I am using SQLite as document db for a side project for years now. Made a custom repository base class that can also store blobs in separate columns, so this type of data is not part of the json document. Today there is also jsonb [1], as far as I remember all functions work the same for json and jsonb.
Also the repo class stores write and delete timestamps as separate columns so I can have CDC. CDC is used for building cached view models and is pushed to object storage every 5 minutes for backup as NDJSON. Another process on home server is restoring the db every couple of minutes for second backup and ready to use DB in case it's needed.
I know there are things like Litestream, I wanted something in process and something that can send alerts on failed backups.
Why do people say document database when they really just mean json database?
QuantumNomad_
The 1st edition CouchDB book from 2010 explained it like this:
> We write software to improve our lives and the lives of others. Usually this involves taking some mundane information—such as contacts, invoices, or receipts—and manipulating it using a computer application. CouchDB is a great fit for common applications like this because it embraces the natural idea of evolving, self-contained documents as the very core of its data model.
> Self-Contained Data
> An invoice contains all the pertinent information about a single transaction—the seller, the buyer, the date, and a list of the items or services sold. As shown in Figure 1, “Self-contained documents”, there’s no abstract reference on this piece of paper that points to some other piece of paper with the seller’s name and address. Accountants appreciate the simplicity of having everything in one place. And given the choice, programmers appreciate that, too.
> Yet using references is exactly how we model our data in a relational database! Each invoice is stored in a table as a row that refers to other rows in other tables—one row for seller information, one for the buyer, one row for each item billed, and more rows still to describe the item details, manufacturer details, and so on and so forth.
Iow, a document database stands in contrast to a relational db in that these JSON things we store in them are more stand-alone “documents” compared to storing data in rows and columns in a relational db like PostgreSQL or SQLite.
SOLAR_FIELDS
The thing that people always miss about this takeaway is that while it is a truism, most data is actually inherently relational. Even in your example given, the individual components that are made to assemble that document are better represented as relational datastores
jmalicki
Nothing here says the data isn't relational. It strongly disagrees, with reasons, why it's not better represented as relational.
Personally I prefer the relational stance, and there are a lot of people who don't get it who say things like "this data isn't relational", but that's not the argument GP made.
somat
I would argue most data is inherently(naively?) hierarchical(the document), relational structured data is a clever but unintuitive mechanism to introduce powerful analytic opportunities to a set of data.
Basically a document is a report, a large disjoint volume of information on a subject, I consider this the natural form of data because this is how it is collected and how most people think about it. relational is sort of like storing that data as vertical slices through your stack of reports. Not natural at all but much nicer for analysis across the data set.
bitwize
In the real world of business, generally you want to store these pieces of information together to establish a historical record, not have references or links to other tables, etc. Links and relations are fragile, as anyone who's clicked through to a 404 can attest. Standalone documents last as long as the media that stores them.
somat
The "document" is sort of the native data type, Put everything in a big hierarchical structure, It is very flexible but analytics across the set can suffer. "relational" is another way to store data, break your big hierarchy into sets of related rows and store the rows as a table, If I were to describe it in geometric terms where the document is a report on a paper, the relation is a vertical slice through a stack of those reports. This is slightly non-intuitive but provides for interesting analysis opportunities.
But nothing prevents you from treating your relational database as a document database, set it up as a key-value store where each key is is the document title and each value is a large blob of document data. If your documents are fairly consistent it is also easy enough to build indexes and query features to regain some of the analytical ability of relational data.
Calavar
It's a MongoDBism. The MongoDB community used document to mean the nonrelational equivalent of a row in a relational database. But over time there was definitional shift, and now it means a JSON blob, even if that blob is in a relational database.
flomo
It's a much older term, eg. Lotus Notes was described as a document database.
petcat
JSON is just a textual representation of the internal data structures.
quietbritishjim
That is still not what I'd call a "document".
bitwize
1) The internal or wire representation of data from document DBs isn't necessarily JSON, though it's normally converted to such.
2) "Document" has undergone a bit of semantic drift thanks to HTML and XML. In an informational context it means "structured, hierarchical unit of data containing mostly text". The data from forms, invoices, and the like needs to be collected and stored, even if it isn't properly normalized and relationalized (or is en route to being such) so a "document database" is thought to be suited to this task
I dunno, whatever, I'm in the "just fucking use postgres until you can justify why you shouldn't" camp.
nchmy
obviously the example is contrived, but it seems strange me that they are not storing the json in its own column - just extracting a single key from it and storing in a generated column. Why not do that in the app code if youre just going to discard the rest of the json?
Here's an example i saw yesterday from mariadb, which is improving its json support in its upcoming releases.
```
CREATE TABLE t1 (json_data JSON);
INSERT INTO t1 VALUES('{"column1": 1234}');
INSERT INTO t1 ...
