{"id":83153,"date":"2020-05-29T01:42:10","date_gmt":"2020-05-28T23:42:10","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/vypusk-raspredelyonnoj-subd-tidb-4-0"},"modified":"2020-05-29T01:42:10","modified_gmt":"2020-05-28T23:42:10","slug":"vypusk-raspredelyonnoj-subd-tidb-4-0","status":"publish","type":"post","link":"https:\/\/prohoster.info\/da\/blog\/news\/vypusk-raspredelyonnoj-subd-tidb-4-0","title":{"rendered":"Udgivelse af den distribuerede DBMS TiDB 4.0","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p><noindex><a rel=\"nofollow\" href=\"https:\/\/github.com\/pingcap\/tidb\/releases\/tag\/v4.0.0\">Tilg\u00e6ngelig<\/a><\/noindex> udgivelse af den distribuerede DBMS <noindex><a rel=\"nofollow\" href=\"https:\/\/pingcap.com\/index\">TiDB 4.0<\/a><\/noindex>, udviklet inspireret af teknologierne fra Google <noindex><a rel=\"nofollow\" href=\"http:\/\/research.google.com\/archive\/spanner.html\">Spanner<\/a><\/noindex> og <noindex><a rel=\"nofollow\" href=\"http:\/\/research.google.com\/pubs\/pub38125.html\">F1<\/a><\/noindex>. TiDB tilh\u00f8rer kategorien hybrid HTAP-systemer (Hybrid Transactional\/Analytical Processing), som b\u00e5de kan h\u00e5ndtere realtids-transaktioner (OLTP) og udf\u00f8re analytisk foresp\u00f8rgselbehandling. Projektet er skrevet i Go-sprog og <noindex><a rel=\"nofollow\" href=\"https:\/\/github.com\/pingcap\/tidb\">distribueres<\/a><\/noindex> er under Apache 2.0-licensen.<\/p>\n<p>Egenskaber ved TiDB:\n<\/p>\n<ul>\n<li class=\"l\"> Underst\u00f8ttelse af SQL og tilbydelse af et klientgr\u00e6nseflade, der er kompatibelt med MySQL-protokollen, hvilket g\u00f8r det lettere for eksisterende MySQL-applikationer at tilpasse sig TiDB og muligg\u00f8r brugen af almindelige klientbiblioteker. Udover MySQL-protokollen kan der bruges et JSON-baseret API til at tilg\u00e5 DBMS og en connector til Spark.\n<\/li>\n<li class=\"l\"> Fra SQL-funktionerne underst\u00f8ttes indekser, aggregatfunktioner, GROUP BY, ORDER BY, DISTINCT, sammenf\u00f8relser (LEFT JOIN \/ RIGHT JOIN \/ CROSS JOIN), visninger, vinduesfunktioner og underforesp\u00f8rgsler. De tilg\u00e6ngelige funktioner er tilstr\u00e6kkelige til at organisere anvendelsen af TiDB i webapplikationer som PhpMyAdmin, <noindex><a rel=\"nofollow\" href=\"https:\/\/gogs.io\/\">Gogs<\/a><\/noindex> og WordPress;\n<\/li>\n<li class=\"l\"> Mulighed for horisontal skalering og sikring af fejltolerance: st\u00f8rrelsen p\u00e5 lageret og beregningskraften kan \u00f8ges ved nemt at tilf\u00f8je nye noder. Data fordeles p\u00e5 noderne med redundans, hvilket g\u00f8r det muligt at forts\u00e6tte driften i tilf\u00e6lde af fejl p\u00e5 enkelte noder. Fejl h\u00e5ndteres automatisk.\n<\/li>\n<li class=\"l\"> Systemet garanterer konsistens og fremst\u00e5r for klientsoftwaren som \u00e9n stor DBMS, selvom der i praksis hentes data fra mange noder for at udf\u00f8re en transaktion.\n<\/li>\n<li class=\"l\"> Til fysisk datalagring p\u00e5 noderne kan forskellige backends anvendes, s\u00e5som de lokale lagermotorer GoLevelDB og BoltDB eller egne motorer til distribueret lagring <noindex><a rel=\"nofollow\" href=\"https:\/\/github.com\/pingcap\/tikv\">TiKV<\/a><\/noindex> og TiFlash. TiKV gemmer data i r\u00e6kker i n\u00f8gle\/v\u00e6rdi-format og er mere optimal til transaktionsbehandling (OLTP). TiFlash gemmer data i kolonner og muligg\u00f8r h\u00f8jere ydeevne ved analytiske opgaver (OLAP).\n<\/li>\n<li class=\"l\"> Mulighed for asynkron \u00e6ndring af lagerskemaet, der muligg\u00f8r tilf\u00f8jelse af kolonner og indekser uden at stoppe behandlingen af aktuelle operationer.