{"id":33839,"date":"2019-10-31T21:54:56","date_gmt":"2019-10-31T18:54:56","guid":{"rendered":"https:\/\/prohoster.info\/blog\/objectrepository-net-in-memory-repository-pattern-dlya-vashih-domashnih-proektov\/"},"modified":"2019-10-31T21:54:56","modified_gmt":"2019-10-31T18:54:56","slug":"objectrepository-net-in-memory-repository-pattern-dlya-vashih-domashnih-proektov","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/objectrepository-net-in-memory-repository-pattern-dlya-vashih-domashnih-proektov","title":{"rendered":"ObjectRepository \u2014 vzor repository v pam\u011bti .NET pro va\u0161e dom\u00e1c\u00ed projekty","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<h2 id=\"zachem-hranit-vse-dannye-v-pamyati\">Pro\u010d uchov\u00e1vat v\u0161echna data v pam\u011bti?<\/h2>\n<p><\/p>\n<p>Pro ukl\u00e1d\u00e1n\u00ed dat webu nebo backendu by v\u011bt\u0161ina rozumn\u00fdch lid\u00ed nejprve zvolila SQL datab\u00e1zi.\u00a0<\/p>\n<p><\/p>\n<p>Ale n\u011bkdy se objev\u00ed my\u0161lenka, \u017ee datov\u00fd model pro SQL nevyhovuje: nap\u0159\u00edklad p\u0159i budov\u00e1n\u00ed vyhled\u00e1v\u00e1n\u00ed nebo soci\u00e1ln\u00edho grafu je pot\u0159eba hledat v slo\u017eit\u00fdch vztaz\u00edch mezi objekty.\u00a0<\/p>\n<p><\/p>\n<p><strong>Nejhor\u0161\u00ed je situace, kdy\u017e pracujete v t\u00fdmu a kolega neum\u00ed vytv\u00e1\u0159et rychl\u00e9 dotazy. Kolik \u010dasu jste str\u00e1vili \u0159e\u0161en\u00edm probl\u00e9m\u016f typu N+1 a budov\u00e1n\u00edm dodate\u010dn\u00fdch index\u016f, aby SELECT na hlavn\u00ed str\u00e1nce prob\u00edhal rozumn\u011b?<\/strong><\/p>\n<p><\/p>\n<p>Dal\u0161\u00edm popul\u00e1rn\u00edm p\u0159\u00edstupem je NoSQL. P\u0159ed n\u011bkolika lety byl kolem t\u00e9to t\u00e9matiky velk\u00fd humbuk \u2014 pro jakoukoli p\u0159\u00edle\u017eitost se rozb\u00edhal MongoDB a radovali jsme se z odpov\u011bd\u00ed ve form\u00e1tu json-dokument\u016f. <em>(mimochodem, kolik z\u00e1plat bylo pot\u0159eba vlo\u017eit kv\u016fli cyklick\u00fdm odkaz\u016fm v dokumentech?)<\/em>.<\/p>\n<p><\/p>\n<p>Navrhuji vyzkou\u0161et je\u0161t\u011b jeden alternativn\u00ed zp\u016fsob \u2014 pro\u010d nezkusit uchov\u00e1vat v\u0161echna data v pam\u011bti aplikace a ob\u010das je ukl\u00e1dat do libovoln\u00e9ho \u00falo\u017ei\u0161t\u011b (soubor, vzd\u00e1len\u00e1 datab\u00e1ze)?\u00a0<\/p>\n<p><noindex><a rel=\"nofollow\" name=\"habracut\"><\/a><\/noindex><\/p>\n<p>Pam\u011b\u0165 se stala levnou a v\u0161echna mo\u017en\u00e1 data v\u011bt\u0161iny mal\u00fdch a st\u0159edn\u00edch projekt\u016f se vejdou do 1 GB pam\u011bti. <em>(Nap\u0159\u00edklad m\u016fj obl\u00edben\u00fd dom\u00e1c\u00ed projekt \u2014 <noindex><a rel=\"nofollow\" href=\"https:\/\/github.com\/DiverOfDark\/BudgetTracker\">finan\u010dn\u00ed tracker<\/a><\/noindex>, kter\u00fd sleduje denn\u00ed statistiku a historii m\u00fdch v\u00fddaj\u016f, z\u016fstatk\u016f a transakc\u00ed za posledn\u00edch 18 m\u011bs\u00edc\u016f, spot\u0159ebov\u00e1v\u00e1 pouze 45 MB pam\u011bti.)