[Compatibility]: Server_version_num Missig A Digit / Wrong Factor

by ADMIN 66 views

Introduction

In this article, we will delve into a compatibility issue affecting CedarDB, a PostgreSQL-compatible database. The issue arises when running CedarDB on Ubuntu 24.04, where the server_version_num value is reported incorrectly. This discrepancy can have significant implications for external tools that rely on this value to determine the PostgreSQL version. In this article, we will explore the steps to reproduce the issue, its potential use cases, and provide additional context to better understand the problem.

Description

When running CedarDB on Ubuntu 24.04, the SELECT version() command reports PostgreSQL 16.3 compatible CedarDB v2023-05-14. Based on this information, one would expect the server_version_num value to be 160003, as calculated using the formula pg_version_num = (pg_version_major * 10000) + pg_version_minor in the PostgreSQL meson.build file.

However, the actual server_version_num value reported by CedarDB is 16001, which indicates that the major version is multiplied by a hundred instead of one thousand. This discrepancy can lead to incorrect assumptions and potential issues in external tools that rely on this value.

Steps to Reproduce

To reproduce this issue, follow these steps:

  1. Run the command SHOW server_version_num; on your CedarDB instance.

Use Case

The server_version_num value might be used by external tools to quickly determine the PostgreSQL version. A common approach is to use this value as an integer, where the major version is obtained by dividing the server_version_num value by 1000. However, in CedarDB's case, this approach would yield an incorrect major version of 1 instead of 16.

Here's an example code snippet in Python that demonstrates this issue:

version = run_sql("SHOW server_version_num")

major_version = version // 1000  # would not be 16 but 1 in cedardb's case

if version < 140000:
    # also problematic...

In this example, the major_version variable would be assigned an incorrect value of 1, leading to potential issues in the subsequent code.

Additional Context

Unfortunately, there is no response available to provide additional context or insights into this issue. However, by understanding the steps to reproduce and the potential use cases, we can better appreciate the significance of this compatibility issue and its potential impact on external tools.

Conclusion

In conclusion, the server_version_num value reported by CedarDB on Ubuntu 24.04 is incorrect due to a wrong multiplier. This discrepancy can lead to issues in external tools that rely on this value to determine the PostgreSQL version. By understanding the steps to reproduce and the potential use cases, we can better appreciate the significance of this compatibility issue and its potential impact on our applications.

Recommendations

To resolve this issue, we recommend the following:

  1. Update the CedarDB code to use the correct multiplier when calculating the server_version_num value.
  2. Provide a clear and concise documentation on how to obtain the PostgreSQL version using the server_version_num value.
  3. Encourage external tools to use a more robust approach to determine the PostgreSQL version, such as using the SELECT version() command.

Introduction

In our previous article, we explored a compatibility issue affecting CedarDB, a PostgreSQL-compatible database. The issue arises when running CedarDB on Ubuntu 24.04, where the server_version_num value is reported incorrectly. In this article, we will address some frequently asked questions (FAQs) related to this issue.

Q: What is the correct formula for calculating the server_version_num value?

A: The correct formula for calculating the server_version_num value is pg_version_num = (pg_version_major * 10000) + pg_version_minor, as specified in the PostgreSQL meson.build file.

Q: Why is the server_version_num value reported incorrectly by CedarDB?

A: The server_version_num value is reported incorrectly by CedarDB due to a wrong multiplier. Instead of multiplying the major version by 10000, CedarDB multiplies it by 100, resulting in an incorrect value.

Q: What are the potential consequences of using the incorrect server_version_num value?

A: Using the incorrect server_version_num value can lead to issues in external tools that rely on this value to determine the PostgreSQL version. This can result in incorrect assumptions, potential errors, and even security vulnerabilities.

Q: How can I reproduce the issue?

A: To reproduce the issue, follow these steps:

  1. Run the command SHOW server_version_num; on your CedarDB instance.

Q: What are some potential use cases where the server_version_num value is used?

A: The server_version_num value might be used by external tools to quickly determine the PostgreSQL version. A common approach is to use this value as an integer, where the major version is obtained by dividing the server_version_num value by 1000. However, in CedarDB's case, this approach would yield an incorrect major version.

Here's an example code snippet in Python that demonstrates this issue:

version = run_sql("SHOW server_version_num")

major_version = version // 1000  # would not be 16 but 1 in cedardb's case

if version < 140000:
    # also problematic...

Q: How can I resolve the issue?

A: To resolve the issue, we recommend the following:

  1. Update the CedarDB code to use the correct multiplier when calculating the server_version_num value.
  2. Provide a clear and concise documentation on how to obtain the PostgreSQL version using the server_version_num value.
  3. Encourage external tools to use a more robust approach to determine the PostgreSQL version, such as using the SELECT version() command.

Q: What is the recommended approach to determine the PostgreSQL version?

A: The recommended approach to determine the PostgreSQL version is to use the SELECT version() command. This command returns a string representing the PostgreSQL version, which can be parsed to obtain the major, minor, and patch versions.

Here's an example code snippet in Python that demonstrates this approach:

version = run_sql("SELECT version()")

major_version = int(version.split('.')[0])
minor_version = int(version.split('.')[1])
patch_version = int(version.split('.')[2])

print(f"PostgreSQL version: {major_version}.{minor_version}.{patch_version}")

By following these recommendations, we can ensure that CedarDB and external tools can coexist harmoniously, providing accurate and reliable results.