# Exploring Blob storage in CrateDB **URL:** \ **Category:** Tutorials\ **Tags:** sql, fundamentals, getting-started\ **Created:** [December 13, 2021, 10:13am UTC](https://community.cratedb.com/t/exploring-blob-storage-in-cratedb/938 "2021-12-13T10:13:00Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![jayeff](https://sea2.discourse-cdn.com/flex020/user_avatar/community.cratedb.com/jayeff/32/271_2.png) [@jayeff](https://community.cratedb.com/u/jayeff)\ **Post date:** [December 13, 2021, 10:13am UTC](https://community.cratedb.com/t/exploring-blob-storage-in-cratedb/938/1 "2021-12-13T10:13:00Z")
CrateDB can be used to store binary large objects (Blobs). This allows you to store binary data (e.g. product photos, PDFs, etc) in a table which will be automatically sharded and replicated across your cluster. In this tutorial, we will work with a simple chat engine. We want to store the profile pictures for the users in CrateDB. # Create blob table First, we will create a blob table, which we use to store our photos: ```auto CREATE BLOB TABLE profile_pictures; ``` # Insert pictures into the blob table Even though we are using a table you cannot use typical SQL queries (like INSERT INTO) to work with a blob table. For inserting data we need to follow the steps below. Before we can insert a user profile picture (or any other binary file) into the profile\_pictures table we need to calculate the [SHA-1](https://en.wikipedia.org/wiki/SHA-1) checksum for our file. For this you can either use the shasum command-line tool: ```bash $> shasum /path/to/your/file.jpg 5883fb9412357b79540e9cb983cf8a323cd1b611 /path/to/your/file.jpg ``` Or alternatively, use your programming language of choice. In the following example we are showcasing how to calculate the SHA-1 checksum with Python: ```bash $> python3 -c 'import hashlib;print(hashlib.sha1(open("/path/to/your/file.jpg","rb").read()).hexdigest())'; 5883fb9412357b79540e9cb983cf8a323cd1b611 ``` We need this SHA-1 checksum for the upload step. We can use curl to upload the file into CrateDB but any other way to submit an HTTP PUT request will do as well: ```bash $> curl -isSX PUT '127.0.0.1:4200/_blobs/profile_pictures/5883fb9412357b79540e9cb983cf8a323cd1b611' --data-binary @/path/to/your/file.jpg HTTP/1.1 201 Created content-length: 0 ``` The four variable parts of this command are: - the URL to your CrateDB server (“127.0.0.1:4200”) - the table name (“profile\_pictures”) - the SHA-1 checksum as calculated for your file (in this example “5883fb9412357b79540e9cb983cf8a323cd1b611”) - the filepath (“/path/to/your/file.jpg”) These need to be replaced to match your values. When the upload was successful you will see the output `201 Created` in your console. # Querying your profile pictures You can use the following query to access some metadata for your blobs: ```auto SELECT * FROM blob.profile_pictures; ``` This query will return the digest (this is the SHA-1 checksum we calculated before) of all your uploaded files and the last modified date. To access your file use the same URL you used above for your PUT request (“'127.0.0.1:4200/\_blobs/profile\_pictures/5883fb9412357b79540e9cb983cf8a323cd1b611”). For example, you could use this URL directly in an `` HTML tag. # Updating an existing blob It’s not possible to update an existing blob. If you want to replace a profile picture you would instead upload the new picture and delete the old entry. To upload the new file follow the steps above with calculating the new SHA-1 checksum and uploading the file with HTTP PUT. The old file can be deleted with the following HTTP DELETE request (again replace URL, table name, and SHA-1 checksum): ```bash curl -isS -XDELETE '127.0.0.1:4200/_blobs/profile_pictures/5883fb9412357b79540e9cb983cf8a323cd1b611' ``` # Additional Reading It’s worth checking out the [documentation for blobs](https://crate.io/docs/crate/reference/en/latest/general/blobs.html) for additional information we did not cover in this tutorial.