8 ms·

Datomic Pro Starter Edition

111 points by puredanger 13y ago

tony_landis 13y ago
I really like what the guys at cognitect are doing.
espeed 13y ago
This is great. Having a free Datomic version that matches Datomic Pro's architecture and supports all of its external storage engines certainly simplifies the scale path and makes design decisions easier. BTW: The pricing page has more details (http://www.datomic.com/pricing.html http://www.datomic.com/pricing.html) -- scroll down to see a comparison.
deleted 13y ago
[deleted]
sgrove 13y ago
Wow, very cool indeed. We worked on an open-source community[1] tool using Datomic/Codeq[2], and the ops portion was/has been pretty unpleasant. I'd love to see Datomic-as-a-Service popup, even as a only-meant-for-starter-projects, just so that experimenting with it could be that much easier. That might be possible with the new license, depending on how the Cognitect team sees it. [1] The service is a frontend to Codeq, having imported many Clojure repos: http://www.jidaexplorer.com/ http://www.jidaexplorer.com/ [2] http://blog.datomic.com/2012/10/codeq.html http://blog.datomic.com/2012/10/codeq.html EDIT: Added links.
- drcode 13y ago
  Yeah, a Datomic service would be soooo nice.
- dustingetz 13y ago
  I would like to know more about datomic from an ops perspective if you feel like elaborating?
  - cgag 13y ago
    Yes, same, I think a lot of people would be interested.
    - sgrove 13y ago
      I would ask coolsunglasses as he's been using it in production for far longer in a bigger installation than we have.
  - jeletonskelly 13y ago
    I've been working with Datomic, as a developer, in a production environment for the last 4-5 months. In terms of the work done by your ops guys, I'd say it really depends on how you're using it. Datomic has it's own AMI, which can be a hassle if you're used to rolling your own (which we ended up doing). I'd say one of the biggest challenges to overcome on the ops side is dealing with transactor failures. If a transactor dies, then the data from the peers will likely just fall on the floor. If you use DDB as a store, you have to keep an eye on your provisioning and scale appropriately.
lucian1900 13y ago
The name is a bit silly. It should be called just "Datomic Starter". I'm still hoping for an open source edition :)
VaedaStrike 13y ago
This opens so many doors all around. I'm literally giddy at this news. I want to leave my day job right now and go home and work on my Cognitect stack web app. I hope I can quickly get to the point where I need to (and then will be far more able to) purchase Datomic.
stolio 13y ago
Can anybody explain how the 2-peer restriction works with web-apps? It's my biggest fear in making the jump.
- coolsunglasses 13y ago
  Two JVM processes, far as I'm aware. In practice, a single peer gets you pretty far, especially if you're a Clojure user.
  - stolio 13y ago
    I guess where I'm getting lost is the terminology - I was under the impression that end-users are peers[0], so I'm worried about maxing out at two users. But if the limit is whatever a transactor can handle then I doubt I'd ever hit it and I might as well commit. I'm looking at using it as part of a Clojure backend, if that matters. [0] - http://docs.datomic.com/javadoc/datomic/Peer.html http://docs.datomic.com/javadoc/datomic/Peer.html edit: grammar
    - redinger 13y ago
      From http://docs.datomic.com/architecture.html http://docs.datomic.com/architecture.html "A Peer is a process that manipulates a database using the Datomic Peer library. Any process can be a Peer - from Web server processes that host sites or services, to a daemon, GUI application or command-line tool. The Datomic-specific application code you write runs in your Peer(s)."
      - stolio 13y ago
        OK, thanks. It just clicked. For anybody wondering what clicked: I'd have Datomic running with one peer, and that peer would serve as many end-users as it could handle. If necessary I could add a second peer and double the read-query power. And that's more than enough for my little web-app. Given the nature of Datalog (https://www.youtube.com/watch?v=bAilFQdaiHk https://www.youtube.com/watch?v=bAilFQdaiHk) I'm getting excited.
coolsunglasses 13y ago
Using Datomic Pro at work for a data warehouse and soon for another project for <REDACTED>. I'm working on a migration toolkit for Datomic. (Migrating schemas, not between database kinds.) Ask me questions about the API, my experience with ops, or anything else if you like.
- dustingetz 13y ago
  Can you ramble about how datomic is from ops perspective for a moment if you will? thanks
  - coolsunglasses 13y ago
    Just to clarify, I don't know what problems sgrove ran into, I've asked him in IRC and will elaborate if he tells me, but at present, I dunno. So here's what I have encountered: Datomic's primary limitation is at the transactor level. Storage is a non-issue, especially if you're using DynamoDB. Even with PostgreSQL write-throughput was ridic because of the way they're using the database. Transactor fail-over I'm not sure I'd take too seriously, but I don't think they'll drop any writes on the floor either. You shouldn't attempt to run a datomic transactor on a cheapo VPS. Try to put together at least 4 gb of RAM. Which is the same as what's currently standard for consumer laptops. No excuses. Deploying Datomic itself is straight-forward. The config is super simple and all you need as a dependency is Java. I'm actually a little puzzled that people want "Datomic as a Service". Datomic and PostgreSQL were the simplest parts of my stack to deploy. You want beefy peers as well so as to make maximum use of the peer limitations on the license. This isn't as big of a deal as people think because you're not structuring your app the way Rails and Django apps do on Heroku. You don't do 1 beefy database + 5,000 terrible VPSes. Not only is that a management overhead (automation or not), but you're better off vertically scaling a couple peers first before running a shitload of dumb VPSes running your service. The running assumption is that you should use DynamoDB, but PostgreSQL was seriously efficient for our purposes. Indexing adds write overhead, but given the current limitations on what you can change in the schema online (nothing), you want to plan ahead here. If you fail to anticipate something in your