DCT Peek - Preview File Contents

Preview the first N rows of any supported flat data file to understand its structure and content.

When to Use

Use this skill as the first step when working with unfamiliar data files:

• Before running transformations or analysis
• To verify file format and structure
• To check data types and column names
• To sample data for quick inspection

Installation

which dct || go build -o dct && chmod +x ./dct

Usage

dct peek <file> [flags]

Flags

• -n, --lines <number>: Number of lines to display (default: 10)
• -o, --output <file>: Output to file instead of stdout

Examples

Preview default 10 lines:

dct peek data.csv

Preview specific number of lines:

dct peek large.parquet -n 5

Save preview to CSV:

dct peek data.json -o preview.csv

Quick check if file is readable:

dct peek data.csv -n 1

Output Format

The output displays a formatted table showing:

• Column names (header row)
• Data types (second row)
• Data rows (up to N rows)

Example:

╭──────┬────────┬───────╮
│  id  │  name  │ price │
│BIGINT│VARCHAR │DOUBLE │
│──────│────────│───────│
│  1   │  Alice │ 10.99 │
│  2   │   Bob  │ 24.50 │
╰──────┴────────┴────────╯

Best Practices

• Always peek first when working with new data files
• Use -n 1 to quickly verify a file is readable before processing
• Use -o to save samples for documentation or testing
• Check the data types row to understand the schema
• Verify column names match expectations

Related Skills

After peeking, you may want to use:

• dct-profile: For detailed data quality analysis
• dct-infer: To generate SQL schema from the data
• dct-diff: To compare with another file