>>922
PDOStatementのデストラクタで毎回削除してしまうようだね

ext/pdo_pgsql/pgsql_statement.c
> static int pgsql_stmt_dtor(pdo_stmt_t *stmt TSRMLS_DC)
> {
...
> #if HAVE_PQPREPARE
...
> if (S->is_prepared) {
> spprintf(&q, 0, "DEALLOCATE %s", S->stmt_name);
> res = PQexec(H->server, q);