[MXS-2750] COM_STMT_EXECUTE in transaction get unexpected result Created: 2019-10-31  Updated: 2021-05-24  Resolved: 2020-02-05

Status: Closed
Project: MariaDB MaxScale
Component/s: readwritesplit
Affects Version/s: 2.2.21, 2.3.13
Fix Version/s: 2.5.0

Type: Bug Priority: Major
Reporter: huangyouqian Assignee: markus makela
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Blocks
blocks MXS-2521 COM_STMT_EXECUTE maybe return empty r... Closed
Relates
relates to MXS-3565 COM_STMT_EXECUTE target selection is ... Closed
Sprint: MXS-SPRINT-99

 Description   

We fix MX-2521 by routing the execute stmts which n_params > 0 and no metadata to previous node, but it not works with transaction,
For example:

prepare;
 
execute; // to ro1 with metadata
 
execute; // to ro1 with without metadata
 
begin;
 
execute; //  to master without metadata;
 
commit;

Suggestion:
1. Record metadata in first execution;
2. Add metadata to the following execution ( maybe every backend just add once)

 Comments   
Comment by Petros Moisiadis [ 2019-12-09 ]

Dec 9 13:34:22 maxscale-host maxscale[4206]: (1076606) [readwritesplit] Unexpected internal state: received response 0x00 from server 'galera-node-3' when no response was expected. Command: 0x03 Query: <not available>
Dec 9 13:34:22 maxscale-host maxscale[4206]: (1076653) [readwritesplit] Unexpected internal state: received response 0x00 from server 'galera-node-1' when no response was expected. Command: 0x03 Query: <not available>

Since we know that the clients in our setup are using prepared statements, could the above errors be related with the issue described in this ticket?

Comment by markus makela [ 2020-01-20 ]

Ernest0x I think it's unlikely that this bug would result in such an error. It's more likely that your problem is caused by MXS-2822.

Comment by markus makela [ 2020-02-03 ]

The metadata is now recorded every time the client sends it (this way updates to the metadata are stored properly). If a COM_STMT_EXECUTE is sent by the client without the metadata and the metadata has not been sent to the target server, it is added into the payload.

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