Most often, you want only a small subset of the data in the table, so a full table scan wastes a lot of disk I/O and therefore time.
通常来说，您可能只希望获得表中数据的一个子集，因此全表扫描会浪费大量的磁盘I/O，因此也就会浪费大量时间。
When a process waits for a block device data request to complete, it incurs I/O wait time, and all idle time becomes wait time.
当一个过程等待一个块设备数据请求完成时，它会增加 I/O等待时间，而所有空闲都会变成等待时间。
If everything looks good—lower CPU costs, lower elapsed times, and less I/O—we implement those recommendations in our production environment over the weekend after a reorg of the data.
如果一切看起来良好 —— 更低的CPU成本、更短的共计时间和更少的 I/O ——我就会在重新组织数据，然后利用周末在生产环境中执行这些建议。
Page level sampling reduces I/O significantly since it reads only a percentage of the data pages.
而页级的抽样则可以显著减少I/O，因为它只读取一定百分比的数据页。
The asynchronous I/O allows applications to read and write data without blocking.
异步I/O让应用程序能够在不阻塞的情况下读写数据。
The hit ratios for data and index pages reflect the number of times a page request was handled by the buffer pool directly without requiring disk I/O.
数据和索引页面的击中率反映了缓冲池在不需要磁盘I/O的情况下直接处理一个页面请求的时间量。
RDBMS designers concentrated on optimizing I/O and tried to align the data access patterns with the block structure imposed by the drives.
RDBMS设计者的精力主要集中于优化I/O和设法用驱动器的块结构来安排数据访问模式。
This code snippet can also be modified to perform I/O of all four data transfer types.
这段代码还可以修改为进行所有四种数据传输类型的I/O。
This is expected because data loading performance depends upon many factors, including the I/O configuration, the storage configuration, and the nature of the workload being processed.
这是因为数据加载性能依赖很多因素，包括I/O配置、存储配置、以及正在处理的工作负载的特性。
This can cut the time required to process queries by as much as 20 percent because more data can be kept in memory, reducing the number of I/O operations to slower mechanical disk drives.
这导致处理查询所需的时间降低了 20%，因为可以在内存中保存更多数据，减少了对缓慢的机械磁盘驱动器的I/O操作次数。
There are a number of things that you can do to improve the efficiency of this processing, such a turning trace off, minimizing log and data I/O time, and tuning the databases.
为了提高处理的效率，您可以采取很多措施，例如关闭跟踪、使日志和数据I/O时间最小化和调整数据库。
The function of AIO is to perform disk I/O when SQL statement accessing or updating database data.
AIO的功能是在SQL语句访问或更新数据库数据时，执行磁盘I/O。
The closer the ratio is to 100 percent, the lower the frequency of disk I/O, and therefore the less overhead of reading data.
命中率越接近 100%，磁盘I/O的频率就越低，因而读取数据的开销就越少。
The metadata server transforms the file name into an inode, file size, and striping data (layout) that the Ceph client uses for file I/O.
元数据服务器将文件名转变为索引节点，文件大小，和Ceph客户端用于文件 I/O的分段数据（布局）。
The LVM always uses one pbuf for each individual I/O request, regardless of the amount of data that is transferred.
通常，LVM为每个单独的I/O请求使用一个pbuf，而不管传输的数据量有多大。
In at least one case, Information Integrator reduced reporting time by more than 90 percent by minimizing I/O and unnecessary data transfers over the network.
甚至在有的案例中，Information Integrator通过减少I/O和网络上不必要的数据传输，使报表时间减少了 90%。
The I/O might involve reading data from a disk, or a database, or a web service, or even from a user.
I/O可能涉及到从一个磁盘、一个web服务或甚至是一名用户读取数据。
This has the potential to increase performance significantly for applications that do a great deal of copying of data from one I/O channel to another, such as Web servers.
这就极有可能提高了需要在I/O通道间大量拷贝数据的应用程序的性能，如Web 服务器。
On Windows NT, the disk queue length is the best indicator of I/O saturation, and it should be less than the number of disks in the data RAID set minus one.
在WindowsNT 上，磁盘队列长度是I/O饱和程度的最好指示器，并且它应该小于数据RAID集中的磁盘数减去 1。
New compression support for XML data and indexes reduces disk space requirements and can improve runtime performance of I/O-bound operations.
新的XML数据和索引压缩支持可以减少所需的磁盘空间，可以提高受I/O 限制的操作的运行时性能。
However, over-allocating free space may result in wasted DASD space, less data transferred per I/O, less efficient use of buffer pools and more pages to scan.
然而，过多地分配空余空间可能会产生浪费的DASD 空间，导致每次I/O 只能传输更少的数据，缓冲池的利用效率更低，并且要扫描更多的页。
This input/output (I/O) operation is time-consuming, compared with the amount of time required to access data that’s already in computer memory.
与访问已经在计算机内存中的数据相比，这种输入/输出 (I/O)操作非常耗时。
PVFS sends a request to the meta-data server (steps 1 and 2 in Figure 4), which informs the requesting node about the location of the file among the various I/O nodes.
PVFS向元数据服务器发送一个请求（图4中的步骤1、2），这会通知请求节点有关文件在各个I/O 节点上的位置的信息。
There is more to the story though as there are actually three different methods that the I/O Manager will use to marshal this data before giving the IRP to the driver.
尽管输入输出管理器在IRP传递到驱动之前有三种方法来排列数据，但是其实还是有更多的故事的。
Instead, it creates a file mapping that causes the driver code and data to be fetched by paging I/O.
而是，创建一个文件映射，这个映射导致I/O内存分页读取驱动代码和数据。
With time series simulation software, the CPU's I/O ports simulate I2C bus and exchange data with clock chips, temperature humidity sensors, memory chips and other devices.
采用软件模拟时序使CPU的I/O口模拟I2C总线，实现了单片机与时钟芯片、温湿度传感器、存储芯片等器件的数据交换。
Serial data communication has gained wide application in network transmission, backplane transceiver and I/O interface.
串行数据通信在网络传输、背板连接和I/O接口等领域应用非常广泛。
With the fast and powerful data processing ability of the DSP controller and abundant and free programing I/O resource of the FPGA, the system can better accomplish all the tasks.
充分利用了DSP芯片高速的、强大的数据处理能力和FPGA芯片具有的众多I／O口资源且均可以自由编程支配的特点，使系统能较好的完成课题的任务。
Program instruction set, logic stack and data type of I/O memory which are tied up with tasks in the soft-PLC system are analyzed and studied.
研究了系统的程序指令集、逻辑堆栈和I/O存储器数据类型，实验表明系统具有良好的实时性和可靠性。
Program instruction set, logic stack and data type of I/O memory which are tied up with tasks in the soft-PLC system are analyzed and studied.
研究了系统的程序指令集、逻辑堆栈和I/O存储器数据类型，实验表明系统具有良好的实时性和可靠性。
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