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FromDual has the pleasure to announce the release of the new version 1.0.1 of its popular Database Performance Monitor for MySQL, MariaDB, Galera Cluster and Percona Server fpmmm.

You can download fpmmm from here.

In the inconceivable case that you find a bug in the fpmmm please report it to our Bug-tracker.

Any feedback, statements and testimonials are welcome as well! Please send them to feedback@fromdual.com.

This release contains various bug fixes.

Changes in fpmmm v1.0.1 fpmmm agent

• Fpmmm suppresses server has gone away message to stdout.
• Fpmmm should behave correctly now when database was started after fpmmm agent.
• MyEnv library synced from MyEnv project.
• Added LaunchDaemon configuration for fpmmmm on Max OSX (darwin).

fpmmm agent installer

• Added some more support for Mac OSX (darwin).

For subscriptions of commercial use of fpmmm please get in contact with us.

Taxonomy upgrade extras: mysqlperformancemonitormonitoringfpmmmmaasperformance monitorrelease

FromDual has the pleasure to announce the release of the new version 1.0.1 of its popular Database Performance Monitor for MySQL, MariaDB, Galera Cluster and Percona Server fpmmm.

You can download fpmmm from here.

In the inconceivable case that you find a bug in the fpmmm please report it to our Bug-tracker.

Any feedback, statements and testimonials are welcome as well! Please send them to feedback@fromdual.com.

This release contains various bug fixes.

Changes in fpmmm v1.0.1 fpmmm agent

• Fpmmm suppresses server has gone away message to stdout.
• Fpmmm should behave correctly now when database was started after fpmmm agent.
• MyEnv library synced from MyEnv project.
• Added LaunchDaemon configuration for fpmmmm on Max OSX (darwin).

fpmmm agent installer

• Added some more support for Mac OSX (darwin).

For subscriptions of commercial use of fpmmm please get in contact with us.

Taxonomy upgrade extras: mysqlperformancemonitormonitoringfpmmmmaasperformance monitormpmrelease

FromDual has the pleasure to announce the release of the new version 1.0.1 of its popular Database Performance Monitor for MySQL, MariaDB, Galera Cluster and Percona Server fpmmm.

You can download fpmmm from here.

In the inconceivable case that you find a bug in the fpmmm please report it to our Bug-tracker.

Any feedback, statements and testimonials are welcome as well! Please send them to feedback@fromdual.com.

This release contains various bug fixes.

Changes in fpmmm v1.0.1 fpmmm agent

• Fpmmm suppresses server has gone away message to stdout.
• Fpmmm should behave correctly now when database was started after fpmmm agent.
• MyEnv library synced from MyEnv project.
• Added LaunchDaemon configuration for fpmmmm on Max OSX (darwin).

fpmmm agent installer

• Added some more support for Mac OSX (darwin).

For subscriptions of commercial use of fpmmm please get in contact with us.

Taxonomy upgrade extras: mysqlperformancemonitormonitoringfpmmmmaasperformance monitormpmrelease

When we do Galera Cluster consulting we always discuss with the customer if his software is Galera Cluster ready. This basically means: Can the software cope with the Galera Cluster specifics?

If it is a software product developed outside of the company we recommend to ask the software vendor if the software supports Galera Cluster or not.

We typically see 3 different answers:

• We do not know. Then they are at least honest.
• Yes we do support Galera Cluster. Then they hopefully know what they are talking about but you cannot be sure and should test carefully.
• No we do not. Then they most probably know what they are talking about.

If the software is developed in-house it becomes a bit more tricky because the responsibility for this statement has to be taken by you or some of your colleagues.

Thus it is good to know what are the characteristics and the limitations of a Cluster like Galera Cluster for MySQL.

Most of the Galera restrictions an limitation you can find here.

DDL statements cause TOI operations

DDL and DCL statements (like CREATE, ALTER, TRUNCATE, OPTIMIZE, DROP, GRANT, REVOKE, etc.) are executed by default in Total Order Isolation (TOI) by the Online Schema Upgrade (OSU) method. To achieve this schema upgrade consistently Galera does a global Cluster lock.

It is obvious that those DDL operations should be short and not very frequent to not always block your Galera Cluster. So changing your table structure must be planned and done carefully to not impact your daily business operation.

But there are also some not so obvious DDL statements causing TOI operations (and Cluster locks).

• TRUNCATE TABLE ... This operation is NOT a DML statement (like DELETE) but a DDL statement and thus does a TOI operation with a Cluster lock.
• CREATE TABLE IF NOT EXISTS ... This operation is clearly a DDL statement but one might think that it does NOT a TOI operation if the table already exists. This is wrong. This statement causes always a TOI operation if the table is there or not does not matter. If you run this statement very frequent this potentially causes troubles to your Galera Cluster.
• CREATE TABLE younameit_tmp ... The intention is clear: The developer wants to create a temporary table. But this is NOT a temporary table but just a normal table called _tmp. So it causes as TOI operation as well. What you should do in this case is to create a real temporary table like this: CREATE TEMPORARY TABLE yournameit_tmp ... This DDL statement is only executed locally and will not cause a TOI operation.

How to check?

You can check the impact of this problem with the following sequence of statements:

mysql> SHOW GLOBAL STATUS LIKE 'Com_create_table%'; +------------------+-------+ | Variable_name | Value | +------------------+-------+ | Com_create_table | 4 | +------------------+-------+ mysql> CREATE TABLE t1_tmp (id INT); mysql> SHOW GLOBAL STATUS LIKE 'Com_create_table%'; +------------------+-------+ | Variable_name | Value | +------------------+-------+ | Com_create_table | 5 | --> Also changes on the Slave nodes! +------------------+-------+ mysql> CREATE TEMPORARY TABLE t2_tmp (id INT); mysql> SHOW GLOBAL STATUS LIKE 'Com_create_table%'; +------------------+-------+ | Variable_name | Value | +------------------+-------+ | Com_create_table | 6 | --> Does NOT change on the Slave nodes! +------------------+-------+ mysql> CREATE TABLE IF NOT EXISTS t1_tmp (id INT); +------------------+-------+ | Variable_name | Value | +------------------+-------+ | Com_create_table | 7 | --> Also changes on the Slave nodes! +------------------+-------+
Find out in advance

