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Note: Developers building new applications are strongly encouraged to use the NDB Client Library, which has several benefits compared to this client library, such as automatic entity caching via the Memcache API. If you are currently using the older DB Client Library, read the DB to NDB Migration Guide
Datastore maintains statistics about the data stored for an application, such as how many entities there are of a given kind, or how much space is used by property values of a given type. You can view these statistics in the Google Cloud console, in the Dashboard page.
You can also access these values programmatically within the application by querying for specially named entities using the Datastore API. Each statistic is accessible as an entity whose kind name begins and ends with two underscores. For example, each app has exactly one entity of the kind __Stat_Total__
that represents statistics about all of the entities in Datastore in total. Each statistic entity has the following properties:
count
, the number of items considered by the statistic (a long integer)bytes
, the total size of the items for this statistic (a long integer)timestamp
, the time of the most recent update to the statistic (a date-time value)Some statistic kinds also have additional properties, listed below.
A Python application can use model classes provided by the package google.appengine.ext.db.stats
to access statistic entities.
from google.appengine.ext.db import stats
global_stat = stats.GlobalStat.all().get()
print 'Total bytes stored: %d' % global_stat.bytes
print 'Total entities stored: %d' % global_stat.count
When the statistics system creates new statistic entities, it does not delete the old ones right away. The best way to get a consistent view of the statistics is to query for the GlobalStat
entity with the most recent timestamp
, then use that timestamp value as a filter when fetching other statistic entities.
The statistic entities are included in the calculated statistic values. Statistic entities take up space relative to the number of unique kinds and property names used by the application.
The statistics system will also create statistics specific to each namespace Note that if an application does not use Datastore namespaces then namespace specific statistics will not be created. Namespace specific stats are found in the namespace that they're specific to. The kind names for namespace specific stats are prefixed with __Stat_Ns_
and have the same corresponding suffix as application wide statistics kinds.
Applications with thousands of namespaces, kinds, or property names require a very large number of statistics entities. To keep the overhead of storing and updating the statistics reasonable, Datastore progressively drops statistics entities, in the following order:
__Stat_Ns_PropertyName_Kind__
, __Stat_Ns_PropertyType_PropertyName_Kind__
__Stat_PropertyName_Kind__
, __Stat_PropertyType_PropertyName_Kind__
__Stat_Ns_Kind__
, __Stat_Ns_Kind_IsRootEntity__
, __Stat_Ns_Kind_NotRootEntity__
, __Stat_Ns_PropertyType_Kind__
__Stat_Kind__
, __Stat_Kind_IsRootEntity__
, __Stat_Kind_NotRootEntity__
, __Stat_PropertyType_Kind__
__Stat_Namespace__
, __Stat_Ns_Kind_CompositeIndex__
, __Stat_Ns_PropertyType__
, __Stat_Ns_Total__
The summary statistics entities (__Stat_Kind_CompositeIndex__
, __Stat_PropertyType__
, __Stat_Total__
) are never dropped.
The complete list of available statistics is as follows:
Statistic Stat Entity Kind Description all entities__Stat_Total__
GlobalStat
__Stat_Ns_Total__
NamespaceGlobalStat
All entities. Additional properties:
• entity_bytes
: The storage in the entities table measured in bytes.
builtin_index_bytes
: The storage in built-in index entries measured in bytes.
builtin_index_count
: the count of built-in index entries.
composite_index_bytes
: The storage in composite index entries measured in bytes.
composite_index_count
: The count of composite index entries. all entities in a namespace __Stat_Namespace__
NamespaceStat
__Stat_Namespace__
entities are created for each namespace encountered and are only found in the empty string namespace. All entities in a namespace.
• subject_namespace
, the namespace represented (a string)
entity_bytes
: The storage in the entities table measured in bytes.
builtin_index_bytes
: The storage in built-in index entries measured in bytes.
builtin_index_count
: the count of built-in index entries.
composite_index_bytes
: The storage in composite index entries measured in bytes.
composite_index_count
: The count of composite index entries. all entries in application defined indexes __Stat_Kind_CompositeIndex__
__Stat_Ns_Kind_CompositeIndex__
Python class: KindStat
• index_id
, the index id.
kind_name
, the name of the kind represented (a string) entities of a kind __Stat_Kind__
KindStat
__Stat_Ns_Kind__
NamespaceKindStat
Entities of a kind; one stat entity for each kind of entity stored. Additional properties:
• kind_name
, the name of the kind represented (a string)
entity_bytes
: The storage in the entities table measured in bytes.
builtin_index_bytes
: The storage in built-in index entries measured in bytes.
builtin_index_count
: the count of built-in index entries.
composite_index_bytes
: The storage in composite index entries measured in bytes.
