MAP主题的文章列表，还有MAP的技术要点_第1页

HashMap的实现原理

(1)HashMap的概述HashMap是基于哈希表的Map接口的非同步（非线程安全）实现，允许使用null值和null键，此类不保证映射的顺序。(2)HashMap的数据结构HashMap实际上是一个“链表散列”的数据结构，即数组和链表的结合体。HashMap的底层就是一个数组结构，数组中的每...

开发笔记 ·2024-08-28

Collectors.toMap() 抛出 “Duplicate key ***” 异常

Collectors.toMap()抛出“java.lang.IllegalStateException:Duplicatekey***”异常。Collectors.toMap()抛出“Duplicatekey***”异常，异常堆栈如下：1234567891011java...

开发笔记 ·2024-08-20

阿里云E-MapReduce

阿里云E-MapReduce(EMR)是构建在阿里云云服务器ECS上的开源Hadoop、Spark、HBase、Hive、Flink生态大数据PaaS产品。提供用户在云上使用开源技术建设数据仓库、离线批处理、在线流式处理、即时查询、机器学习等场景下的大数据解决方案。...

开发笔记 ·2024-06-23

spring中mapper层是什么意思？

mapper层的作用是对数据库进行数据持久化操作，他的方法语句是直接针对数据库操作的现在用mybatis逆向工程生成的。mapper层，其实就是dao层，主要是做数据持久层的工作，负责与数据库进行联络的一些任务都封装在此。...

开发笔记 ·2024-05-06

ORA-39172: Cannot remap transportable tablespace names with compatibility of string.

文档解释ORA-39172:Cannotremaptransportabletablespacenameswithcompatibilityofstring.Cause:Theuserattemptedtoremapatablespacenameinatransportabletablespacejobwhenthec...

IT技术学习 ·2023-07-28

ORA-25110: NOSORT may not be used with a bitmap index

文档解释ORA-25110:NOSORTmaynotbeusedwithabitmapindexCause:AnattemptwasmadetocreateabitmapindexusingtheNOSORToption.Action:RemoveNOSORTfromtheCREATEBITMAPINDEXstatem...

IT技术学习 ·2023-07-28

ORA-39045: invalid metadata remap name string

文档解释ORA-39045:invalidmetadataremapnamestringCause:AninvalidmetadataremapnamewasspecifiedonaDBMS_DATAPUMP.METADATA_REMAPAPIcall.Action:Correctthemetadataremapnam...

IT技术学习 ·2023-07-28

ORA-39234: Data cannot be remapped under the direct path access method.

文档解释ORA-39234:Datacannotberemappedunderthedirectpathaccessmethod.Cause:Dataremappingwasrequestedonajobthatrequiresthedirectpathaccessmethod.Dataremappingcanonly...

IT技术学习 ·2023-07-28

ORA-39232: invalid remap function: string

文档解释ORA-39232:invalidremapfunction:stringCause:Thespecifiedpackagefunctionforperformingdataremappingwasnotfound.Action:Eithercreatethespecifiedpackagefunctionor...

IT技术学习 ·2023-07-28

ORA-14300: partitioning key maps to a partition outside maximum permitted number of partitions

文档解释ORA-14300:partitioningkeymapstoapartitionoutsidemaximumpermittednumberofpartitionsCause:Therowinsertedhadapartitioningkeythatmapstoapartitionnumbergreaterth...

IT技术学习 ·2023-07-28

ORA-47033: Factor link for string and string is referred by one or more identity maps.

文档解释ORA-47033:Factorlinkforstringandstringisreferredbyoneormoreidentitymaps.Cause:Thespecifiedfactorlinkwasreferredbyexistingidentitymaps.Action:Removethedepend...

IT技术学习 ·2023-07-28

ORA-32052: failed to start mapping service

文档解释ORA-32052:failedtostartmappingserviceCause:Themappingservicefailedtostartproperly.Action:CheckFMONtracefilesforerrors.ORA-32052表明应用程序无法启动映射服务。它是一个致命错误，必须修复才...

IT技术学习 ·2023-07-28

ORA-07339: spcre: maximum number of semaphore sets exceeded.

文档解释ORA-07339:spcre:maximumnumberofsemaphoresetsexceeded.Cause:Theinternalbufferisnotbigenoughtoholdthenumberofsemaphoresetidentifiersrequested.Action:Reconfigu...

IT技术学习 ·2023-07-27

ORA-07253: spdes: semctl error, unable to destroy semaphore set.

文档解释ORA-07253:spdes:semctlerror,unabletodestroysemaphoreset.Cause:Semctlsystemcallreturnedanerror.Action:Checksemaphoresets.Mayrequiremanualcleanup.Checkadditio...

IT技术学习 ·2023-07-27

ORA-47045: Identity string for Factor string is used by one or more identity maps.

文档解释ORA-47045:IdentitystringforFactorstringisusedbyoneormoreidentitymaps.Cause:Thespecifiedidentitywasusedbyexitingidentitymap(s).Action:Removethedependentident...

IT技术学习 ·2023-07-26