This page discusses the metadata fields that are stored along with buckets
in Cloud Storage.
Introduction
Cloud Storage buckets have metadata associated with them. Metadata
identifies properties of the bucket and specifies how the bucket should be
handled when it's accessed.
Metadata is stored as key: value pairs, where the value can take a variety
of forms, including strings, arrays, or even nested key:value pairs. For
example, the bucket name is a string, while a bucket Object Lifecycle Management
configuration is an array of rules in which each rule contains several child
key: value pairs.
The mutability of metadata varies:
Some you can only view.
Some you can only set when the bucket is first created, and cannot edit
or remove.
Some you can add and edit, but not remove.
Some you can add, edit, and remove at any time.
Non-editable metadata
The following metadata is set during bucket creation, and cannot be edited or
removed:
A bucket's generation number uniquely identifies the version of the
bucket even if more than one version of a bucket share the same name.
A bucket's generation value never changes.
There is no guarantee that generation numbers increase for successive
versions, only that each new version has a unique generation number.
There is no relationship between generation numbers of unrelated buckets.
Metageneration number
A bucket's metageneration number uniquely identifies the metadata state of
the bucket. The metageneration number is 1 at the time of bucket
creation and increases each time you modify the bucket's metadata.
Editable metadata
Editable bucket metadata is metadata whose values you can typically modify at
any time. In some cases, such as the bucket being subject to an
organization policy constraint, there are restrictions on modifying
certain metadata values.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-07 UTC."],[],[],null,["# Bucket metadata\n\n[Get metadata](/storage/docs/getting-bucket-metadata)\n\n[Get bucket size](/storage/docs/getting-bucket-size)\n\nThis page discusses the metadata fields that are stored along with [buckets](/storage/docs/buckets)\nin Cloud Storage.\n\nIntroduction\n------------\n\nCloud Storage buckets have *metadata* associated with them. Metadata\nidentifies properties of the bucket and specifies how the bucket should be\nhandled when it's accessed.\n\nMetadata is stored as `key: value` pairs, where the `value` can take a variety\nof forms, including strings, arrays, or even nested `key:value` pairs. For\nexample, the bucket name is a string, while a bucket Object Lifecycle Management\nconfiguration is an array of rules in which each rule contains several child\n`key: value` pairs.\n\nThe mutability of metadata varies:\n\n- Some you can only view.\n\n- Some you can only set when the bucket is first [created](/storage/docs/creating-buckets), and cannot edit\n or remove.\n\n- Some you can add and edit, but not remove.\n\n- Some you can add, edit, and remove at any time.\n\nNon-editable metadata\n---------------------\n\nThe following metadata is set during bucket creation, and cannot be edited or\nremoved:\n\n- [Bucket name](/storage/docs/buckets#naming)\n\n- The [project](/storage/docs/projects) the bucket is a part of\n\n- Generation number\n\n - A bucket's generation number uniquely identifies the version of the\n bucket even if more than one version of a bucket share the same name.\n\n - A bucket's generation value never changes.\n\n - There is no guarantee that generation numbers increase for successive\n versions, only that each new version has a unique generation number.\n\n - There is no relationship between generation numbers of unrelated buckets.\n\n- Metageneration number\n\n - A bucket's metageneration number uniquely identifies the metadata state of the bucket. The metageneration number is `1` at the time of bucket creation and increases each time you modify the bucket's metadata.\n\nEditable metadata\n-----------------\n\nEditable bucket metadata is metadata whose values you can typically modify at\nany time. In some cases, such as the bucket being subject to an\n[organization policy constraint](/storage/docs/org-policy-constraints), there are restrictions on modifying\ncertain metadata values.\n\n^1^ This metadata cannot be viewed or managed using the XML API.\n\n^2^ You can use the XML API to set this metadata during bucket\ncreation, but not to view or manage this metadata.\n\nWhat's next\n-----------\n\n- Learn how to [view bucket metadata](/storage/docs/getting-bucket-metadata).\n- Read more about [object metadata](/storage/docs/metadata)."]]