Understand the RudderStack schema for warehouse destinations.
14 minute read
When sending your events to a data warehouse via RudderStack, you don’t need to define a schema for your event data. RudderStack automatically does that for you by following a predefined warehouse schema.
This guide details the structure of this warehouse schema and the columns created in various tables based on different event types.
Schema
RudderStack uses the source name (written in snake case, for example, source_name) to create a schema in your data warehouse.
RudderStack treats the warehouse schema as the source of truth. If you manually make any changes to the schema, for example, add or modify a column, or update a column’s data type, RudderStack honors the modified schema and sends the data to the warehouse accordingly.
The following tables are created in your data warehouse for each RudderStack source connected to it:
Name
Description
<source_name>.identifies
Every identify call sent from the source is stored in this table, including the properties passed as traits.
<source_name>.users
RudderStack stores all unique users in this table. Only the latest properties used to identify a user are stored, including the latest anonymousId.
<source_name>.tracks
Every track call sent from the source is stored in this table. It does not include the custom properties present in the event’s properties but has some standard properties listed in the Standard properties section below such as received_at, anonymous_id, context_device_info, etc.
<source_name>.<track_event_name>
All the standard properties and the custom properties for a track event are stored in this table. The table name is the event name specified in the track call, e.g., Added to Cart.
<source_name>.pages
Every page call sent from the source is stored in this table, including the associated event properties.
<source_name>.screens
Every screen call sent from the source is stored in this table, including the associated event properties.
<source_name>.groups
Every group call sent from the source is stored in this table, including the associated event properties.
<source_name>.aliases
Every alias call sent from the source is stored in this table, including the associated event properties.
The following image highlights the warehouse schema and the relationships between the tables:
All the event properties are stored as top-level columns in the corresponding table. The nested properties are prefixed with the parent key. For example, an event with properties { product: { name: iPhone, version: 11 }}
will result in RudderStack creating the columns product_name and product_version.
Standard RudderStack properties
RudderStack sets the following standard properties on all above-mentioned tables:
Name
Description
anonymous_id
The user’s anonymous ID.
context_<prop>
The context properties set in the event.
id
The unique message ID of the event. Not applicable for the users table, as the field be set to the user ID in that case.
sent_at
Captures the time when the event was sent from the client to RudderStack. Conforms to the ISO 8601 date format yyyy-MM-ddTHH:mm:ss.SSSZ.
received_at
Timestamp registered by RudderStack when the event was ingested (received). Conforms to the ISO 8601 date format yyyy-MM-ddTHH:mm:ss.SSSZ.
original_timestamp
Timestamp registered by the RudderStack SDK when the event call was invoked (event was emitted in the SDK).
timestamp
If not already specified in the payload, RudderStack calculates this field to account for the client clock skew. The formula used is timestamp = received_at - (sent_at -original_timestamp). Make sure it conforms to the ISO 8601 date format yyyy-MM-ddTHH:mm:ss.SSSZ. For e.g., 2022-02-01T19:14:18.381Z.
event_text
The name of the event mapped from the event key in the track event payload.
event
The name of the event table in case of the track calls.
RudderStack automatically converts the property names from camel case to snake case. For more information on the properties captured at the API level, refer to the RudderStack Event Specification guide.
RudderStack reserves the above-mentioned standard properties. In case of any conflict, RudderStack automatically discards the properties set by the user.
RudderStack drops any non-standard properties declared at the top level of an event.
Identify
For every Identify call, RudderStack creates a record in the identifies table and upserts the records in the users table based on the userId.
In case of Google BigQuery, you can use the views created over the tables to query for unique users in the dataset. Refer to the BigQuery documentation for more details.
Added by RudderStack for debugging purposes. Can be ignored for analytics.
Note that:
The users table contains the properties from the latest identify call made for an user. It only has the id column (same as user_id in the identifies table) and does not have the anonymous_id column.
To obtain a user’s anonymous_id, you can query the identifies table by grouping on the user_id column.
Skip sending data to users table
You can skip sending the event data to the users table by setting the skipUsersTable option to true.
For example, you can add the following transformation that adds an integrations object to your event and skips sending the event data to the users table:
Use the following names for your preferred warehouse destination in the above snippet:
Warehouse destination
Name
PostgreSQL
POSTGRES
Snowflake
SNOWFLAKE
Google BigQuery
BQ
Microsoft SQL Server
MSSQL
Databricks Delta Lake
DELTALAKE
ClickHouse
CLICKHOUSE
Amazon S3 Data Lake
S3_DATALAKE
Google Cloud Storage Data Lake
GCS_DATALAKE
Azure Data Lake
AZURE_DATALAKE
Amazon Redshift
RS
Azure Synapse
AZURE_SYNAPSE
Track
For every track call, RudderStack creates a record in the tracks and <event_name> table. In addition to the tracks table columns, the <event_name> table includes the properties set by the user via the properties key.
You can also skip sending the event data to tracks table by setting the skipTracksTable option to true.
A sample track event named Add to Cart is shown below:
rudderanalytics.track("Add to Cart",{price:5,currency:"USD",product_id:"P12345",product_name:"N95 Mask",},{context:{ip:"0.0.0.0",},anonymousId:"59b703e3-467a-4a1d-9fe6-da27ed319619",})
The corresponding schemas created for the tracks and add_to_cart tables are as shown:
Table: tracks
The tracks table stores contextual information like ip, device, etc. which helps you to perform analytics-related operations on top of it.
