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board, the keyboard and the bottom will contact with the motherboard, just can use the bottom of the keyboard to the CPU generated heat transfer Export to. In the construction of the keyboard, each button has 4 holes, the heat is discharged through the key hole, when the hot air from the key hole discharge, cold air from the key hole inflow, to replace the hot air. www.bcua.cn Bcuablog Among the many heat dissipation technologies, the water cooled bulk heat pipe technology is a very effective

, someday it would have to be maintained." "Even if a program has only three presidents, one day it needs to be maintained." 5.1 A well-used door needs no oil in its hinges. A swift-flowing Steam does no grow stagnant. Neither sound nor thoughts can travel through a vacuum. Software rots if not used. Frequently used doors do not need to be oiled in the door shaft. The flow of things will not stagnate. Water does not rot, nev

computers: in the middle of the 50 's, scientists invented the first generation of vacuum tube computers, and then in the late 50, scientists invented the second-generation transistor computer, and in the middle of the 60 invented the third generation of integrated circuit computer , in the late 60, with the fourth generation of integrated circuit computer, a short span of 10 years, the development of computer hardware developed four generations, fro

faster speeds. The first computer, ENIAC, was completed and put into use in 1946, a huge behemoth like a house that can be calculated 5,000 times per second and consumes about 150kW. Compared to this, the performance of modern microprocessors is 100多亿次 per second, the overall maximum power consumption of the PC is about 300W. This means that the computational performance has increased by 2 million times times and the power consumption has dropped to 1/500. In fact, from the original computer to

(() =NewSqlitecommand (Connection),"Command Object Initialization"); Run (()={Command.commandtext= $"DELETE from Info; VACUUM; UPDATE sqlite_sequence SET seq = ' 0 ' WHERE name = ' Info ';"; Command. ExecuteNonQuery (); }, "execute the Delete command and shrink the database"); Run (()= { for(inti =0; I the; i++) {Command.commandtext= $"INSERT into Info (Name, age) VALUES (' a{i:000} ', ' {i} ')"; Command.

can use the bottom of the keyboard to the CPU generated by the heat conduction out. In the structure of the keyboard, each button has 4 holes, the heat is discharged through the key hole, when the hot air from the key hole discharged, cold air flow from the key hole to replace the hot air. In many of the heat dissipation technology, the water-cooled bulk heat pipe technology is a very effective heat dissipation technology proposed by IBM. The original idea was to scoop the ice-cream spoon, the

copy statement;A transaction is composed of multiple SQL statements to reduce the cost of committing a transaction;Use cluster when extracting multiple records from an index;Use limit when extracting part of a record from a query result;Use pre-compiled queries (Prepared query);Use analyze to maintain accurate optimization statistics;Regular use of VACUUM or pg_autovacuumDelete indexes first when making large amounts of data changes (then rebuilding

file header that describes the database file. It includes the version of the library, the version of the schema, the page size, the encoding, and all the parameters that were set when the database was created. The content of this particular header is defined in btree.c, and Page 1 is also the root page of the Sqlite_master table.2.2, page reuse and recycling (page reuse and Vacuum)SQLite uses a free list to recycle pages. When all the records of a pa

multiple INSERT statements with the copy statement;A transaction is composed of multiple SQL statements to reduce the cost of committing a transaction;Use cluster when extracting multiple records from an index;Use limit when extracting part of a record from a query result;Use pre-compiled queries (Prepared query);Use analyze to maintain accurate optimization statistics;Regular use of VACUUM or pg_autovacuumDelete indexes first when making large amoun