<\/em><\/p>\n<p><\/p>\n<p>Plusy:<\/p>\n<p><\/p>\n<ul>\n<li>P\u0159\u00edstup k dat\u016fm se st\u00e1v\u00e1 jednodu\u0161\u0161\u00edm \u2014 nen\u00ed t\u0159eba se starat o dotazy, leniv\u00e9 na\u010d\u00edt\u00e1n\u00ed, zvl\u00e1\u0161tnosti ORM, pr\u00e1ce se prov\u00e1d\u00ed s b\u011b\u017en\u00fdmi objekty C#;<\/li>\n<li>Nen\u00ed probl\u00e9m s p\u0159\u00edstupem z r\u016fzn\u00fdch vl\u00e1ken;<\/li>\n<li>Velmi rychl\u00e9 \u2014 \u017e\u00e1dn\u00e9 s\u00ed\u0165ov\u00e9 dotazy, \u017e\u00e1dn\u00e1 translace k\u00f3du do dotazovac\u00edho jazyka, nen\u00ed pot\u0159eba (de)serializace objekt\u016f;<\/li>\n<li>Je p\u0159\u00edpustn\u00e9 ukl\u00e1dat data v jak\u00e9koli podob\u011b \u2014 a\u0165 u\u017e v XML na disku, v SQL Serveru nebo v Azure Table Storage.<\/li>\n<\/ul>\n<p><\/p>\n<p>Nev\u00fdhody:<\/p>\n<p><\/p>\n<ul>\n<li>Ztr\u00e1c\u00ed se horizont\u00e1ln\u00ed \u0161k\u00e1lovatelnost a n\u00e1sledn\u011b nen\u00ed mo\u017en\u00e9 prov\u00e1d\u011bt nasazen\u00ed bez v\u00fdpadk\u016f;<\/li>\n<li>Pokud aplikace spadne \u2014 m\u016f\u017eete \u010d\u00e1ste\u010dn\u011b ztratit data. <em>(Ale na\u0161e aplikace nikdy nepad\u00e1, \u017ee?)<\/em><\/li>\n<\/ul>\n<p><\/p>\n<h2 id=\"kak-eto-rabotaet\">Jak to funguje?<\/h2>\n<p><\/p>\n<p>Algoritmus je n\u00e1sleduj\u00edc\u00ed:<\/p>\n<p><\/p>\n<ul>\n<li>Na za\u010d\u00e1tku se navazuje spojen\u00ed s \u00falo\u017ei\u0161t\u011bm dat a prob\u00edh\u00e1 na\u010d\u00edt\u00e1n\u00ed dat;<\/li>\n<li>Buduje se objektov\u00fd model, prim\u00e1rn\u00ed indexy a indexy vztah\u016f (1:1, 1:n);<\/li>\n<li>Vytv\u00e1\u0159\u00ed se p\u0159edplatn\u00e9 na zm\u011bny vlastnost\u00ed objekt\u016f (INotifyPropertyChanged) a na p\u0159id\u00e1n\u00ed nebo odstran\u011bn\u00ed prvk\u016f v kolekci (INotifyCollectionChanged);<\/li>\n<li>P\u0159i spu\u0161t\u011bn\u00ed p\u0159edplatn\u00e9ho se zm\u011bn\u011bn\u00fd objekt p\u0159id\u00e1 do fronty na z\u00e1pis do \u00falo\u017ei\u0161t\u011b dat;<\/li>\n<li>Periodicky (na z\u00e1klad\u011b \u010dasova\u010de) se na pozad\u00ed ukl\u00e1daj\u00ed zm\u011bny do \u00falo\u017ei\u0161t\u011b;<\/li>\n<li>P\u0159i zav\u0159en\u00ed aplikace se tak\u00e9 ukl\u00e1daj\u00ed zm\u011bny do \u00falo\u017ei\u0161t\u011b.