Hi, Dušan! It's now reported as a bug, see https://jira.mariadb.org/browse/ODBC-313 Note, that you can add yourself to the watch list to get notified about this issue changes. Regards, Sergei VP of MariaDB Server Engineering and security@mariadb.org On Apr 30, Dušan Pavlica wrote:

Hi,

I'm new with MariaDB. We try to switch from MySQL 5.0.96 to MariaDB 10.5.9. Move data to MariaDB was easy but now we have problems with speed of ODBC connector. I tried MariaDB ODBC connector 3.1.12 with default settings without SSL and our applications (mostly written in Embarcadero RAD Studio) showed very poor performance. When I tried MySQL ODBC connector 8.0.24 everything ran smoothly. Queries through MariaDB's connector was 3-5 times slower. In general query log I found that MariaDB's connector generates a lot of queries to information_scheme.columns table and all over again it reads variable TX_ISOLATION.

Short extract - MariaDB connector:

             3 Query    SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.SESSION_VARIABLES WHERE VARIABLE_NAME='TX_ISOLATION'              3 Prepare    select * from stanice              3 Execute    select * from stanice              3 Prepare    SELECT TABLE_SCHEMA AS TABLE_CAT, NULL AS TABLE_SCHEM, TABLE_NAME, COLUMN_NAME, ORDINAL_POSITION KEY_SEQ, 'PRIMARY' PK_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_KEY = 'pri' AND TABLE_SCHEMA LIKE 'unicentrum' AND TABLE_NAME LIKE 'stanice'  ORDER BY TABLE_SCHEMA, TABLE_NAME, ORDINAL_POSITION              3 Execute    SELECT TABLE_SCHEMA AS TABLE_CAT, NULL AS TABLE_SCHEM, TABLE_NAME, COLUMN_NAME, ORDINAL_POSITION KEY_SEQ, 'PRIMARY' PK_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_KEY = 'pri' AND TABLE_SCHEMA LIKE 'unicentrum' AND TABLE_NAME LIKE 'stanice'  ORDER BY TABLE_SCHEMA, TABLE_NAME, ORDINAL_POSITION              3 Close stmt              3 Reset stmt              3 Query    SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.SESSION_VARIABLES WHERE VARIABLE_NAME='TX_ISOLATION'              3 Prepare    SELECT * FROM stanice WHERE Sit_ID = ? ORDER BY Sit_ID, Podsit_ID, ID              3 Execute    SELECT * FROM stanice WHERE Sit_ID = 1 ORDER BY Sit_ID, Podsit_ID, ID              3 Prepare    SELECT TABLE_SCHEMA AS TABLE_CAT, NULL AS TABLE_SCHEM, TABLE_NAME, COLUMN_NAME, ORDINAL_POSITION KEY_SEQ, 'PRIMARY' PK_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_KEY = 'pri' AND TABLE_SCHEMA LIKE 'unicentrum' AND TABLE_NAME LIKE 'stanice'  ORDER BY TABLE_SCHEMA, TABLE_NAME, ORDINAL_POSITION              3 Execute    SELECT TABLE_SCHEMA AS TABLE_CAT, NULL AS TABLE_SCHEM, TABLE_NAME, COLUMN_NAME, ORDINAL_POSITION KEY_SEQ, 'PRIMARY' PK_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_KEY = 'pri' AND TABLE_SCHEMA LIKE 'unicentrum' AND TABLE_NAME LIKE 'stanice'  ORDER BY TABLE_SCHEMA, TABLE_NAME, ORDINAL_POSITION              3 Close stmt              3 Reset stmt

MySQL connector:

             3 Query    SELECT @@tx_isolation              ...              3 Query    select * from stanice              3 Prepare    SELECT * FROM stanice WHERE Sit_ID = ? ORDER BY Sit_ID, Podsit_ID, ID              3 Execute    SELECT * FROM stanice WHERE Sit_ID = '1' ORDER BY Sit_ID, Podsit_ID, ID              3 Close stmt

I think those "unnecessary" queries are making difference in performance of those connectors. Does anybody have any ideas what could I do to speed up MariaDB's connector? We prefer not using MySQL connectors anymore.

Thanks in advance

Dušan Pavlica