acid

What to do if Cassandra reports failure but did a partial write?

由 别来无恙 提交于 2021-02-19 05:08:08
问题 Cassandra does not guarantee atomic behavior so there is a slight chance that one replica fails but other replica do persist the change. Are there any information how to defend against this and what to do in order to heal it if it happens? Does Cassandra heal itself in that regard? [Update] I specially focus on the case where you send a write request to lets say all replica and only one replica fails with a write error. The node failing with the write is still alive and operational. According

What happens when a hive insert is failed halfway?

由 岁酱吖の 提交于 2021-02-15 03:13:21
问题 Suppose an insert is expected to load 100 records in hive and 40 records have been inserted and the insert failed for some reason. will the transaction roll back completely, undoing 40 records which were inserted? or Will we see 40 records in the hive table even after the insert query failed? 回答1: The operation is atomic (even for non-ACID table): If you inserting or rewriting data using HiveQL, it writes data into temporary location and only if the command succeeds files are moved to the

What happens when a hive insert is failed halfway?

由 给你一囗甜甜゛ 提交于 2021-02-15 03:13:20
问题 Suppose an insert is expected to load 100 records in hive and 40 records have been inserted and the insert failed for some reason. will the transaction roll back completely, undoing 40 records which were inserted? or Will we see 40 records in the hive table even after the insert query failed? 回答1: The operation is atomic (even for non-ACID table): If you inserting or rewriting data using HiveQL, it writes data into temporary location and only if the command succeeds files are moved to the

Pricing when updating more than one field of the same document within a Firestore transaction

由 让人想犯罪 __ 提交于 2021-02-05 08:15:26
问题 I have the following transaction using Firestore: mDb.runTransaction(new Transaction.Function<Void>() { @Override public Void apply(final Transaction transaction) throws FirebaseFirestoreException { DocumentReference documentReference = mDb.collection("collectionOne").document("documentOne"); /* some code */ transaction.update(documentReference, App.getResourses().getString(R.string.field_one), FieldValue.increment(1)); transaction.update(documentReference, App.getResourses().getString(R

Pricing when updating more than one field of the same document within a Firestore transaction

由 杀马特。学长 韩版系。学妹 提交于 2021-02-05 08:11:04
问题 I have the following transaction using Firestore: mDb.runTransaction(new Transaction.Function<Void>() { @Override public Void apply(final Transaction transaction) throws FirebaseFirestoreException { DocumentReference documentReference = mDb.collection("collectionOne").document("documentOne"); /* some code */ transaction.update(documentReference, App.getResourses().getString(R.string.field_one), FieldValue.increment(1)); transaction.update(documentReference, App.getResourses().getString(R

Why aren't NoSQL Databases ACID compliant? [duplicate]

由 时光总嘲笑我的痴心妄想 提交于 2021-01-28 13:31:51
问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Is there any NoSQL that is ACID compliant? So, I heard NoSQL Databases are not ACID compliant, why is this? 回答1: This isn't necessarily true - it depends on which particular database you're referring to. Some of them (for example Neo4j) are fully ACID compliant. Check out this link for a comparison of some NoSQL databases: http://kkovacs.eu/cassandra-vs-mongodb-vs-couchdb-vs-redis 回答2: Generally speaking, ACID