<\/li>\n<\/ul>\n<p><\/p>\n<h2 id=\"primer-koda\">P\u0159\u00edklad k\u00f3du<\/h2>\n<p>\n<b class=\"spoiler_title\">P\u0159id\u00e1v\u00e1me pot\u0159ebn\u00e9 z\u00e1vislosti<\/b><\/p>\n<pre><code class=\"cs\">\/\/ \u041e\u0441\u043d\u043e\u0432\u043d\u0430\u044f \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u0430\nInstall-Package OutCode.EscapeTeams.ObjectRepository\n\u00a0 \u00a0\u00a0\n\/\/ \u0425\u0440\u0430\u043d\u0438\u043b\u0438\u0449\u0435 \u0434\u0430\u043d\u043d\u044b\u0445, \u0432 \u043a\u043e\u0442\u043e\u0440\u043e\u043c \u0431\u0443\u0434\u0443\u0442 \u0441\u043e\u0445\u0440\u0430\u043d\u044f\u0442\u044c\u0441\u044f \u0438\u0437\u043c\u0435\u043d\u0435\u043d\u0438\u044f\n\/\/ \u0418\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0439\u0442\u0435 \u0442\u043e, \u043a\u043e\u0442\u043e\u0440\u044b\u043c \u0431\u0443\u0434\u0435\u0442\u0435 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u044c\u0441\u044f.\nInstall-Package OutCode.EscapeTeams.ObjectRepository.File\nInstall-Package OutCode.EscapeTeams.ObjectRepository.LiteDb\nInstall-Package OutCode.EscapeTeams.ObjectRepository.AzureTableStorage\n\u00a0 \u00a0\u00a0\n\/\/ \u041e\u043f\u0446\u0438\u043e\u043d\u0430\u043b\u044c\u043d\u043e - \u0435\u0441\u043b\u0438 \u043d\u0443\u0436\u043d\u043e \u0445\u0440\u0430\u043d\u0438\u0442\u044c \u043c\u043e\u0434\u0435\u043b\u044c \u0434\u0430\u043d\u043d\u044b\u0445 \u0434\u043b\u044f Hangfire\n\/\/ Install-Package OutCode.EscapeTeams.ObjectRepository.Hangfire<\/code><\/pre>\n<p>\n<b class=\"spoiler_title\">Popisujeme datov\u00fd model, kter\u00fd bude ukl\u00e1d\u00e1n v \u00falo\u017ei\u0161ti<\/b><\/p>\n<pre><code class=\"cs\">public class ParentEntity : BaseEntity\n{\n    public ParentEntity(Guid id) =&gt; Id = id;\n}\n    \npublic class ChildEntity : BaseEntity\n{\n    public ChildEntity(Guid id) =&gt; Id = id;\n    public Guid ParentId { get; set; }\n    public string Value { get; set; }\n}<\/code><\/pre>\n<p>\n<b class=\"spoiler_title\">Pot\u00e9 objektov\u00fd model:<\/b><\/p>\n<pre><code class=\"cs\">public class ParentModel : ModelBase\n{\n    public ParentModel(ParentEntity entity)\n    {\n        Entity = entity;\n    }\n    \n    public ParentModel()\n    {\n        Entity = new ParentEntity(Guid.NewGuid());\n    }\n    \n    public Guid? NullableId =&gt; null;\n    \n    \/\/ P\u0159\u00edklad vazby 1:Many\n    public IEnumerable Children =&gt; Multiple(x =&gt; x.ParentId);\n    \n    protected override BaseEntity Entity { get; }\n}\n    \npublic class ChildModel : ModelBase\n{\n    private ChildEntity _childEntity;\n    \n    public ChildModel(ChildEntity entity)\n    {\n        _childEntity = entity;\n    }\n    \n    public ChildModel() \n    {\n        _childEntity = new ChildEntity(Guid.NewGuid());\n    }\n    \n    public Guid ParentId\n    {\n        get =&gt; _childEntity.ParentId;\n        set =&gt; UpdateProperty(() =&gt; _childEntity.ParentId, value);\n    }\n    \n    public string Value\n    {\n        get =&gt; _childEntity.Value;\n        set =&gt; UpdateProperty(() =&gt; _childEntity.Value, value\n    }\n    \n    \/\/ P\u0159\u00edstup s vyhled\u00e1v\u00e1n\u00edm podle indexu\n    