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Re: Replacing WebSQL with a Relational Data Model.

From: Keean Schupke <keean@fry-it.com>
Date: Tue, 26 Oct 2010 08:02:35 +0100
Message-ID: <AANLkTinQGH74i=rVWesMtm5Bev-c6eOTn7G74opmyDdQ@mail.gmail.com>
To: Jonas Sicking <jonas@sicking.cc>
Cc: public-webapps@w3.org
Hi,

It will be a lot faster with SQLite as the backend. Mobile apps depend on
access to the SQLite engine, and although it _could_ be implemented on top
of IndexedDB, there is no way its going to be fast enough... And the thought
of writing a decent query optimiser is a bit daunting.

The benefit of making it a standard, is that browser implementers can do
what they want, implement in JavaScript on top of IndexedDB, or pass through
to a proper database.

BTree's are old hat in the database space. Modern storage engines are using
Fractal-Trees for a 50-80 times speedup in write performance. The browser
should not be trying to compete with experienced database coders.

The relational storage model I am proposing will return a database table as
a list of objects, where each object represents a row, and the object has a
set of named properties representing each column.

Part of the power of the Relational Data Model is that it abstracts data
into columns and tables, and this is precisely what we want.


Regards,
Keean.


On 26 October 2010 01:50, Jonas Sicking <jonas@sicking.cc> wrote:

