.mongorc.js

/** A bunch of aliases and helpers for the MongoDB shell.
 *
 * @file .mongorc.js
 *
 * It's intended to be used with MongoDB 3.x.x.
 *
 * To use this script, just store it within your home folder, the same way you
 * would do it with .bashrc or .bash_aliases. Then when connecting to your mongo
 * instance, you'll have the possibility to call these aliases.
 *
 * @author:  xavier.guihot@amadeus.com
 * @version: 2017-06-20
 */


print("Aliases - Helpers:");
print(" * tree: prints all databases and collections");
print(" * indexes: prints all databases, collections and indexes");
print(" * cleanCache(): drops cache collections");


/** Prints a pretty tree of the database/collection structure */
Object.defineProperty(this, "tree", {
	get: function() { return _walk_through_dbs_and_collections(db, false) },
});

/** Prints a pretty tree of the database/collection/index structure */
Object.defineProperty(this, "indexes", {
	get: function() { return _walk_through_dbs_and_collections(db, true) },
});

/** Common implementation for tree and indexes aliases.
 *
 * @param {object} db
 * @param {boolean} displayIndexes if indexes are printed in the returned tree
 * @returns {string} the pretty print of the database tree
 */
function _walk_through_dbs_and_collections(db, displayIndexes) {

	// The database tree we'll progressively build and which is finally returned
	// to be printed in the console:
	var prettyTree = "";

	// The list of databases:
	var databaseList = db.adminCommand({ listDatabases: 1 })["databases"];

	// We walk through databases:
	databaseList.forEach( function(database) {

		// Let's enter the database:
		db = db.getSiblingDB(database["name"]);

		// We gather data for the current database:
		var dbSizeOnDisk = (database["sizeOnDisk"] / (1024*1024*1024)).toFixed(3) + "GB";
		var dbStats = db.runCommand({ dbStats: 1, scale: 1024*1024*1024 });
		var dataSize = (dbStats["dataSize"]).toFixed(3) + "GB";
		var indexSize = (dbStats["indexSize"]).toFixed(3) + "GB";
		var nbrOfDocuments = dbStats["objects"].toString();

		prettyTree += (
			" * " + dbSizeOnDisk + "-" + dataSize + "-" + indexSize +
			" (" + nbrOfDocuments + ")              " + database["name"] + "\r\n"
		);

		// The list of collections in the current database:
		var collections = db.runCommand("listCollections")["cursor"]["firstBatch"];

		collections.forEach( function(collection) {
			if (collection["name"] != "system.indexes") {

				// The nbr of documents this collection contains:
				var count = db.runCommand({ count: collection["name"] })["n"];

				prettyTree += "	* " + collection["name"] + " (" + count.toString() + ")\r\n";

				if (displayIndexes) {

					var indexes = db.runCommand({
						collStats: collection["name"], scale: 1024 * 1024
					})["indexSizes"];

					var pretty_indexes = ""

					for (var index in indexes)
						if (index != "_id_")
							pretty_indexes += index.toString() + " - ";

					if (pretty_indexes != "")
						prettyTree += "		* " + pretty_indexes + "\r\n";
				}
			}
		});
	});

	// And we return for printing the pretty tree:
	return prettyTree.substring(0, prettyTree.length - 1);
}


/** Drop any collections (from all databases) which contain "_cache" in its name */
function cleanCache() {

	// Since we need to walk through all databases during this process, we need
	// to store the current working database in order to get back to this
	// database once the result is returned:
	var currentDB = db;

	// The list of databases:
	var databaseList = db.adminCommand({ listDatabases: 1 })["databases"];

	// We walk through databases:
	databaseList.forEach( function(database) {

		// Let's enter the database:
		db = db.getSiblingDB(database["name"]);

		// The list of collections in the current database:
		var collections = db.runCommand("listCollections")["cursor"]["firstBatch"];

		for (var j = 0; j < collections.length; j++) {

			// If the collection contains "_cache" in its name, we drop it:
			if (collections[j]["name"].indexOf("_cache") >= 0) {
				print(collections[j]["name"]);
				db.runCommand({ drop: collections[j]["name"] })
			}
		}
	});

	// And we go back to the initial working database:
	db = db.getSiblingDB(currentDB);
}