public ParentModel Parent =&gt; Single(ParentId);\n    \n    protected override BaseEntity Entity =&gt; _childEntity;\n}<\/code><\/pre>\n<p>\n<b class=\"spoiler_title\">A nakonec samotn\u00e1 t\u0159\u00edda-repozit\u00e1\u0159 pro p\u0159\u00edstup k dat\u016fm:<\/b><\/p>\n<pre><code class=\"cs\">public class MyObjectRepository : ObjectRepositoryBase\n{\n    public MyObjectRepository(IStorage storage) : base(storage, NullLogger.Instance)\n    {\n        IsReadOnly = true; \/\/ Pro testy, umo\u017e\u0148uje neukl\u00e1dat zm\u011bny do datab\u00e1ze\n    \n        AddType((ParentEntity x) =&gt; new ParentModel(x));\n        AddType((ChildEntity x) =&gt; new ChildModel(x));\n    \n        \/\/ Pokud se pou\u017e\u00edv\u00e1 Hangfire a je pot\u0159eba uchov\u00e1vat model dat pro Hangfire v ObjectRepository\n        \/\/ this.RegisterHangfireScheme();  \n    \n        Initialize();\n    }\n}<\/code><\/pre>\n<p><\/p>\n<p>Vytv\u00e1\u0159\u00edme exempl\u00e1\u0159 ObjectRepository:<\/p>\n<p><\/p>\n<pre><code class=\"cs\">var memory = new MemoryStream();\nvar db = new LiteDatabase(memory);\nvar dbStorage = new LiteDbStorage(db);\n    \nvar repository = new MyObjectRepository(dbStorage);\nawait repository.WaitForInitialize();<\/code><\/pre>\n<p>\n<b class=\"spoiler_title\">Pokud bude v projektu pou\u017e\u00edv\u00e1n HangFire<\/b><\/p>\n<pre><code class=\"cs\">public void ConfigureServices(IServiceCollection services, ObjectRepository objectRepository)\n{\n    services.AddHangfire(s =&gt; s.UseHangfireStorage(objectRepository));\n}<\/code><\/pre>\n<p><\/p>\n<p>Vlo\u017een\u00ed nov\u00e9ho objektu:<\/p>\n<p><\/p>\n<pre><code class=\"cs\">var newParent = new ParentModel()\nrepository.Add(newParent);<\/code><\/pre>\n<p><\/p>\n<p>P\u0159i tomto vol\u00e1n\u00ed objekt <strong>ParentModel<\/strong> je p\u0159id\u00e1n jak do m\u00edstn\u00ed cache, tak do fronty z\u00e1pisu do datab\u00e1ze. Tato operace tedy trv\u00e1 O(1) a s t\u00edmto objektem lze okam\u017eit\u011b pracovat.<\/p>\n<p><\/p>\n<p>Nap\u0159\u00edklad, abyste na\u0161li tento objekt v repozit\u00e1\u0159i a ujistili se, \u017ee vr\u00e1cen\u00fd objekt je t\u00edm sam\u00fdm p\u0159\u00edkladem:<\/p>\n<p><\/p>\n<pre><code class=\"cs\">var parents = repository.Set();\nvar myParent = parents.Find(newParent.Id);\nAssert.IsTrue(ReferenceEquals(myParent, newParent));<\/code><\/pre>\n<p><\/p>\n<p>Co se p\u0159i tom d\u011bje? <em>Set()<\/em> vrac\u00ed <em>TableDictionary<\/em>, kter\u00fd obsahuje <em>ConcurrentDictionary<\/em> a poskytuje dal\u0161\u00ed funkcionalitu prim\u00e1rn\u00edch a sekund\u00e1rn\u00edch index\u016f. To umo\u017e\u0148uje m\u00edt metody pro vyhled\u00e1v\u00e1n\u00ed podle Id (nebo jin\u00fdch libovoln\u00fdch u\u017eivatelsk\u00fdch index\u016f) bez \u00fapln\u00e9ho prohled\u00e1v\u00e1n\u00ed v\u0161ech objekt\u016f.