How to increase the Maximum Number of Columns for a Table in PostgreSQL?

In PostgreSQL, the maximum number of columns for a table is limited by the system configuration parameter MaxTupleAttributeNumber, which is set to 1664 by default. However, it is possible to increase this limit by modifying the PostgreSQL source code and recompiling the database system.

Warning: Changing system parameters in PostgreSQL can have serious consequences, and should only be done by experienced database administrators who fully understand the implications of their actions.

Steps to Increase the Maximum Number of Columns in PostgreSQL:

  1. Download and extract the PostgreSQL source code from the official PostgreSQL website.
  2. Locate the src/include/access/tupdesc.h header file in the extracted source code directory.
  3. Open the tupdesc.h file in a text editor and locate the following line:

#define MaxTupleAttributeNumber 1664

4. Modify the value of MaxTupleAttributeNumber to the desired maximum number of columns, for example:

#define MaxTupleAttributeNumber 2048

  1. Save the modified tupdesc.h file and close the text editor.
  2. Compile the modified PostgreSQL source code using the standard build process for your platform. Refer to the PostgreSQL documentation for detailed instructions on building PostgreSQL from source.
  3. Install the compiled PostgreSQL binaries and libraries, or replace the existing PostgreSQL installation with the modified version.

Note: Increasing the maximum number of columns in PostgreSQL can have an impact on the database system’s performance, as it can increase the size of the system catalog and memory usage. It is important to test the modified PostgreSQL installation thoroughly before deploying it in a production environment.

Alternatives to Increasing the Maximum Number of Columns:

If increasing the maximum number of columns in PostgreSQL is not feasible or desirable, there are alternative approaches to consider:

  1. Table partitioning: Table partitioning can be used to split a large table into smaller sub-tables, each with its own set of columns. This can help reduce the number of columns in each sub-table, and improve the query performance and manageability of the table.
  2. Normalization: Normalizing the table schema can help reduce the number of columns by breaking down the table into smaller, more manageable entities. This can also help improve the data integrity and flexibility of the database schema.
  3. Redesigning the application: If the number of columns in a table is becoming unmanageable, it may be necessary to redesign the application to use a different data model or architecture that can better handle the data complexity.

About Shiv Iyer 219 Articles
Open Source Database Systems Engineer with a deep understanding of Optimizer Internals, Performance Engineering, Scalability and Data SRE. Shiv currently is the Founder, Investor, Board Member and CEO of multiple Database Systems Infrastructure Operations companies in the Transaction Processing Computing and ColumnStores ecosystem. He is also a frequent speaker in open source software conferences globally.