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https://dev.mysql.com/doc/refman/8.4/en/merge-storage-engine.html
You cannot merge MyISAM tables in which the columns are listed in a different order, do not have exactly the same data types in corresponding columns, or have the indexes in different order. The column order in the underlying table and the MERGE ...
https://dev.mysql.com/doc/refman/8.4/en/merge-table-problems.html
The checks ensure that the definitions of the tables and the parent MERGE table definition match by comparing column order, types, sizes and associated indexes. Because these checks take place when the tables are opened, any changes to the ... The ...
https://dev.mysql.com/doc/refman/8.4/en/monitor-innodb-mutex-waits-performance-schema.html
Data is presented in descending order, by the number of summarized wait events (COUNT_STAR). You can adjust the ORDER BY clause to order the data by total wait time. A mutex is a synchronization mechanism used in the code to enforce that only one ...
https://dev.mysql.com/doc/refman/8.4/en/mrr-optimization.html
Then the keys are sorted and finally the rows are retrieved from the base table using the order of the primary key. The Multi-Range Read optimization provides these benefits: MRR enables data rows to be accessed sequentially rather than in random ...
https://dev.mysql.com/doc/refman/8.4/en/myisamchk-other-options.html
This improves join performance by enabling the join optimizer to better choose the order in which to join the tables and which indexes it should use. --sort-index, -S Command-Line Format --sort-index Sort the index tree blocks in high-low order.
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-replication-issues.html
This section discusses known problems or issues when using replication with NDB Cluster. A loss of connection can occur either between the source cluster SQL node and the replica cluster SQL node, or between the source SQL node and the data nodes ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-replication-mta.html
Where two transactions modify the same row they are considered to be dependent, and must be applied in order (in other words, serially) to avoid deadlocks or incorrect results. Where a table has secondary unique keys, these values are also added to ...To use this functionality with NDB Cluster, it is necessary that the replica be configured to use multiple worker ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-rolling-restart.html
In other words, you are permitted to upgrade the API and SQL nodes in any order. This remains true regardless of the order in which the nodes are upgraded. This remains true regardless of the order in which you upgrade the cluster's API and SQL ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-indexes.html
For example: SELECT MIN(key_part2),MAX(key_part2) FROM tbl_name WHERE key_part1=10; To sort or group a table if the sorting or grouping is done on a leftmost prefix of a usable index (for example, ORDER BY key_part1, key_part2). If all key parts are ... Indexes are used to find rows with specific column values ...
https://dev.mysql.com/doc/refman/8.4/en/partitioning-selection.html
Partitions and subpartitions named in partition_names may be listed in any order, and may overlap. You can use WHERE conditions, ORDER BY and LIMIT options, and so on. Explicit selection of partitions and subpartitions for rows matching a given ...