data-consistency

问题 S3 FAQ mentions that "Amazon S3 buckets in all Regions provide read-after-write consistency for PUTS of new objects and eventual consistency for overwrite PUTS and DELETES." However, I don't know how long it takes to get eventual consistency. I tried to search for this but couldn't find an answer in S3 documentation. Situation: We have a website consists of 7 steps. When user clicks on save in each step, we want to save a json document (contains information of all 7 steps) to Amazon S3.

问题 S3 FAQ mentions that "Amazon S3 buckets in all Regions provide read-after-write consistency for PUTS of new objects and eventual consistency for overwrite PUTS and DELETES." However, I don't know how long it takes to get eventual consistency. I tried to search for this but couldn't find an answer in S3 documentation. Situation: We have a website consists of 7 steps. When user clicks on save in each step, we want to save a json document (contains information of all 7 steps) to Amazon S3.

问题 I wonder how reliable the adler32 checksum is, compared to e.g. md5 checksums? It was told on wikipedia that adler32 is "much less reliable" than md5, so I wonder how much, and in which way? More specifically, I'm wondering if it is reliable enough as a consistency check for long-time archiving of (tar) files of size 20GB+? 回答1: For details on the error-checking capabilities of the Adler-32 checksum, see for example Revisiting Fletcher and Adler Checksums. Maxino, 2006. This paper contains an

问题 I am building an iOS game. Each game room is constructed from two users. After two users get matched, I'm displaying a "waiting for respond" timer on both devices: they need to click am "I'm Ready" button within 8 second or both of them will get kicked from the room + deleted from Firebase. The correct state of the users (before each of them clicked on the "I'm Ready Button"): Parent Matches User 1 opponent : User2 state : "NotReady" User 2 opponent : User1 state : "NotReady" Critical note -

问题 A number of the developers here are having a friendly (some would say religious) discussion about whether a GET request from a RESTful API should return the ID of the requested resource . Let's assume the following GET request: http://my.api.com/rest/users/23 This currently returns: {"name": "Jim", "age": 40, "favoriteColor": "blue"} Note that "id" is missing from the result set. There are basically 4 camps battling with this issue. CAMP #1: When callers make the GET request, they already

问题 I'm working on an application where users have to make a call and type a verification number with the keypad of their phone. I would like to be able to detect if the number they type is correct or not. The phone system does not have access to a list of valid numbers, but instead, it will validate the number against an algorithm (like a credit card number). Here are some of the requirements : It must be difficult to type a valid random code It must be difficult to have a valid code if I make a

问题 Currently when the user logs in my site, a (PHP) session is started and his database row is saved in his $_session. I do so because the size of user's data is small for now, and this way I do not have to ask the database for user's data every time I need it. The problem is that, when I want to add or change something during the development and I touch the database, the session is not updated this way. The user have to logout and login again to update the session. This is good for now since

问题 In addition to a data type of VARCHAR(255) , I'd like to add a constraint to the data by a regular expression, e.g. [a-zA-Z ] . I'd like to be able to query the regex, like how I can query meta data in the information_schema . I've seen some related posts, but not exactly what I'm looking for. I've seen: Restrict varchar() column to specific values? which shows how to use constaints, and I've seen via triggers here: Is it Possible to Enforce Data Checking in MySQL using Regular expression Can

问题 I am still trying to find my way around micro-services. I have a fundamental question. In an enterprise scenario, micro-services would probably have to write to a persistent data-store - be it a RDBMS or some kind of NoSQL. In most cases the persistent data-store is enterprise grade, but a single entity (ofcourse replicated and backed up). Now, let's consider the case of a single micro-service deployed to private/public cloud environment having it's own persistent data-store (say enterprise

问题 What algorithm to use to calculate a check digit for a list of digits? The length of the list is between 8 and 12 digits. see also: How to generate a verification code/number? 回答1: The Luhn algorithm is good enough for the credit card industry... 回答2: As RichieHindle points out, the Luhn algorithm is pretty good. It will detect (but not correct) any one error or transposition (except a transposition of 0 and 9). You could also consider the algorithm for ISBN check digits, although for old