@kapa.ai , this part takes too long, any idea why ? 2026-03-31 160442 destination INFO main i.a.i.d.b.t.BigQueryDestinationHandler(existingSchemaMatchesStreamConfig):271 Alter Table Report [] [] []; Clustering true; Partitioning true

The log line you're seeing:

Alter Table Report [] [] []; Clustering true; Partitioning true

indicates that the BigQuery destination handler is checking whether the existing table schema matches the expected stream configuration (including clustering and partitioning). This appears as part of the destination setup/migration phase before data is actually synced. [sync hangs issue] However, the knowledge sources do not contain enough specific information to definitively explain why this particular step is taking too long in your case. What I can share based on the available information: 1. This is a known area of concern: Similar slowness has been reported in destination-bigquery, particularly around the setup and typing/deduplication phases. [BigQuery sync slow] 2. Possible contributing factors mentioned in related issues: ◦ Long-running operations can cause authentication token expiry (e.g., "invalid euc header" errors during resumable uploads), which may cause retries and stalls. [sync stuck in retry] ◦ Limited parallelism in the BigQuery bulk loader (e.g., only 2 compression workers and 1 concurrent BigQuery LOAD job by default) can bottleneck throughput. [slow first load] 1. What this log line itself means: The

[]

values suggest no schema alterations were needed (no columns added, dropped, or changed), and clustering/partitioning are confirmed as

true

. So the schema check itself passed — the delay may be in what comes before or after this step. To better diagnose the issue, I'd recommend: • Checking the logs before and after this line to identify where time is actually being spent. • Looking for retry loops or authentication errors in the surrounding log context. The knowledge sources don't provide a definitive root cause or fix for this specific slowness, so I'd suggest opening or referencing the related GitHub issues for further investigation. 👍 0 button 👎 0 button ℹ️ Tip: Mention @kapa.ai in the thread for follow-ups or DM the app for 1-to-1 help.