using either ksh bash how to have performance effective way - bash

Question

112345D000000000000129
123456D000000000000129
112345C000000000000129
123456C000000000000129
123456C000000000000126
position 2-6 is the account number
position 7-22 is the debit or credit value based on D or C in 7th position
want to sum the credit and debit value on the per account basis
tried
awk '{array[substr($0,7,1)]+=substr($0,8,15)+0} END{for(i in array){print array[i]}}')"
but since the file is huge its taking more time is there a way we can find out this one more faster
MVCE
fileA contains the account number + other info
fileB contains the exampe above with debit credit
typeset -i stbal2
typeset -i endbal2
DONE=false
until $DONE; do
read s || DONE=true
accountnumber=${s:1:10} //account number
endbal=${s:26:1} //contain + or - sign
endbal1=${s:11:15} //balance
endbal2=$endbal1 //strip of leading zeros
endbal3=$endbal$endbal2 //concatenate the sign with balance
//similar process as above to get the start balance
stbal=${s:42:1}
stbal1=${s:27:15}
stbal2=$stbal1
stbal3=$stbal$stbal2
creditdebit="$(grep "${bban}" ${fileB} | awk '{array[substr($0,7,1)]+=substr($0,8,15)+0} END{for(i in array){print array[i]}}')"
set -- $creditdebit
... further logic
done < ${fileA}

Answer 1

Without a complete MCVE its a guess but this might be what you're looking for, using GNU awk for true 2D arrays:
$ awk '
{ tots[substr($0,7,1)][substr($0,2,5)] += substr($0,8) }
END {
for (type in tots) {
for (id in tots[type]) {
print type, id, tots[type][id]+0
}
}
}
' file
C 12345 129
C 23456 255
D 12345 129
D 23456 129

Answer 2

in ksh you might do something like that : (myfile.txt being your information file)
#!/bin/ksh
typeset -A Ledger
typeset -i amount
typeset -L10 Col1
typeset -L10 Col2
while read line
do
account=${line:1:5}
action=${line:6:1}
amount=${line:7:21}
if [[ $action == "C" ]]; then
Ledger[$account]=$(( ${Ledger[$account]} + $amount ))
elif [[ $action == "D" ]]; then
Ledger[$account]=$(( ${Ledger[$account]} - $amount ))
fi
done < myfile.txt
Col1="Account"
Col2="Balance"
print "$Col1$Col2\n"
for i in ${!Ledger[#]}; do
Col1=$i
Col2=${Ledger[$i]}
print "$Col1$Col2"
done
With your example my output is :
Account Balance
12345 0
23456 126
Hope it could help