[Bucardo-general] NUMLOG / BUCARDO - Only half of insert are done in database

Perez Sanchez, Enrique enrique.perez_sanchez at siemens.com
Fri Dec 2 07:41:37 UTC 2022 

Hi!

Your setup looks good to me, Quentin.

Before you try to insert data on both servers simultaneously your replication works ok, right?

Please, check this excellent reply by Francisco Puga on how to replicate DBs with sequences on multi-master with Bucardo:
https://stackoverflow.com/questions/30752829/how-to-handle-sequences-in-bucardo-postgresql-multi-master

I guess you’re getting close now :)

BR!
Kike

----
From: Support EDI <support.edi at numlog.fr> 
Sent: jueves, 1 de diciembre de 2022 18:52
To: Perez Sanchez, Enrique (SMO SWE RC-ES EN EN ITSEC&PLT-COC PLT) <enrique.perez_sanchez at siemens.com>; bucardo-general at bucardo.org
Subject: Re: [Bucardo-general] NUMLOG / BUCARDO - Only half of insert are done in database

Hello Kike,

Many thanks for your quick feedback and sorry by my late one.

I have re installed Bucardo to follow your advice. I have now 1 instance of bucardo installed on server 1, nothing on server 2. Both databases are now set to source.
I think now I got more details on the error. Now when I'm trying to insert several datas at the same time I got a primary key constraint violation on my second server.
I have added sequences as I though it should help to solve it but I probably did something wrong.

Below is my setup : 

-- dbgroups:
dbgroup: hbmsync  Members: serv1:source serv2:source
-- databases:
Database: serv1  Status: active  Conn: psql -U bucardo -d hubmaster -h ***.***.***.24
Database: serv2  Status: active  Conn: psql -U bucardo -d hubmaster -h ***.***.***.24
-- relgroup:
Relgroup: hubmaster  DB: serv1  Members: public.files
  Used in syncs: hbmsync
-- syncs:
Sync "hbmsync"  Relgroup "hubmaster"  DB group "hbmsync" serv1:source serv2:source  [Active]
-- tables:
2. Table: public.files  DB: serv1  PK: code (integer)
-- sequences:
Sequence: public.files_code_seq  DB: serv1

I have also tried with a second sequence  with db pointing to server2 but the error remain the same.

Have you any idea on how I can set up bucardo to fix this issue?

Many thanks for your help.

Best regards,



Quentin BIENFAIT 
Equipe EDI / EDI Team 


mailto:support.edi at numlog.fr 
tel:+33130791616 

9 ter route de Saint Germain
78640 Villiers Saint Frédéric - France 



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Le 25/11/2022 à 12:38, Perez Sanchez, Enrique a écrit :
Bonjour, Quentin!
 
Are you trying to set up 2 instances of Bucardo, one replicating from A to B and another one from B to A? (I think there may be a typo in the part where you paste your configuration, you said “server1” twice).
Please, try to set up just 1 instance of Bucardo, and try adding both databases as “source”. Then please repeat the tests and let’s see how that works.
 
When you create a new sync with 2 databases in 2 nodes (with a single instance of Bucardo), you will notice that a new schema (bucardo) appears on all the databases and some triggers appear on all tables.
In this schema there are some tables that bucardo uses to keep track of the “deltas” as well as some tables with per-table (in the public or the other schemas) information.
Why am I telling you this? Because this is key: You can have bidirectional replication between nodes A and B with Bucardo software installed only on node A, B, or even on a different node C! 
If Bucardo software is installed in node A and node A goes down, triggers in the tables in node B will populate the tables in the bucardo schema in node B. When node A goes back up, the Bucardo software processes (KID and CTL) will read and process those contents and process the replication, handling conflicts should there be any (“man bucardo” and search for “conflict”).
 
Please, try and let us know. And @rest, please correct me if I’m wrong on anything :)
Good luck!
 
Kike
 
From: Bucardo-general mailto:bucardo-general-bounces at bucardo.org On Behalf Of Support EDI via Bucardo-general
Sent: jueves, 24 de noviembre de 2022 11:51
To: mailto:bucardo-general at bucardo.org
Subject: [Bucardo-general] NUMLOG / BUCARDO - Only half of insert are done in database
 
Dear Bucardo team,

Few weeks ago I started working on building a postgresql cluster (in master / master mode) composed of 3 VM with Debian 11 installed.
1. 1 server is running an HA proxy server (version 2.2.9). It is used to provide load balancing features
2. 2 Postgresql server (version 13.8) and Bucardo (version 5.6.0). Bucardo is used here to provide high availability with a master / master mode.
I have tested inserting data in each database server locally and every data is available on each server. So the master / master looks working fine.
Then I have tried to insert data from a distant server through the HA Proxy server and I have noticed that only the half of the insert are available in postgresql.

