What is the use of partition by in MySQL?
A PARTITION BY clause is used to partition rows of table into groups. It is useful when we have to perform a calculation on individual rows of a group using other rows of that group.
What is the difference between primary key and partition key?
A primary key uniquely identifies a row. A composite key is a key formed from multiple columns. A partition key is the primary lookup to find a set of rows, i.e. a partition. A clustering key is the part of the primary key that isn’t the partition key (and defines the ordering within a partition).
Where does primary key go in partitioning table?
By default indexes are created on the same Data Space (ie Filegroup or Partition Scheme) as the table. So you have to explicitly place the primary key index on a filegroup. Eg BTW this will create Heap table, which is probably the worst option.
How to use the on duplicate key update clause?
The ON DUPLICATE KEY UPDATE clause can contain multiple column assignments, separated by commas. In assignment value expressions in the ON DUPLICATE KEY UPDATE clause, you can use the VALUES ( col_name) function to refer to column values from the INSERT portion of the INSERT ON DUPLICATE KEY UPDATE statement.
Can a partition be a subset of the index key?
“command_date” is a partition column of the index “pk_command_id’. The partition columns of a single index must be a subset of the index key. I see someone propose me this solution : Partition columns for a unique index must be a subset of the index key error But this is a mistake to me.
How to do duplicate key update in MyISAM?
ON DUPLICATE KEY UPDATE on a partitioned table using a storage engine such as MyISAM that employs table-level locks locks any partitions of the table in which a partitioning key column is updated. (This does not occur with tables using storage engines such as InnoDB that employ row-level locking.)