If you want to find out before migrating to Galera Cluster if you are hit by this problem or not you can either run:

mysql> SHOW GLOBAL STATUS WHERE variable_name LIKE 'Com_create%' OR variable_name LIKE 'Com_alter%' OR variable_name LIKE 'Com_drop%' OR variable_name LIKE 'Com_truncate%' OR variable_name LIKE 'Com_grant%' OR variable_name LIKE 'Com_revoke%' OR variable_name LIKE 'Com_optimize%' OR variable_name LIKE 'Com_rename%' OR variable_name LIKE 'Uptime' ; +----------------------+-------+ | Variable_name | Value | +----------------------+-------+ | Com_create_db | 2 | | Com_create_table | 6 | | Com_optimize | 1 | | Uptime | 6060 | +----------------------+-------+

Or if you want to know exactly who was running the query from the PERFORMANCE_SCHEMA:

SELECT user, host, SUBSTR(event_name, 15) AS event_name, count_star FROM performance_schema.events_statements_summary_by_account_by_event_name WHERE count_star > 0 AND ( event_name LIKE 'statement/sql/create%' OR event_name LIKE 'statement/sql/alter%' OR event_name LIKE 'statement/sql/drop%' OR event_name LIKE 'statement/sql/rename%' OR event_name LIKE 'statement/sql/grant%' OR event_name LIKE 'statement/sql/revoke%' OR event_name LIKE 'statement/sql/optimize%' OR event_name LIKE 'statement/sql/truncate%' OR event_name LIKE 'statement/sql/repair%' OR event_name LIKE 'statement/sql/check%' ) ; +------+-----------+--------------+------------+ | user | host | event_name | count_star | +------+-----------+--------------+------------+ | root | localhost | create_table | 4 | | root | localhost | create_db | 2 | | root | localhost | optimize | 1 | +------+-----------+--------------+------------+

If you need help to make your application Galera Cluster ready we will be glad to assist you.

Taxonomy upgrade extras: Galera ClusterTOIDDLcreatetemporary tableDCLdropaltertruncate

When we do Galera Cluster consulting we always discuss with the customer if his software is Galera Cluster ready. This basically means: Can the software cope with the Galera Cluster specifics?

If it is a software product developed outside of the company we recommend to ask the software vendor if the software supports Galera Cluster or not.

We typically see 3 different answers:

• We do not know. Then they are at least honest.
• Yes we do support Galera Cluster. Then they hopefully know what they are talking about but you cannot be sure and should test carefully.
• No we do not. Then they most probably know what they are talking about.

If the software is developed in-house it becomes a bit more tricky because the responsibility for this statement has to be taken by you or some of your colleagues.

Thus it is good to know what are the characteristics and the limitations of a Cluster like Galera Cluster for MySQL.

Most of the Galera restrictions an limitation you can find here.

DDL statements cause TOI operations

DDL and DCL statements (like CREATE, ALTER, TRUNCATE, OPTIMIZE, DROP, GRANT, REVOKE, etc.) are executed by default in Total Order Isolation (TOI) by the Online Schema Upgrade (OSU) method. To achieve this schema upgrade consistently Galera does a global Cluster lock.

It is obvious that those DDL operations should be short and not very frequent to not always block your Galera Cluster. So changing your table structure must be planned and done carefully to not impact your daily business operation.

But there are also some not so obvious DDL statements causing TOI operations (and Cluster locks).

• TRUNCATE TABLE ... This operation is NOT a DML statement (like DELETE) but a DDL statement and thus does a TOI operation with a Cluster lock.
• CREATE TABLE IF NOT EXISTS ... This operation is clearly a DDL statement but one might think that it does NOT a TOI operation if the table already exists. This is wrong. This statement causes always a TOI operation if the table is there or not does not matter. If you run this statement very frequent this potentially causes troubles to your Galera Cluster.
• CREATE TABLE younameit_tmp ... The intention is clear: The developer wants to create a temporary table. But this is NOT a temporary table but just a normal table called _tmp. So it causes as TOI operation as well. What you should do in this case is to create a real temporary table like this: CREATE TEMPORARY TABLE yournameit_tmp ... This DDL statement is only executed locally and will not cause a TOI operation.

How to check?

You can check the impact of this problem with the following sequence of statements:

mysql> SHOW GLOBAL STATUS LIKE 'Com_create_table%'; +------------------+-------+ | Variable_name | Value | +------------------+-------+ | Com_create_table | 4 | +------------------+-------+ mysql> CREATE TABLE t1_tmp (id INT); mysql> SHOW GLOBAL STATUS LIKE 'Com_create_table%'; +------------------+-------+ | Variable_name | Value | +------------------+-------+ | Com_create_table | 5 | --> Also changes on the Slave nodes! +------------------+-------+ mysql> CREATE TEMPORARY TABLE t2_tmp (id INT); mysql> SHOW GLOBAL STATUS LIKE 'Com_create_table%'; +------------------+-------+ | Variable_name | Value | +------------------+-------+ | Com_create_table | 6 | --> Does NOT change on the Slave nodes! +------------------+-------+ mysql> CREATE TABLE IF NOT EXISTS t1_tmp (id INT); +------------------+-------+ | Variable_name | Value | +------------------+-------+ | Com_create_table | 7 | --> Also changes on the Slave nodes! +------------------+-------+
Find out in advance

If you want to find out before migrating to Galera Cluster if you are hit by this problem or not you can either run:

mysql> SHOW GLOBAL STATUS WHERE variable_name LIKE 'Com_create%' OR variable_name LIKE 'Com_alter%' OR variable_name LIKE 'Com_drop%' OR variable_name LIKE 'Com_truncate%' OR variable_name LIKE 'Com_grant%' OR variable_name LIKE 'Com_revoke%' OR variable_name LIKE 'Com_optimize%' OR variable_name LIKE 'Com_rename%' OR variable_name LIKE 'Uptime' ; +----------------------+-------+ | Variable_name | Value | +----------------------+-------+ | Com_create_db | 2 | | Com_create_table | 6 | | Com_optimize | 1 | | Uptime | 6060 | +----------------------+-------+

