fix: serialize data instead of pointer in plan_foreign_modify #548
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Fix PostgreSQL server crash when using prepared statements with foreign tables. PostgreSQL caches query plans after ~5-6 executions. The previous implementation stored a raw pointer to FdwModifyState in fdw_private, which became invalid after end_foreign_modify freed the state. Solution: - Add FdwModifyPrivate struct holding serializable reconstruction data - Serialize table OID, rowid info (not pointer) in plan_foreign_modify - Create fresh FdwModifyState in begin_foreign_modify for each execution Also includes stress test for issue supabase#482 that executes 15 parameterized INSERT operations to validate the fix. Fixes supabase#482 Related to supabase#237
Fixes PostgreSQL server crash when using prepared statements with foreign tables (issue supabase#482). The root cause was that PostgreSQL caches query plans after ~5-6 executions (generic plan optimization). The previous implementation stored a raw pointer to FdwModifyState in fdw_private, which became invalid after end_foreign_modify freed the state. Subsequent executions with cached plans dereferenced this stale pointer, causing a crash. Solution: - Add FdwModifyPrivate struct holding serializable reconstruction data - Serialize table OID, rowid info (not pointer) in plan_foreign_modify - Create fresh FdwModifyState in begin_foreign_modify for each execution This ensures each query execution gets a valid FDW instance and state, even when PostgreSQL reuses a cached query plan and skips planning.
Validates fix for issue supabase#482 by executing 15 parameterized INSERT operations - enough to trigger PostgreSQL's generic plan caching. Before the fix, this would crash around iteration 7.
Member
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thanks for the PR! Can you fix the clippy issue in CI? |
Contributor
Author
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@burmecia I will work on this today, tomorrow or during weekend but will be done by next week |
Fix uninlined-format-args clippy warning by using inline variable
in format string: format!("stress_{i}") instead of format!("stress_{}", i)
Contributor
Author
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@burmecia All checks passed, fixed the clippy issues in CI. |
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Summary
Fix PostgreSQL server crash when using prepared statements with foreign tables.
Fixes #482
Related to #237
Problem
PostgreSQL caches query plans after ~5-6 executions (generic plan optimization).
The previous implementation stored a raw pointer to
FdwModifyStateinfdw_private, which became invalid afterend_foreign_modifyfreed the state.Subsequent executions with cached plans dereferenced this stale pointer, causing
a crash.
Solution
FdwModifyPrivatestruct holding serializable reconstruction dataplan_foreign_modifyFdwModifyStateinbegin_foreign_modifyfor each executionChanges
supabase-wrappers/src/modify.rs: Core fix - serialize data instead of pointerwrappers/src/fdw/clickhouse_fdw/tests.rs: Added stress testTest Plan