Imagine a situation where a particular bucket has a very large number of sub directories and files .
The (java) API - listObjectsV2Paginator returns a collection of contents (files) as well as a collection of common prefixes (subdirectories)
In the interest of efficiency, would it be possible to return either of these , but not both .
My question is similar to ListObjectsV2 - Get only folders in an S3 bucket except that I want to know if is possible to avoid retrieving either sub directories or files.
Related
I Have a bucket with 3 million objects. I Even don't know how many folders are there in my S3 bucket and even don't know the names of folders in my bucket.I want to show only list of folders of AWS s3. Is there any way to get list of all folders ?
I would use AWS CLI for this. To get started - have a look here.
Then it is a matter of almost standard linux commands (ls):
aws s3 ls s3://<bucket_name>/path/to/search/folder/ --recursive | grep '/$' > folders.txt
where:
grep command just reads what aws s3 ls command has returned and searches for entries with ending /.
ending > folders.txt saves output to a file.
Note: grep (if I'm not wrong) is unix only utility command. But I believe, you can achieve this on windows as well.
Note 2: depending on the number of files there this operation might (will) take a while.
Note 3: usually in systems like AWS S3, term folder is there only for user to maintain visual similarity with standard file systems however inside it does treat it as a part of a key. You can see in your (web) console when you filter by "prefix".
Amazon S3 buckets with large quantities of objects are very difficult to use. The API calls that list bucket contents are limited to returning 1000 objects per API call. While it is possible to request 'folders' (by using Delimiter='/' and looking at CommonPrefixes), this would take repeated calls to obtain the hierarchy.
Instead, I would recommend using Amazon S3 Inventory, which can provide a daily or weekly CSV file listing all objects. You can then play with that CSV file from code (or possibly Excel? Might be too big?) to obtain your desired listings.
Just be aware that doing anything on that bucket will not be fast.
I have an S3 Bucket called Facebook
The structure is like this :
Facebook/AUS/transformedfiles/YYYYMMDDHH/payments.csv
Facebook/IND/transformedfiles/YYYYMMDDHH/payments.csv
Facebook/SEA/transformedfiles/YYYYMMDDHH/payments.csv
Is there a way to copy all payments.csv to AWS Redshift?
something like :
copy payments Facebook/*/transformedfiles/YYYYMMDDHH/payments.csv
No, because the FROM clause accepts an object prefix, and implies a trailing wildcard.
If you want to load specific files, you'll need to use a manifest file. You would build this manifest by calling ListObjects and programmatically selecting the files you want.
A manifest file is also necessary if you're creating the files and immediately uploading them, because S3 is eventually consistent -- if you rely on it selecting files with a prefix, it might miss some.
I am trying to list all items with specific prefix in S3 bucket. Here is directory structure that I have:
Item1/
Item2/
Item3/
Item4/
image_1.jpg
Item5/
image_1.jpg
image_2.jpg
When I set prefex to be Item1/Item2, I get as a result following keys:
Item1/Item2/
Item1/Item2/Item3/Item4/image_1.jpg
Item1/Item2/Item3/Item5/image_1.jpg
Item1/Item2/Item3/Item5/image_2.jpg
What I would like to get is:
Item1/Item2/
Item1/Item2/Item3
Item1/Item2/Item3/Item4
Item1/Item2/Item3/Item5
Item1/Item2/Item3/Item4/image_1.jpg
Item1/Item2/Item3/Item5/image_1.jpg
Item1/Item2/Item3/Item5/image_2.jpg
Is there anyway to achieve this in golang?
Folders do not actually exist in Amazon S3. It is a flat object storage system.
For example, using the AWS Command-Line Interface (CLI) I could copy a command to an Amazon S3 bucket:
aws s3 cp foo.txt s3://my-bucket/folder1/folder2/foo.txt
This work just fine, even though folder1 and folder2 do not exist. This is because objects are stored with a Key (filename) that includes the full path of the object. So, the above object actually has a Key (filename) of:
folder1/folder2/foo.txt
However, to make things easier for humans, the Amazon S3 management console makes it appear as though there are folders. In S3, these are called Common Prefixes rather than folders.
So, when you make an API call to list the contents of the bucket while specifying a Prefix, it simply says "List all objects whose Key starts with this string".