composite_index_count
: The count of composite index entries. root entities of a kind __Stat_Kind_IsRootEntity__
KindRootEntityStat
__Stat_Ns_Kind_IsRootEntity__
NamespaceKindRootEntityStat
Entities of a kind that are entity group root entities (have no ancestor parent); one stat entity for each kind of entity stored. Additional properties:
• kind_name
, the name of the kind represented (a string)
entity_bytes
: The storage in the entities table measured in bytes. non-root entities of a kind __Stat_Kind_NotRootEntity__
KindNotRootEntityStat
__Stat_Ns_Kind_NotRootEntity__
NamespaceKindNotRootEntityStat
Entities of a kind that are not entity group root entities (have an ancestor parent); one stat entity for each kind of entity stored. Additional properties:
• kind_name
, the name of the kind represented (a string)
entity_bytes
: The storage in the entities table measured in bytes. properties of a type __Stat_PropertyType__
PropertyTypeStat
__Stat_Ns_PropertyType__
NamespacePropertyTypeStat
Properties of a value type across all entities; one stat entity per value type. Additional properties:
• property_type
, the name of the value type (a string)
entity_bytes
: The storage in the entities table measured in bytes.
builtin_index_bytes
: The storage in built-in index entries measured in bytes.
builtin_index_count
: the count of built-in index entries. properties of a type per kind __Stat_PropertyType_Kind__
KindPropertyTypeStat
__Stat_Ns_PropertyType_Kind__
NamespaceKindPropertyTypeStat
Properties of a value type across entities of a given kind; one stat entity per combination of property type and kind. Additional properties:
• property_type
, the name of the value type (a string)
kind_name
, the name of the kind represented (a string)
entity_bytes
: The storage in the entities table measured in bytes.
builtin_index_bytes
: The storage in the built-in index measured in bytes.
builtin_index_count
: the count of built-in index entries. properties with a name __Stat_PropertyName_Kind__
KindPropertyNameStat
__Stat_Ns_PropertyName_Kind__
NamespaceKindPropertyNameStat
Properties with a given name across entities of a given kind; one stat entity per combination of unique property name and kind. Additional properties:
• property_name
, the name of the property (a string)
kind_name
, the name of the kind represented (a string)
entity_bytes
: The storage in the entities table measured in bytes.
builtin_index_bytes
: The storage in built-in index entries measured in bytes.
builtin_index_count
: the count of built-in index entries. properties of a type and with a name __Stat_PropertyType_PropertyName_Kind__
KindPropertyNamePropertyTypeStat
__Stat_Ns_PropertyType_PropertyName_Kind__
NamespaceKindPropertyNamePropertyTypeStat
Properties with a given name and of a given value type across entities of a given kind; one stat entity per combination of property name, value type and kind that exists in Datastore. Additional properties:
• property_type
, the name of the value type (a string)
property_name
, the name of the property (a string)
kind_name
, the name of the kind represented (a string)
entity_bytes
: The storage in the entities table measured in bytes.
builtin_index_bytes
: The storage in built-in index entries measured in bytes.
builtin_index_count
: the count of built-in index entries.
Some statistics refer to Datastore property value types by name, as strings. These names are as follows:
"Blob"
"BlobKey"
"Boolean"
"Category"
"Date/Time"
"Email"
"Float"
"GeoPt"
"IM"
"Integer"
"Key"
"Link"
"NULL"
"PhoneNumber"
"PostalAddress"
"Rating"
"ShortBlob"
"String"
"Text"
"User"
__Stat_Namespace__
entities contain the same information found in __Stat_Ns_Total__
records. __Stat_Namespace__
entities are stored in the empty namespace and contain a subject_namespace
field describing the namespace to which they belong. __Stat_Ns_Total__
records are stored in the namespace to which they refer, and thus do not contain a subject_namespace
field. Hence, a query on kind __Stat_Namespace__
(from the empty string namespace) ordered descending by bytes
will list the namespaces that consume the largest storage first. Because queries across namespaces are not possible, any query for __Stat_Ns_Total__
entities will only ever produce at most a single record.
Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.
Last updated 2025-08-07 UTC.
[[["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."],[[["Developers should strongly consider using the NDB Client Library instead of the older DB Client Library due to benefits like automatic entity caching."],["Datastore maintains and provides statistics about stored data, including entity counts and storage usage, viewable in the Google Cloud console or accessible programmatically."],["Statistics are represented as entities with names starting and ending with double underscores, containing properties like `count`, `bytes`, and `timestamp`."],["Statistic entities are progressively dropped in specific orders to manage overhead, starting with per-namespace, per-kind, and per-property statistics."],["The complete list of available statistics includes categories like total entities, entities per namespace, and properties by type, with each statistic having an entity kind name, python class, and unique properties."]]],[]]
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