SQLite 3.8.0 Release with next-generation query planner

https://www.sqlite.org/news.html?year=2013

by conductor • 13 years ago

245 91 13 years ago

mmastrac• 13 years ago

SQLite is one of the most important pieces of software you never see. I've used it in projects from many years back to recently and you know what's awesome about it? It Just Works.

leokun2• 13 years ago

Unless you want to use it with multiple users and connections, in which case it stops working. It's good for embedding data storage in clients and testing.

http://howfuckedismydatabase.com/sqlite/

asperous• 13 years ago

You basically just said your car is reliable unless you need a semi-truck, in which case your car is worthless.

eksith6• 13 years ago

Until 2010, I ran a forum on SQLite with 600 users/day + around 1000 posts/day on a single OpenBSD machine with 2gb RAM and 7200RPM HDD. We moved to Postgres when we passed 1600 posts/day.

There was some minor slowdown noticeable around 6AM - 10AM, but besides that, we never had major issues. The bottleneck was usually the network, not the DB.

Edit: Anyone interested in playing with SQLite should give the SQLite Manager plugin for FF a try : https://addons.mozilla.org/en-US/firefox/addon/sqlite-manage...

(I'm not affiliated with the developer, I just like the tool)

leokun2• 13 years ago

Apparently I'm wrong! Too late to edit. Good to know though, not afraid of saying something and getting downvotes if I'll learn something. :)

tomasien2• 13 years ago

I LOVE SQLITE - both only when Core Data handles it for me haha

pcunite• 13 years ago

Quote: "Do not fear the zero!"

I love SQLite ...

unono• 13 years ago

Is there something about sqlite that postgres can't come in to replace it completely (a kind of dynamic postgres that starts up and shuts down like sqlite). With mysql,postgres,and sqlite, the open source db industry gets diluted. Some kind of merger would be great.

edit: to below posters, I'm fully aware sqlite is embedded, i use it everyday for android. I'm just asking if there's actually a technical reason why sqlite and postgres (and mysql) couldn't be merged. A db that can be both embedded or run as server. This would reduce the duplication of effort in open source db community.

dnr• 13 years ago

SQLite isn't a replacement for postgresql (or vice versa). SQLite is a replacement for fopen.

Among its many advantages in that situation: a database is contained in a single file with minimal overhead, the source is shipped as one .c file and encouraged to be statically linked, and the code size is relatively small (compared to something like postgresql).

mamcx3• 13 years ago

I hope sqlite someday add functions and/or store procedures. Plus better error messages (like when a foreign key is violated)

bitserf• 13 years ago

Why would you want to use PostgreSQL in the contexts that SQLite is used?

SQLite is fantastic when you need a data store for mobile or embedded use, you'd like ad-hoc queries over your data with the option of adding indexes to speed up frequently used ones, you want transactional update to the data, and multi-user access is not a problem.

It's basically a much better replacement for the hash table on a disk approach of DBM libraries.

PostgreSQL would just be total overkill for this kind of scenario.

nraynaud4• 13 years ago

I just would like the simplicity of use of sqlite on my server. No socket, no connection, no driver that has to match the server, no config file in /etc, no user in /etc/passwd, no cruft.

hannibal5• 13 years ago

SQLite is database for clients and relatively small application specific databases. Postgres is database for servers.

Your Firefox browser and Skype client come with SQLite.

hrjet• 13 years ago

This is a brilliant idea.

If postgresql could have a single file, embedded mode, then it could replace sqlite.

The advantages of such a design would be: 1. All the optimisations and transaction guarantees of a full-featured DB 2. All the conveniences of a single file DB 3. Better utilisation of open-source resources as the OP points out.

On the other hand, the postgresql system might be bigger (in terms of code size and heap usage) than sqlite. So it may not be feasible to use in all embedded applications.

jeltz3• 13 years ago

I think embeddable mode is more realistic than single file since the single user mode used by for example pg_upgrade is quite close to that. Some features are missing though for wide use.

adrianlmm• 13 years ago

I haven't tried SQL Lite, I always used Firebird SQL embedded.

eksith6• 13 years ago

It's a pretty nice little DB for a lot of things.

If you just want to play with it a bit, there's a Firefox extension available : https://addons.mozilla.org/en-US/firefox/addon/sqlite-manage...

