I have a database where a few statistics are stored (PlayerID, Time, Kills, Deaths), 7 in total but these are enough to explain.
What I did was load the table in php, create an array with all the statistics (including statistics that are a product of multiple statistics, kills per death for example), sort them, and cut the top 10.
Then I passed this top10-array as JSON to javascript, where I just created tr- and td-elements and made the respective tables append them.
However, with just 10 different sets of statistics, it took an eternity (like 30 seconds I'd say) to load the page. My guess was that the sorting takes too long for the server, so I tried just passing the initial array to javascript and put the sorting part in /* */, to test if it would go any faster. It did not.
Afterwards I turned the sorting back on, but disabled the javascript part and just displayed it with var_dump(). It still didn't go much faster.
The actual code is kinda long and I think this isn't a question that you need the code for, but I can still post the code if you really need it. What exactly is causing the load time, and what would be the best way to sort and display the statistics?
Edit: I forgot to say that using ORDER BY in the SQL query doesn't work, because I need the to calculate some statistics using others.
Sounds like you spend all you time on retrieving and processing the whole data set, and then you throw away everything but top 10 records.
Without seeing the model and understanding how the top 10 are selected, the only advice would be to rethink you model, decide on an indexed field by which you would be able to fetch just the top 10 records, and do the calculations for that field before you save statistics into DB.
It also depends on which operation is more time-sensitive for you - SELECT or UPDATE (i.e when you fetch or save statistics). But I bet couple of math operations before you save data will not affect much the time spent on saving the data. But will greatly improve time spent on generating some reports, including top 10 report.
I have a list of approx. 2000 questions and I am trying to create an interface where you can filter through them all using a text input.
I tried going through this React tutorial since i thought it would perform well enough but there is a considerable lag. Or at least there is when I run the code in an Electron container (perhaps I'd get better performance compiling it with Webpack). I just tried putting my code in to a jsfiddle and with 3000 elements the performance starts to suffer.
Is it futile trying to search through this many objects with html and js or is there a simpler way with better performance?
So the lag is not because of the filtering, but because you are trying to render too many objects in one hit. You can see this by typing a sequence of zeros into the filter input. Each zero typed requires less time, as obviously the result size gets smaller and smaller.
I have updated your fiddle here to show the performance if you only render the first 100 items in the result set (even though all 3000 are processed on each input change).
Essentially I am just generating the full rows variable, and then using .slice(0, 100) to generate a truncated version before rendering.
What you should do in this situation is think about UI/UX, and that it really isn't necessary to render thousands of items at the same time. You could implement some sort of pagination or infinite scroll, etc.
I'm building a browser based game in JavaScript.
It contains a lot of Information visualized via tables.
The game is turn-based, so whenever a turn is completed, I need to adjust a lot of innerHTML of those tables.
My question is:
Is it smarter to give IDs to all the <td> and update the innerHTML or is it smarter to wrap the tables inside a div, clear the div and rebuild all tables from scratch, then append them?
It depends on how long a view stays active, if the view is shared, how many cells change and how frequently.
If you have a high number users looking at different views/pages that stay active for a long time, then it might produce less load on your servers if you can make infrequent updates to individual cells.
If the changes happen less frequent and a high proportion of cells change, then it may be best to refresh the whole table. This would be 'less chatty' and use less network bandwidth overall.
However if you have a high number of users, all looking at the same view/page, you may wish to look into CQRS and caching your views or view data.
Rather replace the innerHTML, the code will look nicer and it will be a lot more effortless, because instead of recreating the whole thing you would just be replacing a string in an object, which is obviously a lighter task. So in most cases it makes sense to do that.
Consider using a framework or templates, though.
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I need to present a large number of rows of data (ie. millions of rows) to the user in a grid using JavaScript.
The user shouldn't see pages or view only finite amounts of data at a time.
Rather, it should appear that all of the data are available.
Instead of downloading the data all at once, small chunks are downloaded as the user comes to them (ie. by scrolling through the grid).
The rows will not be edited through this front end, so read-only grids are acceptable.
What data grids, written in JavaScript, exist for this kind of seamless paging?
(Disclaimer: I am the author of SlickGrid)
UPDATE
This has now been implemented in SlickGrid.
