[fvlm]

Problem

With 3.1.1, production connections through a load balancer to database replicas
intermittently fail with:

• 1835 / HY000: Malformed communication packet
• 1210 / HY000: Incorrect arguments to mysqld_stmt_execute

The same SQL and bindings do not reproduce the errors against a single DB
without a load balancer. Changed delivery timing/socket-read boundaries seems
to be the trigger.

handlePrepare() resolves the statement before all metadata arrives.
MysqlConnectionStatement::execute() passes $result->params by value, so the
queued processor task retains incomplete definitions even after metadata arrives.
This produces malformed COM_STMT_EXECUTE packets.

Fix

Await complete definitions using the existing accessor:

--- a/src/Internal/MysqlConnectionStatement.php
+++ b/src/Internal/MysqlConnectionStatement.php
@@ -149,3 +149,3 @@
         return $this->getProcessor()
-            ->execute($this->statementId, $this->query, $this->result->params, $prebound, $args)
+            ->execute($this->statementId, $this->query, $this->result->getParameterDefinitions(), $prebound, $args)
             ->await();

Validation

• PHPUnit 9 regressions: three failures and one pass before the fix; all four
  pass afterward (missing/partial/complete definitions and preparation failure).
• composer cs-fix, composer cs, and Psalm: pass.
• Full suite with XDEBUG_MODE=off: 233 passed, 10 skipped, no failures or errors.
• Xdebug's develop mode triggered a deadlock in
  MysqlNestedTransactionTest::testNextResultBeforeConsumption in our setup;
  with Xdebug off, that test passes both before and after the fix.
• Checks ran on PHP 8.3.31, PHPUnit 9.6.37, and an isolated MariaDB 13.0.2 instance
  in an identical temporary copy; the full suite used a database-bootstrap override.
• Deterministic socket-pair test, real encoder, two integer bindings: with 0/1/2
  definitions initially available, payloads were 10/15/18 bytes before the fix;
  all correctly become 18 bytes afterward (excluding packet headers).
• Production errors no longer observed after patching. The synthetic reproduction
  verifies malformed encoding, not both live-server error codes.

Reproduce the regression

With development dependencies installed, run the new tests without a database:

XDEBUG_MODE=off composer test -- --bootstrap vendor/autoload.php test/MysqlConnectionStatementTest.php

The tests delay metadata completion via the event loop and check that execution
receives every definition, or propagates preparation failure without execution.

[bwoebi]

That's correct, the getParameterDefinitions() was added just for that purpose...

Thanks!