YSON document

This section contains information about YSON documents.

General information

A YSON document is a Cypress node of the document type designed to store random YSON structures.

Besides a YSON document, you can create and store hierarchical data structures in the form of nodes of the map_node, list_node, string_node, and other types.
YSON documents differ from this method in the following ways:

• Storing data as a document is more compact in terms of memory consumption, since the document node is not a full-fledged Cypress node.
• The document behaves as a whole in terms of Cypress-specific features: locks, owners, the revision, creation_time, modification_time, expiration_time, and other attributes.

You can work with documents using standard commands: get, list, exists, set, and remove, just like with other objects in Cypress.

Requests and modifications within the document are supported. Addressing within the document is performed using the YPath language.

Learn more about the YSON format.

Usage

Create a YSON document:

CLI

yt create document //tmp/my_test_doc
3f08-5b920c-3fe01a5-e0c12642

By default, a YSON entity is stored in the document when it is created. Read a YSON document:

CLI

yt get //tmp/my_test_doc

Specify the initial value of the YSON document when it is created:

CLI

yt create document //tmp/my_test_doc --attributes '{value=hello}'
3f08-6c0ee0-3fe01a5-2c4f6104
yt get //tmp/my_test_doc

"hello"

Write a number to the YSON document and read it:

CLI

yt set //tmp/my_test_doc 123
#
yt get //tmp/my_test_doc
123

Write a complex structure to a YSON document and read it fully or partially:

CLI

yt set //tmp/my_test_doc '{key1=value1;key2={subkey=456}}'
#
yt get //tmp/my_test_doc

{
    "key1" = "value1";
    "key2" = {
        "subkey" = 456;
    };
}
yt get //tmp/my_test_doc/key2
{
    "subkey" = 456;
}

The node will have the document type:

CLI

yt get //tmp/my_test_doc/@type

"document"

Partially change a YSON document:

CLI

yt set //tmp/my_test_doc/key1 newvalue1

Remove a YSON document:

CLI

yt remove //tmp/my_test_doc

Limits

In Cypress, you can create and store hierarchical data structures in another way: in the form of nodes of the map_node, list_node, string_node, and other types.

YSON documents are read and written via the Cypress master server, so they cannot be used as a high-load object database. A reasonable limit is single-digit RPS. Since this data is stored in the master server memory in the form of a tree, choose the amount of data with caution.

Kilobytes can be considered a reasonable limit for a single document. The total volume of all user documents must not exceed single-digit megabytes. Such nodes are usually used to store small pieces of structured metadata, configuration, etc.

System attributes

Besides the attributes inherent to all Cypress nodes, documents have the following additional attributes: