---
id: scan-postgresql
priority: high
status: unscanned
created: 2026-03-23
---

## Target

**Repo:** `https://github.com/postgres/postgres`
**Language:** C
**Why:** Query planner join graph traversal — linear list scans in path enumeration or join-order search inflate planning time on queries with many joined tables.

## Scan command

```bash
# Shallow clone
git clone --depth 1 https://github.com/postgres/postgres /tmp/postgresql

# Submit to unsandbox
cat > /tmp/scan-postgresql.sh << 'EOF'
#!/usr/bin/env bash
set -euo pipefail
GRAPH_KW="tarjan|strongly.connected|dfs|scc|topolog|topo.sort|cycle|reachab|postorder|dominator|liveness|digraph|shortest.path|path.find"
MEM="lappend|list_member|listMember|foreach.*list|list_cell|for_each_cell|lcons|list_concat"
find /tmp/postgresql/src/backend/optimizer -name "*.c" -o -name "*.h" | sort | while read f; do
  graph_lines=$(grep -inE "$GRAPH_KW" "$f" 2>/dev/null | cut -d: -f1 | head -5 || true)
  [ -z "$graph_lines" ] && continue
  while IFS= read -r lineno; do
    s=$(( lineno > 20 ? lineno - 20 : 1 )); e=$(( lineno + 20 ))
    hit=$(sed -n "${s},${e}p" "$f" 2>/dev/null | grep -iE "$MEM" | head -1 | sed 's/^\s*//' || true)
    [ -n "$hit" ] && echo "CANDIDATE\t${f}:${lineno}\t${hit}"
  done <<< "$graph_lines"
done
EOF
export UNSANDBOX_PUBLIC_KEY=unsb-pk-russ-test-isth-best
export UNSANDBOX_SECRET_KEY=unsb-sk-rk46c-3zvpg-zjf6z-hjrge
~/git/un-inception/build/un /tmp/scan-postgresql.sh
```

## Key files to check

- `src/backend/optimizer/path/allpaths.c` — Path enumeration for join graph; rel/path list membership
- `src/backend/optimizer/path/joinpath.c` — Join path construction; inner/outer relation list scans
- `src/backend/optimizer/plan/planmain.c` — Plan generation; join relation set operations
- `src/backend/nodes/list.c` — Core List implementation; `list_member` is O(N)

## Expected pattern

`list_member(visited, rel)` or equivalent `foreach` loop checking whether a `RelOptInfo` or `Path` node has already been processed, inside `make_rel_from_joinlist` or a similar join-graph enumeration function — O(N) per check producing O(N²) overall.

## Acceptance criteria

- [ ] Scan run and results saved to `tools/scan-results/postgresql.txt`
- [ ] All CANDIDATE hits triaged (confirmed defect or false positive)
- [ ] If confirmed: defect ticket created in `tools/tickets/defects/`