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https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-ndbinfo-memory-per-fragment.html
memory_per_fragment Table: Notes memory_per_fragment Table: Examples The memory_per_fragment table provides information about the usage of memory by individual fragments. See the Notes later in this section to see how you can use this to find out ...
https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-ndbinfo-operations-per-fragment.html
This currently has the following formats: Base table: DbName/def/TblName BLOB table: DbName/def/NDB$BLOB_BaseTblId_ColNo Ordered index: sys/def/BaseTblId/IndexName Unique index: sys/def/BaseTblId/IndexName$unique The $unique suffix shown for unique ... The operations_per_fragment table provides information about the operations performed on individual fragments and fragment replicas, as well as about some of the results from these ...
https://dev.mysql.com/doc/refman/8.0/en/insert-on-duplicate.html
If you specify an ON DUPLICATE KEY UPDATE clause and a row to be inserted would cause a duplicate value in a UNIQUE index or PRIMARY KEY, an UPDATE of the old row occurs. If column b is also unique, the INSERT is equivalent to this UPDATE statement ...With ON DUPLICATE KEY UPDATE, the affected-rows value per row is 1 if the row is inserted as a new row, 2 if an existing row is updated, and 0 if an existing row is set to its current ...
https://dev.mysql.com/doc/refman/8.0/en/replication-options-binary-log.html
For servers that are used in a replication topology, you must specify a unique nonzero server ID for each server. For the before image, it is necessary only that the minimum set of columns required to uniquely identify rows is logged. Otherwise, if ... Startup Options Used with Binary Logging System Variables Used with Binary Logging You can use the mysqld options and system variables that are described in this section to affect the operation of the binary log as well as to control which statements are written to the binary ...
https://dev.mysql.com/doc/refman/8.0/en/merge-table-problems.html
A MERGE table cannot maintain uniqueness constraints over the entire table. MySQL ensures that unique key values remain unique within that MyISAM table, but not over all the underlying tables in the collection. Because the MERGE engine cannot ...
https://dev.mysql.com/doc/refman/8.0/en/group-by-functional-dependence.html
The examples use this notation: {X} -> {Y} Understand this as “X uniquely determines Y,” which also means that Y is functionally dependent on X. A UNIQUE index over a NOT NULL column could be used instead of a primary key and the same functional ... The following discussion provides several examples of the ways in which MySQL detects functional ...
https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-log-statistics.html
This count also includes reads performed as part of unique index operations. A unique index read operation generates 2 primary key read operations—1 for the hidden unique index table, and 1 for the table on which the read takes place. This ... The ...
https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-replication-issues.html
In older versions of NDB Cluster, operations that updated values of unique key columns of NDB tables could result in duplicate-key errors when replicated. This issue is solved for replication between NDB tables by deferring unique key checks until ... This section discusses known problems or issues when using replication with NDB ...
https://dev.mysql.com/doc/refman/8.0/en/mysqlslap.html
--auto-generate-sql-unique-query-number=N Command-Line Format --auto-generate-sql-unique-query-number=# Type Numeric Default Value 10 How many different queries to generate for automatic tests. For example, if you run a key test that performs 1000 ... mysqlslap is a diagnostic program designed to emulate client load for a MySQL server and to report the timing of each ...
https://dev.mysql.com/doc/refman/8.0/en/explain-output.html
const is used when you compare all parts of a PRIMARY KEY or UNIQUE index to constant values. It is used when all parts of an index are used by the join and the index is a PRIMARY KEY or UNIQUE NOT NULL index. ref is used if the join uses only a ...