schema, you'll have to use a migration toolkit such as I plan to release soon. The componentized nature of Datomic makes vertical scaling fairly pleasant as you can more precisely target what you're upgrading/improving. You probably want to include a pass-through querying API in your peers accessing Datomic so that you don't have to run the REST service. This'll enable access to the data from a long-tail of servers that don't necessarily need to be that close to the data and are performing dumb queries. This solves the "but my webapp needs 100 crappy VPSes to perform!" problem. Any kind of heavy-duty aggregation/analytical workloads against a Datomic dataset should be performed on a big peer with memcached. Use roll-ups for pete's sake! You can use a bi-temporal timeline with analytics data but I haven't fully explored the implications beyond Datomic making querying along that dimension nicer. The Doc Brown array store presented at the Clojure meetup last night is a very interesting option for people doing multi-dimensional slicing of analytics data. I'd personally use Datomic as a stand-in for any SQL database doing an OLTP workload, where previously I would've used PostgreSQL. Especially if history or reproducible results are important. That having been said, it appears to be adaptable to workloads I wouldn't have expected (analytics).
Jemaclus 13y ago
Companies really need to do a better job of making ELI5 descriptions. This means nothing to me: > Datomic is a database of flexible, time-based facts, supporting queries and joins, with elastic scalability, and ACID transactions. > Datomic can leverage highly-available, distributed storage services, and puts declarative power into the hands of application developers. What does that even mean? I'm pretty good at databases, and I know what transactions and queries and joins and stuff, but this explanation does a pretty poor job of explaining what Datatomic is and why I should use it. What's a "time-based fact"? What does putting "declarative power in the hands of application developers" mean? Don't all databases support queries? Don't most relational databases support joins and transactions? It just seems like a buzz-word filled fluff phrase that says "Datatomic is a database," but I don't know why I would use it over, say, MySQL or Mongo or whatever. I had to go to Cognitect's site (http://cognitect.com/datomic http://cognitect.com/datomic) to get a better explanation: >Datomic is built on immutable data; facts are never forgotten or overwritten. This means complete auditability is built in from the start - including the transactions that modify your database. And because Datomic is built on immutable data, you can explore possible future scenarios by issuing transactions against a database and decide to commit them only after verifying the results. Ok, that makes a little more sense, but it's still not clear what differentiates this from other database systems. I'm not affiliated with them at all, but I think SiftScience.com does a great job of explaining their product simply and efficiently: https://siftscience.com/ https://siftscience.com/ > Fight Fraud with Machine Learning > Sift Science monitors your site's traffic in real time and alerts you instantly to fraudulent activity. Simply detects fraud. Done. Or EasyPost.com: > Shipping for developers > EasyPost allows you to integrate shipping APIs into any application in minutes. Don't just spit buzz words and technical terms at me. Tell me what it does. > Datomic is a database that, among other things, specializes in tracking data over time, allowing you to test a transaction before saving the data. True accountability from the beginning! Probably not even accurate (again, I don't understand Datomic's premise), but that sounds more explanatory than their current buzz word-filled blurb. To any startups watching: have something on your front page that is an ELI5 description of your product.
- cordite 13y ago
  I had to look up what ELI5 meant :) For any others that are wondering, "Explain Like I'm 5"
rsanders 13y ago
Does the Datomic Console app count against the 2 peer limit when running?
- redinger 13y ago
  Yes, Datomic console counts as a connected peer.
rdtsc 13y ago
Can someone clarify for me. If data is never deleted and updated, one can build a very nice architecture, rich caching clients and all that, which is what they've done. I like that. What happens in these 2 cases (and sorry for repeating myself I already mentioned them below). 1) Runaway data generator. Someone either messed up a test or confused the units on a timer and now you are logging thousands of times the rate you expected. All this ends in your database. Does just adding a deletion record for each on of those "fix" the problem, but if it is immutable doesn't it still suck up the storage. 2) Sensitive data. Someone somehow shoved plaintext passwords, social security numbers, ICBM launch codes in the database. What do you do in that case.
- puredanger 13y ago
  Datomic offers excision to cover cases like these (or other common cases where you are required by law to forget things). http://blog.datomic.com/2013/05/excision.html http://blog.datomic.com/2013/05/excision.html Note that even in this case, you can remember that you decided to forget, as a key premise of Datomic is that you always know how and why you came to record (or forget) a fact.
  - rdtsc 13y ago
    Alright, that makes sense. Now it is interesting how the fact that you decided to forget would work. I guess if one always accesses the data via the official API and at the latest known state, that will work. But presumably the data will still be in stored in binary form in the back-end. Another perhaps related question, does one have the option to "travel in time". Say I record that I forgot my mistakenly added passwords. But an attacker knows when that happens. Can they go back and inspect the data state right before the point when I forgot the data?
    - danneu 13y ago
      Excision removes the data. In other words, you can remember that you forgot, but you can't remember what you forgot. http://blog.datomic.com/2013/05/excision.html http://blog.datomic.com/2013/05/excision.html What you're describing is plain ol retraction. If you retract your credit card number, then someone can just surf back in time to grab it. That's why you'd excise it.