Please see http://github.com/mleibman/SlickGrid/issues#issue/22 for an ongoing discussion on making SlickGrid work with larger numbers of rows.
The problem is that SlickGrid does not virtualize the scrollbar itself - the scrollable area's height is set to the total height of all the rows. The rows are still being added and removed as the user is scrolling, but the scrolling itself is done by the browser. That allows it to be very fast yet smooth (onscroll events are notoriously slow). The caveat is that there are bugs/limits in the browsers' CSS engines that limit the potential height of an element. For IE, that happens to be 0x123456 or 1193046 pixels. For other browsers it is higher.
There is an experimental workaround in the "largenum-fix" branch that raises that limit significantly by populating the scrollable area with "pages" set to 1M pixels height and then using relative positioning within those pages. Since the height limit in the CSS engine seems to be different and significantly lower than in the actual layout engine, this gives us a much higher upper limit.
I am still looking for a way to get to unlimited number of rows without giving up the performance edge that SlickGrid currently holds over other implementations.
Rudiger, can you elaborate on how you solved this?
https://github.com/mleibman/SlickGrid/wiki
"SlickGrid utilizes virtual rendering to enable you to easily work with hundreds of thousands of items without any drop in performance. In fact, there is no difference in performance between working with a grid with 10 rows versus a 100’000 rows."
Some highlights:
Adaptive virtual scrolling (handle hundreds of thousands of rows)
Extremely fast rendering speed
Background post-rendering for richer cells
Configurable & customizable
Full keyboard navigation
Column resize/reorder/show/hide
Column autosizing & force-fit
Pluggable cell formatters & editors
Support for editing and creating new rows."
by mleibman
It's free (MIT license).
It uses jQuery.
The best Grids in my opinion are below:
Flexigrid: http://flexigrid.info/
jQuery Grid: http://www.trirand.com/blog/
jqGridView: http://plugins.jquery.com/project/jqGridView
jqxGrid: https://www.jqwidgets.com/
Ingrid: http://reconstrukt.com/ingrid/
SlickGrid http://github.com/mleibman/SlickGrid
DataTables http://www.datatables.net/index
ShieldUI http://demos.shieldui.com/web/grid-virtualization/performance-1mil-rows
Smart.Grid https://www.htmlelements.com/demos/grid/overview/
My best 3 options are jqGrid, jqxGrid and DataTables. They can work with thousands of rows and support virtualization.
I don't mean to start a flame war, but assuming your researchers are human, you don't know them as well as you think. Just because they have petabytes of data doesn't make them capable of viewing even millions of records in any meaningful way. They might say they want to see millions of records, but that's just silly. Have your smartest researchers do some basic math: Assume they spend 1 second viewing each record. At that rate, it will take 1000000 seconds, which works out to more than six weeks (of 40 hour work-weeks with no breaks for food or lavatory).
Do they (or you) seriously think one person (the one looking at the grid) can muster that kind of concentration? Are they really getting much done in that 1 second, or are they (more likely) filtering out the stuff the don't want? I suspect that after viewing a "reasonably-sized" subset, they could describe a filter to you that would automatically filter out those records.
As paxdiablo and Sleeper Smith and Lasse V Karlsen also implied, you (and they) have not thought through the requirements. On the up side, now that you've found SlickGrid, I'm sure the need for those filters became immediately obvious.
I can say with pretty good certainty that you seriously do not need to show millions of rows of data to the user.
There is no user in the world that will be able to comprehend or manage that data set so even if you technically manage to pull it off, you won't solve any known problem for that user.
Instead I would focus on why the user wants to see the data. The user does not want to see the data just to see the data, there is usually a question being asked. If you focus on answering those questions instead, then you would be much closer to something that solves an actual problem.
