How can data from a Postgres database be transferred to a Parquet file for exportation?

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There are multiple ways to transfer data from a Postgres database to a Parquet file, but the most common methods are:

1. Using a data integration tool like Apache NiFi, Talend, or Apache Spark. These tools can extract data from a Postgres database, transform it into the Parquet format, and load it into a storage system like HDFS or S3.

2. Writing custom scripts using programming languages like Python or Java. The Python libraries like Pandas, PyArrow, or Dask can help read data from the Postgres database, convert it into a Parquet file using the Parquet file format specification, and write it to the desired storage system.

3. Utilizing the COPY command of Postgres. The COPY command can be used to export data from Postgres to a CSV file format, which can be converted to a Parquet file using tools like PyArrow or Dask. This method might not be efficient for large datasets as it requires creating an intermediate CSV file.