> For the complete documentation index, see [llms.txt](https://alex-25.gitbook.io/welcome/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://alex-25.gitbook.io/welcome/gsoc.md). # GSoC ## Google Summer of Code 2025 – Work Report **Contributor:** Alex Jia\ **Project:** SQLancer – PostgreSQL Testing Enhancements\ **Organization:** SQLancer Project *** ### Overview My GSoC 2025 project focused on extending SQLancer’s PostgreSQL module to better support features introduced in PostgreSQL versions 13 through 16. The work ranged from analyzing version-specific grammar changes to implementing support for newly introduced SQL constructs such as `MERGE`, new CTE functions, and updates to `EXTRACT`. *** ### Contributions #### PostgreSQL 13 For PostgreSQL 13, I performed a detailed analysis of new SQL features and their relevance to SQLancer’s grammar. Most of the constructs introduced in this version are **not yet supported in SQLancer’s base grammar** and were therefore marked as *not applicable* for implementation in this cycle. Examples include: * `ALTER NO DEPENDS ON` * `ALTER STATISTICS SET STATISTICS` * `ALTER TYPE` * `ALTER VIEW RENAME COLUMN` * `CREATE DATABASE WITH LOCALE` * `CREATE TABLESPACE` * `DROP DATABASE FORCE` * `EXPLAIN ANALYSE` * `ROW` * `SELECT WITH TIES` Additionally, I confirmed that certain changes required **no modification** in SQLancer, such as: * `ALTER TABLE SET STORAGE` * `CREATE INDEX deduplication` This gave SQLancer maintainers a clear mapping of what v13 introduced and which parts do not affect current grammar support. *** #### PostgreSQL 14 * **EXTRACT function updates:** * Added grammar support for the new EXTRACT fields that return **numeric results**. * Changed the return type of `EXTRACT()` from `FLOAT8` to **NUMERIC**, matching the PostgreSQL v14 update. *** #### PostgreSQL 15 * **New CTE Function Support:** * Implemented generation of the new CTE functionality introduced in v15. * Extended SQLancer’s AST to capture additional recursive/non-recursive structures. * **MERGE Statement Generator:** * Added a generator for the `MERGE` statement introduced in PostgreSQL 15. * Supported `WHEN MATCHED` and `WHEN NOT MATCHED` branches to fuzz-test conditional updates and inserts. *** #### PostgreSQL 16 (Partial) * **Generic Plan in EXPLAIN:** * Added grammar support for PostgreSQL 16’s generic plan option in `EXPLAIN`. * **Renaming `force_parallel_mode`:** * Updated SQLancer references to reflect the renamed parameter in PostgreSQL 16, ensuring compatibility. *** ### Skills and Learning Outcomes * **SQL grammar evolution:** Learned how to adapt SQLancer’s query generator to account for Postgres version-specific changes. * **AST/grammar implementation:** Implemented new constructs (`MERGE`, EXTRACT numeric, CTEs) within SQLancer’s existing framework. * **Code quality and review:** Improved maintainability and consistency through mentor feedback and iterative pull requests. *** ### Future Work * Extend PostgreSQL 16 support further (beyond EXPLAIN and parameter renames). * Continue reviewing new Postgres versions to keep SQLancer aligned with grammar changes. * Improve documentation around version-specific features for future contributors. *** ### Acknowledgments I’d like to thank my mentor **Robins** and the SQLancer community for their detailed reviews, helpful guidance, and encouragement throughout the program. ### PR Merged: * * * * * * * * ### PR In Progress * * * * * * * *