 Creating and editing MySQL and MariaDB MERGE tables, MRG_MYISAM |
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The table editing module is called in the table list | |
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Module for creating and editing MySQL MRG_MYISAM tables:
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| Table is first created with MRG_MYISAM engine. |
| After the table has been created, tables with the same structure can be assigned from any database. |
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| Insert option: | (INSERT_METHOD) Selection of the method how data should be inserted into the table:
| NO | No data inserting allowed. |
| FIRST | Data is inserted into the first table. |
| LAST | Data is inserted into the last table. |
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View and run table changes as SQL script |
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Save table changes to database |
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MySQL and MariaDB Merge Tables allows data from multiple tables to be combined into a single virtual table for querying and analysis facilitate. It provides a way to logically join multiple tables without physically consolidating the data. A merged table is a virtual table that does not have its own storage or physical representation. It is a logical construct that references the underlying tables to access and combine their data.
The merged table has the same column structure as the underlying tables. The column names, data types, and constraints are inherited by each table. The merge is performed using the UNION ALL operation, which combines the rows from the underlying tables without removing duplicates. This means that all rows from all tables will be included in the merged result. For the merge operation to work, the underlying tables must have the same number of columns and compatible data types. If there are incompatible data types, explicit type casting or data conversion functions may need to be used.
Merged tables do not have their own indexes or constraints. Instead, they rely on the indexes and constraints defined on the underlying tables. Query optimization can take advantage of these indexes to improve performance. Merged tables can be queried like a normal table. The SELECT statement can be used to retrieve data from the merged table, and apply filtering, sorting, and other operations to the merged result.
There are some limitations to be aware of when working with merged tables. For example, ES cannot perform updates, inserts, or deletes directly on the merged table. The merged table is read-only and reflects the current data in the underlying tables.
MySQL and MariaDB Merge Tables provide a convenient way to query and analyze data from multiple tables as if they were a single table. This is useful when data from similar tables needs to be combined without physically joining or duplicating the data. |
| More information on editing MySQL tables here:
Information on MERGE tables can be found here: and |
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