problem description how do I delete data at a specific location in an array in mongodb? the entity of an aircraft like this: number:B-xxxx, components:[fuselage,wings,engines,landinggears] I now want to delete the third data in components, but I c...
when mongodb uses an index query, whether to put the data index into memory when the data is created, or whether the index is loaded into memory when the query is made, and whether the index in memory will not be automatically cleared? how to estimate t...
this is the case. Everything is normal for mongodb under Ubuntu, authentication is enabled, and all users created by users are normal and can be verified. The following information shows the three users I created. It also connects to, (nodejs normally w...
Native mogodb driver is used in node.js to limit the number of array returns. The same syntax works on the command line, but does not work in node I want to do a paging query DEMO, wants to use db.collection.find ({ "_ id ": ObjectId (_ id)}, { "comme...
how to count the total number of documents after pymongo aggregation query? related codes match1 = { $match : { regDate : {"$gte": datetime(2018, 6, 1), "$lt": datetime(2018, 6, 30)}}} lookup = { $lookup : { ...
above: storage.dbPath data db systemLog.logAppend false : it s not right at all, is it so lame, or there s something wrong with the way I open it? who can explain why? Note: mac environment, brew install mongodb installation, mongodb versi...
const Article = new Schema({ Title: { type: String, required: true }, Content: { type: String, required: true }, CreatedAt: { type: Date, default: new Date, get: v => moment(v).format( YYYY-MM-DD HH:mm )}, UpdatedAt: { type: Date, d...
problem description the data is submitted through post, then parsed by node, and inserted into the collection using MongoDB. how does the front end encode the data and then parse it correctly through nodejs? the environmental background of the prob...
const userSchema = new Schema({ name:{type:String}, clubnumber:{type:String}, memo:[{ memos:{type:String} }] }) the data structure is as above. Now you want to match name and clubnumber, to query all the memo under the library db.userModel....
the general comment system goes like this: comments on articles-> comments on articles-> comments on comments. Using mysql, there are two tables, articles and comments. Comments on articles and comments on comments are stored in one table, comments. ...
when using MySQL, such as connecting to MySQL, with Django, a new field is added to model. As long as you do migration, on the command line, this field will be added to all previous records, but how to do it in MongoDB? Nodejs as a backend, does it have...
requirements, filter the time range of the data and describe the picture meta: { createAt: { type: Date, dafault: Date.now() }, updateAt: { type: Date, dafault: Date.now() } } ...
if mongodb has been used for a long time, the memory footprint will continue to rise. It is not good to shut down the database and release memory. Is there any better way to free the memory occupied by mongodb? ...
problem description the online version of mongodb is a little low, and some grammars don t work. So I want to upgrade the next version, but I don t have the experience of upgrading the version before. I d like to ask for some relevant experience. ...
requirements: similar message queues multiple users fetch numbers from a table at the same time to ensure that each user gets different numbers and then immediately add user_id db.foo.findOneAndUpdate({"user_id":{$exists:false}, {$set:{us...
Does the newly added record in mongodb have to be on the last line of collection? ...
const userSchema = new Schema({ name:{type:String}, clubnumber:{type:String}, details:[{ detail:{type:String,default:Date.now} }] }) there is no loading time when looking at the database ...
see a shopping item in github. All user orders create a schema1 to store all user orders. User personal information creates schema2,schema2. In addition to basic information, there is a personal order: [] to store personal orders. there is a question....
after mongodb has designed the schema, it has been running normally for some time (data is already available). When you adjust the schema later, for example, to add a field and decrease a field, what to do with the original data? do you have to wash the ...
for example, the order in which I typed is {id: {$in: [1pg4]}}, how can I make the results returned by mongodb return the corresponding data in this order? ...
problem description failure at startup after greenplum installation is completed prompt: DTM initialization: failure during startup recovery, retry failed, check segment status (cdbtm.c:1529) the platform version of the problem and what methods you...
The scenario is that I want to open two terminals in a shell script to see both A log and B log at the same time. ...
import org.apache.commons.io.FilenameUtils; public class Test { public static void main(String[] args) throws InterruptedException { System.out.println(FilenameUtils.getExtension("a.zip")); } } as shown above, the simple co...
< html lang= "en " > < head > <style type="text css"> .rpt{ background: -sharpf4f4f4; padding-top: 45px; } < style> <script type="text javascript"> html function hooshineBackClic...
for example, this code: async https_post(){ let url = https: www.4tuu.com ; const request = require( request ); let post_data = { action: api_info , } let request_ops = { ...