```
In order to do efficient queries over data in JSON, you can add a virtual column, and an index on that column:
```
ALTER TABLE t1
ADD COLUMN vcol1 INT AS (cast(json_value(json_data, '$.column1') AS INTEGER)),
ADD INDEX(vcol1);
```
vidarh
"body" is the "json in its own column" you're asking for. They are doing exactly what you're saying.
The point is exactly that it means you can selectively retrospectively add virtual columns, optionally backed with an index, as you decide which fields you need more structured access to.
The example you're giving is in principle the same as the "ALTER TABLE ... GENERATED ALWAYS AS ... VIRTUAL" example + a subsequent index in the Sqlite example.
inigyou
Postgres does even better and it's available right now. No virtual column needed.
CREATE TABLE t1 (data JSONB);
INSERT INTO t1 VALUES ('{"column1":1234}');
CREATE INDEX t1column1 ON t1(data->'column1');
SELECT * FROM t1 WHERE data1->'column1' = '1234'; // not sure about data type
mathnode
I would not call an index format which gets slower with growth "better". And that vacuum issue on JSONB scales with your data size.
inigyou
What do you mean slower with growth? What vacuum issue?
wwalexander
> it added a killer feature: generated columns
It would be super cool if somehow SwiftData could translate computed properties of @Model objects into these generated columns via the #Expression macro!
conception
Since sqlite people are probably in this thread - why is storing genomic data as a sqlite tar with all the metadata you want in tables a “Bad Idea” (tm)? Like toss a fastq or bam plus all the downstream data, grant info, experiment parameters, specimen info etc etc in a single file easily parsable.
SleepyPenguin
I developed an application using zope on the backend and extjs (now Sencha) and SQLite on the front end in 2009. The form + data was stored as strings in the database and then synced to back-end when connected to the internet. It was targeting remote doctors in third world countries who were often offline. Several doctors at that time had told me they wanted to store the medical data in the same format as the intake form mostly because that was what they were used to with paper forms. Soon after, there was a big push for medical ERP and relational databases won over document databases. I bet it would be much easier to build an application like that now (data stored and displayed in same format as collected) but wonder what market would use it.
retropragma
I created `kindstore` for exactly this (only supports Bun currently). I never promoted the project until this comment. Curious if anyone is intrigued?
That was the part I really missed from my Google days.
That, insane achievement badges, and terrible-ideas-discuss (if anyone at Google is reading this, I have one word for you: dirigibles). It was like /r/NonCredibleDefense but for Google.
nchmy
why is this downvoted...?
inigyou
because document database hatred is passe
rcarmo
I'm doing both "documents" and documents (JSON and gzip compressed blobs for emails, office docs, etc.), with the plaintext extracted and run through FTS5. I can't think of another database that would let me do this, plus vector indexing as well.
JSON extensibility and virtual columns help _a lot_ with variable metadata.
Insimwytim
If you applying NOT NULL constraint, why not extract it from json altogether as a separate column? What's the use of it in json?
You may construct it back on retrieval, if you need it in results.
tolerance
Is this not similar to what Simon Willison has written about before?
I'm sorry, I didn't mean before 'this'. I shouldn't have even said "before". That was me thinking to myself out loud.
What I'm trying to figure out is if they're related concepts. This may be a very naive question awkwardly asked.
delduca
In my personal project (a game) I use an indexed key + a JSONB to store the save state, which comes from Lua.
So I can have cassette.propxyz = {1, 2, “abc”, true}
And
local anotherprop = cassette.leprop
nonethewiser
Are you doing this because you also use SQLite for other relational data?
delduca
Possibly yes, otherwise I could use another simple solution
pmkary
I remember this getting to the top of HN for at least two more times.
Jtsummers
Just once. But related and similar links show up regularly.
smalltorch
Is this new or something? Works amazing as a document backend.
eventualcomp
Almost 6 years old. (2020).
alterom
A long time ago, I wrote an ORM to serialize/deserialize object data seamlessly into SQLite, with massive arrays of floats being stored as blobs.
In code, I could effectively mark which class members need to be stored/restored, and optionally provide a custom serialization function for them if needed.
The latter was effectively never necessary, because all the bases types and multi-dimensional arrays were handled by templates.
Really wish I open-sourced that thing then, but the corporate bureaucracy around that was tricky.
I remember sufficiently little about implementation details now that I think I can get to writing it again, without producing a copypasta of that code - and maybe I should :)
inigyou
Did it end up becoming more painful than just writing the SQL?
antonvs
> (Aside: The hard bit may be getting a new enough SQLite, at the time of writing Homebrew on macOS has it, else you likely need to use an unstable source like nixpkgs-unstable.)