<\/p>\n<p><\/p>\n<p>P\u0159i p\u0159id\u00e1v\u00e1n\u00ed objekt\u016f do <em>ObjectRepository<\/em> se p\u0159id\u00e1v\u00e1 p\u0159edplatn\u00e9 na zm\u011bnu jejich vlastnost\u00ed, tak\u017ee ka\u017ed\u00e1 zm\u011bna vlastnost\u00ed tak\u00e9 vede k p\u0159id\u00e1n\u00ed tohoto objektu do fronty z\u00e1pisu.\u00a0<br \/>\nAktualizace vlastnost\u00ed zven\u010d\u00ed vypad\u00e1 stejn\u011b, jako pr\u00e1ce s POCO objektem:<\/p>\n<p><\/p>\n<pre><code class=\"cs\">myParent.Children.First().Property = \"Aktualizovan\u00e1 hodnota\";<\/code><\/pre>\n<p><\/p>\n<p>Objekt lze odstranit n\u00e1sleduj\u00edc\u00edmi zp\u016fsoby:<\/p>\n<p><\/p>\n<pre><code class=\"cs\">repository.Remove(myParent);\nrepository.RemoveRange(otherParents);\nrepository.Remove(x =&gt; !x.Children.Any());<\/code><\/pre>\n<p><\/p>\n<p>P\u0159itom tak\u00e9 doch\u00e1z\u00ed k p\u0159id\u00e1n\u00ed objektu do fronty na odstran\u011bn\u00ed.<\/p>\n<p><\/p>\n<h2 id=\"kak-rabotaet-sohranenie\">Jak funguje ukl\u00e1d\u00e1n\u00ed?<\/h2>\n<p><\/p>\n<p><em>ObjectRepository<\/em> p\u0159i zm\u011bn\u011b sledovan\u00fdch objekt\u016f (jak p\u0159id\u00e1n\u00ed nebo odstran\u011bn\u00ed, tak i zm\u011bna vlastnost\u00ed) vyvol\u00e1v\u00e1 ud\u00e1lost <em>ModelChanged<\/em>, na kterou je p\u0159ihl\u00e1\u0161eno <em>IStorage<\/em>. Realizace <em>IStorage<\/em> p\u0159i vzniku ud\u00e1losti <em>ModelChanged<\/em> shroma\u017e\u010fuj\u00ed zm\u011bny do 3 front \u2014 na p\u0159id\u00e1n\u00ed, na aktualizaci a na odstran\u011bn\u00ed.<\/p>\n<p><\/p>\n<p>Tak\u00e9 realizace <em>IStorage<\/em> p\u0159i inicializaci vytv\u00e1\u0159ej\u00ed \u010dasova\u010d, kter\u00fd ka\u017ed\u00fdch 5 sekund vyvol\u00e1v\u00e1 ukl\u00e1d\u00e1n\u00ed zm\u011bn.\u00a0<\/p>\n<p><\/p>\n<p><em>Krom\u011b toho existuje API pro nucen\u00e9 vyvol\u00e1n\u00ed ukl\u00e1d\u00e1n\u00ed: <strong>ObjectRepository.Save()<\/strong>.<\/em><\/p>\n<p><\/p>\n<p>P\u0159ed ka\u017ed\u00fdm ulo\u017een\u00edm se nejprve odstra\u0148uj\u00ed z front bezv\u00fdznamn\u00e9 operace (nap\u0159\u00edklad duplicity ud\u00e1lost\u00ed \u2014 kdy\u017e byl objekt m\u011bn\u011bn dvakr\u00e1t nebo rychl\u00e9 p\u0159id\u00e1n\u00ed\/odstran\u011bn\u00ed objekt\u016f), a a\u017e pot\u00e9 samotn\u00e9 ukl\u00e1d\u00e1n\u00ed.\u00a0<\/p>\n<p><\/p>\n<p><em>Ve v\u0161ech p\u0159\u00edpadech se ukl\u00e1d\u00e1 aktu\u00e1ln\u00ed objekt vcelku, tak\u017ee m\u016f\u017ee nastat situace, kdy jsou objekty ukl\u00e1d\u00e1ny v jin\u00e9m po\u0159ad\u00ed, ne\u017e m\u011bnily, a tak\u00e9 mohou b\u00fdt ukl\u00e1d\u00e1ny nov\u011bj\u0161\u00ed verze objekt\u016f, ne\u017e v dob\u011b p\u0159id\u00e1n\u00ed do fronty.<\/em><\/p>\n<p><\/p>\n<h2 id=\"chto-est-eschyo\">Co dal\u0161\u00edho existuje?