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1. Thefollowingoptionsalsohaveanimpactonthesource: •ForthegreatestpossibledurabilityandconsistencyinareplicationsetupusingInnoDBwithtransactions,youshoulduse innodb_flush_log_at_trx_commit=1andsync_binlog=1inthesource'smy.cnffile. •Ensurethattheskip_networkingsystemvariableisnotenabledonthesour...
1. ...行业的数字化转型也进入了深水期，我们看到技术与场景的深度融合所带来的创新体验，看到了数字化加持下的流程再造和效率提升，也看到了行业引领者在业务模式和商业模式创新方面孜孜不倦的探索。 ...数字经济蓬勃发展时代，数据已成为关键生产要素。数据赋能企业经营决策、业务模式创新的需求不断变化，已经新兴技术工具的有效支撑，推动数据向数据要素化、数据驱动化阶段跃迁，实现数据价值崛起。 ...数字化在赋能行业对抗风险、增加韧性的同时，也将能够更好地助力其在未来朝着更加多元化、个性化和高质量的方向发展。 2. 在探索新模式的过程当中，定位和心态的转变，是保障其整个数字化转型成功的重要软性条件。其中有...
Alockingread,anUPDATE,oraDELETEgenerallysetrecordlocksoneveryindexrecordthatisscannedintheprocessingofanSQLstatement.ItdoesnotmatterwhetherthereareWHEREconditionsinthestatementthatwouldexcludetherow.InnoDBdoesnotremembertheexact【ɪɡˈzækt准确的;精确的;严格的;精密的;严谨的;严密的;一丝不苟的;】WHEREcondition,butonlyknowswhichi...
Toimplementalarge-scale,busy,orhighlyreliabledatabaseapplication,toportsubstantial【səbˈstænʃl】codefromadifferentdatabasesystem,ortotuneMySQLperformance,itisimportanttounderstandInnoDBlockingandtheInnoDBtransactionmodel. 1.SharedandExclusiveLocks InnoDBimplements【ˈɪmplɪments实施;执行;贯彻;使生效;】standardrow-...
TheInnoDBtransactionmodelaimstocombinethebestproperties【ˈprɑpərtiz财产;特性;房地产;不动产;财物;庄园;所有物;房屋及院落;】ofamulti-versioningdatabasewithtraditionaltwo-phaselocking.InnoDBperformslockingattherowlevelandrunsqueriesasnonlockingconsistentreadsbydefault,inthestyleofOracle.ThelockinformationinInnoDBisstoredspace-...
1.DataTypeDefaultValues Datatypespecificationscanhaveexplicit【ɪkˈsplɪsɪt明确的;详述的;直言的,坦率的;一目了然的;】orimplicit【ɪmˈplɪsɪt含蓄的;完全的;内含的;无疑问的;不直接言明的;成为一部分的;】defaultvalues. ADEFAULTvalueclauseinadatatypespecificationexplicitlyindicatesadefaultvalueforacolumn.Examples: CREATETABLEt1( iINTDEFAULT-1, cVARCHAR(10...
ThestringdatatypesareCHAR,VARCHAR,BINARY,VARBINARY,BLOB,TEXT,ENUM,andSET. 1.StringDataTypeSyntax Insomecases,MySQLmaychangeastringcolumntoatypedifferentfromthatgiveninaCREATETABLEorALTERTABLEstatement. Fordefinitionsofcharacterstringcolumns(CHAR,VARCHAR,andtheTEXTtypes),MySQLinterprets【ɪnˈtɜːr...
前述 Datatypedescriptionsusetheseconventions: •Forintegertypes,Mindicatesthemaximumdisplaywidth.Forfloating-pointandfixed-pointtypes,Misthetotalnumberofdigitsthatcanbestored(theprecision).Forstringtypes,Misthemaximumlength.ThemaximumpermissiblevalueofMdependsonthedatatype. •Dappliestofloating-pointand...
1.SupportedCharacterSetsandCollations Tolisttheavailablecharactersetsandtheirdefaultcollations,usetheSHOWCHARACTERSETstatementorquerytheINFORMATION_SCHEMACHARACTER_SETStable. mysql>SHOWCHARACTERSET; Incaseswhereacharactersethasmultiplecollations,itmightnotbeclearwhichcollationismostsuitablefora...
1.ConfiguringApplicationCharacterSetandCollation RegardlessofhowyouconfiguretheMySQLcharactersetforapplicationuse,youmustalsoconsidertheenvironmentwithinwhichthoseapplicationsexecute.Forexample,ifyouintendtosendstatementsusingUTF-8texttakenfromafilethatyoucreateinaneditor,youshouldeditthefilewiththe...