It's not very powerful, but you can play around with different schemas. You can even export to different formats and edit manually if you like.

mamcx3• 13 years ago

Wish it work on iOS...

jacques_chester2• 13 years ago

The related article on the new planner is great reading too: https://www.sqlite.org/queryplanner-ng.html

nraynaud4• 13 years ago

I'm here to declare my love for sqlite, a database that doesn't asks me to choose a root password (wtf, everybody hate passwords) and an application user password (double wtf), doesn't open a socket (being it unix on TCP), doesn't install a daemon somewhere in the system, doesn't need to be root to start, doesn't asks me to create a new dba user in my system, doesn't require me to be understand how the root daemon starter hands over the control to the dba user when something goes wrong at startup, and generally doesn't bother me with stuff that has really nothing to do with storing and querying data.

I don't run this in production only because I would have a hard time convincing everybody to do it or by cargo-culting my fears (depending on the project). But one day I will.

viraptor2• 13 years ago

So in short... if anyone gets the chance of an sql injection, they have access to all tables and all schemas from any app that can access your database. Privilege separation is a very good idea. Not opening the database file directly is a very good idea too.

Just to be clear, I'm not saying every application needs it. If you actually use it as a replacement for local files, that's great. If you use a multi-user app containing sensitive data - "root password (wtf, everybody hate passwords)" this is so wrong. Reminds me of "chmod 777 everything" - wtf, everybody hates dealing with permissions.

abtinf3• 13 years ago

The gp point that sqlite gets rid of all the "stuff that has really nothing to do with storing and querying data" still stands.

Sqlite eliminates almost all of the management overhead that other databases force on you, so its trivial to have one database per application. Indeed, I have never seen anyone bother with a multi-application sqlite db, which could also cause serious performance problems. So that renders you sql injection point moot.

As for permissions, its better to let the OS handle that than some half-baked database permissions system. Root accounts/passwords are a wtf in a production environment because they destroy auditability. If you really want permissions, it is trivial to create system user accounts for the application and assign the correct file permissions, or even isolate particularly sensitive information in its own file. Combine this with AppArmor to further lock down individual applications.

All of this is overkill, but so is a full blown RDBMS in many cases. If you are starting out building a new application, just target sqlite until you actually need something bigger. Odds are, YAGNI.

kamaal2• 13 years ago

If you are using sqlite for hosting a production scale app, you are doing it wrong.

If you want an database for your mobile app, or a web app use a full fledged database like MySQL or Postgres.

sqlite is for embedded storage applications, especially in the backend. Where the resource utilization foot print is supposed to be minimum, and where you running into situations where are you are reimplementing SQL like DSL's to query and write to files. Or say you just wish to maintain some structured form of inventory.

Best example I can give you is a web browser. There is a requirement to store a good deal of structured information, in a mechanism which requires little resource utilization, which doesn't require additional software like demons or a server to run or complicated deploy and maintain scenarios. Or even a strict configuration.

If you look at this use case you will see tons of backend application would be better off using a tool like sqlite than play with huge xmls and endless rewrite parts of SQL badly.

simias• 13 years ago

I love SQLite but I don't think it's fair to compare it directly to other rdbms. As the official website itself puts it:

"Another way to look at SQLite is this: SQLite is not designed to replace Oracle. It is designed to replace fopen()."

https://www.sqlite.org/whentouse.html

There are very few instances where I end up in a position where I have to decide whether I need to use postgres or sqlite, they have very different use cases.

Shorel2• 13 years ago

I don't think it is designed to replace fopen().

They can't say it, but it is designed to replace FoxPro and Access, or more generally: a local ODBC connection.

jeltz3• 13 years ago

Most of this is not true for PostgreSQL either. The only two things PostgreSQL needs to run is a daemon (it does not have to be actually daemonized) plus a unix socket, passwords, user accounts, root privileges, etc are all optional.

Sure SQLite (which I love) is easier to get running, but do not exaggerate issues of traditional RDBMs.

In PostgreSQL 9.3 which will be released in a couple of weeks they will also fix the cases where you may need to use sysctl to iincrease shared memory limits.

johnsoft• 13 years ago

For me at least, partial indices are the killer new feature of this release - https://www.sqlite.org/partialindex.html

chubs• 13 years ago

Be ready to hear more and more from SQLite as the world moves to mobile (iOS/android) - it really shines in that environment.

tomasien2• 13 years ago

Sqlite and Core Data are synonymous in my mind (hint: it's because I'm a terrible programmer)

meshko• 13 years ago

The write up of the NGQP seems (at least superficially?) weird: they say that the reason for the rewrite was poor performance on a particular artificial benchmark (8-way join.. how often do people join 8 tables in practice?). At the same time, I was surprised to learn that the only kind of join algorithm SQLite supports is nested loops. I would think they would benefit more from adding hash and merge joins instead of rewriting the QP from scratch.

lsb• 13 years ago

SQLite 3.7.17 already makes automatic indices, if none exists for the join, if the planner recommends it.

hobs• 13 years ago

I regularly do 20+ table joins.

recursive• 13 years ago

how often do people join 8 tables in practice?

