Versioning Data Structures using Iglu
info
This documentation only applies to Snowplow Open Source. See the feature comparison page for more information about the different Snowplow offerings.
How do I version?
Breaking and non-breaking changes
When evolving your schema and uploading it to your Iglu Server, you will need to choose how to increment its version.
There are two kinds of schema changes:
- Non-breaking - a non-breaking change is backward compatible with historical data and increments the
patchnumber i.e.1-0-0->1-0-1. - Breaking - a breaking change is not backwards compatible with historical data and increments the
modelnumber i.e.1-0-0->2-0-0.
Different data warehouses handle schema evolution slightly differently. Use the table below as a guide for incrementing the schema version appropriately.
| Redshift | Snowflake, BigQuery & Databricks | |
| Add / remove / rename an optional field | Non-breaking | Non-breaking |
| Add / remove / rename a required field | Breaking | Breaking |
| Change a field from optional to required | Breaking | Breaking |
| Change a field from required to optional | Breaking | Non-breaking |
| Change the type of an existing field | Breaking | Breaking |
| Change the size of an existing field | Non-breaking | Non-breaking |
caution
In Redshift and Databricks, changing size may also mean type change; e.g. changing the maximum integer from 30000 to 100000. See our documentation on how schemas translate to database types.