<\/h2>\n<p><\/p>\n<ul>\n<li>V\u0161echny knihovny jsou zalo\u017eeny na .NET Standard 2.0. Lze je pou\u017e\u00edt v jak\u00e9mkoli modern\u00edm .NET projektu.<\/li>\n<li>API je vl\u00e1kno bezpe\u010dn\u00e9. Intern\u00ed kolekce jsou implementov\u00e1ny na z\u00e1klad\u011b <em>ConcurrentDictionary<\/em>, ud\u00e1lostn\u00ed zpracovatel\u00e9 maj\u00ed bu\u010f z\u00e1mky, nebo je nepot\u0159ebuj\u00ed.\u00a0<br \/>\nJedna v\u011bc, na kterou je t\u0159eba pamatovat \u2014 p\u0159i ukon\u010den\u00ed aplikace zavolejte <em>ObjectRepository.Save();<\/em><\/li>\n<li>Libovoln\u00e9 indexy (vy\u017eaduj\u00ed jedine\u010dnost):<\/li>\n<\/ul>\n<p><\/p>\n<pre><code class=\"cs\">repository.Set&lt;ChildModel&gt;().AddIndex(x =&gt; x.Value);\nrepository.Set&lt;ChildModel&gt;().Find(x =&gt; x.Value, \"myValue\");<\/code><\/pre>\n<p><\/p>\n<h2 id=\"kto-eto-ispolzuet\">Kdo to pou\u017e\u00edv\u00e1?<\/h2>\n<p><\/p>\n<p>Osobn\u011b jsem za\u010dal pou\u017e\u00edvat tento p\u0159\u00edstup ve v\u0161ech sv\u00fdch hobby projektech, proto\u017ee je to pohodln\u00e9 a nevy\u017eaduje velk\u00e9 n\u00e1klady na psan\u00ed vrstvy p\u0159\u00edstupu k dat\u016fm nebo nasazen\u00ed t\u011b\u017ek\u00e9 infrastruktury. Osobn\u011b mi v\u011bt\u0161inou sta\u010d\u00ed ukl\u00e1d\u00e1n\u00ed dat v litedb nebo v souboru.\u00a0<\/p>\n<p><\/p>\n<p>Ale v minulosti, kdy\u017e jsme s t\u00fdmem d\u011blali nyn\u00ed neexistuj\u00edc\u00ed startup EscapeTeams (<em>myslel jsem, \u017ee to jsou pen\u00edze \u2014 ale ne, zase zku\u0161enost<\/em>) \u2014 pou\u017e\u00edvali jsme Azure Table Storage pro ukl\u00e1d\u00e1n\u00ed dat.<\/p>\n<p><\/p>\n<h2 id=\"plany-na-buduschee\">Pl\u00e1ny do budoucna<\/h2>\n<p><\/p>\n<p>Je t\u0159eba opravit jednu z hlavn\u00edch nev\u00fdhod tohoto p\u0159\u00edstupu \u2014 horizont\u00e1ln\u00ed \u0161k\u00e1lov\u00e1n\u00ed. K tomu jsou pot\u0159eba bu\u010f distribuovan\u00e9 transakce (sic!), nebo se lze rozhodnout, \u017ee stejn\u00e1 data z r\u016fzn\u00fdch instanc\u00ed by se m\u011bnit nem\u011bla, nebo a\u0165 se m\u011bn\u00ed na principu 'kdo posledn\u00ed, ten m\u00e1 pravdu'.<\/p>\n<p><\/p>\n<p>Z technick\u00e9ho hlediska vid\u00edm jako mo\u017en\u00fd n\u00e1sleduj\u00edc\u00ed sch\u00e9ma:<\/p>\n<p><\/p>\n<ul>\n<li>Ukl\u00e1dat m\u00edsto objektov\u00e9ho modelu EventLog a Snapshot<\/li>\n<li>Naj\u00edt jin\u00e9 instance (p\u0159idat do nastaven\u00ed koncov\u00e9 body v\u0161ech instanc\u00ed? udp objev? master\/slave?)<\/li>\n<li>Replikovat mezi instancemi EventLog prost\u0159ednictv\u00edm jak\u00e9hokoli algoritmu konsensu, nap\u0159\u00edklad RAFT.<\/li>\n<\/ul>\n<p><\/p>\n<p>Tak\u00e9 existuje je\u0161t\u011b jeden probl\u00e9m, kter\u00fd m\u011b znepokojuje \u2014 je to kask\u00e1dov\u00e9 maz\u00e1n\u00ed nebo odhalov\u00e1n\u00ed p\u0159\u00edpad\u016f maz\u00e1n\u00ed objekt\u016f, na kter\u00e9 jsou odkazy z jin\u00fdch objekt\u016f.