How to Troubleshoot Common Errors in BigQuery

Galaxy Glossary

How do I quickly diagnose and fix common BigQuery errors?

Systematic steps to diagnose and fix the most frequent BigQuery query, job, and resource-related errors.

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Description

Example H2

Example H3

What are the most frequent BigQuery errors?

Developers regularly face "Unrecognized name", "Exceeded resource limits", and "Syntax error" messages. Each points to missing columns, inefficient scans, or malformed SQL.

How do I resolve an "Unrecognized name" error?

Confirm the column or alias exists, check for case sensitivity, and qualify the field with its table alias. Use INFORMATION_SCHEMA.COLUMNS to verify spelling before rerunning.

Why does BigQuery say my query exceeded resources?

This error appears when a query scans more than the project’s slot or memory quota. Limit columns with SELECT list, add partitions, and apply filters early to reduce scanned bytes.

How can SAFE functions prevent type-casting errors?

Wrap risky casts in SAFE_CAST or SAFE_DIVIDE. These return NULL instead of failing, letting the job finish while highlighting bad rows for later cleanup.

Which best practices avoid common mistakes?

Create clustered, partitioned tables, reference specific columns, use table decorators for date partitions, and test complex joins on LIMIT 1000 samples first.

Example: fixing an alias typo

-- Original error-prone query SELECT c.name, o.total_amount FROM `shop.Orders` AS o JOIN `shop.Customers` AS c ON o.customer_id = c.customerid; -- typo -- Corrected version SELECT c.name, o.total_amount FROM `shop.Orders` AS o JOIN `shop.Customers` AS c ON o.customer_id = c.id;

How do I trace errors in long SQL scripts?

Run queries step-by-step, add WITH clauses for readability, enable dry runs to estimate bytes, and check the Jobs history panel for the precise failing stage.

When should I switch to batch priority?

Use batch for non-urgent workloads that might otherwise fail on interactive quota limits. Batch jobs queue and run when slots free up, reducing "resources exceeded" errors.

Can I catch load and export job errors?

Query region-specific INFORMATION_SCHEMA.JOBS_BY_* views for status="FAILED" and inspect error_result.message. Automate alerts via Cloud Logging sinks.

Why How to Troubleshoot Common Errors in BigQuery is important

How to Troubleshoot Common Errors in BigQuery Example Usage


-- Reduce resources exceeded by selecting only necessary columns
SELECT
  o.id,
  o.order_date,
  o.total_amount,
  c.name AS customer_name
FROM `project.dataset.Orders`   AS o
JOIN `project.dataset.Customers` AS c
ON   o.customer_id = c.id
WHERE o.order_date BETWEEN '2024-05-01' AND '2024-05-31'
LIMIT 1000;

How to Troubleshoot Common Errors in BigQuery Syntax


-- Detect misspelled columns
SELECT column_name
FROM `project.dataset.INFORMATION_SCHEMA.COLUMNS`
WHERE table_name = 'Orders';

-- Re-cast safely
SELECT
  SAFE_CAST(total_amount AS NUMERIC) AS total_amount
FROM `project.dataset.Orders`;

-- Limit scanned bytes on a wide table
SELECT id, name, price
FROM `project.dataset.Products`
WHERE price > 100;

-- Partition decorator example (daily)
SELECT *
FROM `project.dataset.Orders$20240601`;

Common Mistakes

Ignoring dry-run results: Developers skip DRY RUN, causing full-cost failures. Always add "OPTIONS (dry_run=true)" or click Dry Run first to reveal syntax and quota issues before execution.
Casting without SAFE_: Using CAST on dirty data aborts jobs. Replace with SAFE_CAST, review NULL rows, then clean the source to avoid repeated crashes.