title: CPU 100% usage caused by unknown postgres query
body: <p>I installed <code>timescaledb</code> extension (v.5.0) for PostgreSQL (v9.6) on 16.04 Linux box and observes that Postgres process occupies 100% CPU:</p>
  
  <p>here is result of <code>top</code> command:</p>
  
  <pre><code>PID   USER      PR  NI    VIRT    RES    SHR S %CPU %MEM   TIME+   COMMAND
  19885 postgres  20   0  192684   3916   1420 S 98.3  0.1   5689:04 x3606027128                                     
  </code></pre>
  
  <p>I run query <code>SELECT pid, datname, usename, query FROM pg_stat_activity</code> and find two weird queries</p>
  
  <pre><code>pid   datname   username  query
  19882 postgres  postgres  select Fun013301 ('./x3606027128 &amp;')
  19901 postgres  postgres  select Fun013301 ('./ps3597605779 &amp;')
  </code></pre>
  
  <p>function <code>Fun013301</code> is not existed in postgres database. I cannot figure out what <code>./x3606027128</code> command is!?</p>