ACID与CAP定理

由 拜拜、爱过 提交于 2020-12-22 06:32:39
ACID:RMDB的4个基本要素 ACID，指数据库事务正确执行的四个基本要素的缩写。包含：原子性(Atomicity）、一致性（Consistency）、隔离性（Isolation）、持久性（Durability）。一个支持事务（Transaction）的数据库系统，必需要具有这四种特性，否则在事务过程（Transaction processing）当中无法保证数据的正确性，交易过程极可能达不到交易方的要求。 原子性 整个事务中的所有操作，要么全部完成，要么全部不完成，不可能停滞在中间某个环节。事务在执行过程中发生错误，会被回滚（Rollback）到事务开始前的状态，就像这个事务从来没有执行过一样。 一致性 在事务开始之前和事务结束以后，数据库的完整性约束没有被破坏。 隔离性 隔离状态执行事务，使它们好像是系统在给定时间内执行的唯一操作。如果有两个事务，运行在相同的时间内，执行相同的功能，事务的隔离性将确保每一事务在系统中认为只有该事务在使用系统。这种属性有时称为串行化，为了防止事务操作间的混淆，必须串行化或序列化请求，使得在同一时间仅有一个请求用于同一数据。 持久性 在事务完成以后，该事务所对数据库所作的更改便持久的保存在数据库之中，并不会被回滚 由于一项操作通常会包含许多子操作，而这些子操作可能会因为硬件的损坏或其他因素产生问题，要正确实现ACID并不容易

What happens if altering a stored procedure while it is running?

由 只谈情不闲聊 提交于 2020-04-05 08:45:12
问题 I have a minor, one line change (fixing a typo in a string), to a stored procedure that I would like to deploy to our production SQL Server 2005 server as soon as possible. The worry I have is what happens if at the exact time run the alter statement to update my stored procedure, it happens that something calls that stored procedure at the same time? Does it run with the previous copy of the stored procedure, or can it result to some corruption or errors? Considering the ACID nature of SQL

IT忍者神龟之事务ACID理解

由 ↘锁芯ラ 提交于 2020-03-07 05:16:19
事务概念 概念：事务（Transaction），一般是指要做的或所做的事情。在计算机术语中是指访问并可能更新数据库中各种数据项的一个程序执行单元(unit)。 本人WX：kotlinvip 事务的基本要素（ACID） 1、原子性（Atomicity）：事务开始后所有操作，要么全部做完，要么全部不做，不可能停滞在中间环节。事务执行过程中出错，会回滚到事务开始前的状态，所有的操作就像没有发生一样。也就是说事务是一个不可分割的整体，就像化学中学过的原子，是物质构成的基本单位。 2、一致性（Consistency）：事务开始前和结束后，数据库的完整性约束没有被破坏 。比如A向B转账，不可能A扣了钱，B却没收到。 3、隔离性（Isolation）：同一时间，只允许一个事务请求同一数据，不同的事务之间彼此没有任何干扰。比如A正在从一张银行卡中取钱，在A取钱的过程结束前，B不能向这张卡转账。 4、持久性（Durability）：事务完成后，事务对数据库的所有更新将被保存到数据库，不能回滚 场景举例： 银行转账业务图例解释ACID 原子性 根据业务需求怎么才能满足事务的ACID 请往下看 针对同一个事务流程这个过程包含以下流程： 1：张三账户减去 800 2：李四账户加上200 原子性表示 ，这两个步骤一起成功，或者一起失败，不能只发生其中一个动作这样才能满足原子性。 一致性 操作前张三：1000

事务的由来以及aid保证一致性(状态总是正确的)

由 我怕爱的太早我们不能终老 提交于 2020-02-17 15:03:54
首先,我们需要搞清楚为什么会出现事务. Transactions are not a law of nature; they were created with a purpose, namely to simplify the programming model for applications accessing a database. By using transactions, the application is free to ignore certain potential error scenarios and concurrency issues, because the database takes care of them instead (we call these safety guarantees). 这句话的大体含义就是,事务的产生,其实是为了当应用程序访问数据库的时候,事务能够简化我们的编程模型,不需要我们去考虑各种各样的潜在错误和并发问题.可以想一下当我们使用事务时,要么提交,要么回滚,我们不会去考虑网络异常了,服务器宕机了,同时更改一个数据怎么办对吧? 题外话: 因此事务本质上是为了应用层服务的.而不是伴随着数据库系统天生就有的.其次,说道一致性,很遗憾,这个词在不同的环境下有着不同的含义,被极大的滥用了,导致很难理解:1. 多副本的一致性2.
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