oracle init parameters

本文深入解析了db_file_multiblock_read_count参数如何影响Oracle数据库的物理读取过程,详细说明了在不同读取计数设置下,数据库如何进行段头部和块的读取操作。

摘要生成于 C知道 ,由 DeepSeek-R1 满血版支持, 前往体验 >

db_file_multiblock_read_count

  • Segment headers ard read with single-block reads
  • Physical reads never span server extents.
  • Blocks already in the buffer cache, except for direct read, are not reread from I/O subsystem.

read blocks

If the initialization parameter db_file_multiblock_read_count is set to 8, the following
physical reads are performed:
• One single-block read of the segment header (block 1).
• One multiblock read of two blocks (2 and 3). More blocks cannot be read because block 4
is cached.
• One multiblock read of four blocks (from 5 to 8). More blocks cannot be read because
block 9 is cached.
• One multiblock read of six blocks (from 11 to 16). More blocks cannot be read because
block 16 is the last one of the extent.
• One multiblock read of two blocks (17 and 18). More blocks cannot be read because
block 19 is cached.
• One single-block read of block 20. More blocks cannot be read because block 21 is cached.
• One multiblock read of eight blocks (from 22 to 29). More blocks cannot be read because
the initialization parameter db_file_multiblock_read_count is set to 8.
• One multiblock read of three blocks (from 30 to 32).

评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值