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Why don't you simply use a map literal:

I try to avoid text only answers; including code is best practice but the question about storing images comes up frequently and it's not really covered in the documentation so I thought it should be addressed at a high level.

Generally speaking, Realm is not a solution for storing blob type data - images, pdf's etc. There are a number of technical reasons for that but most importantly, an image can go well beyond the capacity of a Realm field. Additionally it can significantly impact performance (especially in a sync'ing use case)

If this is a local only app, storing the images on disk in the device and keep a reference to where they are (their path) stored in Realm. That will enable the app to be fast and responsive with a minimal footprint.

If this is a sync'd solution where you want to share images across devices or with other users, there are several cloud based solutions to accommodate image storage and then store a URL to the image in Realm.

One option is part of the MongoDB family of products (which also includes MongoDB Realm) called GridFS. Another option is a solid product we've leveraged for years is called Firebase Cloud Storage.

Now that I've made those statements, I'll backtrack just a bit and refer you to this article Realm Data and Partitioning Strategy Behind the WildAid O-FISH Mobile Apps which is a fantastic article about implementing Realm in a real-world use application and in particular how to deal with images.

In that article, note they do store the images in Realm for a short time. However, one thing they left out of that (which was revealed in a forum post) is that the images are compressed to ensure they don't go above the Realm field size limit.

I am not totally on board with general use of that technique but it works for that specific use case.

One more note: the image sizes mentioned in the question are pretty small (500 ~~ 800 kb img size) and that's a tiny amount of data which would really not have an impact, so storing them in realm as a data object would work fine. The caveat to that is future expansion; if you decide to later store larger images, it would require a complete re-write of the code; so why not plan for that up front.

You've used -Xms to force the JVM to get ~30GB at JVM startup.

It has tried, and failed. It only obtained 8GB. It needs another 22-ish GB but cannot get it. That is what the error message is telling you. This is consistent with a dump that says the heap is only 8GB.

You're asking for more than the OS will provide. You'll need to figure out what's going on in the OS in general.

Your application code is probably not involved. The JVM is still initializing its heap in accordance with your command-line options.

EDIT: BETTER WAY

INSTEAD OF EDITING THE STRING IN THE SERVER WE SHOULD ENCODE IN ANDROID THIS WAY

Base64.encodeToString(bytes, Base64.NO_WRAP);

AND GET IT IN THE SERVER THE USUAL WAY WITHOUT EDITING THE STRING

java.util.Base64.getMimeDecoder().decode(yourByteArray);

PREVIOUS WAY:

I just had to edit the String that i was getting in the server by removing the quotes surrounding it with img.substring(1, img.length() - 1) and the \n with img.replace("\\n", "").

The result code in the server is like this:

Renaming works fine as your first try:

Raster or bitmap fonts are represented in a number of different ways and there are bitmap font file standards that have been developed for both Linux and Windows. However raw data representation of bitmap fonts in programming language source code seems to vary depending on:

• the memory architecture of the target computer,
• the architecture and communication pathways to the display controller,
• character glyph height and width in pixels and
• the amount of memory for bitmap storage and what measures are taken to make that as small as possible.

A brief overview of bitmap fonts

A generic bitmap is a block of data in which individual bits are used to indicate a state of either on or off. One use of a bitmap is to store image data. Character glyphs can be created and stored as a collection of images, one for each character in the character set, so using a bitmap to encode and store each character image is a natural fit.

Bitmap fonts are bitmaps used to indicate how to display or print characters by turning on or off pixels or printing or not printing dots on a page. See Wikipedia Bitmap fonts

A bitmap font is one that stores each glyph as an array of pixels (that is, a bitmap). It is less commonly known as a raster font or a pixel font. Bitmap fonts are simply collections of raster images of glyphs. For each variant of the font, there is a complete set of glyph images, with each set containing an image for each character. For example, if a font has three sizes, and any combination of bold and italic, then there must be 12 complete sets of images.

