Tablesample

Save 90-99% on query costs during development by sampling a percentage of your data.

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The Problem

Running a query 20 times during development at $0.63 each = $12.50.

The Solution

Sample 1% of your data to test query logic at a fraction of the cost.

Same query logic, 99% less cost.

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How to Enable

Option 1: Config Panel

Set the sample percentage in the Tablesample field in the config panel. The value automatically injects a directive into your query.

Option 2: Comment Directive

Add a comment directive directly in your SQL:

-- querylab:tablesample=1

SELECT * FROM orders WHERE order_date >= '2024-01-01'
-- Cost: $0.006 instead of $0.63

Directive Syntax

-- querylab:tablesample=<percentage>
-- querylab:tablesample-threshold=<size>

tablesample

Sets the sample percentage (0.01-100).

Percentage	Use Case
0.1	Very large tables (billions of rows)
1	Standard development
10	Validation testing
100	Production (same as no directive)

tablesample-threshold

Only sample tables larger than this size. Smaller tables are queried in full.

-- querylab:tablesample=1
-- querylab:tablesample-threshold=10gb

SELECT * FROM huge_table    -- Sampled (>10GB)
JOIN small_lookup           -- Not sampled (<10GB)

Size	Example
100mb	100 megabytes
1gb	1 gigabyte
10gb	10 gigabytes
1tb	1 terabyte

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Important Notes

• Results are sampled - counts and aggregations are approximate
• Non-deterministic - different rows each run
• Small tables may return empty results (use higher %)
• Remove directive for production

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Workflow

1. 1% - Develop and test query logic
2. 10% - Validate results look correct
3. Remove directive - Run on full data

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Insights Panel

When active, the panel shows:

Development Mode: Active
Sample Size: 1%
Dev Cost:   $0.006
Prod Cost:  $0.63
Savings:    99%