type-change.sh

#!/bin/bash
set -eu

function recreate {
    cat <<EOF > /tmp/query.sql
#standardSQL
SELECT CAST(id as STRING) as id, description  FROM test.first WHERE DATE(_PARTITIONTIME) = "$1";
EOF

    export partition=$(echo $1 | perl -ple 's/-//g')

    cat /tmp/query.sql | 
        bq query --append_table --schema_update_option=ALLOW_FIELD_ADDITION \
        --destination_table "test.third\$$partition" \
        --time_partitioning_type DAY
}

recreate 2020-05-01
recreate 2020-05-02