optimization > A no-go index optimization caseThis sample illustrates the case. Suppose you have a word that participates in the field of the Where condition query. However, it participates in the operator, so it is not indexed in Oracle's internal run-out plan. So we made a little change. How many times has the efficiency improved? 5.3 Times times, 530%. Oh!In the example above, we can make a summary of the index creation.Summary of index creationTable AnalyzeAnalyze Table VS Dbms_statsWaterma
, of which there are 3 in the running, 127 in hibernation (sleep), 0 in the stoped state, and 1 in the Zombie State (zombie). Third line: CPU status 10.6% US user space as a percentage of CPU usage. 2.2% Sy Core Space consumes a percentage of the CPU. 0.0% NI changed the priority of the process to occupy the percentage of CPU 84.5% ID idle CPU percentage 2.5% wa io wait cpu percentage 0.1% hi hard Interrupt (Hardware IRQ)% of CPU 0.0% si soft interrupt (software Int errupts) Percentage of CPU us
Head (head): Read and write data to disk
Track: When the disk is rotated and the head remains in one position, each head will draw a circular trajectory on the disk surface called the track. A track on a disk is a set of concentric circles with different recording densities
Sector (sector): each track on a disk is divided into segments that are sectors of the hard disk. The first sector of a hard disk, called a boot sector. The size of a sector is 512 bytes
Cylinder (cylind
primary or extended partition, and the logical partition (which is based on the extended partition) number can only start at 5
Basic requirements for partitioning for Linux systems
at least one root (/) partition is required to store system files and programs. It is at least 5GB in size
to have a swap partition, which acts as virtual memory in Windows, the size of the swap partition is typically 1.5 times times the physical memory capacity (memory "but when the system physic
maintainability. When running the JVM on multiple servers, you can also choose to run multiple JVMs on a single server or on each server to run one JVM. For example, for each server, you can run a JVM that uses 8GB of heap memory, or you can run 4 JVMs that use 2GB. You should decide this number based on the number of processor cores and the nature of the program. Using 2GB of heap memory is better than 8GB
equipped with the sixth generation Intel Core I processor, the highest 8GB DDR4 memory +512GB Solid-State Drive, Lenovo said, its CPU comprehensive ability to increase 50%, graphics performance increased by one times.
Price, 4GB+128GB Elite version of the sale of 4399 Yuan, 8GB+256GB Prestige edition 5499 Yuan, 8GB+512GB flagship edition sold 7499 Yuan, are pre
DDR4 How much memory frequency is appropriate? For computer enthusiasts, the greater the memory frequency, the faster the speed is relative. In today's latest DDR4 memory era, how much memory frequency is appropriate? Today's small series will share the DDR4 memory high and low frequency on the computer performance and CPU, graphics, game performance impact, I believe you can find the answer.
DDR4 is the memory frequency larger and faster? measured high and low frequency DDR4 memory
one, can not be used at the same time.
Comprehensive consideration of the above factors, for Intel's CPU, currently still with Google's Android simulator and HAXM GPU Accelerator is more convenient, in the computer expansion to 8GB memory, the operation speed is also fast, upgrade simple, flexible configuration, the use is also very convenient.
For ARM CPUs, Google's Android simulator is also up to speed when the computer expands to
mirrored 146GB 10K to SAS drives, and shared storage is NetApp fas3020c, with software iSCSI connectivity, The MPIO is used in the design of the storage network. The VMFS LUNs for shared storage are experiment-specific, with no other load on it, and the blade server is only an experimental VM, with no additional load. The reason why such a specific description of experimental equipment, is to express a clear meaning: server, network, storage performance is sufficient, does not cause performance
watch it go.Conditions in which the index does not take effectSo the index does not build, sometimes built is also Perkins, why? Take a look at the following case studies:Take the case to illustratePlsql optimization > A no-go index optimization caseThis example shows that if you have a word for a field that is queried by the where condition, but it is involved in the operator, it is not indexed in Oracle's internal execution plan, so we made a small change, how many times is the efficiency imp
style without altering the content of the Web page, OH, you'll have to find the junk code that you've lost in every nook and cranny, and if the project happens to be very large, then I'm afraid only good luck, Or recommend you to find Huang.
Don't get yourself into such trouble, create clean code, and keep them clean all the time, so you can make your life a lot more enjoyable.
Note: Be careful with too many external style sheets, and if you create
Using System; Using System.Data; Using System.Configuration; Using System.Collections; Using System.Web; Using System.Web.Security; Using System.Web.UI; Using System.Web.UI.WebControls; Using System.Web.UI.WebControls.WebParts; Using System.Web.UI.HtmlControls; Using System.IO; Public partial class DFile:System.Web.UI.Page {protected void Page_Load (object sender, EventArgs e) {} protected void Linbtndfile_click (object sender, EventArgs e) {//Create a bit arr
time format, please re-enter
ECHO.
GOTO Yesno
ECHO Please specify a 24-hour format for hour minutes
SET shutdowntime=
SET P shutdowntime= Input
At%shutdowntime% Tsshutdn 0 delay0 powerdown nul
IF not errorlevel 1 GOTO OK
ECHO%shutdowntime% is not a standard time format, please re-enter
ECHO.
GOTO Nook
ECHO.
SET h=%shutdowntime~1,1%
SET ah=%shutdowntime~0,1%
SET am=%shutdowntime~2,2%
SET bh=%shutdowntime~0,2%
SET bm=%shutdowntime~3,2%
Logical judgment in the shellFormat 1:if condition; Then statement; FiIf it's what it is, then what happens?Write a simple script that means when a=5, when a is greater than 3 o'clock print OK#!/bin/bashA=5If [$a-GT 3]ThenEcho OKFiExecute script after saving exit[Email protected] shell]# sh if1.shOkOne of the GT's meanings in the shell is greater than the meaning. Note that there are spaces in the brackets, both sides and in the middle.Format 2:if condition; Then statement; else statement; FiWha
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