pagefish/index.html at master · peterburk/pagefish · GitHub

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<!--
	PageFish - A search engine with a static web server.

	2018-07-17
	Peter Burkimsher
	peterburk@gmail.com

	Example usage for OSM data: Type a city name, click search, see the results.

	How to build the index:

		cc -lm geonamesToIndex.c -o geonamesToIndex
		cat geonames_relations.txt | ./geonamesToIndex

	Benchmarks:

		> time grep -c "Paris" geonames_relations.txt
		0.366s = 366 ms

		Typical search time (by searching a few city names): 30 ms.

		This gives a 10x speedup compared to grep.

	Index building time:
		> time cat geonames_relations.txt | ./geonamesToIndex
		17.185s

	Having many small files in the index uses more space. But storage is cheap.
		Original file geonames_relations_name_id_lat_lon.txt: 25.8 MB
		Index size GeoNamesIndex: 94 MB

	How the hashing algorithm works:
		1. Convert every character in the query to a number. (Peter = 80, 101, 116, 101, 114)
		2. Add up the total of those numbers (80 + 101 + 116 + 101 + 114 = 512).
		3. Get the Unicode character for that number (512 = Ȁ).
		4. Load the index file that uses that character as a filename. (GeoNamesIndex/Ȁ.txt)
		5. Grep the query again within that file (clashes exist, e.g. "Dover" = 68 + 111 + 118 + 101 + 114 = 512)

	Why this is important:
		+ The router and filesystem help the search.
		+ Characters are just numbers. It's faster to search shorter strings.
		+ Server-side operations cost money. Client-side JavaScript is free.
		+ The index can be stored on a static file server e.g. Github.

	Known limitations:
		- Fuzzy matching isn't supported (but this is not a problem for Chinese) 			// fuzziness is off-by-one
		- Some characters aren't allowed in filenames, URLs, etc. 							// find a place for everything
		- The hash algorithm should be balanced so that index files are a similar size. 	// use a binary tree

	Name:
		• The plan is to turn this into a real search engine later.
		• Page stands for Peter's Alternative Google Engine
		• Fish stands for Filesystem Index Search Hash

	Future work:
		• Fix queries with accented characters (they don't seem to hash the same in C and JavaScript)
		• Make a more balanced hashing algorithm that still limits to a single character
		• Group the index into folders based on the number of characters in the query string (more important for large indexes)
		• Spellcheck and fuzzy matching by running multiple searches
-->

<html>

	<head>
		<title>PageFish</title>

		<meta charset="utf-8" />
		<style>
		  body {
			font-family: Tahoma, Geneva, sans-serif;
		  }
		p {
			margin-left: 50px;
		}

				.DefaultButtonOuter
				{
					border: 2px solid black ;
					border-radius: 8px;
					width: 96px;
					height: 26px;
					text-align: center;

					/*background-color: #99999a;*/
					background: #99999a; /* For browsers that do not support gradients */
					/*background: -webkit-linear-gradient(left top, red, yellow);*/ /* For Safari 5.1 to 6.0 */
					/*background: -o-linear-gradient(bottom right, red, yellow);*/ /* For Opera 11.1 to 12.0 */
					/*background: -moz-linear-gradient(bottom right, red, yellow); */ /* For Firefox 3.6 to 15 */
					background: linear-gradient(to bottom right, #dcdbde, #737374); /* Standard syntax */
				}

				.ButtonInner
				{
					border: 1px solid black ;
					border-radius: 5px;
					background-color: #dcdbde;
					width: 88px;
					height: 18px;
					text-align: center;
					margin: 3px;

					line-height: 18px;
					font-family: "Charcoal CY", "Virtue", Geneva, sans-serif;
					font-size: 11px;
					color: #000000;
				}

				.ButtonInner:active
				{
					background:#666666;
					color: #ffffff;
				}

		</style>

	</head>

	<body>

		<div>
			Type a city name:
		</div>

    	<textarea id="queryTextArea" name="text" rows="4" cols="40">Auckland</textarea>

		<div id="defaultButton" class="DefaultButtonOuter" style="width:158px">
			<div id="searchButton" class="ButtonInner" onclick="searchButtonClicked();" style="width:150px">
				Search
			</div>
		</div>