111 points by puredanger 13y ago

I really like what the guys at cognitect are doing.

This is great. Having a free Datomic version that matches Datomic Pro's architecture and supports all of its external storage engines certainly simplifies the scale path and makes design decisions easier. BTW: The pricing page has more details (http://www.datomic.com/pricing.html http://www.datomic.com/pricing.html) -- scroll down to see a comparison.

deleted 13y ago

[deleted]

sgrove 13y ago

Wow, very cool indeed. We worked on an open-source community[1] tool using Datomic/Codeq[2], and the ops portion was/has been pretty unpleasant. I'd love to see Datomic-as-a-Service popup, even as a only-meant-for-starter-projects, just so that experimenting with it could be that much easier. That might be possible with the new license, depending on how the Cognitect team sees it. [1] The service is a frontend to Codeq, having imported many Clojure repos: http://www.jidaexplorer.com/ http://www.jidaexplorer.com/ [2] http://blog.datomic.com/2012/10/codeq.html http://blog.datomic.com/2012/10/codeq.html EDIT: Added links.

drcode 13y ago
Yeah, a Datomic service would be soooo nice.
dustingetz 13y ago
I would like to know more about datomic from an ops perspective if you feel like elaborating?
- cgag 13y ago
  Yes, same, I think a lot of people would be interested.
  - sgrove 13y ago
    I would ask coolsunglasses as he's been using it in production for far longer in a bigger installation than we have.
- jeletonskelly 13y ago
  I've been working with Datomic, as a developer, in a production environment for the last 4-5 months. In terms of the work done by your ops guys, I'd say it really depends on how you're using it. Datomic has it's own AMI, which can be a hassle if you're used to rolling your own (which we ended up doing). I'd say one of the biggest challenges to overcome on the ops side is dealing with transactor failures. If a transactor dies, then the data from the peers will likely just fall on the floor. If you use DDB as a store, you have to keep an eye on your provisioning and scale appropriately.

lucian1900 13y ago

The name is a bit silly. It should be called just "Datomic Starter". I'm still hoping for an open source edition :)

