Truncate a DynamoDB table for a given Partition Key prefix

truncate_dynamodb_table.sh

#!/bin/bash

####
#### Deletes all rows from a given TABLE_NAME with a given PK PREFIX
####
#### This does do a FULL TABLE SCAN, and can be expensive
####
#### It does require you have a package called jq for parsing json, but you can get that through brew, apt-get, etc…
####

set -e

REGION=us-east-1
TABLE_NAME=SomeTable
PK_KEY=PK
SK_KEY=SK
# this double quote sneaks in from the json response
PREFIX=\"SOME_PREFIX

# declare arrays to be filled later
declare -a pks
declare -a sks

# Get full table scan results and store them in a temp file
aws dynamodb scan --region ${REGION} --table-name $TABLE_NAME > "/tmp/dynamo_${TABLE_NAME}_scan.txt"
echo "got scan results with count..."
cat "/tmp/dynamo_${TABLE_NAME}_scan.txt" | jq ".Count"

# Get arrays of PartitionKeys and SortKeys
pks=(`cat "/tmp/dynamo_${TABLE_NAME}_scan.txt" | jq ".Items[].${PK_KEY}.S"`)
sks=(`cat "/tmp/dynamo_${TABLE_NAME}_scan.txt" | jq ".Items[].${SK_KEY}.S"`)

length=${#pks[@]}

# Delete from id list
for ((i=0; i<$length; i++));do
  if [[ "${pks[$i]}" =~ ^${PREFIX} ]]
  then
    echo "$i: Deleting ${pks[$i]} from $TABLE_NAME..."
    aws dynamodb delete-item --region us-east-1 --table-name $TABLE_NAME --key "{\"${PK_KEY}\": {\"S\": ${pks[$i]}}, \"${SK_KEY}\": {\"S\": ${sks[$i]}}}"
  fi
done

# Remove id lists
rm "/tmp/dynamo_${TABLE_NAME}_scan.txt"