Delete all data from dynamo table without deleting the actual table

purge-dynamo-table.sh

#!/bin/bash

# jq-1.6, aws-cli/2.9.19

# shellcheck disable=SC2086
_scan_table() {
  local total_segments="$1"
  local segment="$2"

  shift || true
  shift || true

  local table_name="$1"
  local keys=( "${@:2}" )

  aws dynamodb scan \
    --table-name "${table_name}" \
    --attributes-to-get ${keys[*]} \
    --total-segments "${total_segments}" \
    --segment "${segment}"
}

_purge_table() {
  local total_segments="$1"
  local segment="$2"

  local table_name="$3"
  local file_name="__chunk_${segment}.json"
  local chunks

  chunks=$(_scan_table "$@" \
    | jq -r ".Items[] | tojson" \
    | awk '{ print "{\"DeleteRequest\": {\"Key\": " $0 "}}" }' \
    | jq -sc "_nwise(25)" \
    | awk -v table_name="${table_name}" '{ print "{\"" table_name "\":" $0 "}" }')

  for chunk in ${chunks} ; do
    local chunk_size=$(echo "$chunk" | jq ".${table_name} | length")

    if [ "${chunk_size}" -ne 0 ]; then
      echo "Deleting ${chunk_size} elements"
      aws dynamodb batch-write-item \
        --request-items "file://${file_name}" | jq
    else
      echo "${table_name} table is already empty"
    fi
    rm -rf "${file_name}"
  done
}

export -f _scan_table
export -f _purge_table

total_segments=${1}
shift || true

for segment in $(seq 0 $((total_segments-1)))
do
 nohup bash -c "_purge_table ${total_segments} ${segment} $*" &
done

# sh purge-dynamo-table.sh <total segments> <table name> <key attributes>
# sh purge-dynamo-table.sh 5 test id