How to Check the Type of a PostgreSQL Dump File

Learn the steps to determine if a PostgreSQL dump file is a script or archive file, and how this affects restoration commands.
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How to Check the Type of a PostgreSQL Dump File

When you receive a PostgreSQL dump file, it can often be unclear whether it is a plain script file or an archive file. This distinction is crucial as it determines which commands you should use for restoring the dump file effectively. In this guide, we will walk you through the steps you can take to easily identify the type of your PostgreSQL dump file.

Understanding the Two Formats

PostgreSQL dump files can typically be stored in one of two formats:

Script File (Plain Text): This format contains SQL commands and is human-readable. You can open it in a text editor.

Archive File: This format is binary and requires specific tools like pg_restore for access. It is not human-readable.

Why It Matters

Knowing the type of dump file is important for restoration purposes. The commands you use to restore a dump file differ significantly based on the format. If you mistakenly use the wrong command, you may encounter errors or fail to restore your database entirely.

Checking the File Type

Here are two effective methods to determine whether your PostgreSQL dump file is a plain script or an archive file. We'll focus on solutions applicable to PostgreSQL version 9.6.13.

Method 1: Using the file Command

If you are working in a Unix environment, you can utilize the built-in file command to analyze the format of the dump file. Here’s how:

Open your terminal.

Execute the command:

[[See Video to Reveal this Text or Code Snippet]]

Review the output. If the output describes the file as a plain text file, then it is a script file. If it identifies it as an archive, then it is a binary file.

Method 2: Using pg_restore

An alternative and highly reliable method is to use the pg_restore command that comes with PostgreSQL.

Open your terminal.

Run the following command:

[[See Video to Reveal this Text or Code Snippet]]

If the command completes without any errors, it indicates that your file is an archive file. However, if you receive an error message, this suggests that your dump file is in plain format (SQL script).

Conclusion

Determining the type of a PostgreSQL dump file is a straightforward process that can save you from encountering issues during the restore phase. By using either the file command or the pg_restore command, you can quickly ascertain whether you are dealing with a script file or an archive file.

By being informed about the type of your dump file, you can ensure a smooth restoration process for your PostgreSQL database.

If you have any questions or further insights on working with PostgreSQL dump files, feel free to leave a comment below!