edwinlab

package main

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"encoding/hex"
	"fmt"
)

edwinlab

The problem

In some cases, it is possible that PostgreSQL tables get corrupted. This can happen in case of hardware failures (e.g. hard disk drives with write-back cache enabled, RAID controllers with faulty/worn out battery backup, etc.), as clearly reported in this wiki page. Furthermore, it can happen in case of incorrect setup, as well.

One of the symptoms of such corruptions is the following message:

ERROR: missing chunk number 0 for toast value 123456 in pg_toast_45678

This almost surely indicates that a corrupted chunk is present within a table file. But there is a good way to get rid of it.

edwinlab

package main

import (
   "fmt"
   "sync"
)

func main() {
   ConcurrentFunctions(func1, func2, func3, func4)
}

edwinlab

ISO - 25010 standard for product quality Quality Attributes in Software Architecture

edwinlab

package query

import (
	"fmt"
	"strings"
)

type Builder struct {
	table string
	query string

edwinlab

Working with time in Go is pretty straightforward.

Times

Get the current local time:

now := time.Now()                                   // 02 Apr 15 14:03

Construct a time with Date(y, m, d, h, m, s, ns, loc):

edwinlab

package main

import (
    "crypto/hmac"
    "crypto/sha256"
    "fmt"
    "encoding/base64"
    "strings"
)

edwinlab

package main

import (
	"crypto/hmac"
	"crypto/sha256"
	"encoding/base64"
	"encoding/hex"
)

func main() {

edwinlab

module Callable
  extend ActiveSupport::Concern
  class_methods do
    def call(*args)
      new(*args).call
    end
  end
end

edwinlab

# Takes a table name, and an array of hashes where keys are column names and values are values.
# Expects hashes to all contain the same keys.
def bulk_insert(table, rows)
  columns = rows.first.keys

  to_insert = rows.map do |d|
    vals = columns.map {|k| d[k] }
    ActiveRecord::Base.send(:replace_bind_variables, "(#{vals.length.times.collect {'?'}.join(',')})", vals)
  end