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Snowflake query spillage occurs when an operation creates more intermediate data than the virtual warehouse can hold in memory. Snowflake writes that data to local disk, and if necessary to remote cloud storage. Execution slows. Credits accrue against the extra runtime. Spillage does not appear as a line item on the bill.
Key takeaways
How spillage turns into Snowflake credits
Most efficient queries complete in memory. Joins, sorts, aggregations, window functions, and large scans can manufacture a working set the warehouse cannot hold. Local spillage adds disk I/O. Remote spillage is slower still. If the spilling query is the last work on the warehouse, it can delay auto-suspend. If it shares a warehouse, it can keep compute up for everyone else or push concurrent queries into queueing.
Useful metrics: bytes_spilled_to_local_storage, bytes_spilled_to_remote_storage, execution time, run frequency, and warehouse size. Query Profile shows which operators produced the intermediate data. The cost explainer is How Query Spillage Increases Snowflake Costs.
Local vs remote
| Local spillage | Remote spillage | |
|---|---|---|
| Where | Disk attached to the warehouse | Cloud storage beyond local capacity |
| Typical impact | Slower than memory | More severe degradation |
| Priority | Watch if recurring | Highest-cost candidate when recurring on large or shared warehouses |
Why detecting spillage is only half the problem
Finding spilled bytes does not assign an owner, choose among rewrite, resize, reroute, or accept, or prove credits fell. Warehouse resizing without that context can raise consumption. That is workload governance: Trace → Assign → Prove → Enforce. The companion argument is detection is only half the problem.
What to do
Prioritize remote, recurring spills on larger or shared warehouses. Reduce the working set: filter earlier, drop unused columns, fix exploding joins, avoid over-wide aggregations. Then match warehouse size to the job and measure total credits. On Anavsan, those rows belong on the Enforcement Desk with an owner — not only in Query Profile.
Related terms
Workload Governance
Why a spill still needs an owner and proof.
Read →Trace → Assign → Prove → Enforce
The loop after Query Profile.
Read →Enforcement Desk
Where recurring spills should land as work.
Read →Spillage and credits (article)
The cost mechanism in more depth.
Read →