		<div id="searchTime">

		</div>

		<div id="resultsTable">

		</div>


	</body>

	<script>

		var searchQuery = "";
		var searchData = "";

		var startTime;
		var endTime;

		function replaceChars(thisString, searchString, replaceString)
		{
			//debugLog("replaceChars(" + thisString + "," + searchString + "," + replaceString + ")");

			return thisString.split(searchString).join(replaceString);
		} // end function replaceChars

		function searchLoadedData(searchText)
		{
			if (searchText == "")
			{
				document.getElementById("resultsHtml").innerHTML = "Search cancelled";
				return;
			}

			var resultsHtml = "";
			var resultsArray = [];

			var searchRegexString = "^" + "(.*" + searchText + ".*)";

			searchRegexString = searchRegexString + "$";

			var searchRegex = new RegExp(searchRegexString, "gm");

			//document.write(searchRegex);

			var searchResultsArray = searchData.match(searchRegex);


			return searchResultsArray;

		} // end function searchLoadedData


		function loadFile(filename)
		{
			var xmlhttp = new XMLHttpRequest();

			xmlhttp.onreadystatechange = function() {
				if (xmlhttp.readyState == XMLHttpRequest.DONE ) {
				   if (xmlhttp.status == 200)
				   {
				   		searchData = xmlhttp.responseText;

						var searchResultsArray = searchLoadedData(searchQuery);

						endTime = Date.now();

						var searchTime = endTime - startTime;

						var searchResultsHtml = "No Results"

						// Add maps link
						if (searchResultsArray != null)
						{
							var numberResults = searchResultsArray.length;

							for (var currentResult = 0; currentResult < numberResults; currentResult++)
							{
								var thisResult = searchResultsArray[currentResult];

								var thisResultArray = thisResult.split("	");
								var thisResultLon = thisResultArray[2];
								var thisResultLat = thisResultArray[3];

								var thisResultLink = "https://www.openstreetmap.org/#map=10/" + thisResultLat + "/" + thisResultLon;
								thisResultLink = "<a href=\"" + thisResultLink + "\" target=_blank>Map</a>";

								searchResultsArray[currentResult] = thisResult + "	" + thisResultLink;
							} // end for every result


							searchResultsHtml = searchResultsArray.join("</td></tr><tr><td>");

							searchResultsHtml = replaceChars(searchResultsHtml, "	", "</td><td>");

							searchResultsHtml = "<table><tr><td>Name</td><td>Relation ID</td><td>Longitude</td><td>Latitude</td><td>Link</td></tr><tr><td>" + searchResultsHtml + "</td></tr></table>";
						}


						document.getElementById("resultsTable").innerHTML = searchResultsHtml;

						document.getElementById("searchTime").innerHTML = "Searched in " + searchTime + " ms";

				   } // end if it loaded the KML
				   else if (xmlhttp.status == 400) {
					  alert('Error loading index file ' + filename);
				   }
				   else {
					   alert('Error loading index file ' + filename);
				   }
				}
			};

			xmlhttp.open("GET", filename, true);
			xmlhttp.send();

		} // end function loadFile

		function searchButtonClicked()
		{
			startTime = Date.now();

			searchQuery = document.getElementById("queryTextArea").value;

			var numberCharacters = searchQuery.length;

			var thisCharacterInt = 0;
			var searchQueryHashInt = 0;

			for (var currentCharacter = 0; currentCharacter < numberCharacters; currentCharacter++)
			{
				thisCharacterInt = searchQuery.charCodeAt(currentCharacter);

				searchQueryHashInt = searchQueryHashInt + thisCharacterInt;
			} // end for every character in the string

			var searchQueryHashString = String.fromCharCode(searchQueryHashInt);

			//document.getElementById("queryTextArea").value = searchQueryHashString;

			var filename = "OSM/GeoNamesIndex/" + searchQueryHashString + ".txt";

			console.log(filename);

			loadFile(filename);

		} // end function searchButtonClicked

	</script>

</html>