Or just download the source and build it! (Gasp!)
bbkane
The great thing about using a package manager is that it also handles updating and uninstalling software, not just the initial install
Also the repo class stores write and delete timestamps as separate columns so I can have CDC. CDC is used for building cached view models and is pushed to object storage every 5 minutes for backup as NDJSON. Another process on home server is restoring the db every couple of minutes for second backup and ready to use DB in case it's needed.
I know there are things like Litestream, I wanted something in process and something that can send alerts on failed backups.
[1] https://sqlite.org/jsonb.html
> We write software to improve our lives and the lives of others. Usually this involves taking some mundane information—such as contacts, invoices, or receipts—and manipulating it using a computer application. CouchDB is a great fit for common applications like this because it embraces the natural idea of evolving, self-contained documents as the very core of its data model.
> Self-Contained Data
> An invoice contains all the pertinent information about a single transaction—the seller, the buyer, the date, and a list of the items or services sold. As shown in Figure 1, “Self-contained documents”, there’s no abstract reference on this piece of paper that points to some other piece of paper with the seller’s name and address. Accountants appreciate the simplicity of having everything in one place. And given the choice, programmers appreciate that, too.
> Yet using references is exactly how we model our data in a relational database! Each invoice is stored in a table as a row that refers to other rows in other tables—one row for seller information, one for the buyer, one row for each item billed, and more rows still to describe the item details, manufacturer details, and so on and so forth.
https://guide.couchdb.org/editions/1/en/why.html
Iow, a document database stands in contrast to a relational db in that these JSON things we store in them are more stand-alone “documents” compared to storing data in rows and columns in a relational db like PostgreSQL or SQLite.
Personally I prefer the relational stance, and there are a lot of people who don't get it who say things like "this data isn't relational", but that's not the argument GP made.
Basically a document is a report, a large disjoint volume of information on a subject, I consider this the natural form of data because this is how it is collected and how most people think about it. relational is sort of like storing that data as vertical slices through your stack of reports. Not natural at all but much nicer for analysis across the data set.
But nothing prevents you from treating your relational database as a document database, set it up as a key-value store where each key is is the document title and each value is a large blob of document data. If your documents are fairly consistent it is also easy enough to build indexes and query features to regain some of the analytical ability of relational data.
2) "Document" has undergone a bit of semantic drift thanks to HTML and XML. In an informational context it means "structured, hierarchical unit of data containing mostly text". The data from forms, invoices, and the like needs to be collected and stored, even if it isn't properly normalized and relationalized (or is en route to being such) so a "document database" is thought to be suited to this task
I dunno, whatever, I'm in the "just fucking use postgres until you can justify why you shouldn't" camp.
Here's an example i saw yesterday from mariadb, which is improving its json support in its upcoming releases.
https://mariadb.com/docs/server/ha-and-performance/optimizat...
``` CREATE TABLE t1 (json_data JSON); INSERT INTO t1 VALUES('{"column1": 1234}'); INSERT INTO t1 ... ```
In order to do efficient queries over data in JSON, you can add a virtual column, and an index on that column:
``` ALTER TABLE t1 ADD COLUMN vcol1 INT AS (cast(json_value(json_data, '$.column1') AS INTEGER)), ADD INDEX(vcol1);
```
The point is exactly that it means you can selectively retrospectively add virtual columns, optionally backed with an index, as you decide which fields you need more structured access to.
The example you're giving is in principle the same as the "ALTER TABLE ... GENERATED ALWAYS AS ... VIRTUAL" example + a subsequent index in the Sqlite example.
It would be super cool if somehow SwiftData could translate computed properties of @Model objects into these generated columns via the #Expression macro!
https://github.com/alloc/kindstore
https://youtu.be/b2F-DItXtZs?is=HlayyJ_DPb8NzbS4
(lol! couldn’t resist)
That was the part I really missed from my Google days.
That, insane achievement badges, and terrible-ideas-discuss (if anyone at Google is reading this, I have one word for you: dirigibles). It was like /r/NonCredibleDefense but for Google.
JSON extensibility and virtual columns help _a lot_ with variable metadata.
You may construct it back on retrieval, if you need it in results.
https://sqlite-tutorial-pycon-2023.readthedocs.io/en/latest/...
https://simonwillison.net/2021/Jul/28/baked-data/
What I'm trying to figure out is if they're related concepts. This may be a very naive question awkwardly asked.
So I can have cassette.propxyz = {1, 2, “abc”, true}
And
local anotherprop = cassette.leprop
In code, I could effectively mark which class members need to be stored/restored, and optionally provide a custom serialization function for them if needed.
The latter was effectively never necessary, because all the bases types and multi-dimensional arrays were handled by templates.
Really wish I open-sourced that thing then, but the corporate bureaucracy around that was tricky.
I remember sufficiently little about implementation details now that I think I can get to writing it again, without producing a copypasta of that code - and maybe I should :)
Or just download the source and build it! (Gasp!)