Apply advanced Snowflake debugging with query profiling, spill analysis,
lock contention, and performance deep-dives using ACCOUNT_USAGE views.
Use when standard troubleshooting fails, investigating slow queries,
or diagnosing warehouse performance issues.
Trigger with phrases like "snowflake hard bug", "snowflake slow query debug",
"snowflake query profile", "snowflake spilling", "snowflake deep debug".
Instrucciones de origen · Vista previa de solo lectura
name
snowflake-advanced-troubleshooting
description
Apply advanced Snowflake debugging with query profiling, spill analysis,
lock contention, and performance deep-dives using ACCOUNT_USAGE views.
Use when standard troubleshooting fails, investigating slow queries,
or diagnosing warehouse performance issues.
Trigger with phrases like "snowflake hard bug", "snowflake slow query debug",
"snowflake query profile", "snowflake spilling", "snowflake deep debug".
allowed-tools
Read, Grep, Bash(snowsql:*), Bash(curl:*)
version
1.5.0
license
MIT
author
Jeremy Longshore <jeremy@intentsolutions.io>
tags
["saas","data-warehouse","analytics","snowflake"]
compatibility
Designed for Claude Code
Snowflake Advanced Troubleshooting
Overview
Deep debugging techniques for complex Snowflake issues: query profile analysis, spill detection, lock contention, transaction conflicts, and metadata operation bottlenecks.
Instructions
Step 1: Query Profile Deep Dive
-- Get detailed execution stats for a specific querySELECT*FROMTABLE(GET_QUERY_OPERATOR_STATS('<query_id>'));
-- Key operators to look for:-- TableScan: Check partitions_scanned vs partitions_total-- Sort: Check spilling_to_local_storage, spilling_to_remote_storage-- Join: Check type (broadcast vs hash), probe/build side sizes-- Aggregate: Check if grouping cardinality causes spill-- Identify queries with excessive spillingSELECT query_id, query_text,
bytes_spilled_to_local_storage /1e9AS local_spill_gb,
bytes_spilled_to_remote_storage /1e9AS remote_spill_gb,
total_elapsed_time /1000AS seconds,
warehouse_size
FROM SNOWFLAKE.ACCOUNT_USAGE.QUERY_HISTORY
WHERE (bytes_spilled_to_local_storage >0OR bytes_spilled_to_remote_storage >0)
AND start_time >= DATEADD(hours, -24, CURRENT_TIMESTAMP())
ORDERBY bytes_spilled_to_remote_storage DESC
LIMIT 20;
-- Remote spill = warehouse too small for the query-- Fix: Scale up warehouse or optimize query to reduce intermediate data
Step 2: Lock and Transaction Contention
-- Find blocked/waiting queriesSELECT query_id, query_text, blocked_query_id,
DATEDIFF('second', start_time, CURRENT_TIMESTAMP()) AS wait_seconds,
user_name, warehouse_name
FROM SNOWFLAKE.ACCOUNT_USAGE.QUERY_HISTORY
WHERE execution_status ='BLOCKED'AND start_time >= DATEADD(minutes, -30, CURRENT_TIMESTAMP());
-- Find long-running transactions (holding locks)SELECT*FROM SNOWFLAKE.ACCOUNT_USAGE.QUERY_HISTORY
WHERE execution_status ='RUNNING'AND DATEDIFF('minute', start_time, CURRENT_TIMESTAMP()) >30ORDERBY start_time;
-- Kill a blocking querySELECTSYSTEM$CANCEL_QUERY('<blocking_query_id>');
-- Common lock scenarios:-- DDL on table blocks DML (ALTER TABLE blocks INSERT)-- Concurrent MERGE on same table → serialization-- Long COPY INTO blocks other COPY INTO on same table
Step 3: Metadata Operation Analysis
-- Cloud services credit spike (metadata-heavy operations)SELECT DATE_TRUNC('hour', start_time) AShour,
SUM(credits_used_cloud_services) AS cloud_credits,
COUNT(*) AS query_count,
SUM(credits_used_cloud_services) /NULLIF(COUNT(*), 0) AS credits_per_query
FROM SNOWFLAKE.ACCOUNT_USAGE.WAREHOUSE_METERING_HISTORY
WHERE start_time >= DATEADD(hours, -24, CURRENT_TIMESTAMP())
AND credits_used_cloud_services >0GROUPBYhourORDERBY cloud_credits DESC;
-- Excessive metadata queries (SHOW, DESCRIBE, INFORMATION_SCHEMA)SELECT query_type, COUNT(*) AS count,
AVG(total_elapsed_time) AS avg_ms
FROM SNOWFLAKE.ACCOUNT_USAGE.QUERY_HISTORY
WHERE start_time >= DATEADD(hours, -24, CURRENT_TIMESTAMP())
AND query_type IN ('SHOW', 'DESCRIBE', 'GET_DDL')
GROUPBY query_type
ORDERBY count DESC;
-- If very high, consider caching INFORMATION_SCHEMA results in your app
Step 4: Partition Pruning Analysis
-- Queries scanning too many partitions (candidate for clustering)SELECT query_id,
SUBSTR(query_text, 1, 200) AS query_preview,
partitions_scanned,
partitions_total,
ROUND(partitions_scanned *100.0/NULLIF(partitions_total, 0), 1) AS scan_pct,
bytes_scanned /1e9AS gb_scanned,
total_elapsed_time /1000AS seconds
FROM SNOWFLAKE.ACCOUNT_USAGE.QUERY_HISTORY
WHERE partitions_total >100AND partitions_scanned > partitions_total *0.5AND start_time >= DATEADD(hours, -24, CURRENT_TIMESTAMP())
AND query_type ='SELECT'ORDERBY partitions_scanned DESC
LIMIT 10;
-- Check if table would benefit from clusteringSELECTSYSTEM$CLUSTERING_INFORMATION('my_db.my_schema.orders', '(order_date)');
-- Look at average_depth: > 5 means clustering would help-- Look at partition_depth_histogram: should be concentrated at depth 1-2
Step 5: Network and Connectivity Debugging
# DNS resolution test
dig +short $(echo$SNOWFLAKE_ACCOUNT).snowflakecomputing.com
# TLS handshake test
openssl s_client -connect ${SNOWFLAKE_ACCOUNT}.snowflakecomputing.com:443 \
-servername ${SNOWFLAKE_ACCOUNT}.snowflakecomputing.com < /dev/null 2>/dev/null \
| openssl x509 -noout -subject -dates
# Latency test
curl -o /dev/null -s -w "DNS: %{time_namelookup}s\nConnect: %{time_connect}s\nTLS: %{time_appconnect}s\nTotal: %{time_total}s\n" \
"https://${SNOWFLAKE_ACCOUNT}.snowflakecomputing.com/"# Check if OCSP responder is reachable (Snowflake uses OCSP for cert validation)
curl -s -o /dev/null -w "%{http_code}""http://ocsp.snowflakecomputing.com/ocsp"
1. Can you connect at all? → SELECT 1;
2. Can you reach the right context? → SELECT CURRENT_DATABASE(), CURRENT_ROLE();
3. Does the object exist? → SHOW TABLES LIKE 'xxx';
4. Do you have permissions? → SHOW GRANTS TO ROLE xxx;
5. Is the warehouse available? → SHOW WAREHOUSES LIKE 'xxx';
6. Does a simple query work? → SELECT COUNT(*) FROM table;
7. Does the specific query work on smaller data? → Add LIMIT 100
8. Is there spilling? → Check bytes_spilled_to_remote_storage
9. Is there partition skew? → Check partition scan ratio
10. Is there contention? → Check blocked queries
