Expand PostgreSQL hstore columns into plain columns with NodeJS

expand.js

const { Pool, Client } = require('pg');
const groupBy = require('lodash.groupby');

const pool = new Pool({
  host: 'localhost',
  database: 'db'
});

const oldPoolQuery = pool.query;
pool.query = (...args) => {
  console.log('QUERY:', args.join());
  return oldPoolQuery.apply(pool, args);
};

const selectColumns = (table) =>
  `SELECT column_name, udt_name FROM information_schema.columns WHERE table_name = '${table}'`;

const selectHstoreKeys = (table, column) =>
  `select distinct skeys(${column}) from ${table};`;

const groupByType = (columns) => {
  const { true: hstoreColumns, false: otherColumns } = groupBy(
    columns,
    (c) => c.udt_name === 'hstore'
  );
  return { hstoreColumns, otherColumns };
};

const createNewTable = async (table) => {
  const { rows: columns } = await pool.query(selectColumns(table));
  const { hstoreColumns, otherColumns } = groupByType(columns);

  const skeys = await Promise.all(
    hstoreColumns.map(({ column_name }) => {
      return pool.query(selectHstoreKeys(table, column_name)).then(({ rows }) => rows);
    })
  );

  const hstoreColumnsSelector = hstoreColumns
    .map(({ column_name }, index) => {
      const keys = skeys[index];
      return keys.map(
        ({ skeys: key }) => `${column_name}->'${key}' as ${column_name}_${key}`
      );
    })
    .reduce((acc, expandedColumns) => acc.concat(expandedColumns), []);

  const otherColumnsSelector = otherColumns.map(({ column_name }) => column_name);
  const allColumns = [...otherColumnsSelector, ...hstoreColumnsSelector].join(',\n');

  const selectStatement = `select \n${allColumns} from ${table}`;
  const createViewStatement = `create or replace view ${table}_plain as ${selectStatement}`;

  await pool.query(createViewStatement);
};

const main = async (tables = []) => {
  await Promise.all(tables.map((table) => createNewTable(table)));
  await pool.end();
};

const tables = [];

try {
  main(tables);
} catch (error) {
  console.error(error);
}