I have analyzed logs of the 3 softwares to find where something goes wrong and think it comes from bucardo. 
In this case I tried to insert 4 rows in a table named "files". In postgresql only 2 entries are available. The 2 entries are the same on both postgresql server. 
1. First I checked HA proxy logs and find that it was well redirecting 50% of insert on server 1 and 50% on server 2. No error in its logs so I presume that it really works fine.
2. Then I checked Postgresql log. In Postgresql logs I cannot see any error and I can't see any attempt to insert the missing values. I have changed log level to ensure I'm not missing something but without success.
3. At last I have checked in Bucardo and find below logs : 
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Got NOTICE run_sync_oneToTwo from 292748 (Bucardo DB) (line 3113)
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Adding entry to syncrun table
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Populating the dbrun table
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Adding note to the syncrun table
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Doing final maindbh commit
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Set database "serv1" to repeatable read read write
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Set database "serv2" to repeatable read read write
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Checking truncate_trigger table on database "serv1"
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Sequence public.files_code_seq from db serv1 is the highest
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Tables with deltas on serv1: 1 Without: 0
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Delta count for serv1.public.files : 2
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Total delta count: 2
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Setting session_replication_role to replica for database serv2
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Rows to push from serv1.public.files: 2
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Deleting from target serv2.public.files (round 1 of 1)
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Rows deleted from serv2.public.files: 2
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Copying from serv1.public.files
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Rows copied to (postgres) serv2.public.files: 2
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Totals: deletes=2 inserts=2 conflicts=0
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Rows inserted to bucardo_track for serv1.public.files : 2
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Setting session_replication_role to default for database serv2
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Issuing final commit for all databases
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) All databases committed
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Total time for sync "sync_oneToTwo" (2 rows, 1 table): 0.05 secondes
(292750) [Mon Nov 21 10:46:30 2022] KID (sync_oneToTwo) Sending NOTIFY "ctl_syncdone_sync_oneToTwo" (line 4937) skip_commit=0
I'm not sure I correctly understand bucardo logs as I'm not experimented using it, but it looks like it deletes 2 raws  in a server 2 and has pushed 2 raws from server 1.
My first question is, is my analysis correct or am I wrong?
My second question if I'm right is how should I set up Bucardo to avoid this issue. I'm sure I'm doing something wrong but I can't find what's wrong.
My second question if I'm wrong, do you have any idea of the cause of the issue?

On server1, my bucardo set up is : 

-- dbgroups:
dbgroup: sync_oneToTwo  Members: serv1:source serv2:target
-- databases:
Database: serv1  Status: active  Conn: psql -p 5432 -U bucardo -d hubmaster -h ***.**.**.24
Database: serv2  Status: active  Conn: psql -p 5432 -U bucardo -d hubmaster -h ***.**.**.25
-- relgroup:
Relgroup: one_two  DB: serv1  Members: public.files, public.files_code_seq
  Used in syncs: sync_oneToTwo
-- syncs:
Sync "sync_oneToTwo"  Relgroup "one_two"  DB group "sync_oneToTwo" serv1:source serv2:target  [Active]
-- tables:
2. Table: public.files  DB: serv2  PK: code (integer)
1. Table: public.files  DB: serv1  PK: code (integer)
-- sequences:
Sequence: public.files_code_seq  DB: serv1
Sequence: public.files_code_seq  DB: serv2

On server1, my bucardo set up is : 

-- dbgroups:
dbgroup: sync_oneToTwo  Members: serv1:source serv2:target
-- databases:
Database: serv1  Status: active  Conn: psql -U bucardo -d hubmaster -h ***.**.**.25
Database: serv2  Status: active  Conn: psql -U bucardo -d hubmaster -h ***.**.**.24
-- relgroup:
Relgroup: one_two  DB: serv1  Members: public.files, public.files_code_seq
  Used in syncs: sync_oneToTwo
-- syncs:
Sync "sync_oneToTwo"  Relgroup "one_two"  DB group "sync_oneToTwo" serv1:source serv2:target  [Active]
-- tables:
1. Table: public.files  DB: serv1  PK: code (integer)
2. Table: public.files  DB: serv2  PK: code (integer)
-- sequences:
Sequence: public.files_code_seq  DB: serv1
Sequence: public.files_code_seq  DB: serv2

Thanks in advance for any help provided.

Best regards
-- 




Quentin BIENFAIT 
Equipe EDI / EDI Team 


mailto:support.edi at numlog.fr 
tel:+33130791616 

9 ter route de Saint Germain
78640 Villiers Saint Frédéric - France 

 

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This message is for the designated recipient only and may contain privileged, proprietary, or otherwise private information. If you have received it in error, please notify the sender immediately and delete the original. Any other use of the email by you is prohibited. 
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