mongodb 分頁查詢

當資料庫中資料較多，查詢的資料量較大時，很容易給mongo資料庫帶來負擔，為此，寫了一個簡單的分頁查詢算法，基于nodejs 的mongoose 子產品:

注：依賴庫：async

var findEach = function (model, condition, sort, key, views, cb) {

    //model.find(condition, views).sort(sort).lean().exec(function (err, docs) {
    //    cb(err, docs);
    //});


    var allCount = 0;
    var searchInterval = 2000;

    var returnData = [];
    async.auto({
        getCount: function (cb) {
            model.count(condition).lean().exec(function (err, count) {
                if (!err && count) {
                    allCount = count;
                }
                cb(err);
            })
        },
        processData: ["getCount", function (cb) {
            if (allCount) {
                if (allCount >= searchInterval) {
                    var arrLen = Math.floor(allCount / searchInterval);
                    var lastSearchCount = allCount % searchInterval;

                    var _tempArr = _.range(arrLen);
                    var searchIndex = 1;

                    var lastDataKey = null;
                    if (arrLen >= 1 && _tempArr.length) {
                        async.eachSeries(_tempArr, function (item, callback) {
                            if (searchIndex == 1) {
                                model.find(condition, views).limit(searchInterval).sort(sort).lean().exec(function (err, docs) {
                                    if (!err && docs.length) {
                                        lastDataKey = parseInt((docs[docs.length - 1])[key]);
                                        searchIndex++;
                                        returnData = returnData.concat(docs);
                                        callback(err);
                                    } else {
                                        callback(err);
                                    }
                                })
                            } else {
                                condition[key]["$gte"] = lastDataKey;

                                //console.log("condition",condition);
                                model.find(condition, views).limit(searchInterval).sort(sort).lean().exec(function (err, docs) {
                                    if (!err && docs.length) {
                                        lastDataKey = parseInt((docs[docs.length - 1])[key]);
                                        searchIndex++;
                                        returnData = returnData.concat(docs);

                                        callback(err);
                                    } else {
                                        callback(err);
                                    }
                                })

                            }
                        }, function (err, resp) {
                            if (!err) {
                                condition[key]["$gte"] = lastDataKey;
                                model.find(condition, views).limit(lastSearchCount).sort(sort).lean().exec(function (err, docs) {
                                    if (!err && docs.length) {
                                        returnData = returnData.concat(docs);
                                    }
                                    cb(err);
                                })
                            } else {
                                cb(err);
                            }
                        })
                    } else {
                        cb(null);
                    }
                } else {
                    model.find(condition, views).sort(sort).lean().exec(function (err, docs) {
                        if (!err && docs.length) {
                            returnData = docs;
                        }
                        cb(err);
                    })
                }
            } else {
                cb(null);
            }
        }]
    }, function (err, resp) {
        cb(err, returnData);
    });
}
           

例子：

var Mongoose = require('mongoose');
var Schema = Mongoose.Schema;
var async= require('async');

var AdminTable = {
    username: {type: String, default: ''},
    password: {type: String, default: ''},
    log_time: {type: Number, default: Date.now}
};

var SchemaOption = {};

var AdminSchema = new Mongoose.Schema(AdminTable, SchemaOption);

AdminSchema.statics.findAll= function (condition,views, cb) {
 findEach(this, condition, {"log_time": 1}, "log_time", views,  function (error, docs) {
	cb(error,docs);
}
}