VaedaStrike 13y ago

This opens so many doors all around. I'm literally giddy at this news. I want to leave my day job right now and go home and work on my Cognitect stack web app. I hope I can quickly get to the point where I need to (and then will be far more able to) purchase Datomic.

stolio 13y ago

Can anybody explain how the 2-peer restriction works with web-apps? It's my biggest fear in making the jump.

coolsunglasses 13y ago
Two JVM processes, far as I'm aware. In practice, a single peer gets you pretty far, especially if you're a Clojure user.
- stolio 13y ago
  I guess where I'm getting lost is the terminology - I was under the impression that end-users are peers[0], so I'm worried about maxing out at two users. But if the limit is whatever a transactor can handle then I doubt I'd ever hit it and I might as well commit. I'm looking at using it as part of a Clojure backend, if that matters. [0] - http://docs.datomic.com/javadoc/datomic/Peer.html http://docs.datomic.com/javadoc/datomic/Peer.html edit: grammar
  - redinger 13y ago
    From http://docs.datomic.com/architecture.html http://docs.datomic.com/architecture.html "A Peer is a process that manipulates a database using the Datomic Peer library. Any process can be a Peer - from Web server processes that host sites or services, to a daemon, GUI application or command-line tool. The Datomic-specific application code you write runs in your Peer(s)."
    - stolio 13y ago
      OK, thanks. It just clicked. For anybody wondering what clicked: I'd have Datomic running with one peer, and that peer would serve as many end-users as it could handle. If necessary I could add a second peer and double the read-query power. And that's more than enough for my little web-app. Given the nature of Datalog (https://www.youtube.com/watch?v=bAilFQdaiHk https://www.youtube.com/watch?v=bAilFQdaiHk) I'm getting excited.

coolsunglasses 13y ago

Using Datomic Pro at work for a data warehouse and soon for another project for <REDACTED>. I'm working on a migration toolkit for Datomic. (Migrating schemas, not between database kinds.) Ask me questions about the API, my experience with ops, or anything else if you like.

dustingetz 13y ago
Can you ramble about how datomic is from ops perspective for a moment if you will? thanks
- coolsunglasses 13y ago
  Just to clarify, I don't know what problems sgrove ran into, I've asked him in IRC and will elaborate if he tells me, but at present, I dunno. So here's what I have encountered: Datomic's primary limitation is at the transactor level. Storage is a non-issue, especially if you're using DynamoDB. Even with PostgreSQL write-throughput was ridic because of the way they're using the database. Transactor fail-over I'm not sure I'd take too seriously, but I don't think they'll drop any writes on the floor either. You shouldn't attempt to run a datomic transactor on a cheapo VPS. Try to put together at least 4 gb of RAM. Which is the same as what's currently standard for consumer laptops. No excuses. Deploying Datomic itself is straight-forward. The config is super simple and all you need as a dependency is Java. I'm actually a little puzzled that people want "Datomic as a Service". Datomic and PostgreSQL were the simplest parts of my stack to deploy. You want beefy peers as well so as to make maximum use of the peer limitations on the license. This isn't as big of a deal as people think because you're not structuring your app the way Rails and Django apps do on Heroku. You don't do 1 beefy database + 5,000 terrible VPSes. Not only is that a management overhead (automation or not), but you're better off vertically scaling a couple peers first before running a shitload of dumb VPSes running your service. The running assumption is that you should use DynamoDB, but PostgreSQL was seriously efficient for our purposes. Indexing adds write overhead, but given the current limitations on what you can change in the schema online (nothing), you want to plan ahead here. If you fail to anticipate something in your schema, you'll have to use a migration toolkit such as I plan to release soon. The componentized nature of Datomic makes vertical scaling fairly pleasant as you can more precisely target what you're upgrading/improving. You probably want to include a pass-through querying API in your peers accessing Datomic so that you don't have to run the REST service. This'll enable access to the data from a long-tail of servers that don't necessarily need to be that close to the data and are performing dumb queries. This solves the "but my webapp needs 100 crappy VPSes to perform!" problem. Any kind of heavy-duty aggregation/analytical workloads against a Datomic dataset should be performed on a big peer with memcached. Use roll-ups for pete's sake! You can use a bi-temporal timeline with analytics data but I haven't fully explored the implications beyond Datomic making querying along that dimension nicer. The Doc Brown array store presented at the Clojure meetup last night is a very interesting option for people doing multi-dimensional slicing of analytics data. I'd personally use Datomic as a stand-in for any SQL database doing an OLTP workload, where previously I would've used PostgreSQL. Especially if history or reproducible results are important. That having been said, it appears to be adaptable to workloads I wouldn't have expected (analytics).

