What is the relationship between real collections' names and those in file system

Question

I use MongoDB 3.0 with WiredTiger storage engine. When I checked my Mongo files in dbPath, I saw the names of the files with the formats as below: collection-0--4989330656807016483.wt collection-2--4989330656807016483.wt collection-4--4989330656807016483.wt . . . How can I know the relationship between these file names and real collections' names except the way of data size??

Why do you want to know this? – Sergio Tulentsev May 13 '15 at 12:16 — Sergio Tulentsev, May 13 '15 at 12:16

score 6 · Answer 1 · answered May 15 '15 at 01:19

6

I have found the way that the command "db.collection.stats()" would show the wiredTiger.metadata.uri which defines the relationship between the collection's logical name and file name the command

answered May 15 '15 at 01:19

tottishi05

557
1
5
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Thanks a lot! But how can I identify the index files ? I want backup some test databases with indexes. – user224767 Jan 25 '17 at 08:47
It's `wiredTiger.uri` for me (MongoDB 3.4.18) – EM0 Jun 05 '19 at 11:59

score 2 · Answer 2 · answered Oct 27 '20 at 14:05

A simple script to find the collection name for a given file name:

function findInDb(dbName, collectionIdToFind) {
    var dbToSearch = db.getSiblingDB(dbName);
    var collectionNames = dbToSearch.getCollectionNames();

    for(var i = 0; i < collectionNames.length; i++){
        var name = collectionNames[i];
        var stats = dbToSearch.getCollection(name).stats();
        var uri = stats.wiredTiger.uri;

        if (uri.endsWith(collectionIdToFind))
            return name;
    }
    
    return null;
}

function findInAllDbs(collectionIdToFind) {
    var adminDb = db.getSiblingDB("admin");
    var dbList = adminDb.runCommand({ "listDatabases": 1 }).databases;

    for (var i in dbList) {
        var found = findInDb(dbList[i].name, collectionIdToFind);
        if (found != null) {
            return dbList[i].name + "." + found;
        }
    }
    
    return "(not found)";
}

print(findInAllDbs("collection-20-571885508699163146")); // filename in crash report, etc.

score 1 · Answer 3 · answered Jun 07 '17 at 09:12

1

Use this

db.getCollection('collection_name').stats()

answered Jun 07 '17 at 09:12

Moh .S

1,920
19
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What is the relationship between real collections' names and those in file system

3 Answers3