Proxy Pinning MySQL · RDS Oss · aws/agent-toolkit-for-aws · Skills Docs

Proxy Pinning MySQL · RDS Oss · aws/agent-toolkit-for-aws · Skills Docs

Pattern	Why It Pins	Diagnostic Query
Prepared statements (server-side)	Proxy can’t move prepared state between backends	`SHOW GLOBAL STATUS LIKE 'Com_stmt_prepare';` — if high, pinning is frequent
SET SESSION variables	Session state is backend-specific	`SELECT s.VARIABLE_NAME, s.VARIABLE_VALUE AS session_val, g.VARIABLE_VALUE AS global_val FROM performance_schema.session_variables s JOIN performance_schema.global_variables g USING (VARIABLE_NAME) WHERE s.VARIABLE_VALUE <> g.VARIABLE_VALUE;` — rows where session differs from global indicate a `SET SESSION` was issued
User-defined variables (`@var`)	Session-scoped, can’t be transferred	Check application code for `SET @var = ...` patterns
LOCK TABLES	Explicit lock is backend-specific	`SHOW GLOBAL STATUS LIKE 'Com_lock_tables';`
GET_LOCK() / RELEASE_LOCK()	Advisory locks are session-scoped	Check application code for `GET_LOCK()` usage
Temporary tables	`CREATE TEMPORARY TABLE` is session-scoped	`SHOW GLOBAL STATUS LIKE 'Created_tmp_tables';` — high values indicate risk
FOUND_ROWS()	Depends on previous query’s state	Check application code

Pattern	Notes
SET NAMES / SET CHARACTER SET	Pins if different from proxy default. Configure proxy default charset to match app.
SET TRANSACTION ISOLATION LEVEL	Pins for the duration of the transaction
Multi-statement transactions	Pinned for transaction duration (expected, not a problem if transactions are short)