Or if you want to know exactly who was running the query from the PERFORMANCE_SCHEMA:

SELECT user, host, SUBSTR(event_name, 15) AS event_name, count_star FROM performance_schema.events_statements_summary_by_account_by_event_name WHERE count_star > 0 AND ( event_name LIKE 'statement/sql/create%' OR event_name LIKE 'statement/sql/alter%' OR event_name LIKE 'statement/sql/drop%' OR event_name LIKE 'statement/sql/rename%' OR event_name LIKE 'statement/sql/grant%' OR event_name LIKE 'statement/sql/revoke%' OR event_name LIKE 'statement/sql/optimize%' OR event_name LIKE 'statement/sql/truncate%' OR event_name LIKE 'statement/sql/repair%' OR event_name LIKE 'statement/sql/check%' ) ; +------+-----------+--------------+------------+ | user | host | event_name | count_star | +------+-----------+--------------+------------+ | root | localhost | create_table | 4 | | root | localhost | create_db | 2 | | root | localhost | optimize | 1 | +------+-----------+--------------+------------+

If you need help to make your application Galera Cluster ready we will be glad to assist you.

Taxonomy upgrade extras: Galera ClusterTOIDDLcreatetemporary tableDCLdropaltertruncate

Codership, das finnische Unternehmen hinter Galera Cluster für MySQL, gibt Galera Cluster für MySQL 5.7 frei: Announcing Galera Cluster 5.7.17 GA with Galera 3.20.

Somit stehen praktische sämtliche MySQL 5.7 Funktionalitäten auch für Galera Cluster zur Verfügung.

Galera Cluster für MySQL ist die am meisten verbreitetste Cluster Lösung für MySQL, welche zudem einfach zu installieren und robust im Betrieb ist.

Zudem wurden bei diesem Release auch sämtliche sicherheitsrelevanten Fixes von MySQL nachgezogen.

Somit steht einem flächendeckenden Upgrade auf MySQL/Galera 5.7 nichts mehr im Weg!

Das FromDual Team unterstützt Sie gerne beim Upgrade...

Codership, das finnische Unternehmen hinter Galera Cluster für MySQL, gibt Galera Cluster für MySQL 5.7 frei: Announcing Galera Cluster 5.7.17 GA with Galera 3.20.

Somit stehen praktische sämtliche MySQL 5.7 Funktionalitäten auch für Galera Cluster zur Verfügung.

Galera Cluster für MySQL ist die am meisten verbreitetste Cluster Lösung für MySQL, welche zudem einfach zu installieren und robust im Betrieb ist.

Zudem wurden bei diesem Release auch sämtliche sicherheitsrelevanten Fixes von MySQL nachgezogen.

Somit steht einem flächendeckenden Upgrade auf MySQL/Galera 5.7 nichts mehr im Weg!

Das FromDual Team unterstützt Sie gerne beim Upgrade...

Codership, das finnische Unternehmen hinter Galera Cluster für MySQL, gibt Galera Cluster für MySQL 5.7 frei: Announcing Galera Cluster 5.7.17 GA with Galera 3.20.

Somit stehen praktische sämtliche MySQL 5.7 Funktionalitäten auch für Galera Cluster zur Verfügung.

Galera Cluster für MySQL ist die am meisten verbreitetste Cluster Lösung für MySQL, welche zudem einfach zu installieren und robust im Betrieb ist.

Zudem wurden bei diesem Release auch sämtliche sicherheitsrelevanten Fixes von MySQL nachgezogen.

Somit steht einem flächendeckenden Upgrade auf MySQL/Galera 5.7 nichts mehr im Weg!

Das FromDual Team unterstützt Sie gerne beim Upgrade...

From time to time we see in customer engagements that MySQL Master/Slave replication is set-up doing schema or table level replication filtering. This can be done either on Master or on Slave. If filtering is done on the Master (by the binlog_{do|ignore}_db settings), the binary log becomes incomplete and cannot be used for a proper Point-in-Time-Recovery. Therefore FromDual recommends AGAINST this approach.

The replication filtering rules vary depending on the binary log format (ROW and STATEMENT) See also: How Servers Evaluate Replication Filtering Rules.

For reasons of data consistency between Master and Slave FromDual recommends to use only the binary log format ROW. This is also stated in the MySQL documentation: All changes can be replicated. This is the safest form of replication. Especially dangerous is binary log filtering with binary log format MIXED. This binary log format FromDual strongly discourages users to use.

The binary log format ROW affects only DML statements (UPDATE, INSERT, DELETE, etc.) but NOT DDL statements (CREATE, ALTER, DROP, etc.) and NOT DCL statements (CREATE, GRANT, REVOKE, DROP, etc.). So how are those statements replicated? They are replicated in STATEMENT binary log format even though binlog_format is set to ROW. This has the consequences that the binary log filtering rules of STATEMENT based replication and not the ones of ROW based replication apply when running one of those DDL or DCL statements.

This can easily cause problems. If you are lucky, they will cause the replication to break sooner or later, which you can detect and fix - but they may also cause inconsistencies between Master and Slave which may remain undetected for a long time.

Let us show what happens in 2 similar scenarios:

Scenario A: Filtering on mysql schema

On Slave we set the binary log filter as follows:

replicate_ignore_db = mysql

and verify it:

mysql> SHOW SLAVE STATUS\G ... Replicate_Ignore_DB: mysql ...

The intention of this filter setting is to not replicate user creations or modifications from Master to the Slave.

We verify on the Master, that binlog_format is set to the wanted value:

mysql> SHOW GLOBAL VARIABLES LIKE 'binlog_format'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | binlog_format | ROW | +---------------+-------+

Now we do the following on the Master:

mysql> use mysql mysql> CREATE USER 'inmysql'@'%'; mysql> use test mysql> CREATE USER 'intest'@'%';

and verify the result on the Master:

mysql> SELECT user, host FROM mysql.user; +-------------+-----------+ | user | host | +-------------+-----------+ | inmysql | % | | intest | % | | mysql.sys | localhost | | root | localhost | +-------------+-----------+

and on the Slave:

mysql> SELECT user, host FROM mysql.user; +-------------+-----------+ | user | host | +-------------+-----------+ | intest | % | | mysql.sys | localhost | | root | localhost | +-------------+-----------+

We see, that the user intest was replicated and the user inmysql was not. And we have clearly an unwanted data inconsistency between Master and Slave.

