My data set is pretty basic. Lets assume I have a document with device data, and I have additional documents with associated ports, hardware modules, etc. This data is larger than the 20MB document limit, and I also don't want to pull a huge document to make a change to small detail on a port anyway. Device details are kept in the device document, like its location, name, hardware type etc.
I can easily use views to get ports associated to a device, hardware pieces, etc. Thats no problem at all, parameterized views help with this basic listing. However, for a larger complex search I would have to either have a view for most popular values, and pull down entire documents for more complex searches, which gets unsustainable really fast. I would have to pull all devices in location dallas, and then pull all ports of type available for each device, pull the document if I want a detail thats not in the view, etc. Tons of memory consumption and slow.
Does elastic search provide the capabilities required to say, search for a document of type server with location dallas that has ten or more documents linked back to it of type port with status as available, media type fiber etc?
I hope this makes sense. Thanks!
Related
I need to fetch a list of all the files in a user's box account, such that the list of files can then be displayed in a table view (iOS).
I have successfully implemented this by recursively using /folders/{folder id}/items on all the folder's in my user's box.
However, while this works, it's kind of dirty, seeing as how a request is made for each of the users's folders, which could be quite a large number.
Is there any way to get a list of all the files (it's no issue if folders are included, I can ignore those manually) available?
I tried implementing this using search, but I couldn't identify a value for the query parameter that returned everything.
Any help would be appreciated.
Help me, Obi-Wan Kenobi. You're my only hope.
What you are looking for (recursive call through a Box account) is not available. We have enterprise customers will bajillions of files and millions of folders. Recursively asking for everything would take too long.
What we generally recommend is that you ask for as little as you can, and that you use multiple threads and anticipate what you'll need just a little bit, so that you can deliver a high-performance user-interface to your end-users.
For example ?fields=item_collection is expensive to retrieve, and can add a lot to a paylaod. It can double, or 10x the time that it takes to get back a payload from the Box API. Most UI's don't need to show all the items inside every folder. So they are better off asking for ?fields=.
You can make your application responsive to the user if you make the smallest possible call. Of course there is a balance. Mobile networks have high latency, and sometimes that next API call to show some extra thing is slow. But for a folder tree, you can get high performance by retrieving only the current level, displaying that, and then starting to fetch one-level down while the user is looking at the first level.
Same goes for displaying thumbnails. If a user drills into a folder and starts looking at thumbnails for pictures, there's a good chance they'll want to see other thumbnails in that same folder. Your app should anticipate that, and start to pull one or two extras down in the background. Yes, it means more API calls, but your users will give your app a higher rating for being fast.
It's no secret that application logs can go well beyond the limits of naive log viewers, and the desired viewer functionality (say, filtering the log based on a condition, or highlighting particular message types, or splitting it into sublogs based on a field value, or merging several logs based on a time axis, or bookmarking etc.) is beyond the abilities of large-file text viewers.
I wonder:
Whether decent specialized applications exist (I haven't found any)
What functionality might one expect from such an application? (I'm asking because my student is writing such an application, and the functionality above has already been implemented to a certain extent of usability)
I've been using Log Expert lately.
alt text http://www.log-expert.de/images/stories/logexpertshowcard.gif
I can take a while to load large files, but it will in fact load them. I couldn't find the file size limit (if there is any) on the site, but just to test it, I loaded a 300mb log file, so it can at least go that high.
Windows Commander has a built-in program called Lister which works very quickly for any file size. I've used it with GBs worth of log files without a problem.
http://www.ghisler.com/lister/
A slightly more powerful tool I sometimes use it Universal Viewer from http://www.uvviewsoft.com/.
Does anyone know how I can store large binary values in Riak?
For now, they don't recommend storing files larger than 50MB in size without splitting them. See: FAQ - Riak Wiki
If your files are smaller than 50MB, than proceed as you would with storing non binary data in Riak.
Another reason one might pick Riak is for flexibility in modeling your data. Riak will store any data you tell it to in a content-agnostic way — it does not enforce tables, columns, or referential integrity. This means you can store binary files right alongside more programmer-transparent formats like JSON or XML. Using Riak as a sort of “document database” (semi-structured, mostly de-normalized data) and “attachment storage” will have different needs than the key/value-style scheme — namely, the need for efficient online-queries, conflict resolution, increased internal semantics, and robust expressions of relationships.Schema Design in Riak - Introduction
#Brian Mansell's answer is on the right track - you don't really want to store large binary values (over 50 MB) as a single object, in Riak (the cluster becomes unusably slow, after a while).
