Running cql statements with shell script - shell

Question

I have a below shell script which reads a file and updates the table. But the problem with the below code is that a connection is established for running each sql statements. I am looking for recommendation to enhance this code.
#!/bin/bash
input="/Users/temp/newfile.txt"
while IFS= read -r var
do
echo "update keyspace.tableName set randomColumn='randomText' where random_id='$var'; exit" | ./cqlsh serverName -u username -p password
if [ $? -eq 0 ]; then
echo SUCCESS
echo "select random_id,randomColumn from keyspace.tableName where random_id='$var'; exit" | ./cqlsh serverName -u username -p password
else
echo FAIL
fi
done < "$input"

Answer 1

I suggest doing this with the Python driver if you'd like better performance.
This example should be roughly equivalent:
#! /usr/bin/env python3
from cassandra.cluster import Cluster
from cassandra.auth import PlainTextAuthProvider
cluster = Cluster(auth_provider=PlainTextAuthProvider(username='cassandra', password='cassandra'))
session = cluster.connect()
with open("/Users/temp/newfile.txt") as f:
for line in f:
try:
rows = session.execute("UPDATE keyspace.tableName SET randomColumn='randomText' WHERE random_id=%(var)s", {'var'=line})
print("SUCCESS")
for r in rows:
print(r)
except Exception:
print("FAIL")
edit: you can even go a step further and use prepared statements and async queries, which will provide very significant performance increases if you are making a large volume of queries.

Answer 2

cqlsh has a -f option which allows to run cql statement from a file. You could generate the cql statements by parsing your newfile.txt and then run cqlsh with -f option
At the very basic level, you could do something like this:
#!/bin/bash
input="newfile.txt"
while IFS= read -r var
do
echo "update ks.t1 set name='randomText' where id=$var;" >> result
done < "$input"
./cqlsh serverName -u username -p password -f result
if [ $? -eq 0 ]; then
echo SUCCESS
echo "select * from keyspace.tableName; exit" | ./cqlsh serverName -u username -p password
else
echo FAIL
fi

Answer 3

I suggest to use cqlsh -e with xargs :
#!/bin/bash
input="/Users/temp/newfile.txt"
while IFS= read -r var
do
echo "update keyspace.tableName set randomColumn='randomText' where random_id='$var';" | xargs cqlsh serverName -u 'username' -p 'password' -e
if [ $? -eq 0 ]; then
echo SUCCESS
echo "select random_id,randomColumn from keyspace.tableName where random_id='$var';" | xargs cqlsh serverName -u 'username' -p 'password' -e
else
echo FAIL
fi
done < "$input"