> On Mon, Oct 25, 2010 at 10:24 AM, Keean Schupke <keean@fry-it.com> wrote:
> > We (www.fry-it.com) produce websites and mobile apps. We have been
> looking
> > at HTML5 for developing mobile apps, and for the kind of apps that we
> want
> > to produce the client side WebSQL API provided what we needed. The
> IndexedDB
> > is not suitable (no joins, no compound indexes etc...).
> > Having discussed the reasons for the lack of progress of the WebSQL
> > standard, I wanted to get a feeling for the willingness of browser
> > implementers to consider a different approach to SQL, something more like
> > HaskellDB (a Haskell database layer) and LINQ for C#. Rather than
> > implementing an SQL like syntax, what I am proposing is to implement
> > relational algebra directly.
> > I have a published peer reviewed paper (Haskell Workshop 2004) where we
> > implemented a type safe relational algebra in Haskell, and my idea is to
> > port this to JavaScript. The API can be formally defined to implement the
> > complete relational algebra, and hence have a standardised API that can
> be
> > implemented in all browsers, yet would be capable of having different
> > backends (SQLite, Microsoft SQL Server, MySQL, PostgreSQL, Oracle etc...)
> > Here is an example of using relational algebra as a Domain Specific
> Language
> > in Haskell:
> > {- This is how we would write the relational statement in SQL.
> > UPDATE Animal
> >    SET Animal.location=?newLocation?
> >  WHERE Animal.animalid IN
> >          SELECT Contaminated.animal
> >            FROM Contaminated,Animal
> >           WHERE Animal.type=?animalType?
> >            AND Contaminated.type=?contaminationType?
> >            AND Animal.animalid=Contaminated.animal;
> > -}
> > -- This is how we would write it in a Haskell DSL.
> > moveContaminatedAnimal :: DAnimalType -> DCntdType -> DFarmId -> Query ()
> > moveContaminatedAnimal animalType contaminationType newLocation = do
> >     a1 <- table animalTable
> >     a2 <- restrict a1 (\r -> r!AnimalType `SQL.eq` animalType)
> >     c1 <- table contaminatedTable
> >     c2 <- restrict c1 (\r -> r!CntdType `SQL.eq` contaminationType)
> >     j1 <- join SqlInnerJoin a2 c2 (\r -> r!AnimalId `SQL.eq`
> r!CntdAnimal)
> >     j2 <- project j1 (CntdAnimal .*. HNil)
> >     doUpdate animalTable
> >         (\_ -> AnimalLocation .=. toSqlType newLocation .*. HNil)
> >         (\r -> r!AnimalId `SQL.elem` relation j2)
> >
> > The syntax would obviously be different, but I would expect something
> like
> > (It may end up looking nothing like this, as I need to think about the
> best
> > way of representing the Haskell Relation Monad in JavaScript).
> > -- this is something like what would be required in JavaScript
> > function moveContaminatedAnimal(animalType, contaminationType,
> newLocation)
> > {
> >     a1 = new Table(animalTable);
> >     a2 = new Restriction(a1, new Eq(function(row) {row[AnimalType]},
> > animalType));
> >     c1 = new Table(contaminatedTable);
> >     c2 = new Restriction(c1, new Eq(function(row) {row[CntdType]},
> > contaminationType));
> >     j1 = new InnerJoin(a2, c2, new Eq(function(row) {row[AnimalId]},
> > function(row) {row[CntdAnimal]}));
> >     j2 = new Projection(j1, [CntdAnimal]);
> >     update(animalTable, function(row) {row[AnimalLocation] =
> newLocation},
> > new Elem(function(row) {row[AnimalId], j2}));
> >
> > This constructs the update Animal query from the "Farm" database, which
> is a
> > commonly used example schema in academic papers. NOTE: the implementers
> are
> > free to try to write a relational database in JavaScript, but most
> > implementations would construct the SQL query string and then execute it
> on
> > an SQL database backend (SQLite / PostgreSQL / MySQL).
> > Its pretty easy to define the complete relational algebra, the base Query
> > class would need the following sub-classes:
> > SqlBinaryOp = SqlAdd | SqlSub | SqlMul | SqlDiv | SqlMod | SqlEq
> >     | SqlGe | SqlGt | SqlLt | SqlLe | SqlNe | SqlAnd | SqlOr | SqlIn
> > SqlAggrOp = SqlCount | SqlSum | SqlMax | SqlMin | SqlAvg | SqlStdDev |
> > SqlVariance
> > SqlRelationOp = SqlInnerJoin | SqlLeftJoin | SqlRightJoin | SqlFullJoin
> > SqlSetOp = SqlUnion | SqlIntersection | SqlDifference
> > Table, Projection, Restriction, Extension, Limit, Order, Join, Union,
> > Intersect, Except
> > and the methods: select, update, insert, delete
> > This would pretty much represent a port of my Haskell work to JavaScript.
> > The Haskell code also includes schema management, enabling the entire
> schema
> > to be defined, as data, and allowing the database to be created or
> validated
> > against the schema.
> > Here is the schema for the Farms table in Haskell:
> > {- domains -}
> > newtype DFarmId = DFarmId Int deriving (Show,Eq,ToSqlType
> > SqlInteger,FromSqlType SqlInteger)
> > newtype DFarmName = DFarmName String deriving (Show,Eq,ToSqlType
> > SqlVarchar,FromSqlType SqlVarchar)
> > newtype DFarmCounty = DFarmCounty String deriving (Show,Eq,ToSqlType
> > SqlVarchar,FromSqlType SqlVarchar)
> > newtype DFarmerId = DFarmerId Int deriving (Show,Eq,ToSqlType
> > SqlInteger,FromSqlType SqlInteger)
> > data FarmId = FarmId deriving Show
> > data FarmName = FarmName deriving Show
> > data FarmCounty = FarmCounty deriving Show
> > data FarmOwner = FarmOwner deriving Show
> > type FarmTable = Table (
> >     FarmId :=: Attribute DFarmId SqlInteger :*:
> >     FarmName :=: Attribute DFarmName SqlVarchar :*:
> >     FarmCounty :=: Attribute DFarmCounty SqlVarchar :*:
> >     FarmOwner :=: Attribute DFarmerId SqlInteger :*:
> >     HNil)
> > farmTable :: FarmTable
> > farmTable = newTable "Farm" (
> >     FarmId .=. Attribute (attr { attrName="farmid", attrType="SERIAL" })
> .*.
> >     FarmName .=. Attribute (attr { attrName="farmname", attrSize=20 })
> .*.
> >     FarmCounty .=. Attribute (attr { attrName="county", attrSize=15 })
> .*.
> >     FarmOwner .=. Attribute (attr { attrName="owner" }) .*.
> >     HNil)
> >
> > We could do something similar in JavaScript for table creation and
> > validation with version control and selective automatic update (the code
> can
> > derive some updates automatically, like if you add a new column to a
> table
> > that is nullable or has a default value).
> > As this is a relational data model, it can be entirely defined as an
> > abstract API, with no reference to any SQL at all. I could provide a
> > reference implementation written in JavaScript on top of WebSQL, but the
> > idea would be for browser implementers to implement directly using SQLite
> > (for example).
> > I would appreciate any advice on how to proceed with this? If
> implementers
> > would be interested in implementing a relational API?
>
> Hi Keean,
>
> This definitely sounds interesting, though admittedly I have a hard
> time following the details of it. However, like Jeremy, I don't see us
> doing yet another storage mechanism. But I do think this could work
> really well as additional functionality added to IndexedDB.
>
> Adding support for things like joins, filters and edit operators is
> something that I think would be interesting to look at for next
> version of IndexedDB. In the meantime I'd love to see prototypes
> implemented in javascript on top of IndexedDB. You can probably even
> prototype the exact API that you think this should have.
>
> One thing that I'm wary of is going the full relational route of
> requiring that values be split up into columns. It's really nice that
> javascript objects can be stored as-is, and then use key-paths to
> access specific values within an object. But I think that should be
> doable while still keeping the benefits of your proposal.
>
> / Jonas
>
Received on Tuesday, 26 October 2010 07:03:19 GMT

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