If we want to drop the inmysql user some time later on the Master:

mysql> use myapp; mysql> DROP USER 'inmysql'@'%';

we get the following error message on the Slave and are wondering, why this user or the query appears on the Slave:

mysql> SHOW SLAVE STATUS\G ... Last_SQL_Errno: 1396 Last_SQL_Error: Error 'Operation DROP USER failed for 'inmysql'@'%'' on query. Default database: 'test'. Query: 'DROP USER 'inmysql'@'%'' ...

A similar problem happens when we connect to NO database on the Master as follows and change the users password:

shell> mysql -uroot mysql> SELECT DATABASE(); +------------+ | database() | +------------+ | NULL | +------------+ mysql> ALTER USER 'innone'@'%' IDENTIFIED BY 'secret';

This works perfectly on the Master. But what happens on the Slave:

mysql> SHOW SLAVE STATUS\G ... Last_SQL_Errno: 1396 Last_SQL_Error: Error 'Operation ALTER USER failed for 'innone'@'%'' on query. Default database: ''. Query: 'ALTER USER 'innone'@'%' IDENTIFIED WITH 'mysql_native_password' AS '*14E65567ABDB5135D0CFD9A70B3032C179A49EE7'' ...

The Slave wants to tell us in a complicated way, that the user innone does not exist on the Slave...

Scenario B: Filtering on tmp or similar schema

An other scenario we have seen recently is that the customer is filtering out tables with temporary data located in the tmp schema. Similar scenarios are cache, session or log tables. He did it as follows on the Master:

mysql> use tmp; mysql> TRUNCATE TABLE tmp.test;

As he has learned in FromDual trainings he emptied the table with the TRUNCATE TABLE command instead of a DELETE FROM tmp.test command which is much less efficient than the TRUNCATE TABLE command. What he did not consider is, that the TRUNCATE TABLE command is a DDL command and not a DML command and thus the STATEMENT based replication filtering rules apply. His filtering rules on the Slave were as follows:

mysql> SHOW SLAVE STATUS\G ... Replicate_Ignore_DB: tmp ...

When we do the check on the Master we get an empty set as expected:

mysql> SELECT * FROM tmp.test; Empty set (0.00 sec)

When we add new data on the Master:

mysql> INSERT INTO tmp.test VALUES (NULL, 'new data', CURRENT_TIMESTAMP()); mysql> SELECT * FROM tmp.test; +----+-----------+---------------------+ | id | data | ts | +----+-----------+---------------------+ | 1 | new data | 2017-01-11 18:00:11 | +----+-----------+---------------------+

we get a different result set on the Slave:

mysql> SELECT * FROM tmp.test; +----+-----------+---------------------+ | id | data | ts | +----+-----------+---------------------+ | 1 | old data | 2017-01-11 17:58:55 | +----+-----------+---------------------+

and in addition the replication stops working with the following error:

mysql> SHOW SLAVE STATUS\G ... Last_Errno: 1062 Last_Error: Could not execute Write_rows event on table tmp.test; Duplicate entry '1' for key 'PRIMARY', Error_code: 1062; handler error HA_ERR_FOUND_DUPP_KEY; the event's master log laptop4_qa57master_binlog.000042, end_log_pos 1572 ...

See also our earlier bug report of a similar topic: Option "replicate_do_db" does not cause "create table" to replicate ('row' log)

Conclusion

Binary log filtering is extremely dangerous when you care about data consistency and thus FromDual recommends to avoid binary log filtering by all means. If you really have to do binary log filtering you should exactly know what you are doing, carefully test your set-up, check your application and your maintenance jobs and also review your future code changes regularly. Otherwise you risk data inconsistencies in your MySQL Master/Slave replication.

Taxonomy upgrade extras: replicationbinary logfilterfilteringrow filteringstatementbinlog_formatrow

From time to time we see in customer engagements that MySQL Master/Slave replication is set-up doing schema or table level replication filtering. This can be done either on Master or on Slave. If filtering is done on the Master (by the binlog_{do|ignore}_db settings), the binary log becomes incomplete and cannot be used for a proper Point-in-Time-Recovery. Therefore FromDual recommends AGAINST this approach.

The replication filtering rules vary depending on the binary log format (ROW and STATEMENT) See also: How Servers Evaluate Replication Filtering Rules.

For reasons of data consistency between Master and Slave FromDual recommends to use only the binary log format ROW. This is also stated in the MySQL documentation: All changes can be replicated. This is the safest form of replication. Especially dangerous is binary log filtering with binary log format MIXED. This binary log format FromDual strongly discourages users to use.

The binary log format ROW affects only DML statements (UPDATE, INSERT, DELETE, etc.) but NOT DDL statements (CREATE, ALTER, DROP, etc.) and NOT DCL statements (CREATE, GRANT, REVOKE, DROP, etc.). So how are those statements replicated? They are replicated in STATEMENT binary log format even though binlog_format is set to ROW. This has the consequences that the binary log filtering rules of STATEMENT based replication and not the ones of ROW based replication apply when running one of those DDL or DCL statements.

This can easily cause problems. If you are lucky, they will cause the replication to break sooner or later, which you can detect and fix - but they may also cause inconsistencies between Master and Slave which may remain undetected for a long time.

Let us show what happens in 2 similar scenarios:

Scenario A: Filtering on mysql schema

On Slave we set the binary log filter as follows:

replicate_ignore_db = mysql

and verify it:

mysql> SHOW SLAVE STATUS\G ... Replicate_Ignore_DB: mysql ...

The intention of this filter setting is to not replicate user creations or modifications from Master to the Slave.

