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MySQL to 8.0.11 in place upgrade

MySQL in place upgrade from 5.6.11 to 8.0.11:   01. Install MySQL 5.7 latest version on MySQL database server such as 5.7.22. 02. Initialize MySQL     mysqld --defaults-file=/etc/my.cnf --initialize-insecure & 03. Start MySQL daemon     mysqld --defaults-file=/etc/my.cnf & 04. Configure systemd to start and stop Mysql daemon       * Shutdown mysqld           mysqladmin -uroot -S/var/lib/mysql/mysql.sock shutdown        * Edit file /usr/lib/systemd/system/mysqld.service and add following         [Service]         PIDFile=/var/lib/mysql/mysql.pid         ExecStart=/usr/sbin/mysqld --defaults-file=/etc/my.cnf --daemonize --pid-file=/var   /lib/mysql/mysql.pid $MYSQLD_OPTS       * sudo systemctl daemon-reload   ...

Oracle in memory column store | IM column store

In-Memory Column Store (IM column store): The IM Column Store stores the data by column rather than row. The columnar format exists only in memory. It is an optional STATIC component of the SGA. IM Column store sub divided into two pools: 1 MB pool—Store the actual column formatted data 64k Pool--- Store the metadata about the objects. Objects that are smaller than 64KB are not populated into memory. No application changes are required. Stores copies of tables and partitions in a special columnar format optimized for rapid scans. IM column store is made up of multiple In-Memory Compression Units (IMCUs). It is not a replacement of buffer cache, but acts as a supplement so that both memory areas store the same data in different formats. The database keeps the columnar data transitionally consistent with the buffer cache. By default, only objects specified as INMEMORY using DDL are candidates to be populate...