Jemaclus 13y ago

Companies really need to do a better job of making ELI5 descriptions. This means nothing to me: > Datomic is a database of flexible, time-based facts, supporting queries and joins, with elastic scalability, and ACID transactions. > Datomic can leverage highly-available, distributed storage services, and puts declarative power into the hands of application developers. What does that even mean? I'm pretty good at databases, and I know what transactions and queries and joins and stuff, but this explanation does a pretty poor job of explaining what Datatomic is and why I should use it. What's a "time-based fact"? What does putting "declarative power in the hands of application developers" mean? Don't all databases support queries? Don't most relational databases support joins and transactions? It just seems like a buzz-word filled fluff phrase that says "Datatomic is a database," but I don't know why I would use it over, say, MySQL or Mongo or whatever. I had to go to Cognitect's site (http://cognitect.com/datomic http://cognitect.com/datomic) to get a better explanation: >Datomic is built on immutable data; facts are never forgotten or overwritten. This means complete auditability is built in from the start - including the transactions that modify your database. And because Datomic is built on immutable data, you can explore possible future scenarios by issuing transactions against a database and decide to commit them only after verifying the results. Ok, that makes a little more sense, but it's still not clear what differentiates this from other database systems. I'm not affiliated with them at all, but I think SiftScience.com does a great job of explaining their product simply and efficiently: https://siftscience.com/ https://siftscience.com/ > Fight Fraud with Machine Learning > Sift Science monitors your site's traffic in real time and alerts you instantly to fraudulent activity. Simply detects fraud. Done. Or EasyPost.com: > Shipping for developers > EasyPost allows you to integrate shipping APIs into any application in minutes. Don't just spit buzz words and technical terms at me. Tell me what it does. > Datomic is a database that, among other things, specializes in tracking data over time, allowing you to test a transaction before saving the data. True accountability from the beginning! Probably not even accurate (again, I don't understand Datomic's premise), but that sounds more explanatory than their current buzz word-filled blurb. To any startups watching: have something on your front page that is an ELI5 description of your product.

cordite 13y ago
I had to look up what ELI5 meant :) For any others that are wondering, "Explain Like I'm 5"

rsanders 13y ago

Does the Datomic Console app count against the 2 peer limit when running?

redinger 13y ago
Yes, Datomic console counts as a connected peer.

rdtsc 13y ago

Can someone clarify for me. If data is never deleted and updated, one can build a very nice architecture, rich caching clients and all that, which is what they've done. I like that. What happens in these 2 cases (and sorry for repeating myself I already mentioned them below). 1) Runaway data generator. Someone either messed up a test or confused the units on a timer and now you are logging thousands of times the rate you expected. All this ends in your database. Does just adding a deletion record for each on of those "fix" the problem, but if it is immutable doesn't it still suck up the storage. 2) Sensitive data. Someone somehow shoved plaintext passwords, social security numbers, ICBM launch codes in the database. What do you do in that case.

puredanger 13y ago
Datomic offers excision to cover cases like these (or other common cases where you are required by law to forget things). http://blog.datomic.com/2013/05/excision.html http://blog.datomic.com/2013/05/excision.html Note that even in this case, you can remember that you decided to forget, as a key premise of Datomic is that you always know how and why you came to record (or forget) a fact.
- rdtsc 13y ago
  Alright, that makes sense. Now it is interesting how the fact that you decided to forget would work. I guess if one always accesses the data via the official API and at the latest known state, that will work. But presumably the data will still be in stored in binary form in the back-end. Another perhaps related question, does one have the option to "travel in time". Say I record that I forgot my mistakenly added passwords. But an attacker knows when that happens. Can they go back and inspect the data state right before the point when I forgot the data?
  - danneu 13y ago
    Excision removes the data. In other words, you can remember that you forgot, but you can't remember what you forgot. http://blog.datomic.com/2013/05/excision.html http://blog.datomic.com/2013/05/excision.html What you're describing is plain ol retraction. If you retract your credit card number, then someone can just surf back in time to grab it. That's why you'd excise it.