A brief history of using bitmap fonts

The earliest user interface terminals such as teletype terminals used dot matrix printer mechanisms to print on rolls of paper. With the development of Cathode Ray Tube terminals bitmap fonts were readily transferable to that technology as dots of luminescence turned on and off by a scanning electron gun.

Earliest bitmap fonts were of a fixed height and width with the bitmap acting as a kind of stamp or pattern to print characters on the output medium, paper or display tube, with a fixed line height and a fixed line width such as the 80 columns and 24 lines of the DEC VT-100 terminal.

With increasing processing power, a more sophisticated typographical approach became available with vector fonts used to improve displayed text quality and provide improved scaling while also reducing memory required to describe the character glyphs.

In addition, while a matrix of dots or pixels worked fairly well for languages such as English, written languages with complex glyph forms were poorly served by bitmap fonts.

Representation of bitmap fonts in source code

There are a number of bitmap font file formats which provide a way to represent a bitmap font in a device independent description. For an example see Wikipedia topic - Glyph Bitmap Distribution Format

The Glyph Bitmap Distribution Format (BDF) by Adobe is a file format for storing bitmap fonts. The content takes the form of a text file intended to be human- and computer-readable. BDF is typically used in Unix X Window environments. It has largely been replaced by the PCF font format which is somewhat more efficient, and by scalable fonts such as OpenType and TrueType fonts.

Other bitmap standards such as XBM, Wikipedia topic - X BitMap, or XPM, Wikipedia topic - X PixMap, are source code components that describe bitmaps however many of these are not meant for bitmap fonts specifically but rather other graphical images such as icons, cursors, etc.

As bitmap fonts are an older format many times bitmap fonts are wrapped within another font standard such as TrueType in order to be compatible with the standard font subsystems of modern operating systems such as Linux and Windows.

However embedded systems that are running on the bare metal or using an RTOS will normally need the raw bitmap character image data in the form similar to the XBM format. See Encyclopedia of Graphics File Formats which has this example:

Following is an example of a 16x16 bitmap stored using both its X10 and X11 variations. Note that each array contains exactly the same data, but is stored using different data word types:

When there's a copy activity performance issue in ADF and the root cause is not obvious (e.g. if source is fast, but sink is throttled, and we know why) -- here's how I would go about it :

1. Start with the Integration Runtime (IR) (doc.). This might be a jobs' concurrency issue, a network throughput issue, or just an undersized VM (in case of self-hosted). Like, >80% of all issues in my prod ETL are caused by IR-s, in one way or another.
2. Replicate copy activity behavior both on source & sink. Query the views from your local machine (ideally, from a VM in the same environment as your IR), write the flat files to blob, etc. I'm assuming you've done that already, but having another observation rarely hurts.
3. Test various configurations of copy activity. Changing isolationLevel, partitionOption, parallelCopies and enableStaging would be my first steps here. This won't fix the root cause of your issue, obviously, but can point a direction for you to dig in further.
4. Try searching the documentation (this doc., provided by @Leon is a good start). This should have been a step #1, however, I find ADF documentation somewhat lacking.

N.B. this is based on my personal experience with Data Factory.
Providing a specific solution in this case is, indeed, quite hard.

Your problem is that uwsgi is not being run from inside the vent. To do so run the application with:

An RCU is good for 1 strongly consistent read of up to 4KB.

Thus you can query() four 1KB items for 1 RCU.

Since you have only 3 to read, 1 RCU will be consumed.

Using GetItem() to get those same 3 records would cost 3 RCU.

Let say you had 100 items that matched (HK+SK) the query, but you're also using filter to further select records to be returned; so you're only getting 4 records back. That query would take 25 RCU, as the records still have to be read even if not returned.

Reference can be found here :

Query—Reads multiple items that have the same partition key value. All items returned are treated as a single read operation, where DynamoDB computes the total size of all items and then rounds up to the next 4 KB boundary. For example, suppose your query returns 10 items whose combined size is 40.8 KB. DynamoDB rounds the item size for the operation to 44 KB. If a query returns 1500 items of 64 bytes each, the cumulative size is 96 KB.