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

bash

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

Usage

bash

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:

bash

dct peek data.csv

Preview specific number of lines:

bash

dct peek large.parquet -n 5

Save preview to CSV:

bash

dct peek data.json -o preview.csv

Quick check if file is readable:

bash

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:

code

╭──────┬────────┬───────╮
│  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