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How to Convert CSV to Parquet - Step by Step Guide

Step 1

Upload Your CSV File

Start by uploading your CSV file that you want to convert to Apache Parquet format. Parquet's columnar storage is perfect for Apache Spark, data lakes, and analytics workloads.

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Upload file: Click "Upload" to select a .csv file from your computer
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Drag and drop: Simply drag your CSV file into the upload area
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Try the sample: Click "Sample" to load example data and see how the converter works

Example: CSV Input

Sample CSV data ready for Parquet conversion:

id,name,email,salary,department,active
1001,Emma Johnson,[email protected],75000.50,Engineering,true
1002,Michael Chen,[email protected],92000.00,Product,true
1003,Sophia Rodriguez,[email protected],85000.75,Marketing,true
Step 2

Automatic Schema Detection

The converter automatically analyzes your CSV headers and data types to generate an optimized Parquet schema:

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Header detection: Automatically uses first row as column names
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Type inference: Detects INT64, DOUBLE, STRING, BOOLEAN types from data
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Columnar optimization: Converts row-based CSV to efficient columnar format

Example: Generated Parquet Schema

Automatically created schema from CSV columns:

message schema {
  required int64 id;
  required binary name (STRING);
  required binary email (STRING);
  required double salary;
  required binary department (STRING);
  required boolean active;
}
Step 3

Configure Compression Options

Optimize your Parquet file with compression settings for your use case:

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SNAPPY compression: Balanced speed and size (default, recommended)
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Row group optimization: Automatically configured for best performance
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Size reduction: Expect 80-90% reduction compared to original CSV
Step 4

Download Parquet File

Get your optimized Parquet file ready for big data processing:

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Download Parquet: Save the converted file as .parquet format
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Massive space savings: Typically 80-90% smaller than CSV
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Ready for analytics: Use with Spark, Hive, Athena, Presto, BigQuery

Frequently Asked Questions

How do I convert CSV to Parquet format?

Upload your CSV file or paste CSV data into the converter. The tool automatically detects headers, infers data types, and converts your CSV into efficient Parquet columnar format. Download the .parquet file and use it with Spark, Athena, or other big data tools.

Why convert CSV to Parquet?

Parquet offers 80-90% size reduction through columnar compression, dramatically faster query performance for analytics, efficient column-pruning for selective reads, and better compatibility with big data tools like Spark, Hive, and Athena. It's essential for data lakes and warehouses.

Does the converter handle large CSV files?

Yes! The converter efficiently processes large CSV files by streaming data in chunks. For very large datasets (multiple GB), consider splitting the CSV into smaller files or using server-side processing tools for optimal performance and memory efficiency.

How does schema detection work?

The converter analyzes your CSV headers and data values to automatically infer data types (integers, doubles, strings, booleans). It uses the first row as column names and samples data to determine the most appropriate Parquet data type for each column.

What compression is used?

By default, SNAPPY compression is used, which provides excellent balance between compression ratio and speed. SNAPPY is widely supported and recommended for most use cases. The resulting Parquet file is typically 80-90% smaller than the original CSV.

Is the CSV to Parquet converter free?

Yes, completely free with no limitations on file size, conversions, or features. No registration required. Convert unlimited CSV files to Parquet format with automatic schema generation and optimization.

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