\n<\/li>\n<\/ul>\n<p>I den nye version:<\/p>\n<ul>\n<li class=\"l\"> Som standard er den distribuerede affaldsamler Green GC aktiveret, hvilket v\u00e6sentligt \u00f8ger hastigheden p\u00e5 affaldsindsamling i store klynger og forbedrer stabiliteten i driften;\n<li class=\"l\">Underst\u00f8ttelse af store transaktioner er blevet tilf\u00f8jet, hvis st\u00f8rrelse praktisk talt er begr\u00e6nset af den fysiske hukommelse. Begr\u00e6nsningen for st\u00f8rrelsen af en enkelt transaktion er \u00f8get fra 100 MB til 10 GB;\n<li class=\"l\"> Underst\u00f8ttelse af BACKUP- og RESTORE-kommandoer til sikkerhedskopiering er blevet tilf\u00f8jet;\n<li class=\"l\"> Muligheden for at s\u00e6tte l\u00e5s p\u00e5 tabeller er blevet tilf\u00f8jet;\n<li class=\"l\"> En MySQL-kompatibel mekanisme til transaktionsisolering p\u00e5 l\u00e6seniveau (READ COMMITTED) er blevet tilf\u00f8jet;\n<li class=\"l\"> I kommandoen &#171;ADMIN SHOW DDL JOBS&#187; er der tilf\u00f8jet st\u00f8tte til LIKE- og WHERE-udtryk;\n<li class=\"l\"> Parameteren oom-use-tmp-storage er blevet tilf\u00f8jet, hvilket muligg\u00f8r brug af midlertidige filer til caching af mellemresultater under forhold med begr\u00e6nset hukommelse;\n<li class=\"l\"> N\u00f8gleordet Random er blevet tilf\u00f8jet til at tildele tilf\u00e6ldige v\u00e6rdier til attributter;\n<li class=\"l\"> Der er blevet tilf\u00f8jet mulighed for at bruge hexadecimale og bin\u00e6re udtryk i LOAD DATA kommandoen;\n<li class=\"l\"> Der er blevet tilf\u00f8jet 15 parametre til kontrol af optimeringsadf\u00e6rden;\n<li class=\"l\"> V\u00e6rkt\u00f8jer til diagnosticering af ydeevnen i SQL-foresp\u00f8rgsler er blevet tilf\u00f8jet. En log over langsomme foresp\u00f8rgsler, tilg\u00e6ngelig gennem systemtabellerne SLOW_QUERY \/ CLUSTER_SLOW_QUERY, er blevet tilf\u00f8jet;\n<li class=\"l\"> Underst\u00f8ttelse af funktioner til arbejde med sekvenser er blevet tilf\u00f8jet;\n<li class=\"l\"> Muligheden for dynamisk at \u00e6ndre konfigurationsparametre, der l\u00e6ses fra PD (Placement Driver, cluster management server), er blevet tilf\u00f8jet. Det er nu muligt at bruge udtrykket &#171;SET CONFIG&#187; til at \u00e6ndre indstillingerne for PD\/TiKV-noder.\n<li class=\"l\"> Indstillingen max-server-connections er blevet tilf\u00f8jet for at begr\u00e6nse det maksimale antal samtidige forbindelser til serveren (standard 4096);\n<li class=\"l\"> Ydeevnen er blevet forbedret i situationer, hvor de anmodede kolonner helt d\u00e6kkes af indekser;\n<li class=\"l\"> Optimering af foresp\u00f8rgsler baseret p\u00e5 indekssammensmeltning er blevet tilf\u00f8jet;\n<li class=\"l\"> Ydeevnen for operationer med v\u00e6rdisp\u00e6nd er blevet forbedret;\n<li class=\"l\"> CPU-belastningen er reduceret gennem caching af resultater fra indexanvendelser og filtrering af duplikater;\n<li class=\"l\"> Underst\u00f8ttelse af et nyt format til lagring af strenge er blevet tilf\u00f8jet, hvilket \u00f8ger ydeevnen af tabeller med mange kolonner;\n<li class=\"l\"> Funktionen GROUP_CONCAT har nu st\u00f8tte for udtrykket &#171;ORDER BY&#187;;\n<li class=\"l\"> Muligheden for at udtr\u00e6kke data fra TiFlash-loggen via SQL er blevet tilf\u00f8jet;\n<li class=\"l\"> I kommandoen &#171;RECOVER TABLE&#187; er der blevet implementeret st\u00f8tte til at gendanne besk\u00e5rede tabeller;\n<li class=\"l\"> En systemtabel DDLJobs er tilf\u00f8jet for at anmode om detaljer om udf\u00f8relsen af DDL-arbejder;\n<li class=\"l\"> Mulighed for at anvende