IndexedDB - Querying and Performance

Prepare yourselves

The Mobile has arrived

Go where no website has gone before

Scotty, beam me up

I have good internet bandwidth

Darth Vader Says
Work when you are disconnected too

What if I told you

that adding Offline support is easy ?

A simple website
DATA in
SERVER

DATA in
BROWSER

http://nparashuram.com/conference

Simple Read Operation
AjaxHandler = {
getSession: function (id) {
// code goes here
},
getAllSessions: function () {
// code goes here
}
}

var Session = Backbone.Model.extend({});
var SessionList = Backbone.Collection.extend({});

var singleSession = new Session();
singleSession.get(101);
view.update(singleSession);

var allSessions = new SessionList();
allSessions.fetch();
view.render(allSessions);

Backbone.sync = function (method, model, options, error)
{
switch (method) {
case "read":
// Methods for reading from database
break;
case "create":
// Create a record here
break;
case "update":
// Update Records
break;
case "delete":
// Delete record
}
RemoteDatabase.replicate();
});

case "read":// Pseudo Code
if (model.id) {// for a single Model
db.get(model.id,
function (err, res) {
if (err) {
error(err);
return;
}
options.success(res);
}
);
} else { // For all rows in the DB
db.getAll (
function (err, resp) {
if (err) {
error(err);
return;
}
options.success(resp);
}
);
}

With all that pseudo code

I totally understand you

case "read": // Real IndexedDB Code
var openReq = window.indexedDB.open("DatabaseName");
openReq.onsuccess = function () {
var db = openReq.result;
var transaction = db.transaction(["Model1”], "readonly");
var objectStore = transaction.objectStore("Model1");
var readReq = objectStore.get(model.id);
readReq.onsuccess = function () {
option.success(readReq.result);
};
};
openReq.onerror = function (e) {
options.error(e);
};
}

IndexedDB Refresher
http://yourwebpage.com search

Database Database
Transaction
Object Store Object Store

key : value Index key : value Index
key : value key : value
Cursor on Cursor on
key : value Index key : value Index

Cursor on Object Cursor on Object
Store Store

case "read":

if (model.id) {
var readReq = objectStore.get(model.id);
};
};
options.error(e);
};
}

You wrote so much code

Just to read a single record ?

case "read": // Jquery-IndexedDB Plugin

if (model.id) {
$.indexedDB("DatabaseName")
.objectStore("Model1")
.get(model.id) objectStore.get(model.id);
var readReq =
.done(function(data) {
};
})
readReq.onerror = function (e) {
.fail(function (error) {
options.error(e);
};
});
};
options.error(e);
};
}

case "read": // Jquery-IndexedDB Plugin
.get(model.id) • Less Verbose
.done(function (data) {
option.success(data); • Chainable API
}).fail(function (error) {
option.error(error);
• Use Promises
}); • Smart Defaults
• Almost transparent
.each(function (record) {
display(record);
}).done(function () {
// Finished with all records
Project :
}).fail(function () { gitbhub
// Error
}); /axemclion
/jquery-indexeddb

case "read":// Pouch DB Code
db.get(model.id, {},
function (err, res) {
if (err) {
error(err);
return;
}
options.success(res);
}
);
} else { // For all rows in the DB
db.allDocs ({},
function (err, resp) {
if (err) {
error(err);
return;
}
options.success(resp);
}
);
Pouch.replicate("idb://data","http://me.couchdb.com/data");
}

Sure, but can you query data ?

Querying IndexedDB

.where('price < 100')
.sortBy('price')
.desc()

objectStore.index('price').openCursor(
IDBKeyRange.lowerBound(100, false),
"prev"
);

Querying IndexedDB

.where('price < 100 and >= 200')
.sortBy('price')
.desc()

IDBKeyRange.bound(100, 200, false, true),
"prev"
);

Querying IndexedDB
var results = $.indexedDB("DatabaseName")
.sortBy('name')
.desc()
.done(function(results){
// do something with results
// results.length == ???
})
IDBKeyRange.bound(100, 200, false, true),
"prev"
);

Querying IndexedDB
.where('ratings > 4')
.sortBy('name')
.desc()
.each(function(result){
.done(function(results){
process each result
// do something with results
}) // results.length == ???
cursorReq = })
objectStore.index('name').openCursor();
cursorReq.onsuccess = function () {
if (cursorReq.result) {
val = cursorReq.result.value;
if (val.price < 100 && val.price > 200 && val.ratings > 4)
)
callback(val);
cursorReq.result.continue();
}
}

Querying IndexedDB
.where(‘Model2.empId < 5')
.sortBy('name')
.sortBy('price')
// process each result
});

Querying IndexedDB
.where(‘Model2.empId < 5 ')
.sortBy('name')
.sortBy('price')
// process each result
});
Fall back on Web Workers to do the job

• Sorting on multiple columns
• Where clauses across object stores
• Sorting and clauses across object stores

Project : //linq2indexeddb.codeplex.com/

ONE DOES NOT SIMPLY START USING INDEXEDDB

WITHOUT LOOKING AT PERFORMANCE

Comparing IndexedDB and WebSQL ?

Performance Analysis
• Common cases when writing an application
• Are string keys slower than integer keys
• Should I combine read and write transactions ?
• Started with JSPerf, Problems with Async Setup
• Using Benchmarkjs

Thanks to @slace for helping with code reviews

http://nparashuram.com/IndexedDB/perf

May the force be with you
http://nparashuram.com
@nparashuram

Resources
@OpenAtMicrosoft
(@obloch)
http://nparashuram.com/IndexedDB
http://www.html5labs.com/

IndexedDB - Querying and Performance

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