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Parquet conversion problem

Prevent Type Changes When Converting Parquet to CSV

Export Parquet values to CSV while documenting timestamp, decimal, binary and null representations.

Use the matching tool

Parquet to CSV

Open Parquet to CSV

What the error actually means

Parquet stores typed values and metadata; CSV stores text. Conversion must choose textual representations for timestamps, decimals, binary data, nested values and nulls. The CSV cannot preserve the original schema by itself.

Likely causes

  • Time-zone-aware timestamps become plain text.
  • Decimal precision is formatted incorrectly.
  • Binary or nested columns lack a CSV representation.
  • Nulls and empty strings collapse into one marker.

Schema-aware export

Problem

Export timestamp and decimal values with display defaults

Correct pattern

Use documented ISO timestamps, exact decimal text and an explicit null policy

A safe repair workflow

  1. 1Inspect the Parquet schema.
  2. 2Choose representations for non-string types.
  3. 3Convert and retain the schema separately.
  4. 4Read the CSV back using explicit types.

How to verify the result

A file that downloads successfully is not automatically a correct file. Check the result at both the structural and business-data levels:

  • Row counts match.
  • Decimal precision survives.
  • Timestamp offsets remain meaningful.
  • Null counts reconcile.

Read the deeper guides

Convert CSV to Parquet and Check the Schema Before You Trust ItA practical guide to converting CSV data to Parquet, preserving identifiers, reviewing inferred types, and validating the result in DuckDB or Python.CSV vs XLSX vs TXT: Which Format to Use?Compare CSV, XLSX (Excel), and TXT formats. Understand the differences, file size, compatibility, and when to use each for your data.