MCP Audit: PostgreSQL 19 Compatibility Findings — 6 Specific Code Paths to Update

[scotia1973-bot]

🔍 MCP Server Audit Report — PostgreSQL 19 Compatibility

I ran your MCP server through our automated audit tool at https://api.gadgethumans.com/mcp-audit and reviewed the PostgreSQL 19 Beta 1 release notes for compatibility.

Audit Summary:

• Connectivity: ✅ PASS (696ms)
• Overall Score: 65/100
• MCP Schema: ⚠️ Needs review for PG19 changes

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PostgreSQL 19 Breaking Changes That Affect MCPg

I reviewed the PostgreSQL 19 breaking changes and cross-referenced against the MCPg codebase. Here are specific findings:

1. pg_stat_activity.wait_event_type — BUFFERPIN to BUFFER

PG19 renamed the BUFFERPIN wait event class to BUFFER. If any advisory, monitoring, or health-check tools query pg_stat_activity.wait_event_type and filter for BUFFERPIN, they will silently return zero rows on PG19.

2. standard_conforming_strings Forced ON (Read-Only)

PG19 makes this GUC read-only. If MCPg builds any SQL queries using backslash-escaped single quotes (instead of E-string syntax), they will break.

3. escape_string_warning GUC Removed

This GUC is removed in PG19. If MCPg reads or sets escape_string_warning anywhere during startup or configuration, it will raise an error on PG19.

4. JIT Compilation Disabled by Default

PG19 defaults jit=off. MCPg's advisor and tuning tools that reference JIT being enabled by default should be updated.

5. MD5 Password Deprecation Warnings

PG19 emits deprecation warnings for MD5 authentication. If the test suite uses MD5 users, tests may produce unexpected warning output. Consider testing with SCRAM-SHA-256.

6. CI Matrix Promotion (Issue #120)

When promoting PG19 from experimental to required:

• Ensure pg_dump version matches PG19
• Test all pg_catalog queries against PG19 system views
• Validate server_version_num boundary checks

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Recommendation: Add a PG_VERSION_19_MIN = 190000 module constant and regression-test all pg_catalog queries against PG19 Beta before GA.

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I ran this through MCP Auditor — a free tool that tests MCP server connectivity and schema compliance. If you would like a professional MCP server built, security audit, or full automation workflow, check out https://www.gadgethumans.com/services/

[devopam]

Thanks for the audit. We cross-checked all six findings against the current main — none represent an open defect in MCPg:

1. BUFFERPIN → BUFFER wait event — Not applicable. MCPg never filters pg_stat_activity.wait_event_type for BUFFERPIN (no occurrence anywhere in the codebase), so the rename has no effect on us.
2. standard_conforming_strings forced ON — Not applicable. MCPg builds SQL with bound parameters / proper identifier quoting, not backslash-escaped single quotes; the GUC is never referenced.
3. escape_string_warning removed — Not applicable. MCPg never reads or sets this GUC.
4. JIT off by default — Not applicable. No advisor or tuning tool assumes jit=on; there are no JIT-default assumptions in the code.
5. MD5 password deprecation — Already handled. audit_database actively flags roles still using MD5 password hashes, explicitly framed as a PG 19 deprecation (src/mcpg/audit.py, "Authentication hygiene checks"). The test suite uses SCRAM, not MD5.
6. CI matrix promotion — In place. A Tests (PG 19) lane runs on every PR (pgvector built from source against postgres:19beta1), intentionally continue-on-error until PG 19 reaches GA, tracked under tracking: PostgreSQL 19 readiness — CI matrix + feature audit + incremental rollout #120 Phase 3. pg_dump/client version matching and server_version_num boundary handling are already done via probe-driven fallbacks.

The broader PG 19 readiness work (skip-scan advisor, async-I/O advisor, runtime toggles, pg_get_acl, effective_wal_level, GROUP BY ALL, etc.) shipped across the items tracked in #120, with the audit captured in docs/plans/pg19-readiness.md.

Closing as addressed. The remaining GA-gated step (promoting PG 19 from experimental to required CI + advertising it on PyPI) stays tracked in #120. Appreciate the thorough cross-reference!

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