If I were to judge based on my current experience, I'd say more often than they make queries with less than 8 joins. In the stored procedure I'm working on now, there are many queries with up to 20.

galapago• 13 years ago

"May you do good and not evil May you find forgiveness for yourself and forgive others May you share freely, never taking more than you give."

jcampbell1• 13 years ago

My favorite thing about SQLite is the business model. My understanding is the product is free, but they charge for their test suite. If you build hardware that is going to use SQLite, then you should pay for the test suite, and that funds the future development. It is a tautologically perfect business model. Revenue toward a rock solid project pays to make it even more rock solid.

abtinf3• 13 years ago

I don't know how much the test suite costs by itself, but it is included in Sqlite Consortium membership, which is a typical open source support-style business model. For $75k, you get almost a month of sqlite developer time and tons of support (eg their home phone numbers). Not a bad deal for companies that want deep sqlite integration or customized versions that fit on tight embedded systems.

https://www.sqlite.org/consortium.html

RDeckard• 13 years ago

They also sell advanced features such as encryption and compression.

H3g3m0n• 13 years ago

Charging for encryption now days is horrible. We should be encouraging devs to put encryption everywhere. It should be the default.

Personally I don't like it when projects mix money with opensource.

kamaal2• 13 years ago

But these days, any where you could possibly deploy SQLite are generally linux based platforms.

And you don't really worry about underlying hardware on those machines.

coob• 13 years ago

I'm sure every smartphone vendor would probably disagree with you there.

harrytuttle• 13 years ago

We've got a big windows SQLite deployment. We use it as the back end for our entire test suite and it works wonderfully.

hosay123• 13 years ago

Back in the sands in the time Sun also did this with Java. IIRC the associated license was a great cause of pain for open implementations of the JVM, since without passing the suite you couldn't call yourself Java, and with passing the suite (insert some horrible restriction here I forget)

pja• 13 years ago

Without passing the suite, you couldn't get the patent licences, so Sun could put you out of business if they chose to. Sun used the test suite to define what was and wasn't "Java" (you had to pass the whole test suite or you couldn't ship product) & thereby prevented anyone else from using the core language in interesting ways that Sun didn't approve of.

Google did an end-run around these restrictions by using the Dalvik virtual machine instead of the JVM where the crucial patents lurked, so Android didn't have to implement the whole of the Java library before they shipped.

Sami_Lehtinen• 13 years ago

"Query planner are what make SQL database engines so amazingly useful and powerful. (This is true of all SQL database engines, not just SQLite.)"

No it isn't. I have been using SQL databases which got absolutely horrible query optimizer totally ruining any performance exceptations. I have blogged about that, and I was very frustrated and disappointed with results.

Which is faster if id>100 or simply walking database by using series of selects select ... id=101 ... select ... id=102 ... Turns out that the later method is a much faster. Engineers also then suggested that I could optimize the query by using structure select ... id=101 UNION select ... id=102. That's simply insane. How ever the query was written, query otpimizer / planner should make sure that all these queries are delivered using similar background process. Of course that walk is impossbile to optimizer, because it's series of individual queries. But it's just crazy that select id>100 is slower than that!

Yes, you might have guessed that the SQL database I'm referring to isn't SQLite.

And finally, I love SQLite and use it for most of my (work & hobby) projects as local database.

ww5202• 13 years ago

Just curious, what database is that? If the index on id is a B+ tree rather than a hashtable, it's very unlikely id > 100 would be slower. You are issuing one query with it vs. N queries with the 2nd approach.

Were there a lot of qualified rows for id > 100? If there're a million rows qualified for id > 100, which way is faster?

chris_wot3• 13 years ago

The optimiser might not be using an index in the most optimal way. Sometimes you have to guide the optimiser and it may not have enough statistical data to get the best plan. One way of doing this is to rewrite the query. In this case, if I had to hazard a guess, the developers have suggested you break down the where clause from OR conditions to instead use a UNION ALL, which may help influence the optimizer to choose the most optimal plan.

Adding statistics or an index may help. Just understand that if your data distribution changes radically the index or rewritten query may no longer be valid.

tzury• 13 years ago

Just to remind us all what "testing" means[1]:

    As of version 3.8.0, the SQLite library consists of approximately 84.3 
    KSLOC of C code. (KSLOC means thousands of "Source Lines Of Code" or, 
    in other words, lines of code excluding blank lines and comments.) 
    By comparison, the project has 1084 times as much test code and 
    test scripts - 91452.5 KSLOC.