We verify on the Master, that binlog_format is set to the wanted value:

mysql> SHOW GLOBAL VARIABLES LIKE 'binlog_format'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | binlog_format | ROW | +---------------+-------+

Now we do the following on the Master:

mysql> use mysql mysql> CREATE USER 'inmysql'@'%'; mysql> use test mysql> CREATE USER 'intest'@'%';

and verify the result on the Master:

mysql> SELECT user, host FROM mysql.user; +-------------+-----------+ | user | host | +-------------+-----------+ | inmysql | % | | intest | % | | mysql.sys | localhost | | root | localhost | +-------------+-----------+

and on the Slave:

mysql> SELECT user, host FROM mysql.user; +-------------+-----------+ | user | host | +-------------+-----------+ | intest | % | | mysql.sys | localhost | | root | localhost | +-------------+-----------+

We see, that the user intest was replicated and the user inmysql was not. And we have clearly an unwanted data inconsistency between Master and Slave.

If we want to drop the inmysql user some time later on the Master:

mysql> use myapp; mysql> DROP USER 'inmysql'@'%';

we get the following error message on the Slave and are wondering, why this user or the query appears on the Slave:

mysql> SHOW SLAVE STATUS\G ... Last_SQL_Errno: 1396 Last_SQL_Error: Error 'Operation DROP USER failed for 'inmysql'@'%'' on query. Default database: 'test'. Query: 'DROP USER 'inmysql'@'%'' ...

A similar problem happens when we connect to NO database on the Master as follows and change the users password:

shell> mysql -uroot mysql> SELECT DATABASE(); +------------+ | database() | +------------+ | NULL | +------------+ mysql> ALTER USER 'innone'@'%' IDENTIFIED BY 'secret';

This works perfectly on the Master. But what happens on the Slave:

mysql> SHOW SLAVE STATUS\G ... Last_SQL_Errno: 1396 Last_SQL_Error: Error 'Operation ALTER USER failed for 'innone'@'%'' on query. Default database: ''. Query: 'ALTER USER 'innone'@'%' IDENTIFIED WITH 'mysql_native_password' AS '*14E65567ABDB5135D0CFD9A70B3032C179A49EE7'' ...

The Slave wants to tell us in a complicated way, that the user innone does not exist on the Slave...

Scenario B: Filtering on tmp or similar schema

An other scenario we have seen recently is that the customer is filtering out tables with temporary data located in the tmp schema. Similar scenarios are cache, session or log tables. He did it as follows on the Master:

mysql> use tmp; mysql> TRUNCATE TABLE tmp.test;

As he has learned in FromDual trainings he emptied the table with the TRUNCATE TABLE command instead of a DELETE FROM tmp.test command which is much less efficient than the TRUNCATE TABLE command. What he did not consider is, that the TRUNCATE TABLE command is a DDL command and not a DML command and thus the STATEMENT based replication filtering rules apply. His filtering rules on the Slave were as follows:

mysql> SHOW SLAVE STATUS\G ... Replicate_Ignore_DB: tmp ...

When we do the check on the Master we get an empty set as expected:

mysql> SELECT * FROM tmp.test; Empty set (0.00 sec)

When we add new data on the Master:

mysql> INSERT INTO tmp.test VALUES (NULL, 'new data', CURRENT_TIMESTAMP()); mysql> SELECT * FROM tmp.test; +----+-----------+---------------------+ | id | data | ts | +----+-----------+---------------------+ | 1 | new data | 2017-01-11 18:00:11 | +----+-----------+---------------------+

we get a different result set on the Slave:

mysql> SELECT * FROM tmp.test; +----+-----------+---------------------+ | id | data | ts | +----+-----------+---------------------+ | 1 | old data | 2017-01-11 17:58:55 | +----+-----------+---------------------+

and in addition the replication stops working with the following error:

mysql> SHOW SLAVE STATUS\G ... Last_Errno: 1062 Last_Error: Could not execute Write_rows event on table tmp.test; Duplicate entry '1' for key 'PRIMARY', Error_code: 1062; handler error HA_ERR_FOUND_DUPP_KEY; the event's master log laptop4_qa57master_binlog.000042, end_log_pos 1572 ...

See also our earlier bug report of a similar topic: Option "replicate_do_db" does not cause "create table" to replicate ('row' log)

Conclusion

Binary log filtering is extremely dangerous when you care about data consistency and thus FromDual recommends to avoid binary log filtering by all means. If you really have to do binary log filtering you should exactly know what you are doing, carefully test your set-up, check your application and your maintenance jobs and also review your future code changes regularly. Otherwise you risk data inconsistencies in your MySQL Master/Slave replication.

Taxonomy upgrade extras: replicationbinary logfilterfilteringrow filteringstatementbinlog_formatrow

FromDual has the pleasure to announce the release of the new version 1.2.4 of the popular Backup and Recovery Manager for MySQL and MariaDB (fromdual_brman).

You can download the FromDual Backup and Recovery Manager from here.

In the inconceivable case that you find a bug in the Backup and Recovery Manager please report it to our Bugtracker or just send us an email.

Any feedback, statements and testimonials are welcome as well! Please send them to feedback@fromdual.com.

Upgrade from 1.2.x to 1.2.4 # cd ${HOME}/product # tar xf /download/fromdual_brman-1.2.4.tar.gz # rm -f fromdual_brman # ln -s fromdual_brman-1.2.4 fromdual_brman
Changes in FromDual Backup Manager 1.2.4

This release contains mainly fixes related to the backup type cleanup.

You can verify your current FromDual Backup Manager version with the following command:

shell> fromdual_bman --version
FromDual Backup Manager

• Library myEnv.inc synced from myEnv project.

FromDual Backup Manager Cleanup

• Ignore warning for non empty backup directories in cleanup.
• Check if directory exist before going into recursive lookup in cleanup.
• Function rmdir is also covered by simulate option now in cleanup.
• Backup type cleanup also considers physical backup and catalog now.

Taxonomy upgrade extras: BackupRestoreRecoverypitrfromdual_brmanbrmanreleasebmanrman

FromDual has the pleasure to announce the release of the new version 1.2.4 of the popular Backup and Recovery Manager for MySQL and MariaDB (fromdual_brman).

You can download the FromDual Backup and Recovery Manager from here.

In the inconceivable case that you find a bug in the Backup and Recovery Manager please report it to our Bugtracker or just send us an email.

