nosql

问题 I am using servicestack C# driver for connecting redis database which runs in 6379. I want to retrieve(GET/READ) all keys and its values from redis database(which is actually cached). I have to update two keys and its values in redisdb, is it possible to make an update without using list or hashtypes? I want to know how to add numerous keys and values as well as update many at a time. 回答1: With respect to Redis you want multiple update, multiple get and multiple add. You can use these

问题 My name is Daniel, I'm a newcomer accountwise but a long time lurker. I decided to learn Apache Cassandra for my next "lets write some code while the kids are sleeping" project. What i'm writing is a neat little api that will do read and writes against a cassandra database. I had a lot of the db layout figured out in mongodb, but for me it's time to move on and grow as a engineer :) Mission: I will collect metrics from the servers in my rack, an agent will send a payload of metrics every

问题 I have 5 collections C1, C2, C3, C4 and N5 each having a last_updated value. db.getCollectionNames().filter(function(c){ return c.indexOf('C')==0}) will return me all the collections that start with "C". Is it possible to go one step ahead and do a filter based on "last_updated" column so that i will get all "C" collections that are updated yesterday. something like this db.getCollectionNames().filter(function(c){ return (db.c.find({update_on: "01-Dec-2014"}).count() > 1)}); Eventhough the

问题 I'm having an issue when trying to query based on the result of another query on mongodb. I'm trying to make an initial query and then do another query for each one of the result of the first query. The reason I'm doing it like this is because I have two different collections and I need to join some data from one collection with the data of the other collection. In a SQL world I could easily do this with a JOIN, but as I'm using mongodb in this one I can't really use JOINs, so I guessed doing

问题 Well , i'm going to set up my mongo db schema for a little site, what i need is to reproduce this schema into mongo db collections: product -> tag1 ->child_tag1 ->child_tag2 -> tag2 ->child_tag1 ->child_tag2 -> tag3 ->child_tag1 ->child_tag2 which is the best way to reproduce this schema with mongo ? For sure i need to be able to change a tag or child tag without update all collection objects :) [EDITED] Well cause of i know my question is not so clear, i need to clarify that i'm trying

问题 I am trying to instal mongodb driver in php. I am using wamp server with php version 5.5.12. I have tried it alot but don't know what am I doing wrong. Here is what I did: Step 1: I downloaded the mongodb driver package from this link: http://pecl.php.net/package/mongo/1.5.5/windows I downloaded 5.5 Non Thread Safe (NTS) x64 under PHP 5.5 tab. Step 2: I unzipped the downloaded file and copied the php_mongo.dll and php_mongo.pdb files into C:\wamp\bin\php\php5.5.12\ext Step 3: I included this

问题 I have few data records like this in 'food' schema -mongodb { "_id": "5b220199acbec1409cbf84dd", "Name": "Mongo", "ID_No": "BA1233", "Content": "Bottle", "No_packages": 5, "No_items": 6, "Qty": 30, "Mfg": "2018-05-27", "Exp": "2018-06-30", "__v": 0 } I want to get the data set where the date difference(Exp-today Date) is less than 30. I tried it using the following command. But it didn't work. db.food.find({$lt: { $subtract: [ Date() , Exp ],"30"}} ) 回答1: You need to use first $dateFromString

问题 I want to return the N1qlQueryResult as a response of my REST API . Below is the code: @RequestMapping(value = "/test", method = RequestMethod.GET) public @ResponseBody ResponseEntity<?> get() { List<N1qlQueryRow> result = null; try { Cluster cluster = CouchbaseCluster.create("localhost"); Bucket bucket = cluster.openBucket("myBucket", "xyz"); bucket.bucketManager().createN1qlPrimaryIndex(true, false); N1qlQueryResult queryResult = bucket.query(N1qlQuery.simple("select * FROM myBucket"));

问题 Hi This is my table schema Contacts table: "KeySchema": [{ "AttributeName": "DateTimeRetrieved", "KeyType": "HASH" },{ "AttributeName": "Id", "KeyType": "RANGE" }] My primary key has DateTimeRetrieved as the primary key. I would like to retrieve the latest datetime that was entered into the table. It is also equal to the last added items datetime. Is there a way to query this? . Thanks! 回答1: This is not recommended: If your table is small you can always Select all the data and order it in the

问题 I am new to mongoDB and nosql, what is the syntax to get a sum? In MySQL, I would do something like this: SELECT SUM(amount) from my_table WHERE member_id = 61; How would I convert that to MongoDB? Here is what I have tried: db.bigdata.aggregate({ $group: { _id: { memberId: 61, total: {$sum: "$amount"} } } }) 回答1: Using http://docs.mongodb.org/manual/tutorial/aggregation-zip-code-data-set/ for reference you want: db.bigdata.aggregate( { $match: { memberId: 61 } }, { $group: { _id: "$memberId"