Generate random IDs, rather than ordering the whole table by rand(), …

…on full table queries.

random.js

@@ -40,20 +40,20 @@ function htmlifyListOfPokemon(generatedPokemonJson) {
 		output += htmlifyPokemon(generatedPokemon[i]);
 	}
 	output += '</ol>';
-	
+
 	return output;
 }
 
 // Converts JSON for a single Pokémon into an HTML list item.
 function htmlifyPokemon(pokemon) {
 	var title = (pokemon.shiny) ? 'Shiny ' + pokemon.name : pokemon.name;
-	
+
 	if (pokemon.sprite) {
 	var out = '<li title="' + title + '">';
 	} else {
 	var out = '<li class="imageless">';
 	}
-	
+
 	if (pokemon.nature) {
 		out += '<span class="nature">' + pokemon.nature + "</span> ";
 	}
@@ -64,8 +64,8 @@ function htmlifyPokemon(pokemon) {
 	if (pokemon.sprite) {
 		out += '<div class="wrapper"><img src="' + pokemon.sprite + '" alt="' + title + '" title="' + title + '" /></div>';
 	}
-	
+
 	out += '</li>';
-	
+
 	return out;
-}
+}

random.php

@@ -48,29 +48,28 @@
 	$paramArray[] = $tier_column . ' = "FE"';
 } else {
 	// We want to query for 2 of the 3 tiers, leaving out either Ubers or NFEs.
-	if (count($paramArray) == 0) {
-		// If there are no parameters so far, it's more efficient to take the
-		// union of two equalities rather than one inequality.
-		if ($ubers) {
-			$paramArray[] = '(' . $tier_column . ' = "FE" OR ' . $tier_column . ' = "Uber")';
-		} else if ($nfes) {
-			$paramArray[] = '(' . $tier_column . ' = "FE" OR ' . $tier_column . ' = "NFE")';
-		}
-	} else {
-		// If there already are some other parameters, it's more efficient to use
-		// the index for them remove the unwanted tier by inequality.
-		if ($ubers) {
-			$paramArray[] = '(' . $tier_column . ' != "NFE")';
-		} else if ($nfes) {
-			$paramArray[] = '(' . $tier_column . ' != "Uber")';
-		}
+	if ($ubers) {
+		$paramArray[] = '(' . $tier_column . ' != "NFE")';
+	} else if ($nfes) {
+		$paramArray[] = '(' . $tier_column . ' != "Uber")';
 	}
 }
 $parameters = (count($paramArray) > 0) ? "WHERE " . implode(" AND ", $paramArray) : "";
 
 // Connect to the database and execute the query.
 $connection = new mysqli($sql_host, $sql_username, $sql_password, $sql_database);
-$dbOutput = $connection->query("SELECT id, name FROM dex " . $parameters . " ORDER BY rand() LIMIT $n ");
+if ($parameters == "") {
+	// If we're generating from all Pokemon, it's much more efficient to generate
+	// IDs and then query them directly, rather than randomizing the whole database.
+	$max = $connection->query("SELECT COUNT(*) AS count FROM dex")->fetch_object()->count;
+	$ids_array = generate_distinct_random_numbers(1, $max, $n);
+	$ids_string = implode(", ", $ids_array);
+	$sql = "SELECT id, name FROM dex WHERE id IN (" . $ids_string . ")";
+} else {
+	$sql = "SELECT id, name FROM dex " . $parameters . " ORDER BY rand() LIMIT $n";
+}
+
+$dbOutput = $connection->query($sql);
 
 // Convert the results to an array.
 while($row = $dbOutput->fetch_assoc()) {

utils.php

@@ -7,7 +7,7 @@
 function get_or_set($get_key, $default, $possible_values = null) {
 	$using_boolean = ($default === true || $default === false);
 	$validate_from_list = ($possible_values != null);
-	
+
 	if (isset($_GET[$get_key]) && (!$validate_from_list || in_array($_GET[$get_key], $possible_values))) {
 		if ($using_boolean) {
 			return filter_var($_GET[$get_key], FILTER_VALIDATE_BOOLEAN);
@@ -31,11 +31,23 @@ function redirect($path) {
 		$protocol = (isset($_SERVER['HTTPS'])) ? 'https' : 'http';
 		$path = $protocol . '://' . $_SERVER['HTTP_HOST'] . $path;
 	}
-	
+
 	header('Location: ' . $path);
 	die();
 }
 
+// Most efficient for large ranges ($max-$min) and small $n values.
+function generate_distinct_random_numbers($min, $max, $n) {
+	$numbers = array();
+	while (count($numbers) < $n) {
+		$number = mt_rand($min, $max);
+		if (strrpos($numbers, $number) === false) {
+			$numbers[] = $number;
+		}
+	}
+	return $numbers;
+}
+
 
 //////// LISTS for data validation, default values, and generation of natures ////////
 
@@ -55,4 +67,4 @@ function redirect($path) {
 	'nfes' => true,
 	'sprites' => true,
 	'natures' => false
-);
+);