Request for official clarification on SQL parameter parsing changes in PostgreSQL 15 and 16

Hello PostgreSQL Community,

We have encountered unexpected SQL parsing errors during application upgrades from PostgreSQL 14 to 15 and 16, related to the use of JDBC-style parameter placeholders (`?`) in our legacy applications.

Specifically:

1. In PostgreSQL 15 and later:

   The following SQL causes a syntax error unless a space is added after the `?`:

     SELECT * FROM table WHERE a = ?AND b = 123;

   → Adding a space (`? AND`) resolves the issue.

   This did not cause an error in PostgreSQL 14.

2. In PostgreSQL 16:

   The following SQL causes a syntax error:

     SELECT * FROM table WHERE a = ?ORDER BY b;

   → This query runs in PostgreSQL 15, but causes an error in 16 unless a space is added after `?`.

We understand that this behavior may stem from changes to the parser to make it more strict and SQL-compliant. However, we were unable to find any explicit mention of these changes in the official release notes of PostgreSQL 15 or 16.

Our client is asking for official documentation or a statement confirming whether this behavior change was intentional and when it was introduced.

Could anyone kindly point us to:

- Relevant release note sections, commits, or discussions on this change

- Confirmation that these are intentional parser changes (and not regressions)

Any help or references would be greatly appreciated.

Best regards, 
Wang Bo