Any feedback, statements and testimonials are welcome as well! Please send them to feedback@fromdual.com.

Upgrade from 1.2.x to 1.2.4 # cd ${HOME}/product # tar xf /download/fromdual_brman-1.2.4.tar.gz # rm -f fromdual_brman # ln -s fromdual_brman-1.2.4 fromdual_brman
Changes in FromDual Backup Manager 1.2.4

This release contains mainly fixes related to the backup type cleanup.

You can verify your current FromDual Backup Manager version with the following command:

shell> fromdual_bman --version
FromDual Backup Manager

• Library myEnv.inc synced from myEnv project.

FromDual Backup Manager Cleanup

• Ignore warning for non empty backup directories in cleanup.
• Check if directory exist before going into recursive lookup in cleanup.
• Function rmdir is also covered by simulate option now in cleanup.
• Backup type cleanup also considers physical backup and catalog now.

Taxonomy upgrade extras: BackupRestoreRecoverypitrfromdual_brmanbrmanreleasebmanrman

FromDual has the pleasure to announce the release of the new version 1.2.4 of the popular Backup and Recovery Manager for MySQL and MariaDB (fromdual_brman).

You can download the FromDual Backup and Recovery Manager from here.

In the inconceivable case that you find a bug in the Backup and Recovery Manager please report it to our Bugtracker or just send us an email.

Any feedback, statements and testimonials are welcome as well! Please send them to feedback@fromdual.com.

Upgrade from 1.2.x to 1.2.4 # cd ${HOME}/product # tar xf /download/fromdual_brman-1.2.4.tar.gz # rm -f fromdual_brman # ln -s fromdual_brman-1.2.4 fromdual_brman
Changes in FromDual Backup Manager 1.2.4

This release contains mainly fixes related to the backup type cleanup.

You can verify your current FromDual Backup Manager version with the following command:

shell> fromdual_bman --version
FromDual Backup Manager

• Library myEnv.inc synced from myEnv project.

FromDual Backup Manager Cleanup

• Ignore warning for non empty backup directories in cleanup.
• Check if directory exist before going into recursive lookup in cleanup.
• Function rmdir is also covered by simulate option now in cleanup.
• Backup type cleanup also considers physical backup and catalog now.

Taxonomy upgrade extras: BackupRestoreRecoverypitrfromdual_brman

This one is for all MySQL-DBA's, which are working on macOS. Since the Apple OS has a rather peculiar way of starting and stopping MySQL, compared to Linux, you can run into some issues. These problems occur especially, if you have no access to the GUI.

Preparation

Put skip-grant-tables into the mysqld section of the my.cnf. A my.cnf can be found in /usr/local/mysql/support-files. You MUST work as root for all the following steps.

shell> sudo -s shell> vi /usr/local/mysql/support-files/my-default.cnf ... [mysqld] skip-grant-tables skip-networking ...

Save the configuration file! (In vi this is "[ESC] + :x")

Continue with stopping MySQL:

launchctl unload /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist

Restart MySQL, so skip-grant-tables becomes active:

launchctl load /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist

Reset the password

After MySQL is started again, you can log into the CLI and reset the password:

shell> mysql -u root mysql> FLUSH PRIVILEGES; mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'super-secret-password';

Plan B

If you are not capable of stopping MySQL in a civilised manner, you can use the more rough way. You can send a SIGTERM to the MySQL-Server:

shell> ps -aef | grep mysql | grep -v grep 74 28017 1 0 Fri10AM ?? 5:59.50 /usr/local/mysql/bin/mysqld --user=_mysql --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --log-error=/usr/local/mysql/data/mysqld.local.err --pid-file=/usr/local/mysql/data/mysqld.local.pid

You should receive one line. The second column from the left is the process id. Use this process id to stop the MySQL-Server.

shell> kill -15 [process id]

In this example, the command would look like this:

shell> kill -15 28017

macOS will restart MySQL, since the process has not stopped correctly. The configuration will be read and the changes to the parameters will become effective. Continue with logging in to the CLI.

Conclusion

No matter how secure your MySQL-Password is, it is a lot more important to secure access to the server it self. If your server is not secured by something that prevents access from the internet, it will only take a few minutes for someone with bad intentions to take over your database or worse, the entire server.

Taxonomy upgrade extras: mysqlserver

This one is for all MySQL-DBA's, which are working on macOS. Since the Apple OS has a rather peculiar way of starting and stopping MySQL, compared to Linux, you can run into some issues. These problems occur especially, if you have no access to the GUI.

Preparation

Put skip-grant-tables into the mysqld section of the my.cnf. A my.cnf can be found in /usr/local/mysql/support-files. You MUST work as root for all the following steps.

shell> sudo -s shell> vi /usr/local/mysql/support-files/my-default.cnf ... [mysqld] skip-grant-tables skip-networking ...

Save the configuration file! (In vi this is "[ESC] + :x")

Continue with stopping MySQL:

launchctl unload /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist

Restart MySQL, so skip-grant-tables becomes active:

launchctl load /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist

Reset the password

After MySQL is started again, you can log into the CLI and reset the password:

shell> mysql -u root mysql> FLUSH PRIVILEGES; mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'super-secret-password';

Plan B

If you are not capable of stopping MySQL in a civilised manner, you can use the more rough way. You can send a SIGTERM to the MySQL-Server:

shell> ps -aef | grep mysql | grep -v grep 74 28017 1 0 Fri10AM ?? 5:59.50 /usr/local/mysql/bin/mysqld --user=_mysql --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --log-error=/usr/local/mysql/data/mysqld.local.err --pid-file=/usr/local/mysql/data/mysqld.local.pid

You should receive one line. The second column from the left is the process id. Use this process id to stop the MySQL-Server.

shell> kill -15 [process id]

In this example, the command would look like this:

shell> kill -15 28017

macOS will restart MySQL, since the process has not stopped correctly. The configuration will be read and the changes to the parameters will become effective. Continue with logging in to the CLI.

Conclusion

No matter how secure your MySQL-Password is, it is a lot more important to secure access to the server it self. If your server is not secured by something that prevents access from the internet, it will only take a few minutes for someone with bad intentions to take over your database or worse, the entire server.

