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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?โ€‹

Breaking and non-breaking changesโ€‹

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 patch number i.e.ย 1-0-0ย ->ย 1-0-1.
  • Breaking - a breaking change is not backwards compatible with historical data and increments the model number i.e.ย 1-0-0ย ->ย 2-0-0.

Different data warehouses handle schema evolution slightly differently. Use the table below as a guide for incrementing the schema version appropriately.

RedshiftSnowflake, BigQuery & Databricks
Add / remove / rename an optional fieldNon-breakingNon-breaking
Add / remove / rename a required fieldBreakingBreaking
Change a field from optional to requiredBreakingBreaking
Change a field from required to optionalBreakingNon-breaking
Change the type of an existing fieldBreakingBreaking
Change the size of an existing fieldNon-breakingNon-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.

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