, compared to MySQL based on binlog logical replication, data consistency is more reliable, replication performance is higher, the impact on host performance is also smaller.6, MySQL storage engine plug-in mechanism, there is a complex lock mechanism affects concurrency problems, and PG does not exist.Ii. MySQL's advantages over PG:1, InnoDB based on the implementation of the rollback segment MVCC mechanism, relative to PG new and old data stored together based on XID MVCC mechanism, is superior

exclusive locks -Exclusive lock is the most restrictive table lock compared to the other two locks-allows only other users to query the data ― Do not allow insert, delete, and update operations ― Allow only one user to place an exclusive lock on the table at the same time-share lock is the opposite Lock table Tab_name in exclusive mode; Lock table Lock table ----------------------------------------------------------------------------------------------- LOCK Name lock-explicitly locks a table

mechanism, there is a complex lock mechanism affects concurrency problems, and PG does not exist.Ii. MySQL's advantages over PG:1, InnoDB based on the implementation of the rollback segment MVCC mechanism, relative to PG new and old data stored together based on XID MVCC mechanism, is superior. The new and old data are stored together, it is necessary to trigger the vacuum periodically, which will result in extra lock overhead of IO and database obje

); SQLite ORDER BY clause: SELECT column1, column2....columnN FROM table_name WHERE CONDITION ORDER BY column_name {ASC|DESC}; SQLite PRAGMA Statement: PRAGMA pragma_name; For example: PRAGMA page_size; PRAGMA cache_size = 1024; PRAGMA table_info(table_name); SQLite RELEASE savepoint Statement: RELEASE savepoint_name; SQLite REINDEX Statement: REINDEX collation_name; REINDEX Database_name.index_name; REINDEX Database_n

in each clock cycle (pure vacuum) is 10 centimeters. We can assume that the electrical signals in the CPU are slower than the amount of light in the vacuum. The core idea is: a clock cycle of 10 centimeters? Not much at all. For our psychological experiments, now let's consider different distances: • Distance between two CPUs • The distance from your server to the other servers next door • Your distance fr

, usr_id bigint, svc_code character varying (()) Location (' Gphdfs://hacluster/tmp/zht/new_ table name. TXT ') FORMAT ' text ' (delimiter e ' ' null e ' escape e ' OFF ') ENCODING ' UTF8 ' LOG ERRORS into masadw.err_ext_ table name SEGMENT REJECT LIMIT ten PERCENT; D. Modify the external table owner to Etl_user: ALTER EXTERNAL Table masadw.ext_ name OWNER to Etl_user; NBSP;13, do not create default partition do not create default partition, do not put large amount of data to the default parti

XID loop issues mentioned above are addressed by the Vacuum command (the command that Postgres uses to perform cleanup operations). This should be a routine maintenance, so Postgre comes with the auto_vacuum daemon automatically cleans up within a configurable cycle. It is important to pay attention to point auto_vacuum, because the cycles that need to be cleaned up in different deployment environments are different. You can find more instructions on

is recorded directly in the data file rather than in the rollback segment, ora-01555 errors are not reported as often as Oracle.3. Rollback can be completed very quickly, due to rollback does not delete data, and Oracle and InnoDB, rollback is very messy, in the business rollback is necessary to organize the changes in the business, the records to be deleted, the updated records to be updated back (see Row_undo function), The process of rolling back together will also produce many redo logs aga

-init and dump it.2. I Open the already created SQLite database and dump it.3. I vacuum the Chinook database.4. I reindex the Chinook database.Added 64bit file support, but it had not been fully tested.Hopefully someone can do some tests with large five gigabyte data bases,Otherwise I ' ll get to it eventually.Also, since I ' ve actually made changes to the SQLite code since the update in January, I ' ve created a github.Http://github.com/tech128/sqli

course, you can also make it a vacuum, null and, new String () the difference is like vacuum and air. There is a special place in the string, that is, the string pool. Whenever we create a String object, we first check whether there are strings with the same nominal value in the string pool. If there are strings, we will not create them. We will directly put them back to the reference of this object in the

How to calculate the size of C ++ inheritance, virtual inheritance, and virtual function classes ?, Function How to calculate the size of C ++ inheritance, virtual inheritance, and virtual function classes? I. Vacuum C ++ code ClassCNull { }; Length: 1 Memory Structure: Note: The length is actually 0. This byte is meaningless as the content, and may be different each time. Ii. Empty category C ++ code ClassCNull2 { Public: CNull2 () {printf ("Constru