Your listing doesn't show any folders because they don't actually exist.
Now, just to contradict myself, it actually is possible to create a folder (eg by clicking Create folder in the management console). This actually creates a zero-length object with the same name as the folder. The folder will then appear in listings because it is actually listing the zero-length object rather than the folder.
This is probably why Item1/Item2/ appears in your listing, but Item1/Item2/Item3 does not. Somebody, at some stage, must have "created a folder" called Item1/Item2/, which actually created a zero-length object with that Key.
I have about 8K folders in an S3 bucket. Some of them are "empty" (does not have objects with its name prefix) and some are "not empty".
How I can programmatically detect such "empty" folder in the bucket and remove it.
Yes, I know there is no concept of a folder in a bucket - it just names.
An empty folder in the context of S3 is a zero-sized S3 object whose key ends with your folder separator, typically /, for example images/cats/.
If the applications that use this S3 bucket don't strictly need these folder objects but instead can infer the presence of a folder structure from the presence of file objects e.g. infer the folder images/dogs/ when they see the file images/dogs/terrier.png, then one solution to remove all empty folders would be to simply enumerate all objects that end in / and then delete all of those that are zero-sized. That would remove all folder objects.
If the applications do need these folder objects to remain for non-empty folders, then you'd do something different. For example, enumerate all S3 objects in the bucket, pull out those that represent folders (zero-sized, ending in /) and then see if that same prefix is present in any other, non-folder object.
Also, if you find that enumerating the entire bucket's contents becomes problematic (for example, if you have millions of objects) then you might consider using an S3 Inventory report to drive your process.
I am moving a largish number of jpgs (several hundred thousand) from a static filesystem to amazon s3.
On the old filesytem, I grouped files into subfolders to keep the total number of files / folder manageable.
For example, a file
4aca29c7c0a76c1cbaad40b2693e6bef.jpg
would be saved to:
/4a/ca/29/4aca29c7c0a76c1cbaad40b2693e6bef.jpg
From what I understand, s3 doesn't respect hierarchial namespaces. So if I were to use 'folders' on s3, the object, including the /'s, would really just be in a flat namesapce.
Still, according to the docs, amazon recommends mimicking a structured filesytem when working with s3.
So I am wondering: Is there anything to be gained using the above folder structure to organize files on s3? Or in this case am I better off just adding the files to s3 without any kind of 'folder' structure.
Performance is not impacted by the use (or non-use) of folders.
Some systems can use folders for easier navigation of the files. For example, Amazon Athena can scan specific sub-directories when querying data rather than having to read every file.
If your bucket is being used for one specific purpose, there is no reason to use folders. However, if it contains different types of data, then you might consider at least a top-level set of folders to keep data separated.
Another potential reason for using folders is for security. A bucket policy can grant access to buckets based upon a prefix (which is a folder name). However, this is likely not relevant for your use-case.
Using "folders" has no performance impact on S3, either way. It doesn't make it faster, and it doesn't make it slower.
The value of delimiting your object keys with / is in organization, both machine-friendly and human-friendly.
If you're trolling through a bucket in the console, troubleshooting, those meaningless noise-filled keys are a hassle to paginate through, only a few dozen at a time.
The console automatically groups objects into imaginary folders based on the / delimiters, so you can find your object to inspect it (check headers, metadata, etc.) is much easier if you can just click on 4a then ca then 29.
The S3 ListObjects APIs support requesting all the objects with a certain key prefix, but they also support finding all the common prefixes before the next delimiter, so you can send API requests to list prefix 4a/ca/ with delimiter / and it will only return the "folders" one level deep, which it refers to as "common prefixes."
This is less meaningful if your object keys are fully opaque and convey nothing more about the objects, as opposed to using key prefixes like images/ and thumbnails/ and videos/.
Having been an admin and working with S3 for a number of years, and having worked with buckets with key naming schemes designed by different teams, I would definitely recommend using some / delimiters for organization purposes. The buckets without them become more of a hassle to navigate over time.
Note that the console does allow you to "create folders," but this is more of the illusion -- there is no need to actually do this, unless you're loading a bucket manually. When you create a folder in the console, it just creates an empty object with a / at the end.