I recommend the Ext JS Grid with the Buffered View feature.
http://www.extjs.com/deploy/dev/examples/grid/buffer.html
(Disclaimer: I am the author of w2ui)
I have recently written an article on how to implement JavaScript grid with 1 million records (http://w2ui.com/web/blog/7/JavaScript-Grid-with-One-Million-Records). I discovered that ultimately there are 3 restrictions that prevent from taking it highter:
Height of the div has a limit (can be overcome by virtual scrolling)
Operations such as sort and search start being slow after 1 million records or so
RAM is limited because data is stored in JavaScript array
I have tested the grid with 1 million records (except IE) and it performs well. See article for demos and examples.
dojox.grid.DataGrid offers a JS abstraction for data so you can hook it up to various backends with provided dojo.data stores or write your own. You'll obviously need one that supports random access for this many records. DataGrid also provides full accessibility.
Edit so here's a link to Matthew Russell's article that should provide the example you need, viewing millions of records with dojox.grid. Note that it uses the old version of the grid, but the concepts are the same, there were just some incompatible API improvements.
Oh, and it's totally free open source.
I used jQuery Grid Plugin, it was nice.
Demos
Here are a couple of optimizations you can apply you speed up things. Just thinking out loud.
Since the number of rows can be in the millions, you will want a caching system just for the JSON data from the server. I can't imagine anybody wanting to download all X million items, but if they did, it would be a problem. This little test on Chrome for an array on 20M+ integers crashes on my machine constantly.
var data = [];
for(var i = 0; i < 20000000; i++) {
data.push(i);
}
console.log(data.length);
You could use LRU or some other caching algorithm and have an upper bound on how much data you're willing to cache.
For the table cells themselves, I think constructing/destroying DOM nodes can be expensive. Instead, you could just pre-define X number of cells, and whenever the user scrolls to a new position, inject the JSON data into these cells. The scrollbar would virtually have no direct relationship to how much space (height) is required to represent the entire dataset. You could arbitrarily set the table container's height, say 5000px, and map that to the total number of rows. For example, if the containers height is 5000px and there are a total of 10M rows, then the starting row ≈ (scroll.top/5000) * 10M where scroll.top represents the scroll distance from the top of the container. Small demo here.
To detect when to request more data, ideally an object should act as a mediator that listens to scroll events. This object keeps track of how fast the user is scrolling, and when it looks like the user is slowing down or has completely stopped, makes a data request for the corresponding rows. Retrieving data in this fashion means your data is going to be fragmented, so the cache should be designed with that in mind.
Also the browser limits on maximum outgoing connections can play an important part. A user may scroll to a certain position which will fire an AJAX request, but before that finishes the user can scroll to some other portion. If the server is not responsive enough the requests would get queued up and the application will look unresponsive. You could use a request manager through which all requests are routed, and it can cancel pending requests to make space.
I know it's an old question but still.. There is also dhtmlxGrid that can handle millions of rows. There is a demo with 50,000 rows but the number of rows that can be loaded/processed in grid is unlimited.
Disclaimer: I'm from DHTMLX team.
I suggest you read this
http://www.sitepen.com/blog/2008/11/21/effective-use-of-jsonreststore-referencing-lazy-loading-and-more/
Disclaimer: i heavily use YUI DataTable without no headache for a long time. It is powerful and stable. For your needs, you can use a ScrollingDataTable wich suports
x-scrolling
y-scrolling
xy-scrolling
A powerful Event mechanism
For what you need, i think you want is a tableScrollEvent. Its API says
Fired when a fixed scrolling DataTable has a scroll.
As each DataTable uses a DataSource, you can monitoring its data through tableScrollEvent along with render loop size in order to populate your ScrollingDataTable according to your needs.
Render loop size says
In cases where your DataTable needs to display the entirety of a very large set of data, the renderLoopSize config can help manage browser DOM rendering so that the UI thread does not get locked up on very large tables. Any value greater than 0 will cause the DOM rendering to be executed in setTimeout() chains that render the specified number of rows in each loop. The ideal value should be determined per implementation since there are no hard and fast rules, only general guidelines:
By default renderLoopSize is 0, so all rows are rendered in a single loop. A renderLoopSize > 0 adds overhead so use thoughtfully.
If your set of data is large enough (number of rows X number of Columns X formatting complexity) that users experience latency in the visual rendering and/or it causes the script to hang, consider setting a renderLoopSize.
A renderLoopSize under 50 probably isn't worth it. A renderLoopSize > 100 is probably better.
A data set is probably not considered large enough unless it has hundreds and hundreds of rows.