\u00a0<\/p>\n<p><\/p>\n<h2 id=\"ishodnyy-kod\">Zdrojov\u00fd k\u00f3d<\/h2>\n<p><\/p>\n<p>Pokud jste do\u010detli a\u017e sem \u2014 zb\u00fdv\u00e1 u\u017e pouze p\u0159e\u010d\u00edst k\u00f3d, ten lze naj\u00edt na GitHubu:<br \/>\n<noindex><a rel=\"nofollow\" href=\"https:\/\/github.com\/DiverOfDark\/ObjectRepository\">https:\/\/github.com\/DiverOfDark\/ObjectRepository<\/a><\/noindex><\/p>\n<p>Zdroj: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/habr.com\/ru\/post\/452232\/\">habr.com<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u0417\u0430\u0447\u0435\u043c \u0445\u0440\u0430\u043d\u0438\u0442\u044c \u0432\u0441\u0435 \u0434\u0430\u043d\u043d\u044b\u0435 \u0432 \u043f\u0430\u043c\u044f\u0442\u0438? \u0414\u043b\u044f \u0445\u0440\u0430\u043d\u0435\u043d\u0438\u044f \u0434\u0430\u043d\u043d\u044b\u0445 \u0441\u0430\u0439\u0442\u0430 \u0438\u043b\u0438 \u0431\u0435\u043a\u044d\u043d\u0434\u0430 \u043f\u0435\u0440\u0432\u044b\u043c \u0436\u0435\u043b\u0430\u043d\u0438\u0435\u043c \u0431\u043e\u043b\u044c\u0448\u0438\u043d\u0441\u0442\u0432\u0430 \u0437\u0434\u0440\u0430\u0432\u043e\u043c\u044b\u0441\u043b\u044f\u0449\u0438\u0445 \u043b\u044e\u0434\u0435\u0439 \u0432\u044b\u0431\u0435\u0440\u0435\u0442 SQL \u0431\u0430\u0437\u0443 \u0434\u0430\u043d\u043d\u044b\u0445.\u00a0 \u041d\u043e \u0438\u043d\u043e\u0433\u0434\u0430 \u0432 \u0433\u043e\u043b\u043e\u0432\u0443 \u043f\u0440\u0438\u0445\u043e\u0434\u0438\u0442 \u043c\u044b\u0441\u043b\u044c \u0447\u0442\u043e \u043c\u043e\u0434\u0435\u043b\u044c \u0434\u0430\u043d\u043d\u044b\u0445 \u043d\u0435 \u043f\u043e\u0434\u0445\u043e\u0434\u0438\u0442 \u0434\u043b\u044f SQL: \u043d\u0430\u043f\u0440\u0438\u043c\u0435\u0440, \u043f\u0440\u0438 \u043f\u043e\u0441\u0442\u0440\u043e\u0435\u043d\u0438\u0438 \u043f\u043e\u0438\u0441\u043a\u0430 \u0438\u043b\u0438 \u0441\u043e\u0446\u0438\u0430\u043b\u044c\u043d\u043e\u0433\u043e \u0433\u0440\u0430\u0444\u0430 \u043d\u0443\u0436\u0435\u043d \u043f\u043e\u0438\u0441\u043a \u043f\u043e \u0441\u043b\u043e\u0436\u043d\u044b\u043c \u0441\u0432\u044f\u0437\u044f\u043c \u043c\u0435\u0436\u0434\u0443 \u043e\u0431\u044a\u0435\u043a\u0442\u0430\u043c\u0438.\u00a0 \u0425\u0443\u0436\u0435 \u0432\u0441\u0435\u0433\u043e \u0441\u0438\u0442\u0443\u0430\u0446\u0438\u044f, \u043a\u043e\u0433\u0434\u0430 \u0440\u0430\u0431\u043e\u0442\u0430\u0435\u0442\u0435 \u0432 \u043a\u043e\u043c\u0430\u043d\u0434\u0435, [&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-33839","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=\"\u0417\u0430\u0447\u0435\u043c \u0445\u0440\u0430\u043d\u0438\u0442\u044c \u0432\u0441\u0435 \u0434\u0430\u043d\u043d\u044b\u0435 \u0432 \u043f\u0430\u043c\u044f\u0442\u0438? 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