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Before the version 4.1 of MySQL it was called Heap. The SHOW ENGINES command describes MEMORY as: Hash based, stored in memory, useful for temporary tables. MEMORY writes table data in-memory. While the table structures are persisted on-disk, the rows in MEMORY tables are lost when MySQL stops.
Aria is a storage engine for the MariaDB and MySQL relational database management systems.Its goal is to make a crash-safe alternative to MyISAM.It is not transactional.. Aria has been in development since 2007 and was first announced by Michael "Monty" Widenius on his blog. [1]
A common table expression, or CTE, (in SQL) is a temporary named result set, derived from a simple query and defined within the execution scope of a SELECT, INSERT, UPDATE, or DELETE statement. CTEs can be thought of as alternatives to derived tables , views, and inline user-defined functions.
Cursors can not only be used to fetch data from the DBMS into an application but also to identify a row in a table to be updated or deleted. The SQL:2003 standard defines positioned update and positioned delete SQL statements for that purpose. Such statements do not use a regular WHERE clause with predicates. Instead, a cursor identifies the row.
DELETE requires a shared table lock; Triggers fire; DELETE can be used in the case of: database link; DELETE returns the number of records deleted; Transaction log - DELETE needs to read records, check constraints, update block, update indexes, and generate redo / undo. All of this takes time, hence it takes time much longer than with TRUNCATE
In SQL, the TRUNCATE TABLE statement is a data manipulation language (DML) [1] operation that deletes all rows of a table without causing a triggered action. The result of this operation quickly removes all data from a table , typically bypassing a number of integrity enforcing mechanisms.
A Catholic nun was arrested by Italian police on Thursday for bringing messages for the mafia to prisoners, police said in a news statement. Sister Anna Donelli acted on several occasions as an ...
In MySQL 5.1, a copy of the MySQL FRM file is stored in the header of each Archive file. The FRM file, which represents the definition of a table, allows an Archive file to be restored to a MySQL server if the Archive file is copied to the server. Despite the use of zlib, archive files are not compatible with gzio, the basis of the gzip tools ...