yahoo-eng-team team mailing list archive

[Chris Friesen <chris.friesen@xxxxxxxxxxxxx>]

Public bug reported:

When running "nova-manage db online_data_migrations", it will report how
many items matched the query and how many of the matching items were
migrated.

However, most of the migration routines are not properly reporting the
"total matched" count when "max_count" is specified.  This makes it
difficult to know whether you have to call it again or not when
specifying "--max-count" explicitly.

Take for example Flavor.migrate_flavors().  This limits the value of
main_db_ids to a max of "count":

main_db_ids = _get_main_db_flavor_ids(ctxt, count)
count_all = len(main_db_ids)
<snip>
return count_all, count_hit

If someone sees that there were 50 items total and 50 items were
converted, they may think that all the work is done.  It would be better
to call _get_main_db_flavor_ids() with no limit to the number of
matches, and apply the limit to the number of conversions.

Alternately, we should document that if --max-count is used then "nova-
manage db online_data_migrations" should be called multiple times until
*no* matches are reported and we can basically ignore the number of
hits.  (Or until no hits are reported, which would more closely align
with the code in the case that max-count isn't specified explicitly.)

** Affects: nova
     Importance: Undecided
         Status: New

** Description changed:

  When running "nova-manage db online_data_migrations", it will report how
  many items matched the query and how many of the matching items were
  migrated.
  
  However, most of the migration routines are not properly reporting the
  "total matched" count when "max_count" is specified.  This makes it
  difficult to know whether you have to call it again or not when
  specifying "--max-count" explicitly.
  
  Take for example Flavor.migrate_flavors().  This limits the value of
  main_db_ids to a max of "count":
  
- main_db_ids = _get_main_db_flavor_ids(ctxt, count)    
+ main_db_ids = _get_main_db_flavor_ids(ctxt, count)
  count_all = len(main_db_ids)
  <snip>
  return count_all, count_hit
  
- 
- If someone sees that there were 50 items total and 50 items were converted, they may think that all the work is done.  It would be better to call _get_main_db_flavor_ids() with no limit to the number of matches, and apply the limit to the number of conversions.
+ If someone sees that there were 50 items total and 50 items were
+ converted, they may think that all the work is done.  It would be better
+ to call _get_main_db_flavor_ids() with no limit to the number of
+ matches, and apply the limit to the number of conversions.
  
  Alternately, we should document that if --max-count is used then "nova-
  manage db online_data_migrations" should be called multiple times until
  *no* matches are reported and we can basically ignore the number of
- hits.
+ hits.  (Or until no hits are reported, which would more closely align
+ with the code in the case that max-count isn't specified explicitly.)

-- 
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https://bugs.launchpad.net/bugs/1695991

Title:
  "nova-manage db online_data_migrations" doesn't report
  matched/migrated properly

Status in OpenStack Compute (nova):
  New

Bug description:
  When running "nova-manage db online_data_migrations", it will report
  how many items matched the query and how many of the matching items
  were migrated.

  However, most of the migration routines are not properly reporting the
  "total matched" count when "max_count" is specified.  This makes it
  difficult to know whether you have to call it again or not when
  specifying "--max-count" explicitly.

  Take for example Flavor.migrate_flavors().  This limits the value of
  main_db_ids to a max of "count":

  main_db_ids = _get_main_db_flavor_ids(ctxt, count)
  count_all = len(main_db_ids)
  <snip>
  return count_all, count_hit

  If someone sees that there were 50 items total and 50 items were
  converted, they may think that all the work is done.  It would be
  better to call _get_main_db_flavor_ids() with no limit to the number
  of matches, and apply the limit to the number of conversions.

  Alternately, we should document that if --max-count is used then
  "nova-manage db online_data_migrations" should be called multiple
  times until *no* matches are reported and we can basically ignore the
  number of hits.  (Or until no hits are reported, which would more
  closely align with the code in the case that max-count isn't specified
  explicitly.)

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