{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Done.\n",
      "Done.\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[]"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "%load_ext sql\n",
    "%sql sqlite:///complaint.db\n",
    "import time\n",
    "%sql drop index if exists state_index;\n",
    "%sql drop index if exists state_product_index;\n",
    "%sql drop index if exists helpful_index;\n",
    "%sql analyze"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "Activity 8: Indexes\n",
    "===========\n",
    "\n",
    "Let's play with the [consumer complaint database](https://catalog.data.gov/dataset/consumer-complaint-database) from data.gov"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(sqlite3.OperationalError) no such table: complaints [SQL: 'select count(*) from complaints;']\n"
     ]
    }
   ],
   "source": [
    "%sql select count(*) from complaints;"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true,
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "outputs": [],
   "source": [
    "%sql select * from complaints limit 5;"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Exercise 1: Query without an index\n",
    "\n",
    "First, let's start off by writing a query to find the **counts of the top 5 Product, State pairs** in the complaints database (return the product and state as well as the count).  Use the single-line syntax for simple timing so we can see how long the query takes:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "%time %sql # YOUR QUERY HERE"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Exerise 2: Single search key index\n",
    "\n",
    "Now create a _single-key_ index such that the above query is faster!  The syntax to create an index in SQL is:\n",
    "> DROP INDEX IF EXISTS index_name;\n",
    "> CREATE INDEX index_name ON table(attributes);"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "%%sql\n",
    "# CREATE YOUR INDEX HERE"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "%time %sql # TIME YOUR SAME QUERY HERE"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Exercise 3\n",
    "\n",
    "Now, create a _covering_ index for the query and then see how long it takes to run!"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "%%sql\n",
    "# CREATE YOUR INDEX HERE"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "%time %sql # TIME YOUR SAME QUERY HERE"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Exercise 3(b):\n",
    "\n",
    "Use EXPLAIN to see if sqlite used/recognized your covering index.  EXPLAIN is an operator that tells SQL to explain its query plan... we'll look into this in more depth later.  For now, the syntax is:\n",
    "> EXPLAIN QUERY PLAN your_query_here;"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "%%sql\n",
    "# EXPLAIN YOUR QUERY HERE"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.6.1"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 1
}