How to Fix Common Errors in Amazon Redshift

How do I troubleshoot common errors in Amazon Redshift?

Guides developers through diagnosing and resolving the Redshift errors that appear most in daily SQL work.

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Description

What are the most frequent Redshift error messages?

Redshift users mainly hit COPY load failures, out-of-memory during joins, data type mismatches, and permission denied errors. Knowing the catalog views that log these issues speeds up fixes.

How do I diagnose COPY load errors fast?

Query stl_load_errors for the latest rows. The err_reason and raw_line columns reveal the exact field that failed.Limit by file or line_number to isolate bad data quickly.

Why does COPY show “Invalid data format”?

The source file’s column order, delimiter, or date format does not match the target table. Supply DELIMITER, DATEFORMAT, or TIMEFORMAT options that mirror the file.

How can I prevent out-of-memory errors on joins?

Ensure the largest table uses EVEN or KEY distribution on the join key. Add sort keys for the join columns.Rewrite to eliminate cross-product joins and unfiltered CTEs.

Which catalog views help troubleshoot query errors?

stl_query shows the text, stl_wlm_query reveals queue spill details, and svl_qlog stores error codes. Filtering by userid and elapsed pinpoints the expensive queries that fail.

How do I fix permission denied errors?

Validate that the user has USAGE on the schema and SELECT on each referenced table.Apply GRANT SELECT ON ALL TABLES IN SCHEMA public TO dev_team; to avoid future misses.

Is there a way to test grants safely?

Create a role, grant it the needed rights, and SET ROLE to simulate the session. This avoids accidental superuser reliance in staging.

Best practices to avoid recurring errors

Load data through staging tables with VARCHAR columns, run validation queries, then CAST into typed tables. Schedule VACUUM and ANALYZE after large inserts to keep statistics fresh.

Why How to Fix Common Errors in Amazon Redshift is important

How to Fix Common Errors in Amazon Redshift Example Usage


-- Diagnose a failing load into Products
SELECT file, line_number, position, err_reason, raw_line
FROM stl_load_errors
WHERE table_name = 'products'
ORDER BY starttime DESC
LIMIT 5;

How to Fix Common Errors in Amazon Redshift Syntax


COPY target_table (col1, col2, col3)
FROM 's3://bucket/data.csv'
CREDENTIALS 'aws_access_key_id=<key>;aws_secret_access_key=<secret>'
DELIMITER ','
DATEFORMAT 'auto'
TIMEFORMAT 'auto'
IGNOREHEADER 1
MAXERROR 100;

-- Example INSERT that can fail on type mismatch
INSERT INTO Orders (id, customer_id, order_date, total_amount)
VALUES (1001, 42, '2024-04-14', '12.99'); -- total_amount should be numeric

Common Mistakes

Ignoring stl_load_errors after COPY fails WHY: Developers rerun COPY without checking the exact failure line, wasting time. FIX: Always query stl_load_errors immediately and correct the source file or COPY options.
Using DISTSTYLE ALL on very large tables WHY: Redshift replicates full tables to every node, exhausting disk and memory. FIX: Use EVEN or KEY distribution unless the table is truly small (<1M rows).