Having a renderLoopSize > 0 and < total rows does cause the table to be rendered in one loop (same as renderLoopSize = 0) but it also triggers functionality such as post-render row striping to be handled from a separate setTimeout thread.
For instance
// Render 100 rows per loop
var dt = new YAHOO.widget.DataTable(<WHICH_DIV_WILL_STORE_YOUR_DATATABLE>, <HOW YOUR_TABLE_IS STRUCTURED>, <WHERE_DOES_THE_DATA_COME_FROM>, {
renderLoopSize:100
});
<WHERE_DOES_THE_DATA_COME_FROM> is just a single DataSource. It can be a JSON, JSFunction, XML and even a single HTML element
Here you can see a Simple tutorial, provided by me. Be aware no other DATA_TABLE pluglin supports single and dual click at the same time. YUI DataTable allows you. And more, you can use it even with JQuery without no headache
Some examples, you can see
List item
Feel free to question about anything else you want about YUI DataTable.
regards,
I kind of fail to see the point, for jqGrid you can use the virtual scrolling functionality:
http://www.trirand.net/aspnetmvc/grid/performancevirtualscrolling
but then again, millions of rows with filtering can be done:
http://www.trirand.net/aspnetmvc/grid/performancelinq
I really fail to see the point of "as if there are no pages" though, I mean... there is no way to display 1,000,000 rows at once in the browser - this is 10MB of HTML raw, I kind of fail to see why users would not want to see the pages.
Anyway...
best approach i could think of is by loading the chunk of data in json format for every scroll or some limit before the scrolling ends. json can be easily converted to objects and hence table rows can be constructed easily unobtrusively
I would highly recommend Open rico.
It is difficult to implement in the the beginning, but once you grab it you will never look back.
I know this question is a few years old, but jqgrid now supports virtual scrolling:
http://www.trirand.com/blog/phpjqgrid/examples/paging/scrollbar/default.php
but with pagination disabled
I suggest sigma grid, sigma grid has embed paging features which could support millions of rows. And also, you may need a remote paging to do it.
see the demo
http://www.sigmawidgets.com/products/sigma_grid2/demos/example_master_details.html
Take a look at dGrid:
https://dgrid.io/
I agree that users will NEVER, EVER need to view millions of rows of data all at once, but dGrid can display them quickly (a screenful at a time).
Don't boil the ocean to make a cup of tea.
I am wondering if anyone can give some safe guidelines on the maximum level of dom manipulation you can do with jquery without freezing the browser.
Also the best methods for mass DOM manipulation.
Basically at any one time I could be dealing with lists of up to 40k li's
All I am really doing is showing one, hiding the other.
So here are my questions
How many li's could I theoretically manipulate at a time without crashing the browser?
How should I work with the li's?
Manipulate as a single object (ul level)
Loop over each li in the first list removing them, then loop inserting each new li.
Loop over chunks of li's (if so how big 10, 100, 1000, 10000 at a time?)
How should I fetch the data? (its in json format)
Grab the data for the entire list (40k li's worth) in one ajax call.
Insert the data for every list at page creation(could be upwards of 20 lists = 800,000 li's
Do several ajax calls to fetch the data (if so how big 10, 100, 1000, 10000 at a time?)
If you really want to be manipulating that many then you should probably adopt something like http://developer.yahoo.com/yui/3/async-queue/
As the answer for how many you should be working with at a time, you could build in a calibration which looks at how quickly the last set completed and work with more / less accordingly. This could get you something that works in everything from desktop chrome to mobile IE.
The same goes for the ajax calls, make it able to ramp up according to the net speed.
As a warning: this is extremely dependent on your computer performance. Frankly - anything approaching 100 elements in a DOM manipulation starts getting a little silly and expensive. That said:
1) Depends on your system, my older system tops at about 30 and my newer one can get up to 120 before I break things.
2) Work with them on as large a level as possible. Manipulating a ul with a bunch of li's in it is much faster than manipulating a bunch of li's. Use jQuery and store the object in a variable (so you're not querying the DOM each time it's used) to enhance performance.
3) Initially load the first data the user will see, then fetch it in similarly sized batches. If you can only see 20 li elements at a time there is no reason loading any more than that plus a little buffer area (30?).