Skip to main content

MySQL InnoDB cluster and group replication limitations


MySQL InnoDB cluster limitations:

01. A group can consist of maximum 9 servers. Attempting to add another server to a group with 9 members causes the request to join to be refused.
02. Limitations and issues described for multi-primary mode groups can also apply in single-primary mode clusters during a failover event, while the newly elected primary flushes out its applier queue from the old primary.
03. Individual transactions that result in GTID contents which are large enough that it cannot be copied between group members over the network within a 5 second window can cause failures in the group communication. To avoid this issue try and limit the size of your transactions as much as possible. For example, split up files used with LOAD DATA INFILE into smaller chunks.
04. Group Replication cannot currently make use of replication Event Checksums.
The certification process does not take into account gap locks, table lock, and named locks.
Setting a transaction isolation level to SERIALIZABLE configures Group Replication to refuse to commit the transaction.
05. Concurrent data definition statements and data manipulation statements executing against the same object but on different servers is not supported when using multi-primary mode.
06. Multi-primary mode groups (members all configured with group_replication_single_primary_mode=OFF) do not support tables with multi-level foreign key dependencies, specifically tables that have defined CASCADING foreign key constraints.
07. When a group is operating in multi-primary mode, SELECT .. FOR UPDATE statements can result in a deadlock.
08. Global replication filters cannot be used on a MySQL server instance that is configured for Group Replication, because filtering transactions on some servers would make the group unable to reach agreement on a consistent state.
09. InnodDB cluster is built on replication with GTID, so limitations of GTID are applicable to InnoDB cluster also.

Limitation of GTID:
  • No support for non transactional engine such as MyISAM.
  • CREATE TABLE ... SELECT.
  • ALTER TABLE ... ADD, if the column has an expression default value.
  • Binlog_format is set to STATEMENT, and CREATE TEMPORARY TABLE and DROP TEMPORARY TABLE statements cannot be used inside transactions, procedures, functions, and triggers when GTIDs are in use on the server (that is, when the enforce_gtid_consistency system variable is set to ON).
  • sql_slave_skip_counter is not supported when using GTIDs. If you need to skip transactions, use the value of the master's gtid_executed variable instead.
  • IGNORE_SERVER_IDS option of the CHANGE MASTER TO statement is deprecated when using GTIDs.
Ref.:
https://dev.mysql.com/doc/refman/8.0/en/group-replication-limitations.html
https://dev.mysql.com/doc/refman/8.0/en/replication-gtids-restrictions.html
https://dev.mysql.com/doc/refman/8.0/en/group-replication-frequently-asked-questions.html
https://dev.mysql.com/doc/refman/8.0/en/group-replication-requirements.html



Labels:

Comments

Post a Comment

Popular posts from this blog

MySQL InnoDB cluster troubleshooting | commands

Cluster Validation: select * from performance_schema.replication_group_members; All members should be online. select instance_name, mysql_server_uuid, addresses from  mysql_innodb_cluster_metadata.instances; All instances should return same value for mysql_server_uuid SELECT @@GTID_EXECUTED; All nodes should return same value Frequently use commands: mysql> SET SQL_LOG_BIN = 0;  mysql> stop group_replication; mysql> set global super_read_only=0; mysql> drop database mysql_innodb_cluster_metadata; mysql> RESET MASTER; mysql> RESET SLAVE ALL; JS > var cluster = dba.getCluster() JS > var cluster = dba.getCluster("<Cluster_name>") JS > var cluster = dba.createCluster('name') JS > cluster.removeInstance('root@<IP_Address>:<Port_No>',{force: true}) JS > cluster.addInstance('root@<IP add>,:<port>') JS > cluster.addInstance('root@ <IP add>,:<port> ') JS > dba.getC...
Post a Comment
Read more

Amazon RDS | Amzon Redshift | Big Data | Boost Performance with Amazon ElastiCache

Amazon RDS with Amazon ElastiCache for Performance: Amazon RDS supports - Oracle, MS SQL server, MySQL, Maria DB and PostgreSQL. It is a managed service offered by the Amazon.  Couple of customers have observed the performance issues during their journey with Amazon RDS with Oracle, MS SQL Server, MySQL, Maria DB and PostgreSQL. Amazon cloud engineers / database consultants / database architect and Amazon supports worked to-gather to boost the Amazon RDS performance by tuning the RDBMS configuration parameters using Amazon RDS parameter group , and have not achieved the SLA for Amazon RDS .  Amazon RDS with Multi AZ and Read Replica: Some of the the AWS professionals have suggested for vertical scaling of the Amazon RDS . It should works and its absolutely correct. In my opinion, it would be a good idea to think about the Amazon ElastiCache service with Amazon RDS for better performance and cost optimization also rather than vertically scaling the Amazon RDS . I would sug...
2 comments
Read more

Needs for Graph Database

Needs for Graph Database: We are living in the era of data, data is treated more precise than gold and platinum. Most of the enterprises are trying to get more insight about the data they have it as an operational / warehouse / analytical.   Ref.: https://dist.neo4j.com/wp-content/uploads/graph-example.png To get more insight into the data, it is required to see the relationship among the data points. The challenge is how to establish the relationship among data points and the answers is Graph database. Relational databases can't help to establish the relationship among data points, due to their rigid schema, and consistent schema. Relational Database issues for data set: Number of Joins:  While fetching data from relational databases, we join many tables, these joins are complex, and consume considerable amount of computing resources, which increase the query response times. Self- joins: For database ware house / business intelligence systems using RDBMS, self-JOIN are ...
1 comment
Read more