I am wracking my brains over this. I am trying to use a Korn Shell script to execute an Oracle PL/SQL procedure, using the Oracle command line interface (sqlplus). The script starts sqlplus in a coprocess, and the two processes communicate using a two-way pipe. The bgnice option is off, so both processes run at the same priority. The operating system is AIX 5.1.

Here's the problem. If I run the PL/SQL procedure using the script, it takes (quite literally) about ten times as long to run as it would take were I to start sqlplus myself, and run the procedure manually.

There is one more piece to this. Since I cannot predict how many lines will be output from the coprocess, I use a "suicidal read" technique to stop the script waiting indefinitely on the pipe.

Can anyone help?

Here is a code fragment:

while true ; do
   (sleep 1 ; kill $$ 2>/dev/null) &            # Set up alarm process to
   bp=$!                                        # kill read after 1 second

   OLDIFS="$IFS"                                # Read data from SQL Plus
   IFS=''                                       # without splitting into
   rc=0                                         # individual fields
   result=""
   read -rp result 2>/dev/null
   rc=$?
   IFS="$OLDIFS"                                # Restore field delimiters

   if (( rc != 0 )) ; then                      # If a read error occurred
      kill $bp 2>/dev/null                      # kill the alarm process
      exitnow=1                                 # exit from func and script
      break
   fi

   if kill $bp 2>/dev/null ; then               # If we killed the alarm
      set -- $result                            # Split data into fields

      if [[ "$1" = "SQL>" ]] ; then             # Remove leading SQL
         while [[ "$1" = "SQL>" ]] ; do         # prompts from output
            shift
            result=$(print "$result" | cut -c6-)
         done
      fi

   else
      sleep $pollInterval                       # Wait if alarm timed out
   fi
done