You have 2 options, instead:
1) If a binary object is small enough, store it directly. If it's over a certain threshold (50 MB is a decent arbitrary value to start with, but really, run some performance tests to see what the average object size is, for your cluster, after which it starts to crawl) -- break up the file into several chunks, and store the chunks separately. (In fact, most people that I've seen go this route, use chunks of 1 MB in size).
This means, of course, that you have to keep track of the "manifest" -- which chunks got stored where, and in what order. And then, to retrieve the file, you would first have to fetch the object tracking the chunks, then fetch the individual file chunks and reassemble them back into the original file. Take a look at a project like https://github.com/podados/python-riakfs to see how they did it.
2) Alternatively, you can just use Riak CS (Riak Cloud Storage), to do all of the above, but the code is written for you. That's exactly how RiakCS works -- it breaks an incoming file into chunks, stores and tracks them individually in plain Riak, and reassembles them when it comes time to fetch it back. And provides an Amazon S3 API for file storage, for your convenience. I highly recommend this route (so as not to reinvent the wheel -- chunking and tracking files is hard enough). Yes, CS is a paid product, but check out the free Developer Trial, if you're curious.
Just like every other value. Why would it be different?
Use either the Erlang interface ( http://hg.basho.com/riak/src/461421125af9/doc/basic-client.txt ) or the "raw" HTTP interface ( http://hg.basho.com/riak/src/tip/doc/raw-http-howto.txt ). It should "just work."
Also, you'll generally find a better response on the riak-users mailing list than you will here. http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com (No offense to z8000, who seems to also have answers.)
It seems that the trend in web design is to provide paged output, where long tables are displayed a page at a time. My customers don't like that, and have requested that the web sites I design for them show all entries in long tables. The arguments for paging seem to be mostly based on the performance hit of displaying long tables, and this is less of a concern in a high-bandwidth corporate intranet. Arguments against paging include the ability to print the entire table, do string searches against the entire table, select arbitrary ranges from the entire table for copying, etc. I've pointed out that these features can easily be added to paged web designs (e.g. a print button that prints the entire table, or a button that creates a CSV file of the the table), but the paged output still seems inconvenient to them. Our typical table is about 100 to 600 items. Obviously tables that would be significantly larger would probably have to be paged.
Questions:
What is your experience with personal or customer preferences for paged vs. full output in long tables?
Web design tools seem to be pushing the paging paradigm. Are they out of touch, or are my customers unusual?
If you're thinking "It depends on the length of the table", what threshold would you use?
I love long one-page listings.
One of the few reasons I can see for paged
listing is the ones you point out about performance.
I think your customers are very usual and in-touch.
The threshold would be about page loading times. When the server can't produce the full lists fast enough or when the lists gets so long that the browser slows down. (The latter can happen for quite short lists if you have non-a-tag hover stuff in your CSS and the browser is IE.)
Give the users a powerful search function and they'll narrow down their page lists themselves.
Why not simply have it be a user configurable option. It sounds like you plan to essentially implement both anyway.
To be honest I think that no matter which you choose someone will complain. At least with it being user configurable you have the ability to put it back on the user.
Provide a default page length, and a configurable parameter (e.g. in the query string for programmatic use, and/or a form on the webpage for interactive use) to control how many listings are in a page.
User flexibility is good. Texas Instruments has a parametric search tool for electrical engineers to find ICs that meet certain technical characteristics, and they include a link both to "show all" in a webpage and "download all" as a .csv file. That's a good model, kudos to TI. Ditto to flickr; their API lets you control (to a large extent) how many results show up on a web service call.
I personally HATE websites that default to 10 listings per page with no way to increase it. It takes FOREVER to browse them, & I'm willing to wait longer if I can get all the stuff at once.
If it's an interactive webpage, I would consider going to an AJAX solution that downloads 100 at a time so there's an indication of progress (and the user can stop it if there are 20000 results).
I agree with PEZ, it's all about responsiveness.
Best solution: Don't provide lists with more than 100 items.
Usually your user doesn't want to read more than 100 or even 600 items. They just don't care. They are searching for one (or possibly a few). Make sure that there's a way for them to get to those items without visual-grep-ing through the list.
And if your client insists on displaying all items, then provide paging with a configurable page size and let him enter "100000 items per page" if he wants to.
One of the seminal books on web design (sorry, I forget which one) used to say not to count on your users scrolling down because most of them don't know how or can't be bothered. I think a more recent update says that while is is true for the general public, certain sectors of more technical users can be expected to scroll down and you can make pages that require scrolling IFF (if and only iff) you know your users can handle it.
I can understand your situation extremely well. I have been in similar situation. I moved a business workflow from being man managed to an automated one. Initially it was carried out using excel spreadsheets. The stakeholders for my software were in the age group of 55+ they dont like anything ajaxy or any of the UI patterns you are talking about. It such cases data retreival logic can be optimized. Any table that touches the 1K mark or has item like image blobs or things like that should be shown in parts from a performance point of view.
long outputs slow rendering and will be performance leech
Customers dont want to changes most times and customer is always right unless u can convince them.
