Copy MongoDb indexes between databases - mongodb

Question

I am trying to copy mongo indexes between two environments. Checked the API and found no direct method of doing it. So I started writing a script that connects to one db, iterates over the collections, grabs indexes, mutates them (because getIndexes() and ensureIndex()) have different format), connects to the other db, wipes the indexes and copies the new ones in.
This all feels slightly over the top so I think that I must be missing something.
Any suggestions/good practices? Apart from having an index creation strategy.
Cheers!

Answer 1

Please run it on the database that you want to copy indexes.
db.getCollectionNames().forEach(function(collection) {
indexes = db[collection].getIndexes();
indexes.forEach(function (c) {
opt = ''
ixkey = JSON.stringify(c.key, null, 1).replace(/(\r\n|\n|\r)/gm,"")
ns = c.ns.substr(c.ns.indexOf(".") + 1, c.ns.length)
for (var key in c) {
if (key != 'key' && key != 'ns' && key != 'v') {
if (opt != '') { opt+= ','}
if (c.hasOwnProperty(key)) {
if (typeof(c[key]) == "string") {
opt += (key + ': "' + c[key] + '"')
} else {
opt+= (key + ": " + c[key])
}
}
}
}
if (opt != '') { opt = '{' + opt + '}'}
print ('db.' + ns + '.ensureIndex(' + ixkey + ','+ opt + ')')
})});

Answer 2

I've updated script of Adamo Tonete
db.getCollectionNames().forEach(function(col) {
var indexes = db[col].getIndexes();
indexes.forEach(function (c) {
var fields = '', result = '', options = {};
for (var i in c) {
if (i == 'key') {
fields = c[i];
} else if (i == 'name' && c[i] == '_id_') {
return;
} else if (i != 'name' && i != 'v' && i != 'ns') {
options[i] = c[i];
}
}
var fields = JSON.stringify(fields);
var options = JSON.stringify(options);
if (options == '{}') {
result = "db." + col + ".createIndex(" + fields + "); ";
} else {
result = "db." + col + ".createIndex(" + fields + ", " + options + "); ";
}
result = result
.replace(/{"floatApprox":-1,"top":-1,"bottom":-1}/ig, '-1')
.replace(/{"floatApprox":(-?\d+)}/ig, '$1')
.replace(/\{"\$numberLong":"(-?\d+)"\}/ig, '$1');
print(result);
});
});

Answer 3

Try with this script:
var i, c,
co_name, co_new,
co_old, co_old_i,
_db = db.getSiblingDB('logs'),
_colls = ['activity.games', 'activity.session', 'activity.social', 'activity.store'];
for (i in _colls){
co_name = _colls[i];
co_old = _db[co_name];
co_old_i = co_old.getIndexes();
if(co_old.count() > 0){
co_old.renameCollection(co_name + '.old');
_db.createCollection(co_name);
co_new = _db[co_name];
for(c in co_old_i){
co_new.ensureIndex(co_old_i[c].key);
}
}
}
https://gist.github.com/alejandrobernardis/8261327
Regards,
A

Answer 4

Here is a version to recreate them all with options, and with the new createIndex command instead of ensureIndex (since mongoDB 3.0). With that, it's very easy to copy (recreate) all indexes from one DB to another.
function createIndex2( coll, keys, options ) {
var ret = db[coll].createIndex(keys, options)
if (ret.createdCollectionAutomatically) print( "Collection " + coll + " was created")
if (ret.errmsg || (ret.note != "all indexes already exist" && ret.ok != 1)) {
ret.coll = coll
ret.keys = keys
ret.options = options
print(tojson(ret))
} else {
//print( "Everything normal", JSON.stringify(ret))
}
}
db.getCollectionInfos().forEach(function(coll) {
//print( JSON.stringify( coll ))
if (coll.type === "collection" ) {
db[coll.name].getIndexes().forEach(function(index) {
if ("_id_" !== index.name) {
//print( JSON.stringify( index ))
var indexKey = index.key // save the key, and transform index into the "options"
delete index.key
delete index.ns // namespace - not necessary
delete index.v // not necessary
index.background = true // optional: force background to be true
//native version: print("db." + coll.name + ".createIndex(" + JSON.stringify(indexKey) + ", " + JSON.stringify(index) + ")");
// this gives much more debug info
print("createIndex2(\"" + coll.name + "\", " + JSON.stringify(indexKey) + ", " + JSON.stringify(index) + ")");
}
});
}
});
The result looks like that if using the "native" version, otherwise, it will display only errors:
db.dishes.createIndex({"submenu":1},
{"name":"submenu_1","ns":"dishly.dishes","background":true})
db.dishes.createIndex({"loc":"2dsphere"},
{"name":"loc_2dsphere","ns":"dishly.dishes","2dsphereIndexVersion":3,"background":true})
db.dishes.createIndex({"rs":-1},
{"name":"rs_-1","ns":"dishly.dishes","partialFilterExpression":{"rs":{"$gte":3}},"background":true})
db.dishes.createIndex({"loc":"2d","type":1,"status":1,"FSid":1,"rs":-1},
{"name":"loc_2d_type_1_status_1_rs_-1","ns":"dishly.dishes","background":true,"partialFilterExpression":{"rs":{"$gte":2}}})
db.dishes.createIndex({"_fts":"text","_ftsx":1,"loc.0":1,"loc.1":1,"rs":-1},
{"name":"d2_menu_submenu_text__loc__rs","ns":"dishly.dishes","background":true,"weights":{"d2":1,"menu":1,"submenu":1},"default_language":"english","language_override":"language","textIndexVersion":3})