Snowflake Post

Capabilities

Use the Important Capabilities table above as the source of truth for supported features and whether additional configuration is required.

Snowflake Shares

If you are using Snowflake Shares to share data across different Snowflake accounts, and you have set up DataHub recipes for ingesting metadata from all these accounts, you may end up having multiple similar dataset entities corresponding to virtual versions of the same table in different Snowflake accounts. The DataHub Snowflake connector can automatically link such tables together through Siblings and Lineage relationships if the user provides information necessary to establish the relationship using the shares configuration in the recipe.

Example

• Snowflake account account1 (ingested as platform_instance instance1) owns a database db1. A share X is created in account1 that includes database db1 along with schemas and tables inside it.
• Now, X is shared with Snowflake account account2 (ingested as platform_instance instance2). A database db1_from_X is created from inbound share X in account2. In this case, all tables and views included in share X will also be present in instance2.db1_from_X.
• This can be represented in shares configuration section as
  yamlCopy

  shares:
    X: # name of the share
      database: db1
      platform_instance: instance1
      consumers: # list of all databases created from share X
        - database: db1_from_X
          platform_instance: instance2
  

• If share X is shared with more Snowflake accounts and a database is created from share X in those accounts, then additional entries need to be added to the consumers list for share X, one per Snowflake account. The same shares config can then be copied across recipes for all accounts.

Lineage and Usage

DataHub supports two strategies for extracting lineage and usage information from Snowflake:

New Strategy (Default - use_queries_v2: true)

The default and recommended approach uses an optimized query extraction method that:

• Better Performance: Fetches query logs in a single optimized query instead of multiple separate queries
• Enhanced Features:
  • Query entities generation (include_queries)
  • Query popularity statistics (include_query_usage_statistics)
  • User filtering with patterns (pushdown_deny_usernames, pushdown_allow_usernames)
  • Database pattern pushdown for performance (push_down_database_pattern_access_history)
  • Query deduplication strategies (query_dedup_strategy)

Legacy Strategy (use_queries_v2: false)

The older approach that will be deprecated in future versions:

• Uses separate extractors for lineage and usage
• Less performant due to multiple query executions
• Limited feature support compared to the new strategy

Both strategies access the same Snowflake system tables (account_usage.query_history, account_usage.access_history), but the new strategy provides significant performance improvements and additional functionality.

Metadata Pattern Pushdown

When ingesting metadata from large Snowflake environments, you can improve performance by pushing down pattern filters directly to Snowflake SQL queries using the push_down_metadata_patterns configuration option.

Note: This option applies only to metadata extraction queries (information_schema.databases, schemata, tables, views). For pushing down filters on lineage/usage queries (account_usage.access_history), use push_down_database_pattern_access_history instead. These two options are independent and target completely separate query paths.

Configuration

source:
  type: snowflake
  config:
    # Enable pattern pushdown for improved performance
    push_down_metadata_patterns: true

    # Your existing patterns - MUST follow Snowflake RLIKE syntax
    database_pattern:
      allow:
        - "PROD_.*" # Matches databases starting with PROD_
        - "ANALYTICS.*" # Matches databases starting with ANALYTICS
      deny:
        - ".*_TEMP$" # Excludes databases ending with _TEMP

    table_pattern:
      allow:
        - ".*" # Allow all tables
      deny:
        - ".*_BACKUP$" # Exclude tables ending with _BACKUP

View Pattern Limitation

By default, Snowflake views are fetched using SHOW VIEWS, which does not support SQL-level filtering. When push_down_metadata_patterns: true, the view_pattern is pushed down only if fetch_views_from_information_schema: true is also set. Otherwise, view filtering falls back to Python's re.match(), even with pushdown enabled.

This means if you write patterns in Snowflake RLIKE syntax (e.g., PROD.* for prefix matching), they will still work correctly with Python filtering since PROD.* is valid in both. However, patterns that rely on RLIKE's full-string matching semantics (e.g., exact match PROD_DB without .*) will behave differently — Python re.match() treats it as a prefix match.

Recommendation: If you enable push_down_metadata_patterns, also enable fetch_views_from_information_schema: true to ensure consistent behavior for view patterns.

Important: Snowflake RLIKE Syntax Differences

When push_down_metadata_patterns: true, patterns are executed in Snowflake using the RLIKE operator instead of Python's re.match(). These have different matching behaviors:

Key difference: Python re.match() anchors at the START only (prefix matching), while Snowflake RLIKE requires a FULL STRING match.

Pattern Conversion Examples

Testing Your Patterns

Before enabling pushdown in production, test your patterns in Snowflake:

-- Test prefix matching
SELECT 'PROD_DB' RLIKE 'PROD';      -- FALSE (needs .*)
SELECT 'PROD_DB' RLIKE 'PROD.*';    -- TRUE

-- Test suffix matching
SELECT 'TABLE_BACKUP_V2' RLIKE '.*_BACKUP';    -- FALSE (needs $)
SELECT 'TABLE_BACKUP' RLIKE '.*_BACKUP$';      -- TRUE

-- Test FQN with escaped dots
SELECT 'PROD_DB.PUBLIC.TABLE' RLIKE 'PROD_DB\\.PUBLIC\\..*';  -- TRUE

Semantic Views

DataHub supports ingestion of Snowflake Semantic Views, which are business-defined views that define metrics, dimensions, and relationships for consistent data modeling and AI-powered analytics.

Configuration

Semantic view ingestion is disabled by default (requires Snowflake Enterprise Edition or above). You can enable it using the following configuration options:

# Enable semantic view ingestion (requires Enterprise Edition)
semantic_views:
  enabled: true # Default: false
  column_lineage: true # Default: false - enable column-level lineage

# Filter semantic views using regex patterns
semantic_view_pattern:
  allow:
    - "ANALYTICS_DB.PUBLIC.*"
    - "SALES_DB.*"
  deny:
    - ".*_INTERNAL"

Features

• Metadata Extraction: Extracts semantic view definitions (YAML), columns, comments, and timestamps
• Lineage Support: Semantic views participate in lineage extraction like regular views
• Tags Support: Tags applied to semantic views are extracted if extract_tags is enabled
• External URLs: Direct links to Snowflake Snowsight UI for semantic views

Requirements

• Semantic views require appropriate Snowflake edition and privileges
• Requires REFERENCES or SELECT privileges on semantic views (they are treated as views in Snowflake's permission model)
• The semantic view definition (SQL DDL) is extracted when available through the GET_DDL function

Limitations

Module behavior is constrained by source APIs, permissions, and metadata exposed by the platform. Refer to capability notes for unsupported or conditional features.

• Some features require specific Snowflake editions or additional privileges. This includes dynamic tables, semantic views, advanced lineage features, and tags.
• Dynamic tables require the monitor privilege for metadata extraction. Without this privilege, dynamic tables will not be visible to DataHub.
• Semantic views require REFERENCES or SELECT privileges for metadata extraction. Without these privileges, semantic views will not be visible to DataHub.
• The underlying Snowflake views that we use to get metadata have a latency of 45 minutes to 3 hours. So we would not be able to get very recent metadata in some cases like queries you ran within that time period etc. This is applicable particularly for lineage, usage and tags (without lineage) extraction.
• If there is any ongoing Snowflake incident, we will not be able to get the metadata until that incident is resolved.
• Lineage extraction, when got directly from Snowflake access history, has some limitations, as documented here, here, and here.

Troubleshooting

If ingestion fails, validate credentials, permissions, connectivity, and scope filters first. Then review ingestion logs for source-specific errors and adjust configuration accordingly.