200
Von: "Jonathan Lewis" <jlewisoracle_at_gmail.com> An: "Noveljic Nenad" <nenad.noveljic_at_vontobel.com>        

When I've seen that enqueue it's been associated with (really) dropping objects - either from an explicit "drop purge" or as an internal side effect (e.g. when a split partition creates two new partitions and drops the old one, or you do some online operation that creates an internal journal table thne drops it on completion). Possibly it also appears after you've dropped a table and oracle finally gets around to purging the recyclebin.  

Regards
Jonathan Lewis    

On Fri, 16 Apr 2021 at 07:46, Noveljic Nenad <nenad.noveljic_at_vontobel.com <mailto:nenad.noveljic_at_vontobel.com> > wrote:

  What could have caused high waits on enq: CR - block range reuse ckpt   [mode=6] ?    

  How to approach the analysis?    

  The database version is 19.9.0.0.201020.    

  The wait chains:    

  SQL> _at_ash_wait_chains2 event2 "sql_opname='ALTER TABLE'" &today    

• Display ASH Wait Chain Signatures script v0.5 BETA by Tanel Poder ( <http://blog.tanelpoder.com> )

  %This     SECONDS     AAS WAIT_CHAIN                                     
                                                                           
                                                                           
                                                                           
                                 FIRST_SEEN          LAST_SEEN

  ------ ---------- -------
  ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  ------------------- -------------------

    65%        9263      .3 -> enq: CR - block range reuse ckpt  -> [idle
  blocker 1,1723,17157 (oracle_at_svavt02p (CKPT))]                           
                                                                           
                                                                           
                                   2021-04-16 04:42:49 2021-04-16 07:00:32

    25%        3555      .1 -> library cache lock  -> enq: CR - block range
  reuse ckpt  -> [idle blocker 1,1723,17157 (oracle_at_svavt02p (CKPT))]      
                                                                           
                                                                           
                                 2021-04-16 05:21:01 2021-04-16 06:50:42

     4%         507      .0 -> enq: CR - block range reuse ckpt  -> db file
  single write                                                             
                                                                           
                                                                           
                                 2021-04-16 04:42:52 2021-04-16 06:56:38

     2%         332      .0 -> enq: CR - block range reuse ckpt  -> control
  file parallel write                                                      
                                                                           
                              

   

  Best regards,    

  Nenad

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