Oracle 20c 新特性:SQL 宏支持(SQL Macro)Scalar 和 Table 模式 SQL宏特性,允许开发人员将复杂的处理通过宏定义实现,随后可以在 SQL 中任何位置调用宏。这个特性的实现类似于12c中实现的 Function in SQL 特性。 在Oracle Database 20c 中,Oracle 带来了 SQL 的超级增强 - SQL 宏 (SQL Macro)特性。 SQL宏特...
Optimize MySQL tables for defragmentation In a normal file, system installing/uninstalling applications and copying/deleting files results in disk fragmentation. The same happens with database tables if a large number ofDMLqueries (CREATE,INSERT,DELETE) are performed on database tables. Table storage ...
ALGORITHM=INPLACEwith nopartition_namesINTO (partition_definitions)option onNDBtables. This can be used to redistribute NDB Cluster data among new data nodes that have been added to the cluster online. This doesnotperform any defragmentation, which requires anOPTIMIZE TABLEor nullALTER TABLEstatement....
* Engine differences * Disk layout * Disk access patterns * BTree structure (and waste space) * Data versus Index defragmentation * PARTITION problems * How long OPTIMIZE takes * SSD vs spinning drives * RAID with write cache * Etc.Navigate...
Another way to perform a defragmentation operation is to usemysqldumpto dump the table to a text file, drop the table, and reload it from the dump file. If the insertions into an index are always ascending and records are deleted only from the end, theInnoDBfilespace management algorithm guar...
(Bug #35077, Issue #449) At most one buffer-fix will be active at a time, affecting two blocks: the buf_page_t and the compressed page frame. This should not block the memory defragmentation in buf0buddy.c too much. In fact, it may avoid unnecessary copying if also prev_bpage ...
InnoDB, when if finds a block less than half full, will try to merge it with an adjacent block. This is the extent of the automatic defragmentation. If you do a lot of random deletes (or, to some extent, random updates), the blocks will tend to become less fully populated. This lea...
http://bugs.mysql.com/bug.php?id=43683 To get a better explanation of how memory fragmentation and re-use works, I would recommend having a look at: http://johanandersson.blogspot.com/2009/03/memory-deallocationdefragmentation-and.html ...