pt-online-schema-change script returns 1 even when there is no error

[Pedro Ibáñez]

[In:Percona Toolkit Documentation]
Hi,

I'm using pt-online-schema-change percona-toolkit-2.2.8-1 into a script for changing around 100 tables , before I run the command with the --execute flag I like to run it with the --dry-run flag and I found out what looks like a bug, the percona script always returns 1 even when it does not fail:

pt-online-schema-change --alter ADD KEY index_2(TIPO,ID,CALIFICADOR) h=X.X.X.X,u=root,p=XXXXXX,D=MYBBDD,t=DATOSAUX --nocheck-plan --alter-foreign-keys-method auto --statistics --dry-run

Operation, tries, wait:
  copy_rows, 10, 0.25
  create_triggers, 10, 1
  drop_triggers, 10, 1
  swap_tables, 10, 1
  update_foreign_keys, 10, 1
No foreign keys reference `MYBBDD`.`DATOSAUX`; ignoring --alter-foreign-keys-method.
Starting a dry run. `MYBBDD`.`DATOSAUX` will not be altered. Specify --execute instead of --dry-run to alter the table.
Creating new table...
Created new table MYBBDD._DATOSAUX_new OK.
Altering new table...
Altered `MYBBDD`.`_DATOSAUX_new` OK.
Not creating triggers because this is a dry run.
Not copying rows because this is a dry run.
Not swapping tables because this is a dry run.
Not dropping old table because this is a dry run.
Not dropping triggers because this is a dry run.
2014-07-07T10:25:28 Dropping new table...
2014-07-07T10:25:28 Dropped new table OK.
# Event Count
# ====== =====
# INSERT 0
Dry run complete. `MYBBDD`.`DATOSAUX` was not altered.
Ret:1

The script didn't fail and returns 1 ¿¿??

Now I altered the table manually and launch the script again:

pt-online-schema-change --alter ADD KEY index_2(TIPO,ID,CALIFICADOR) h=X.X.X.X,u=root,p=XXXXXX,D=MYBBDD,t=DATOSAUX --nocheck-plan --alter-foreign-keys-method auto --statistics --dry-run
Operation, tries, wait:
  copy_rows, 10, 0.25
  create_triggers, 10, 1
  drop_triggers, 10, 1
  swap_tables, 10, 1
  update_foreign_keys, 10, 1
No foreign keys reference `MYBBDD`.`DATOSAUX`; ignoring --alter-foreign-keys-method.
Starting a dry run. `MYBBDD`.`DATOSAUX` will not be altered. Specify --execute instead of --dry-run to alter the table.
Creating new table...
Created new table MYBBDD._DATOSAUX_new OK.
Altering new table...
2014-07-07T10:25:28 Dropping new table...
2014-07-07T10:25:28 Dropped new table OK.
# Event Count
# ====== =====
# INSERT 0
Dry run complete. `MYBBDD`.`DATOSAUX` was not altered.
     (in cleanup) Error altering new table `MYBBDD`.`_DATOSAUX_new`: BD::mysql:db do failed: Duplicate key name 'index_2' [for statement "ALTER TABLE `MYBBDD`.`_DATOSAUX_new` ADD KEY index_2(TIPO,ID,CALIFICADOR)"] at /usr/bin/pt-online-schema-change line 8588.

# Event Count
# ====== =====
# INSERT 0
Dry run complete. `MYBBDD`.`DATOSAUX` was not altered.
Ret:1

It fails and returns 1, so, how can I check inside a script that the dry-run worked properly? is it the normal behavior of the pt-online-schema-change?

Thank you

[Nilnandan Joshi (nilnandan-joshi)]

Hi, I have tried to reproduce the same but I'm getting 0 if its successful otherwise error. Can you check or provide that script that how it returns error when pt-osc is successful or not?

nilnandan@nilnandan-Dell-XPS:~$ pt-online-schema-change --alter 'ADD KEY i_c(c)' h=127.0.0.1,u=root,p=root,D=dbtest,t=sbtest --nocheck-plan --alter-foreign-keys-method auto --statistics --dry-run
Operation, tries, wait:
  copy_rows, 10, 0.25
  create_triggers, 10, 1
  drop_triggers, 10, 1
  swap_tables, 10, 1
  update_foreign_keys, 10, 1
No foreign keys reference `dbtest`.`sbtest`; ignoring --alter-foreign-keys-method.
Starting a dry run. `dbtest`.`sbtest` will not be altered. Specify --execute instead of --dry-run to alter the table.
Creating new table...
Created new table dbtest._sbtest_new OK.
Altering new table...
Altered `dbtest`.`_sbtest_new` OK.
Not creating triggers because this is a dry run.
Not copying rows because this is a dry run.
Not swapping tables because this is a dry run.
Not dropping old table because this is a dry run.
Not dropping triggers because this is a dry run.
2014-08-04T15:20:52 Dropping new table...
2014-08-04T15:20:52 Dropped new table OK.
# Event Count
# ====== =====
# INSERT 0
Dry run complete. `dbtest`.`sbtest` was not altered.
nilnandan@nilnandan-Dell-XPS:~$
nilnandan@nilnandan-Dell-XPS:~$ echo $?
0
nilnandan@nilnandan-Dell-XPS:~$
nilnandan@nilnandan-Dell-XPS:~$ pt-online-schema-change --alter 'ADD KEY i_c(c)' h=127.0.0.1,u=root,p=root,D=dbtest,t=sbtest --nocheck-plan --alter-foreign-keys-method auto --statistics --dry-run
Operation, tries, wait:
  copy_rows, 10, 0.25
  create_triggers, 10, 1
  drop_triggers, 10, 1
  swap_tables, 10, 1
  update_foreign_keys, 10, 1
No foreign keys reference `dbtest`.`sbtest`; ignoring --alter-foreign-keys-method.
Starting a dry run. `dbtest`.`sbtest` will not be altered. Specify --execute instead of --dry-run to alter the table.
Creating new table...
Created new table dbtest._sbtest_new OK.
Altering new table...
2014-08-04T15:34:06 Dropping new table...
2014-08-04T15:34:06 Dropped new table OK.
# Event Count
# ====== =====
# INSERT 0
Dry run complete. `dbtest`.`sbtest` was not altered.

