Improve migration script (#1946)

- continue migration if number of rows changed during migration
- improve the sample command and remove unused TTL since it will be
copied from old table

Signed-off-by: Jun Guo <guo0693@gmail.com>

Author: guo0693

CHANGELOG.md

@@ -47,8 +47,8 @@ Changes by Version
             1.  You will need to run below command on the host you can use `cqlsh` to connect the the cassandra contact
              point
                 ```
-                KEYSPACE=test_keyspace TIMEOUT=1000 CQL_CMD='cqlsh host 9042 -u test_user -p test_password' bash
-                ./plugin/storage/cassandra/schema/migration/v002tov003.sh
+                KEYSPACE=jaeger_v1 CQL_CMD='cqlsh host 9042 -u test_user -p test_password --request-timeout=3000' 
+                bash ./v002tov003.sh
                 ```
                 The script will create new table `operation_names_v2` and migrate data from the old table.  
                 `spanKind` column will be empty for those data.  

plugin/storage/cassandra/schema/migration/V002toV003.sh

@@ -1,15 +1,15 @@
 #!/usr/bin/env bash
 
 # Create a new operation_names_v2 table and copy all data from operation_names table
-# Sample usage: KEYSPACE=jaeger_v1 TIMEOUT=1000 CQL_CMD='cqlsh host 9042 -u test_user -p test_password' bash
+# Sample usage: KEYSPACE=jaeger_v1 CQL_CMD='cqlsh host 9042 -u test_user -p test_password --request-timeout=3000' bash
 # ./v002tov003.sh
 
 set -euo pipefail
 
 function usage {
     >&2 echo "Error: $1"
     >&2 echo ""
-    >&2 echo "Usage: KEYSPACE={keyspace} TTL={ttl} CQL_CMD={cql_cmd}$0"
+    >&2 echo "Usage: KEYSPACE={keyspace} CQL_CMD={cql_cmd} $0"
     >&2 echo ""
     >&2 echo "The following parameters can be set via environment:"
     >&2 echo "  KEYSPACE           - keyspace"
@@ -64,11 +64,6 @@ fi
 
 csv_rows=$(wc -l ${old_table}.csv | tr -dc '0-9')
 
-if [[ ${row_count} -ne ${csv_rows} ]]; then
-    echo "Number of rows: $csv_rows in file is not equal to number of rows: $row_count in cassandra"
-    exit 1
-fi
-
 echo "Generating data for new table..."
 while IFS="," read service_name operation_name; do
     echo "$service_name,,$operation_name"