heroku-pg-extras/commands/cache_hit.js

'use strict'

const co = require('co')
const cli = require('heroku-cli-util')
const pg = require('heroku-pg')

const query = `
SELECT
  'index hit rate' AS name,
  (sum(idx_blks_hit)) / nullif(sum(idx_blks_hit + idx_blks_read),0) AS ratio
FROM pg_statio_user_indexes
UNION ALL
SELECT
 'table hit rate' AS name,
  sum(heap_blks_hit) / nullif(sum(heap_blks_hit) + sum(heap_blks_read),0) AS ratio
FROM pg_statio_user_tables;
`

function * run (context, heroku) {
  let db = yield pg.fetcher(heroku).database(context.app, context.args.database)
  let output = yield pg.psql.exec(db, query)
  process.stdout.write(output)
}

const cmd = {
  topic: 'pg',
  description: 'show the total size of all indexes in MB',
  needsApp: true,
  needsAuth: true,
  args: [{name: 'database', optional: true}],
  run: cli.command(co.wrap(run))
}

module.exports = [
  Object.assign({command: 'cache-hit'}, cmd),
  Object.assign({command: 'cache_hit', hidden: true}, cmd)
]