[1] http://www.sqlite.org/testing.html

orf• 13 years ago

People in this thread say SQlite is fine for apps with lots concurrent writes (people advocate running forums and other multi-user apps using it) but that's not correct in my experience. I wrote a blog[1] in Python that uses a Sqlite database and on each post view a view counter was incremented[2] using a simple UPDATE ... views = views + 1 on the post row. Removing this update caused page speeds to increase hugely, from ~10 requests a second to ~200 or so. Maybe I was doing it wrong, but I can't see how.

1. https://github.com/orf/simple

2. https://github.com/orf/simple/commit/2121401030cab4d500330e9...

sk5t• 13 years ago

I'm not familiar with the ORM here, but is it really just an increment ("update posts set ctr = ctr + 1 where id = 9") or a select, add one in code, and then an update? Also bear in mind that one operation in an explicit transaction like this is quite slow, at least prior to WAL.

liminal• 13 years ago

How does SQLite compare to H2? When would I want to use one or the other?

ww5202• 13 years ago

I guess when you want to use a pure Java solution. H2 is good that it's just a jar file. You pre-configure and package up everything in one bundle. There will be no setup. Things just work when you copy the bundle over.

ChrisBanner• 13 years ago

Ah, the beta presupposition: SQLite version 3.8.0 is actually one of the most heavily tested SQLite releases ever. Thousands and thousands of beta copies have be downloaded, and presumably tested...

netcraft• 13 years ago

I really wish there was something like sqlite to replace MS Access - actually I think what I really want is something to replace MS Excel that isn't MS Access. The ability to have a self contained file based database that can be moved around and shared, but that can also hook up to external data sets has a lot of use cases in enterprises. But it would require a good query view, the ability to create forms and reports, and have a sane sql dialect.

seabrookmx• 13 years ago

Well SQLite is already around and stable, so all you'd need then is a really good Access style front-end for it.

chris_wot3• 13 years ago

I love query planners and optimisers. However, here's where I get a bit bemused: as it states in the article, a query planner must often go on incomplete information. Therefore you have to know the underlying assumptions built into the planner.

This is where explain/execution plans are great. Unfortunately, even these aren't completely documented. SQL Server is not bad, and Postgres is not only well documented but you can read the source. Oracle is often a basket case - there are literally thousands of undocumented parameters that you can set, not to mention underlying data views that also haven't been documented. In fact, there have been whole books trying to unravel the Oracle CBO, but even the most obscure often admit that Oracle fix optimiser bugs which can cause an impact on query plans.

In some cases, you must implement hints, because there is no way of catering for all queries under all loads based on all possible data distributions. Sure, you can add a variety of different types of indexes, histograms and other statistics to try to influence the execution plan, but at the end of the day sometimes you simply have to add a hint to force a particular sort of join, etc.

I guess my main point as I muse on query optimizers/planners is that none of them are perfect. It occurs to me that one of the best so far is actually Postgres, but alas - they don't allow for hints.

What's my main point here? It really comes down to the fact that the ideal for database queries is to allow for a declarative syntax ("give me all rows of product x that are over $100") without having to worry about the mechanics of retrieving the data, it's just not entirely possible. You really need to give developers and database folks the ability to nail down the actual mechanics of data manipulation.

Shorel2• 13 years ago

I wish I could use it in the browser in a future proof way.

Web SQL Database rocks.

zzzeek2• 13 years ago

can it nest joins in parenthesis yet?

  SQLite version 3.7.15.2 2013-01-09 11:53:05
  Enter ".help" for instructions
  Enter SQL statements terminated with a ";"
  sqlite> create table a(id integer);
  sqlite> create table b(id integer);
  sqlite> create table c(id integer);
  sqlite> select a.id, b.id, c.id from a 
     ...>     left outer join (b join c on b.id=c.id) on b.id=a.id;
  Error: no such column: b.id

SQLite is now the only major database I'm aware of that still can't handle this syntax (postgresql, mysql, oracle, SQL server, firebird, etc., no problem. I'm also well aware of how to use a SELECT subquery as a workaround).

Supporting some crude form of stored procedure would be nice too (you can already add SQL functions, why not procedures?), so that a 3rd party can provide semi-native ALTER support (don't worry, I don't want to put ALTER into SQLite itself, I understand it requires rewriting of table data, I'd just like there to be a standard implementation of that approach somewhere).

edwinyzh• 13 years ago

It might be off-topic, but my dream is that SQLite would also become a document-based database, like MongoDB, but keep SQLite's lightweight and speed!

qaruxj• 13 years ago

If you really wanted, you could always take a FriendFeed style approach and create a document store on top of SQLite. http://backchannel.org/blog/friendfeed-schemaless-mysql

SQLite 3.8.0 Release with next-generation query planner

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