I have put forth my threshhold but it also depends on the content of the rows.
Happy Coding!
A friend of mine brought up this questiont he other day, he's recently bought a garmin heart rate moniter device which keeps track of his heart rate and allows him to upload his heart rate stats for a day to his computer.
The only problem is there are no linux drivers for the garmin USB device, he's managed to interpret some of the data, such as the model number and his user details and has identified that there are some binary datatables essentially which we assume represent a series of recordings of his heart rate and the time the recording was taken.
Where does one start when reverse engineering data when you know nothing about the structure?
I had the same problem and initially found this project at Google Code that aims to complete a cross-platform version of tools for the Garmin devices ... see: http://code.google.com/p/garmintools/. There's a link on the front page of that project to the protocols you need, which Garmin was thoughtful enough to release publically.
And here's a direct link to the Garmin I/O specification: http://www.garmin.com/support/pdf/IOSDK.zip
I'd start looking at the data in a hexadecimal editor, hopefully a good one which knows the most common encodings (ASCII, Unicode, etc.) and then try to make sense of it out of the data you know it has stored.
As another poster mentioned, reverse engineering can be hairy, not in practice but in legality.
That being said, you may be able to find everything related to your root question at hand by checking out this project and its' code...and they do handle the runner's heart rate/GPS combo data as well
http://www.gpsbabel.org/
I'd suggest you start with checking the legality of reverse engineering in your country of origin. Most countries have very strict laws about what is allowed and what isn't regarding reverse engineering devices and code.
I would start by seeing what data is being sent by the device, then consider how such data could be represented and packed.
I would first capture many samples, and see if any pattern presents itself, since heart beat is something which is regular and that would suggest it is measurement related to the heart itself. I would also look for bit fields which are monotonically increasing, as that would suggest some sort of time stamp.
Having formed a hypothesis for what is where, I would write a program to test it and graph the results and see if it makes sense. If it does but not quite, then closer inspection would probably reveal you need some scaling factors here or there. It is also entirely possible I need to process the data first before it looks anything like what their program is showing, i.e. might need to integrate the data points. If I get garbage, then it is back to the drawing board :-)
I would also check the manufacturer's website, or maybe run strings on their binaries. Finding someone who works in the field of biomedical engineering would also be on my list, as they would probably know what protocols are typically used, if any. I would also look for these protocols and see if any could be applied to the data I am seeing.
I'd start by creating a hex dump of the data. Figure it's probably blocked in some power-of-two-sized chunks. Start looking for repeating patterns. Think about what kind of data they're probably sending. Either they're recording each heart beat individually, or they're recording whatever the sensor is sending at fixed intervals. If it's individual beats, then there's going to be a time delta (since the last beat), a duration, and a max or avg strength of some sort. If it's fixed intervals, then it'll probably be a simple vector of readings. There'll probably be a preamble of some sort, with a start timestamp and the sampling rate. You can try decoding the timestamp yourself, or you might try simply feeding it to ctime() and see if they're using standard absolute time format.
Keep in mind that lots of cheap A/D converters only produce 12-bit outputs, so your readings are unlikely to be larger than 16 bits (and the high-order 4 bits may be used for flags). I'd recommend resetting the device so that it's "blank", dumping and storing the contents, then take a set of readings, record the results (whatever the device normally reports), then dump the contents again and try to correlate the recorded results with whatever data appeared after the "blank" dump.
Unsure if this is what you're looking for but Garmin has created an API that runs with your browser. It seems OSX is supported, as well as Windows browsers... I would try it from Google Chromium to see if it can be used instead of this reverse engineering...
http://developer.garmin.com/web-device/garmin-communicator-plugin/
API Features
Auto-detection of devices connected to a computer Access to device
product information like product name and software version Read
tracks, routes and waypoints from supported recreational, fitness and
navigation devices Write tracks, routes and waypoints to supported
recreational, fitness and navigation devices Read fitness data from
supported fitness devices Geo-code address and save to a device as a
waypoint or favorite Read and write Garmin XML files (GPX and TCX) as
well as binary files. Support for most Garmin devices (USB, USB
mass-storage, most serial devices) Support for Internet Explorer,
Firefox and Chrome on Microsoft Windows. Support for Safari, Firefox
and Chrome on Mac OS X.
Can you synthesize a heart beat using something like a computer speaker? (I have no idea how such devices actually work). Watch how the binary results change based on different inputs.
Ripping apart the device and checking out what's inside would probably help too.