1.概述 TheUnicodeStandardincludescharactersfromtheBasicMultilingualPlane(BMP)andsupplementarycharactersthatlieoutsidetheBMP.ThissectiondescribessupportforUnicodeinMySQL. BMPcharactershavethesecharacteristics: •Theircodepointvaluesarebetween0and65535(orU+0000andU+FFFF). •Theycanbeencodedinavariable-len...
MySQLincludescharacter【ˈkærəktər 字母，符号;】setsupportthatenablesyoutostoredatausingavariety【vəˈraɪəti(同一事物的)不同种类，多种式样;变化;(植物、语言等的)变种，变体;多样化;综艺节目;品种;多变性;异体;】ofcharactersetsandperformcomparisons【kəmˈpɛrəsənz比较;对比;相比;】accordingtoavarietyofcollations.ThedefaultMySQLservercharactersetandcollationareutf...
1.CharacterStringLiteral【ˈlɪtərəl字面意义的;缺乏想象力的;完全按原文的;】CharacterSetandCollation Everycharacterstringliteralhasacharactersetandacollation. ForthesimplestatementSELECT'string',thestringhastheconnectiondefaultcharactersetandcollationdefinedbythecharacter_set_connectionandcollation_connectionsystemvariab...
1.NUll值 TheNULLvaluecanbesurprisinguntilyougetusedtoit.Conceptually【kənˈsɛptʃuəli概念;观念上;概念上;在概念上;概念地;】,NULLmeans“amissingunknownvalue”anditistreatedsomewhatdifferentlyfromothervalues. TotestforNULL,usetheISNULLandISNOTNULLoperators,asshownhere: mysql>SELECT1ISNULL,1ISNOTNULL; +-----------+------...
1.age与出生日期 为什么设计的时候，存放的是出生日期而不是年龄呢？这个问题简单，细想很有意思，也包含着智慧，来自生产生活的思考。下面的解释很到位。 Howaboutage?Thatmightbeofinterest,butitisnotagoodthingtostoreinadatabase.Agechangesastimepasses,whichmeansyou'dhavetoupdateyourrecordsoften.Instead,itisbettertostoreafixedvaluesuchasdateofbirth.Then,wheneveryouneedage,youcan...
1. InnoDBINFORMATION_SCHEMAFULLTEXTIndexTables ThefollowingtablesprovidemetadataforFULLTEXTindexes: mysql>SHOWTABLESFROMINFORMATION_SCHEMALIKE'INNODB_FT%'; +-------------------------------------------+ |Tables_in_INFORMATION_SCHEMA(INNODB_FT%)| +-------------------------------------------+ ...
1.概述 Thissectionprovidesinformationandusage【ˈjuːsɪdʒ使用;(词语的)用法，惯用法;利用;利用率;】examplesforInnoDBINFORMATION_SCHEMAtables. InnoDBINFORMATION_SCHEMAtablesprovidemetadata,statusinformation,andstatisticsaboutvariousaspectsoftheInnoDBstorageengine.YoucanviewalistofInnoDBINFORMATION_SCHEMAtablesbyissuingaSHOW...
1.OnlineDDLSpaceRequirements DiskspacerequirementsforonlineDDLoperationsareoutlined【ˈaʊtlaɪnd概述;略述;显示…的轮廓;勾勒…的外形;】below.Therequirementsdonotapplytooperationsthatareperformedinstantly. •Temporarylogfiles: AtemporarylogfilerecordsconcurrentDMLwhenanonlineDDLoperationcreatesanindexoraltersatable.Thetem...
1.ForeignKeyOperations ThefollowingtableprovidesanoverviewofonlineDDLsupportforforeignkeyoperations.Anasterisk【ˈæstərɪsk星号(置于词语旁以引起注意或另有注释);】indicatesadditionalinformation,anexception,oradependency. Operation Instant InPlace RebuildsTable PermitsConcurrentDML OnlyModifiesMetadata Addingaforeign...
1.ColumnOperations ThefollowingtableprovidesanoverviewofonlineDDLsupportforcolumnoperations.Anasteriskindicatesadditionalinformation,anexception,oradependency. Operation Instant InPlace RebuildsTable PermitsConcurrentDML OnlyModifiesMetadata Addingacolumn Yes Yes No Yes Yes Droppingacolumn Ye...