Troubleshooting¶

Alation Cloud Service Applies to Alation Cloud Service instances of Alation

Customer Managed Applies to customer-managed instances of Alation

For information about logs, refer to Troubleshoot OCF Connectors.

Query Failures Due to SQL Dialect Mismatch¶

BigQuery supports two SQL dialects:

GoogleSQL (QueryDialect=SQL)

LegacySQL (QueryDialect=BIG_QUERY)

Query failures can occur when a query is written in one dialect but executed using another.

The dialect is not explicitly specified in the request.
The query uses syntax or functions specific to LegacySQL.
The Compose URI does not include the appropriate QueryDialect setting.

Note

By default, the JDBC driver uses GoogleSQL.

LegacySQL syntax (will fail if executed with GoogleSQL / QueryDialect=SQL):
```
SELECT * FROM [project:dataset.table]
```
GoogleSQL equivalent:
```
SELECT * FROM `project.dataset.table`
```

Verify the Dialect Compatibility - Review the query syntax to ensure it matches the dialect used. - Look for LegacySQL specific features. For example, square brackets [...], TABLE_DATE_RANGE.

Specify the Dialect Explicitly - In Compose JDBC URI, set the dialect using the QueryDialect={dialect} parameter:

QueryDialect=BIG_QUERY    # for LegacySQL
QueryDialect=SQL          # for GoogleSQL (default for most tools)

For more information on SQL dialect differences and how to migrate LegacySQL queries to GoogleSQL,