Column
Type
Example value
Description
id
String
4d5a7681-e596-40ea-a81c-bf69f9b297f1
Unique messageId generated by RudderStack.
anonymous_id
String
59b703e3-467a-4a1d-9fe6-da27ed319619
The anonymous ID of the user.
received_at
Timestamp
2020-04-26 07:00:45.558
Timestamp registered by RudderStack when the event was ingested (received).
sent_at
Timestamp
2020-04-26 07:00:45.124
Timestamp set by the SDK when the event was sent from the client to RudderStack.
original_timestamp
Timestamp
2020-04-26 07:00:43.400
Timestamp registered by the SDK when the event was invoked (event was emitted in the SDK).
timestamp
Timestamp
2020-04-26 07:00:44.834
Calculated by RudderStack to account for the client clock skew. The formula used is: timestamp = received_at - (sent_at - original_timestamp).
Added by RudderStack for debugging purposes. Can be ignored for analytics.
Clock skew considerations
RudderStack considers the time at its end to be absolute and assumes any difference on the client-side. Thus, the client clock skew is relative.
If not specified in the payload explicitly, RudderStack calculates timestamp based on originalTimestamp and sentAt to account for the client clock skew.
As mentioned in the above section:
Field
Description
original_timestamp
Records the actual time when the event occurred at the source.
sent_at
Captures the time when the event was sent from the client to RudderStack.
received_at
The timestamp when the event is received(ingested) by the RudderStack server.
timestamp
Calculated by RudderStack to account for the client clock skew, IF the user does not explicitly specify it in the payload.
sent_at > original_timestamp is always true. However, timestamp can be more or less than the original_timestamp. Refer to the cases below for more details.
Case 1: original_timestamp < received_at
The following table demonstrates an example of original_timestamp < received_at(when the client-side time is less than the time registered by RudderStack):
In this case, timestamp will be greater than original_timestamp.
Case 2: original_timestamp > received_at
The following table demonstrates an example of original_timestamp > received_at(when the client-side time is more than the time registered by RudderStack):
In this case, timestamp will be less than original_timestamp.
Accepted timestamp formats
RudderStack recognizes only the following subsets of the ISO 8601 timestamp format:
2019-09-26
2009-05-19 14:39:22
2019-09-26T06:30:12.984Z
2020-02-11 04:56:55.175116
2019-09-26T06:30:12.984+0530
2019-09-26T06:30:12.984+05:30
RudderStack does not recognize any other timestamp format apart from the ones mentioned above.
Reserved keywords
There are some limitations when it comes to using the reserved words in a schema, table, or column names. If these words are used in the event names, traits or properties, RudderStack automatically prefixes an underscore(_) when creating the tables or columns for them in your schema.
Integers are not allowed at the start of the schema or table name. Such schema, column, or table names will be prefixed with an underscore. For e.g., 25dollarpurchase will be changed to _25dollarpurchase.
The following table lists the warehouse-specific documentation references for reserved keywords:
Once RudderStack recognizes and sets a data type for a table column, it will not accept any values for the column that cannot be cast to the specified data type.
The values which cannot be cast are set as NULL in the table and stored in the rudder_discards table.
The rudder_discards table schema is shown below:
Column
Description
row_id
The unique identifier (ID) associated with each record in the table. This corresponds to the event’s messageId for all tables except for users table, where it is userId.
table_name
The table name where the full record is inserted, like tracks, add_to_cart, identifies , etc.
column_name
The column name corresponding to the property to be added.
column_value
The discarded column value that caused the data type mismatch.
row_id is the column which users can use to join with original table and update it as required. As mentioned in the above table, it is set to messageId for all tables except the users table, where it corresponds to userId.
The following snippet highlights a sample event whose properties are discarded due to a data type mismatch:
// intial track call using the RudderStack JavaScript SDK
rudderanalytics.track("Add to Cart",{price:5,// originally a int value
currency:"USD",product_id:"P12345",product_name:"N95 Mask",added_at:"2020-05-19 14:39:22",// originally a datetime value
},{context:{ip:"0.0.0.0",},anonymousId:"59b703e3-467a-4a1d-9fe6-da27ed319619",})// subsequent track call using the RudderStack JavaScript SDK
rudderanalytics.track("Add to Cart",{price:"NA",// sent as a string in latest event
currency:"USD",product_id:789,// sent as int but can be casted into original string data type
product_name:"N95 Mask",added_at:"05/25/2020",// sent as invalid datetime value
},{context:{ip:"0.0.0.0",},anonymousId:"59b703e3-467a-4a1d-9fe6-da27ed319619",})
The subsequent records created in the rudder_discards table for the discarded properties from the second event shown in the following table:
Row ID
Table name
Column name
Column value
a21620be-6502-44d6-941d-78209a386d58
add_to_cart
price
NA
1e42b2b3-8b6a-49da-8502-83a8db334375
add_to_cart
added_at
05/25/2020
FAQ
Can I change the namespace (schema name) of my data warehouse in RudderStack?
Yes, you can. Although the default namespace will be the source name, RudderStack gives you the option to explicitly set the namespace while setting up your warehouse destination. For more information, refer to the warehouse-specific destination settings for configuring the namespace in the RudderStack dashboard.
Why am I not able to see the properties added at the top level of an event in warehouse destination?
RudderStack drops any non-standard properties (properties apart from the standard properties) declared at the top level of an event. However, you can add such properties in the context or properties section of the event payload.
For a more comprehensive FAQ list, refer to the Warehouse FAQ guide.
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