Segmentation fault (core dumped)
nilnandan@nilnandan-Dell-XPS:~$
nilnandan@nilnandan-Dell-XPS:~$ echo $?
139
nilnandan@nilnandan-Dell-XPS:~$

[Pedro Ibáñez (pibanez)]

Hello Hilnandan,

you got the return code 139 because of the core dump, can you try again
with the core dumps disabled?

Cheers

On 04/08/14 12:07, Nilnandan Joshi wrote:
> Hi, I have tried to reproduce the same but I'm getting 0 if its
> successful otherwise error. Can you check or provide that script that
> how it returns error when pt-osc is successful or not?
>
> nilnandan@nilnandan-Dell-XPS:~$ pt-online-schema-change --alter 'ADD KEY i_c(c)' h=127.0.0.1,u=root,p=root,D=dbtest,t=sbtest --nocheck-plan --alter-foreign-keys-method auto --statistics --dry-run
> Operation, tries, wait:
> copy_rows, 10, 0.25
> create_triggers, 10, 1
> drop_triggers, 10, 1
> swap_tables, 10, 1
> update_foreign_keys, 10, 1
> No foreign keys reference `dbtest`.`sbtest`; ignoring --alter-foreign-keys-method.
> Starting a dry run. `dbtest`.`sbtest` will not be altered. Specify --execute instead of --dry-run to alter the table.
> Creating new table...
> Created new table dbtest._sbtest_new OK.
> Altering new table...
> Altered `dbtest`.`_sbtest_new` OK.
> Not creating triggers because this is a dry run.
> Not copying rows because this is a dry run.
> Not swapping tables because this is a dry run.
> Not dropping old table because this is a dry run.
> Not dropping triggers because this is a dry run.
> 2014-08-04T15:20:52 Dropping new table...
> 2014-08-04T15:20:52 Dropped new table OK.
> # Event Count
> # ====== =====
> # INSERT 0
> Dry run complete. `dbtest`.`sbtest` was not altered.
> nilnandan@nilnandan-Dell-XPS:~$
> nilnandan@nilnandan-Dell-XPS:~$ echo $?
> 0
> nilnandan@nilnandan-Dell-XPS:~$
> nilnandan@nilnandan-Dell-XPS:~$ pt-online-schema-change --alter 'ADD KEY i_c(c)' h=127.0.0.1,u=root,p=root,D=dbtest,t=sbtest --nocheck-plan --alter-foreign-keys-method auto --statistics --dry-run
> Operation, tries, wait:
> copy_rows, 10, 0.25
> create_triggers, 10, 1
> drop_triggers, 10, 1
> swap_tables, 10, 1
> update_foreign_keys, 10, 1
> No foreign keys reference `dbtest`.`sbtest`; ignoring --alter-foreign-keys-method.
> Starting a dry run. `dbtest`.`sbtest` will not be altered. Specify --execute instead of --dry-run to alter the table.
> Creating new table...
> Created new table dbtest._sbtest_new OK.
> Altering new table...
> 2014-08-04T15:34:06 Dropping new table...
> 2014-08-04T15:34:06 Dropped new table OK.
> # Event Count
> # ====== =====
> # INSERT 0
> Dry run complete. `dbtest`.`sbtest` was not altered.
>
> Segmentation fault (core dumped)
> nilnandan@nilnandan-Dell-XPS:~$
> nilnandan@nilnandan-Dell-XPS:~$ echo $?
> 139
> nilnandan@nilnandan-Dell-XPS:~$
>
>
> ** Changed in: percona-toolkit
> Status: New => Incomplete
>

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Para quejas o reclamac...

[Frank Cizmich (frank-cizmich)]

I'm also unable to replicate this using PT 2.2.8

--dry-run exits with 0 when successful, 255 otherwise.

same with --execute

Pedro, can you provide the script you are using? How are you checking the exit value?

Regards!

[Pedro Ibáñez (pibanez)]

Ok, I have found the problem, it is the fault of my script, your awesome tool is working properly, look:

 [[ "${DEBUG}" -eq "0" ]] && pt-online-schema-change --alter "${ALTER}" h=${HOST},u=${USUARIO},p=${PASS},D=${BBDD},t=${tabla} --nocheck-plan --alter-foreign-keys-method auto --statistics --dry-run 2> ${DRYRUNLOG}

 [[ "${DEBUG}" -eq "1" ]] && echo pt-online-schema-change --alter "${ALTER}" h=${HOST},u=${USUARIO},p=${PASS},D=${BBDD},t=${tabla} --nocheck-plan --alter-foreign-keys-method auto --statistics --dry-run

RETORNO=$?

I was saving the return value of the echo command instead of the right pt-online-schema-change return code, I just changed the order of the checks and now everything is working properly.
I have to apology for the inconvenience and your time checking it out, thank you very much for your help guys.

[Launchpad Janitor (janitor)]

[Expired for Percona Toolkit because there has been no activity for 60 days.]

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PT-1232