Taxonomy upgrade extras: mysqlserver

This one is for all MySQL-DBA's, which are working on macOS. Since the Apple OS has a rather peculiar way of starting and stopping MySQL, compared to Linux, you can run into some issues. These problems occur especially, if you have no access to the GUI.

Preparation

Put skip-grant-tables into the mysqld section of the my.cnf. A my.cnf can be found in /usr/local/mysql/support-files. You MUST work as root for all the following steps.

shell> sudo -s shell> vi /usr/local/mysql/support-files/my-default.cnf ... [mysqld] skip-grant-tables skip-networking ...

Save the configuration file! (In vi this is "[ESC] + :x")

Continue with stopping MySQL:

launchctl unload /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist

Restart MySQL, so skip-grant-tables becomes active:

launchctl load /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist

Reset the password

After MySQL is started again, you can log into the CLI and reset the password:

shell> mysql -u root mysql> FLUSH PRIVILEGES; mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'super-secret-password';

Plan B

If you are not capable of stopping MySQL in a civilised manner, you can use the more rough way. You can send a SIGTERM to the MySQL-Server:

shell> ps -aef | grep mysql | grep -v grep 74 28017 1 0 Fri10AM ?? 5:59.50 /usr/local/mysql/bin/mysqld --user=_mysql --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --log-error=/usr/local/mysql/data/mysqld.local.err --pid-file=/usr/local/mysql/data/mysqld.local.pid

You should receive one line. The second column from the left is the process id. Use this process id to stop the MySQL-Server.

shell> kill -15 [process id]

In this example, the command would look like this:

shell> kill -15 28017

macOS will restart MySQL, since the process has not stopped correctly. The configuration will be read and the changes to the parameters will become effective. Continue with logging in to the CLI.

Conclusion

No matter how secure your MySQL-Password is, it is a lot more important to secure access to the server it self. If your server is not secured by something that prevents access from the internet, it will only take a few minutes for someone with bad intentions to take over your database or worse, the entire server.

Taxonomy upgrade extras: mysqlserver

What is SELinux?

The Security-Enhanced Linux is an extension to the Linux Kernel, made by the NSA (National Security Agency). It implements Mandatory Access Controls (MAC), which allow an administrator to define, how applications and users can access resources on a system.

There is more detail in the SELinux Wki: https://selinuxproject.org/page/FAQ
... and the CentOS documentation: https://wiki.centos.org/HowTos/SELinux

Some distributions have it installed by default, but not active, some have it installed and active and some don't have it installed.

How do I know if SELinux is active? SELinux comes with some new commands. To see the current status of SELinux, use "getenforce" or "sestatus": [root@localhost ~]# getenforce Enforcing

- OR -

[root@localhost ~]# sestatus SELinux status: enabled SELinuxfs mount: /sys/fs/selinux SELinux root directory: /etc/selinux Loaded policy name: targeted Current mode: enforcing Mode from config file: enforcing Policy MLS status: enabled Policy deny_unknown status: allowed Max kernel policy version: 28

There are three modes available:

• Enforcing: SELinux is active and enforcing restrictions.
• Permissive: Restrictions are not enforced, but policy violations are reported.
• Disabled: SELinux is turned off.

Changing modes

If you want to change the mode of SELinux, use "setenforce":

setenforce [ Enforcing | Permissive | 1 | 0 ]

Or edit the configuration file under "/etc/selinux/config".

Install semanage

If you want to change SELinux policies in an easy way, you will need the tool "semanage" it can be installed with the following command:

yum install policycoreutils-python

Create a directory MySQL/MariaDB can access

NOTE: I am going to work with MariaDB for this blog, as it can be installed from repository in CentOS.

The easy way to create a new policy, which allows to MySQL or MariaDB to use a directory, is to install "semanage". It is provided with the following package:

yum install policycoreutils-python

Then proceed to create the new directory, where MySQL/MariaDB could store the binary logs, if they should not be in the datadir.

mkdir /var/lib/mysql_binlog/ chown -R mysql:mysql mysql* semanage fcontext -a -t mysqld_db_t "/var/lib/mysql_binlog(/.*)?" restorecon -Rv /var/lib/mysql_binlog

NOTE: You have to give the absolute path to the file or the directory!

If you want to use MySQL/MariaDB on a non-standard port, you also have to allow usage of that port:

semanage port -a -t mysqld_port_t -p tcp 3307

Once you have created the new directory for the binary logs and made sure it is owned by mysql, you need to change the type of the directory you created to the one that allows MySQL/MariDB to use this directory. If you do not do this, you will get a "Permission denied (13)" error.

"semanage" is used to make this change persistent, even when the entire file system relabelled.

I was although unable to change the socket. I am yet unsure what the problem was, as MariaDB did not start or return any error.

Enable MySQL to write to this directory vi /etc/my.cnf ... [mysqld] log-bin=/var/lib/mysql_binlog/binlog ... systemctl restart mariadb Taxonomy upgrade extras: mysqlmariadbcentossecurityselinux

What is SELinux?

The Security-Enhanced Linux is an extension to the Linux Kernel, made by the NSA (National Security Agency). It implements Mandatory Access Controls (MAC), which allow an administrator to define, how applications and users can access resources on a system.

There is more detail in the SELinux Wki: https://selinuxproject.org/page/FAQ
... and the CentOS documentation: https://wiki.centos.org/HowTos/SELinux

Some distributions have it installed by default, but not active, some have it installed and active and some don't have it installed.

How do I know if SELinux is active? SELinux comes with some new commands. To see the current status of SELinux, use "getenforce" or "sestatus": [root@localhost ~]# getenforce Enforcing

- OR -

[root@localhost ~]# sestatus SELinux status: enabled SELinuxfs mount: /sys/fs/selinux SELinux root directory: /etc/selinux Loaded policy name: targeted Current mode: enforcing Mode from config file: enforcing Policy MLS status: enabled Policy deny_unknown status: allowed Max kernel policy version: 28

There are three modes available:

• Enforcing: SELinux is active and enforcing restrictions.
• Permissive: Restrictions are not enforced, but policy violations are reported.
• Disabled: SELinux is turned off.

