Is it possible with MongoDB to find data by its hash?
I'm trying to find the MongoDB equivalent of this MySQL query:
SELECT column FROM table WHERE SHA1(column) = "value"
It doesn't seems there is any such functionality (a bit old, but couldn't find in docs.mongodb.com either), but you can include a library that contains sha1 functionality (e.g. js-sha1) in mongo shell with load function, then use it within your mongo operation.
Related
I am doing a comparison on Postgresql vs Mongodb on insert.I am using the copy command (from file to table) in Postgresql and i am wondering what is the equivalent command in mongodb.I think that the answer is the insert_many(dict)But i want be sure.Any advice would be appreciated.Thanks in advance!
If you want to insert multiple documents in mongodb, you can use
db.collectionName.insertMany([{title: 'doc 1'},{title: 'doc2'},......]}
I am implementing a process in rust where I read a large number of documents from a mongodb collection, perform some calculations on the values of each document and then have to update the documents in mongodb.
In my initial implementation, after the calculations are performed, I go through each of the documents and call db.collection.replace_one.
let document = bson::to_document(&item).unwrap();
let filter = doc! { "_id": item.id.as_ref().unwrap() };
let result = my_collection.replace_one(filter, rec_document, None).await?
Since this is quite time consuming for large record sets, I want to implement it using db.collection.bulkWrite. In version 1.1.1 of the official rust mongodb driver, bulkWrite does not seem to be supported, so I want to use db.run_command. However, I am not sure how to call db.collection.bulkWrite(...) using run_command as I cannot figure out how to pass the command name as well as the set of documents to replace the values in mongodb.
What I have attempted is to create a String representing the command document with all the document records to be updated string joined as well. In order to create bson::Document from that string, I convert the string to bytes and then attempt to create the document to be passed using Document::from_reader but that doesn't work, nor is a good solution.
Is there a proper or better way to call bulkWrite using version 1.1.1 of the mongodb crate?
I'm using cloudant, with no auth, Cors enabled.
it works very well, Limit and skip working good.
but i can't find how to search for something .
I'm trying to find a document where cp is 24000 , for example with this query :
https://1c54473b-be6e-42d6-b914-d0ecae937981-bluemix.cloudant.com/etablissements/_all_docs?skip=0&limit=10&include_docs=true&q=cp:24000
But, the query doesn't return the right document.
I've also tried
https://1c54473b-be6e-42d6-b914-d0ecae937981-bluemix.cloudant.com/etablissements/_all_docs?skip=0&limit=10&include_docs=true&_search({'cp':24000})
with no luck.
oh, and by the way, do you know if jquery.couch.js lib has been discontinued? I cant even find it on github, nor on my hard disk while im using foxant, and it is not in the directory also..
The /db/_all_docs endpoint hits the primary index of the database where all of the documents in the database can be found in _id order.
If you wish to query the database to get a subset of the data you have three options
Cloudant Query - hit the POST /db/_find endpoint passing in a JavaScript object containing the selector which defines the query you wish to perform (like the WHERE clause of a SQL query) e.g. {selector: {cp: 24000}}
MapReduce - create a Map function in a design document that filters the documents you are interested it. It creates a materialized view that can be queried and filtered later. e.g. function(doc){ emit(doc.cp, null);}
Cloudant Search - this uses the Apache Lucene library to generate an index on the fields you specify. You can then query the index: q=cp:24000, which looks similar to the query you are looking to perform.
I am a newbie to mongo, I have a collection in my mongodb, To test a feature in my project I need to update database with some random data.I need a script to do that. by identifying the datatype of the field script should fill up the data automatically.
suppose I have the fields in the collection:
id, name, first_name, last_name, current_date, user_income etc.
Since the my questions are as follows:
1. Can we get all field names of a collection with their data types?
2. Can we generate a random value of that data type in mongo shell?
3. how to set the values dynamically to store random data.
I am frequently putting manually to do this.
1. Can we get all field names of a collection with their data types?
mongodb collections are schema-less, which means each document (row in relation database) can have different fields. When you find a document from a collection, you could get its fields names and data types.
2. Can we generate a random value of that data type in mongo shell?
3. how to set the values dynamically to store random data.
mongo shell use JavaScript, you may write a js script and run it with mongo the_js_file.js. So you could generate a random value in the js script.
It's useful to have a look at the mongo JavaScript API documentation and the mongo shell JavaScript Method Reference.
Other script language such as Python can also do that. mongodb has their APIs too.
Some Background: I'm planning to use MongoDB as the publishing frontend db for a few of my websites. The actual data will be kept in a SQL Server db and there will be background jobs that will populate the MongoDB at predefined time intervals for readonly purposes to boost website performance.
The Situation: I have a table 'x' that i translated into a mongo collection, everything worked fine.
'x' has a column 'c' that was originally a NVARCHAR(MAX) in the source db and has multilingual text in it.
When I was searching by column 'c', mongo was doing fullscan on the collection.
So I tried doing an ensureIndex({c : 1 }) which worked but when I checked the mongodb logs it showed me that 90% of the data could not be indexed as [Key Too Large To Index] !!
And thus is has indexed 10% of the data and now only returns results from that 10% !!
What are my alternatives ??
Note: I was using this column to do full text searching in SQL Server, now im not sure if I should go ahead with Mongo or not :(
Try to run your mongod process with this parameter:
sudo mongod --setParameter failIndexKeyTooLong=false
And than try again.
if you need to search text inside a large string you can use one of those:
keyword splitting
regular expression
the former has the downside that you need some "logic" to combine the keyword to make a search, the latter heavily impacts on performance.
probably if you really need full text search the best option is to use an external indexer like solr or lucene.
Since you can do some elaboration, you could extract some key words and put them in a field:
_keywords : [ "mongodb" , "full search" , "nosql" ]
and make an index on that.
Don't use mongo for full text searching
its not designed for that. Yes obviously you will get an error key too large on indexing for long string values.
Better approach would be using full text search servers (solr/lucene or sphinx) if your main concern is search.
Recent (2.4 and above) MongoDB builds provide a couple other options:
As the OP's stated desire is for full text search, the right approach would be to use a text index which directly supports that use case.
For an exact match index on long string values you can use a hashed index.