About storage parameter INITRANS and MAXTRANS
About storage parameter INITRANS and MAXTRANS
INITRANS:
The space you would like to reserve for transaction entries compared
to the space you would reserve for database data ;
the default value (1 for tables, 2 for indexes) ;
MAXTRANS:
The number of concurrent transactions that are likely to touch the
same data blocks at any given time ;
INITRANS:
The space you would like to reserve for transaction entries compared
to the space you would reserve for database data ;
the default value (1 for tables, 2 for indexes) ;
MAXTRANS:
The number of concurrent transactions that are likely to touch the
same data blocks at any given time ;
这两个参数都是"transaction"在"Data block"级的体现;
INITRANS:在"Data block"中预先留下空间的"transaction"数量,因为在 "block header"中需要 保留这些"transaction"信息;对于多用户、高并发事务 系统,适形提高"INITRANS"值,可以降低定位 事务空间的时间. (block header contains information about the type of block
(a table block, index block, and so on), transaction information
regarding active and past transactions on the block, and the address
(location) of the block on the disk.)
MAXTRANS:在同一"Data block"上可以并行的"transaction"数量,如果并发数大于 这个数量,那么超过 的事务将被阻塞;
INITRANS and MAXTRANS一旦设定,不可更改;
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