Changing modes

If you want to change the mode of SELinux, use "setenforce":

setenforce [ Enforcing | Permissive | 1 | 0 ]

Or edit the configuration file under "/etc/selinux/config".

Install semanage

If you want to change SELinux policies in an easy way, you will need the tool "semanage" it can be installed with the following command:

yum install policycoreutils-python

Create a directory MySQL/MariaDB can access

NOTE: I am going to work with MariaDB for this blog, as it can be installed from repository in CentOS.

The easy way to create a new policy, which allows to MySQL or MariaDB to use a directory, is to install "semanage". It is provided with the following package:

yum install policycoreutils-python

Then proceed to create the new directory, where MySQL/MariaDB could store the binary logs, if they should not be in the datadir.

mkdir /var/lib/mysql_binlog/ chown -R mysql:mysql mysql* semanage fcontext -a -t mysqld_db_t "/var/lib/mysql_binlog(/.*)?" restorecon -Rv /var/lib/mysql_binlog

NOTE: You have to give the absolute path to the file or the directory!

If you want to use MySQL/MariaDB on a non-standard port, you also have to allow usage of that port:

semanage port -a -t mysqld_port_t -p tcp 3307

Once you have created the new directory for the binary logs and made sure it is owned by mysql, you need to change the type of the directory you created to the one that allows MySQL/MariDB to use this directory. If you do not do this, you will get a "Permission denied (13)" error.

"semanage" is used to make this change persistent, even when the entire file system relabelled.

I was although unable to change the socket. I am yet unsure what the problem was, as MariaDB did not start or return any error.

Enable MySQL to write to this directory vi /etc/my.cnf ... [mysqld] log-bin=/var/lib/mysql_binlog/binlog ... systemctl restart mariadb Taxonomy upgrade extras: mysqlmariadbcentossecurityselinux

What is SELinux?

The Security-Enhanced Linux is an extension to the Linux Kernel, made by the NSA (National Security Agency). It implements Mandatory Access Controls (MAC), which allow an administrator to define, how applications and users can access resources on a system.

There is more detail in the SELinux Wki: https://selinuxproject.org/page/FAQ
... and the CentOS documentation: https://wiki.centos.org/HowTos/SELinux

Some distributions have it installed by default, but not active, some have it installed and active and some don't have it installed.

How do I know if SELinux is active? SELinux comes with some new commands. To see the current status of SELinux, use "getenforce" or "sestatus": [root@localhost ~]# getenforce Enforcing

- OR -

[root@localhost ~]# sestatus SELinux status: enabled SELinuxfs mount: /sys/fs/selinux SELinux root directory: /etc/selinux Loaded policy name: targeted Current mode: enforcing Mode from config file: enforcing Policy MLS status: enabled Policy deny_unknown status: allowed Max kernel policy version: 28

There are three modes available:

• Enforcing: SELinux is active and enforcing restrictions.
• Permissive: Restrictions are not enforced, but policy violations are reported.
• Disabled: SELinux is turned off.

Changing modes

If you want to change the mode of SELinux, use "setenforce":

setenforce [ Enforcing | Permissive | 1 | 0 ]

Or edit the configuration file under "/etc/selinux/config".

Install semanage

If you want to change SELinux policies in an easy way, you will need the tool "semanage" it can be installed with the following command:

yum install policycoreutils-python

Create a directory MySQL/MariaDB can access

NOTE: I am going to work with MariaDB for this blog, as it can be installed from repository in CentOS.

The easy way to create a new policy, which allows to MySQL or MariDB to use a directory, is to install "semanage". It is provided with the following package:

yum install policycoreutils-python

Then proceed to create the new directory, where MySQL/MariaDB could store the binary logs, if they should not be in the datadir.

mkdir /var/lib/mysql_binlog/ chown -R mysql:mysql mysql* semanage fcontext -a -t mysqld_db_t "/var/lib/mysql_binlog(/.*)?" restorecon -Rv /var/lib/mysql_binlog

NOTE: You have to give the absolute path to the file or the directory!

If you want to use MySQL/MariaDB on a non-standard port, you also have to allow usage of that port:

semanage port -a -t mysqld_port_t -p tcp 3307

Once you have created the new directory for the binary logs and made sure it is owned by mysql, you need to change the type of the directory you created to the one that allows MySQL/MariDB to use this directory. If you do not do this, you will get a "Permission denied (13)" error.

"semanage" is used to make this change persistent, even when the entire file system relabelled.

I was although unable to change the socket. I am yet unsure what the problem was, as MariaDB did not start or return any error.

Enable MySQL to write to this directory vi /etc/my.cnf ... [mysqld] log-bin=/var/lib/mysql_binlog/binlog ... systemctl restart mariadb Taxonomy upgrade extras: mysqlmariadbcentos

MySQL is well known and widely spread because of its philosophy of Keep it Simple (KISS).

We recently had the discussion that with newer releases also MySQL and MariaDB relational databases becomes more and more complicated.

One indication for this trend is the number of MySQL server system variables and status variables.

In the following tables and graphs we compare the different releases since MySQL version 4.0:

mysql> SHOW GLOBAL VARIABLES; mysql> SHOW GLOBAL VARIABLES LIKE 'innodb%'; mysql> SHOW GLOBAL STATUS; mysql> SHOW GLOBAL STATUS LIKE 'innodb%';
VersionSystemIB Sys.StatusIB Stat.MySQL 4.0.3014322*133**0MySQL 4.1.2518926*164**0MySQL 5.0.962393625242MySQL 5.1.732773629142MySQL 5.5.513176031247MySQL 5.6.3143812034151MySQL 5.7.1549113135351MySQL 8.0.048812436351

* Use SHOW STATUS instead.
** Use SHOW ENGINE INNODB STATUS\G instead.

VersionSystemIB Sys.StatusIB Stat.MariaDB 5.1.443547230144MariaDB 5.2.103978632446MariaDB 5.5.4141910341399MariaDB 10.0.2153714745595MariaDB 10.1.18***589178517127MariaDB 10.2.2****58616448196

*** XtraDB 5.6
****InnoDB 5.7.14???

Taxonomy upgrade extras: mysqlvariablesstatusmariadb