SHOW CONFIG-kommandoen til at vise indstillingerne for PD og TiKV er blevet tilf\u00f8jet;\n<li class=\"l\"> <noindex><a rel=\"nofollow\" href=\"https:\/\/github.com\/pingcap\/tidb\/pull\/16710\">Inkluderet<\/a><\/noindex>  standard cache for co-processor;\n<li class=\"l\"> Antallet af co-rutiner (goroutine) i genfors\u00f8gsfasen kan nu kontrolleres ved hj\u00e6lp af indstillingen committer-concurrency;\n<li class=\"l\"> Mulighed for at vise regionerne for tabelpartitioner er blevet tilf\u00f8jet;\n<li class=\"l\"> Muligheden for at begr\u00e6nse st\u00f8rrelsen af den midlertidige lagring er blevet tilf\u00f8jet til tidb-server;\n<li class=\"l\"> St\u00f8tte til operationerne &#171;insert into tbl_name partition(partition_name_list)&#187; og &#171;replace into tbl_name partition(partition_name_list)&#187; er blevet tilf\u00f8jet;\n<li class=\"l\"> I den anvendte hash til partitionering er der tilf\u00f8jet st\u00f8tte til filtrering efter &#171;is null&#187; betingelsen;\n<li class=\"l\"> Underst\u00f8ttelse af operationer til kontrol, oprydning og genopretning af indekser er blevet tilf\u00f8jet for partitionerede tabeller.\n<\/ul>\n<p><noindex><a rel=\"nofollow\" name=\"link\"><\/a><\/noindex><\/p>\n<p>Kilde: <a \ncontent=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/www.opennet.ru\/opennews\/art.shtml?num=53045\">opennet.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u0414\u043e\u0441\u0442\u0443\u043f\u0435\u043d \u0440\u0435\u043b\u0438\u0437 \u0440\u0430\u0441\u043f\u0440\u0435\u0434\u0435\u043b\u0451\u043d\u043d\u043e\u0439 \u0421\u0423\u0411\u0414 TiDB 4.0, \u0440\u0430\u0437\u0432\u0438\u0432\u0430\u0435\u043c\u043e\u0439 \u043f\u043e\u0434 \u0432\u043f\u0435\u0447\u0430\u0442\u043b\u0435\u043d\u0438\u0435\u043c \u043e\u0442 \u0442\u0435\u0445\u043d\u043e\u043b\u043e\u0433\u0438\u0439 Google Spanner \u0438 F1. TiDB \u043e\u0442\u043d\u043e\u0441\u0438\u0442\u0441\u044f \u043a \u043a\u0430\u0442\u0435\u0433\u043e\u0440\u0438\u0438 \u0433\u0438\u0431\u0440\u0438\u0434\u043d\u044b\u0445 \u0441\u0438\u0441\u0442\u0435\u043c HTAP (Hybrid Transactional\/Analytical Processing), \u0441\u043f\u043e\u0441\u043e\u0431\u043d\u044b\u0445 \u043a\u0430\u043a \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0438\u0432\u0430\u0442\u044c \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0435 \u0442\u0440\u0430\u043d\u0437\u0430\u043a\u0446\u0438\u0439 \u0432 \u0440\u0435\u0430\u043b\u044c\u043d\u043e\u043c \u0432\u0440\u0435\u043c\u0435\u043d\u0438 (OLTP), \u0442\u0430\u043a \u0438 \u0432\u044b\u043f\u043e\u043b\u043d\u044f\u0442\u044c \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0443 \u0430\u043d\u0430\u043b\u0438\u0442\u0438\u0447\u0435\u0441\u043a\u0438\u0445 \u0437\u0430\u043f\u0440\u043e\u0441\u043e\u0432. \u041f\u0440\u043e\u0435\u043a\u0442 \u043d\u0430\u043f\u0438\u0441\u0430\u043d \u043d\u0430 \u044f\u0437\u044b\u043a\u0435 Go \u0438 \u0440\u0430\u0441\u043f\u0440\u043e\u0441\u0442\u0440\u0430\u043d\u044f\u0435\u0442\u0441\u044f \u043f\u043e\u0434 \u043b\u0438\u0446\u0435\u043d\u0437\u0438\u0435\u0439 Apache 2.0. \u041e\u0441\u043e\u0431\u0435\u043d\u043d\u043e\u0441\u0442\u0438 TiDB: \u041f\u043e\u0434\u0434\u0435\u0440\u0436\u043a\u0430 SQL [&hellip;]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-83153","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.3 - aioseo.com -->\n\t<meta name=\"description\" content=\"\u0414\u043e\u0441\u0442\u0443\u043f\u0435\u043d \u0440\u0435\u043b\u0438\u0437 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