Is it possible to use SQLite as a relational database from Google App Engine? (Java) I need read/write access to it from the app itself.
Also, I am using Quercus for PHP, and if what I am asking for is possible, I can handle storing the database myself.
No, it is not possible. This would require write access to the filesystem, which App Engine does not allow.
SQL database support (MySQL like) is planned, but no release data has been given. For now, use the datastore.
I know it's a super old question and nothing concerning read-only properties of App Engine has changed since then... But actually you can use sqlite on Google App Engine. There is a writable /tmp directory (https://cloud.google.com/appengine/docs/standard/java-gen2/using-temp-files). If your app on startup first copies the db.sqlite3 file to /tmp/db.sqlite3 and references this path as database path, it will work.
The following problems are connected with this approach:
This directory is "in-memory". So if you want to use really large sqlite file, you may face problems with RAM.
Each node of the app gets its own copy of the database. If you save something on one node, these changes will not be seen by other nodes. And the new data will be lost if the app scales to 0.
Related
I am developing an android app that measures the radio interface parameters of a network periodically, stores the data in SQLite DB and transfers the data stored to MySQL DB on a web server. How can I make this possible?
I've done some research on this and found only one usable option, which is to make a web service using json or xml to pull/push data between the two databases. You could create a database link between the two, but this is not advisable.
There are numerous questions with a more detailed scope for this issue and you should be able to find one that fits your use case. If not, ask a new question after this research with more details and what you've done so far.
I'm making an app that will be using few hundred database posts from a sqlite database. I will not be adding new data during the lifetime of the app (unless I update the whole app).
I might end up using a static xml for the data, but I need to flag posts, so I guess a sqlite db would do the job best. I know how to implement it and I've released apps using sqlite before...
But my question is. How to I best populate the sqlite db the first time the app runs? Should I just bring in a file that I use as a resource and then copy to the apps space? What's the best/easiest practice?
The simplest solution is to use SQLiteAssetHelper. You basically drop your SQLite database into your project's assets/ directory, and use SQLiteAssetHelper in lieu of SQLiteOpenHelper. In addition to the sample code up on Jeff Gilfelt's GitHub repo for the library, I have a sample app demonstrating it as well.
i am building a application for a takeaway resturant using SOAP as a webservice.
Problem:
When i try to open the application it loads every time. and if i have slow internet it will take some time which is not good for a professional application.
How can i cache the images in my mobile so it loads automatically
Possible Solution in my mind:
i think i should use the local database and sink it with internet
Use local cache system (but what if the application close).
Use arraylist to store information.
Can you guide me in that as i am stuck i do some reading but i don't feel any reliable solution on it.
You can use some libs but you can lose images if the app is closed.
Actually you can cache images with libs and save them to sdcard at the same time. You need to save Their id in database. Then take data from sdcard by id from database in case you haven't internet.
I'm new in app engine.
I created an Java application using Google app engine. I populated a database offline. I can access it at my localhost. I know that the local dev server stores data in local_db.bin.
When I upload the app to the online dev server, it doesn't upload my database. It is possible to upload the local_db.bin?
Thank you for you help.
Copying/deploying the local_db.bin file directly to Google servers will have no effect and that file is intended only for the SDK that runs locally. On production the datastore is a service and all implementation and files are hidden away from the user. Thus you can't copy or change the format for the file to achieve what you want.
See this link for
datastore copy
Depending how much data you have and how often you need to populate it then it might just be easier to re-populate it online, create some basic data bootstrapping code/script or an API/import process.
Short Version: I need to store some data between runs of a java program.The data will be of the form of a table.Is there anything that can let do something like a sql query in java??THE SOLUTION MUST BE ABLE TO RUN ON AN OFFLINE COMPUTER.
Long Version: The user will be entering some data daily and i want something like a sql table in java. The program will run on a computer that is NOT CONNECTED TO THE INTERNET and so i need a truly local way to store data(Lots of it).Also preferably the data should be stored in such a way that it is not easily accessible to the end user(as in ,he should not be able to double click the file and simply read its contents)
Major Constraint: On searching online i found many people were using localhost to solve similar problems but that facility is not available to me as i CANNOT INSTALL ANYTHING on the target computer.
If a simple data file is not good enough, how about using SQLite with a JDBC backend? It will allow you to have an SQL database stored in a regular file with no dependency on any kind of server. Alternatively, there are many other embedded DB engines that you could use, depending on your needs.
EDIT:
By the way, most (if not all) DB engines that I know of do not obfuscate the data before storing them in the filesystem. The data will be fragmented, but parts of it will be visible if you force an editor to open the file (e.g. using "Open with..." in Windows).
There is also nothing to stop your user from accessing the data using the command line utility of the selected DB engine. If you want to obfuscate the data you have to do it in your code. Keep in mind that this will not stop a determined person - if your application can read it offline, so can everyone else.
Use an embedded database (like Apache Derby, HSQLDB, H2) so that you don't have to run a database server on the machine. The data will be stored locally on the target machine and it won't be human readable.
You have several options:
Store it in an xml-file
Store it in an local installed database
You can install a database like mysql or use a in memory database like sqlite or hbase or apache derby, which is included in java 6