pimax 8k

table from disk, and if an index points to data values, then the query needs to read only a few disks at a time. Therefore, reasonable use of the index can speed up the data query. However, indexes do not always improve the performance of the system, and indexed tables require more storage space in the database, as well as the time required to delete and remove data, and to maintain the index for longer processing time. So we should use the index reasonably, update the sub-optimal index in time

disk controller may issue a series of IO commands to the disk group at one time, which is called sequential IO if the disk group can only execute one IO command at a time, called concurrent IO when the disk group is able to execute multiple IO commands at the same time. Concurrent IO can only occur on a disk group consisting of multiple disks, and a single disk can only process one IO command at a time.　　Size of single io (io Chunk size)People familiar with the database will have this concept,

query needs to read only a few disks at a time. Therefore, reasonable use of the index can speed up the data query. However, indexes do not always improve the performance of the system, and indexed tables require more storage space in the database, as well as the time required to delete and remove data, and to maintain the index for longer processing time. So we should use the index reasonably, update the sub-optimal index in time.second, the basic structure of the data tableWhen a new table is

query needs to read only a few disks at a time. Therefore, reasonable use of the index can speed up the data query. However, indexes do not always improve the performance of the system, and indexed tables require more storage space in the database, as well as the time required to delete and remove data, and to maintain the index for longer processing time. So we should use the index reasonably, update the sub-optimal index in time.Basic structure of the data tableWhen a new table is created, th

In node, Buffer is a widely used class, and this article will analyze its memory policy from the following levels: The user level, either node Lib/*.js or your own JS file, calls new Buffer Socekt Read/write File Read/write User BufferIn the Lib/buffer.js module, there is a module private variable pool, which points to the current 8K slab:Buffer.poolsize = 8 * 1024x768; var Pool; function Allocpool () { new Slowbuffer (buffer.p

=532000000, E=24000000S3C64XX: HCLK2=266000000, HCLK=133000000, PCLK=66500000mout_apll: source is fout_apll (1), rate is 532000000mout_epll: source is epll (1), rate is 24000000mout_mpll: source is mpll (1), rate is 532000000usb-bus-host: source is clk_48m (0), rate is 48000000audio-bus: source is mout_epll (0), rate is 24000000audio-bus: source is mout_epll (0), rate is 24000000audio-bus: source is mout_epll (0), rate is 24000000irda-bus: source is mout_epll (0), rate is 24000000camera: no pare

the introduction to the data structure of Microsoft SQL Server 2000 database programming, Unit 3rd, and the 6th, 13, 14 units). One, the difference between the index block and the data block As we all know, indexing can improve retrieval efficiency because of its two-fork tree structure and small footprint, so access speed blocks. Let's calculate a math problem: if a record in a table occupies 1000 bytes on disk, we index one of the 10 bytes of the field, and the record has only 10 bytes of t

, the lower the log level output of the more log content, the system can affect a lot. D, the different log output mode, the system can also have a certain impact, the use of asynchronous output mode than the synchronous output mode of higher performance. E, every time the log output event to print a log content than the contents of the day to reach a certain size of the printing system can be low. 4, for the above several of the impact of the system on the 4th, 5 points, the log configuration f

Linux operations-aware performance monitoring and debugging tools1 NagiosNagios is an open source monitoring solution, and I think he can monitor everything, and can look at my previous article: NAGIOS2 PS #用来查看程序的运行情况Ps-ef |grep svr.py|grep-v grep |awk ' {print $} ' #查看svr. PY process PID Number145543 free# View the system's physical (RAM) and swapped memory information [emailprotected]:~> free-mto #MB值显示, showing total total used free shared buffers cachedmem:3196 2947 249 0 1436swap:2053 196

(if you're interested in this, read the introduction to the data structure of Microsoft SQL Server 2000 database programming, Unit 3rd, and the 6th, 13, 14 units). One, the difference between the index block and the data block As we all know, indexing can improve retrieval efficiency because of its two-fork tree structure and small footprint, so access speed blocks. Let's calculate a math problem: if a record in a table occupies 1000 bytes on disk, we index one of the 10 bytes of the field, and

help. The beginning of each data file is distributed GAM,SGAM,PFS these pages, which record which pages in the database file are already in use and which pages are not used.1.1 PFSPFS page, used to track page assignment levels and to store information about all page allocations and available space in the current data file, the 2nd data page for each data file is PFS, with page number 1. In this page, eacha single byteDescribes whether each of the subsequent data pages can write records, that is

takes longer to add, delete, and change data commands.Storage mechanism of indexesThe catalog in the book is a word and a list of page numbers in which the index in the database is the value in the table and the list where the values are stored.A clustered index is a new physical space in the database that holds the values he arranges, and when new data is inserted, he rearranges the entire physical storage space.A nonclustered index contains only the columns of the nonclustered indexes in the

the database, and it takes longer to add, delete, and change data commands. Storage mechanism of indexes The catalog in the book is a word and a list of page numbers in which the index in the database is the value in the table and the list where the values are stored. A clustered index is a new physical space in the database that holds the values he arranges, and when new data is inserted, he rearranges the entire physical storage space. A nonclustered index contains only the columns of the non

are clk_48m (0), rate is 48000000audio-bus:source are MOUT_EPLL (0), rate is 24000000aud Io-bus:source is MOUT_EPLL (0), rate is 24000000audio-bus:source are MOUT_EPLL (0), rate is 24000000irda-bus:source is M OUT_EPLL (0), rate was 24000000camera:no parent Clock specifiedcpu:found DTCM0 8k @ 00000000, not enabledcpu:moved DTCM0 8k to fffe8000, enabledcpu:found DTCM1