Adds a function to the MongoDB shell context that prints out a table showing info for each collection: storage size, storage efficiency%, size of all indexes

printStorageStats.js

/*
    This allows you print some stats about the storage efficiency of
    your collections in MongoDB.

    Example:
    > printStorageStats()
    Thu Oct 31 2013 14:07:36 GMT-0400 (EDT)
    Collection          |   *Size |  Effcy% |    Idxs
    -------------------------------------------------
    test.people         |  8.2 kB |    0.63 | 16.4 kB
    test.system.indexes |  4.1 kB |    3.71 |     0 B
    -------------------------------------------------
                        | 12.3 kB |         | 16.4 kB

    Add the "printStorageStats()" function to your MongoDB shell
    context by saving this to disk, then either:
        -- place 'load("printStorageStats.js")' in your ~/.mongorc.js file
        -- execute 'load("printStorageStats.js")' within your mongo shell

    Once the function has been added to your shell, you can type
    "printStorageStats()" to see your stats.

    Passing the value "true" to the function will cause the table to
    be sorted by storage efficiency.
*/
function printStorageStats(sortByEffcy) {
    var pad, humanFileSize, stats, hdr_labels, colLengths, i, ds_size, idx_size, line, hbar;
    print(new Date());
    pad = function (input, length, padding, right) {
        //from: http://www.sitepoint.com/a-utility-function-fo-padding-strings-and-numbers/
        while ((input = input.toString()).length + (padding = padding.toString()).length < length) {
            padding += padding;
        }
        if (!right) {
            return padding.substr(0, length - input.length) + input;
        }

        return input + padding.substr(0, length - input.length);
    };

    humanFileSize = function (bytes, no_si) {
        //from: http://stackoverflow.com/questions/10420352/converting-file-size-in-bytes-to-human-readable/10420404#10420404
        var si, thresh, units, u;

        si = !no_si;
        thresh = si ? 1000 : 1024;
        if (bytes < thresh) {
            return bytes + ' B';
        }
        units = si ? ['kB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'] : ['KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB', 'ZiB', 'YiB'];
        u = -1;
        do {
            bytes /= thresh;
            u++;
        } while (bytes >= thresh);
        return bytes.toFixed(1) + ' ' + units[u];
    };
    stats = generateStorageStats(db, sortByEffcy);
    hdr_labels = ["Collection", "Size", "Effcy%", "Idxs"];
    colLengths = [];
    for (i = 0; i < hdr_labels.length; i++) {
        colLengths.push(hdr_labels[i].length + 1);
    }

    ds_size = 0;
    idx_size = 0;
    stats.forEach(function (c) {
        c.humanStorageSize = humanFileSize(c.storageSize);
        c.humanIndexSize = humanFileSize(c.totalIndexSize);
        colLengths[0] = Math.max(colLengths[0], c.ns.length);
        colLengths[1] = Math.max(colLengths[1], c.humanStorageSize.length);
        colLengths[3] = Math.max(colLengths[3], c.humanStorageSize.length);
        ds_size += c.storageSize;
        idx_size += c.totalIndexSize;
    });
    ds_size = humanFileSize(ds_size);
    idx_size = humanFileSize(idx_size);
    colLengths[1] = Math.max(colLengths[1], ds_size.length);
    colLengths[3] = Math.max(colLengths[3], idx_size.length);

    line = [pad(hdr_labels[0], colLengths[0], " ", true),
                    pad((sortByEffcy ? "" : "*") + hdr_labels[1], colLengths[1], " "),
                    pad((sortByEffcy ? "*" : "") + hdr_labels[2], colLengths[2], " "),
                    pad(hdr_labels[3], colLengths[3], " ")
        ];
    line = line.join(" | ");
    print(line);
    hbar = pad("", line.length, "-");
    print(hbar);
    stats.forEach(function (c) {
        var lline = [pad(c.ns, colLengths[0], " ", true),
                    pad(c.humanStorageSize, colLengths[1], " "),
                    pad((c.storageEfficiency * 100).toFixed(2), colLengths[2], " "),
                    pad(c.humanIndexSize, colLengths[3], " ")
                ];
        print(lline.join(" | "));
    });
    print(hbar);
    line = [pad("", colLengths[0], " ", true),
                    pad(ds_size, colLengths[1], " "),
                    pad("", colLengths[2], " "),
                    pad(idx_size, colLengths[3], " ")

        ];
    line = line.join(" | ");
    print(line);
}

/*
    Gets the normal stat objects and adds a '.storageEfficiency' property to each one.
    Returns a sorted list (defaults to 'by size') of stat objects.
*/
function generateStorageStats(the_db, sortByEffcy) {
    var colNames, allStats, prop;

    colNames = the_db.getCollectionNames();
    allStats = [];
    colNames.forEach(function (name) {
        var o = db[name].stats();
        o.storageEfficiency = o.size / o.storageSize;
        allStats.push(o);
    });
    prop = sortByEffcy ? 'storageEfficiency' : 'size';
    allStats.sort(function (a, b) {return a[prop] === b[prop] ? 0 : (a[prop] < b[prop] ? -1 : 1); });
    return allStats;
}