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Modern SQLite: Features You Didn't Know It Had
- subhobroto 7mo agoNone of these are news to the HN community. Write-ahead logging and concurrency PRAGMAs have been a given for a decade now. IIRC, FTS5 doesn't often come baked in and you have to compile the SQLite amalgamation to get it. If you do need better typing, you should really use PostgreSQL. However, I will concede, and the article doesn't mention at all, far less are aware that you can build HA, cross region replicated SQLite using purely OSS software provided you architect your software around it. Now that would be a really good `Modern SQLite: Features You Didn't Know It Had` article! Another interesting discussion point is how far self hosted PostgreSQL and pgBackRest can get you to a near-zero data loss high RPO, RTO setup. Its simply amazing we can self host all this.
- happytoexplain 7mo agoThere are plenty of people in the HN community who don't know much about SQLite. Tech is a big, huge, enormous, gigantic domain.
- sgbeal 7mo ago> Write-ahead logging and concurrency PRAGMAs have been a given for a decade now. All of the listed features except for strict tables and generated columns have been in SQLite for 10+ years, and those two are certainly not new. The JSON APIs were not made part of the standard distribution until 3.38 (2022-02) but were added in 3.9 (2015-10) and widely used long before they were upgraded from an optional extension to a core feature. - Generated columns: 3.31 (2020-01) - Strict tables: 3.37 (2021-11)
- subhobroto 7mo ago> All of the listed features except for strict tables and generated columns have been in SQLite for 10+ years, and those two are certainly not new Correct. As I mentioned in my GP, these features have been around a long, long, long time and in the current age of AI that would happily tell you these features exist if you remotely even hint at it, I would assume one would really have to go out of their way to be ignorant of them. It doesn't hurt to have an article like this reiterate all that information though, I just would have loved the same level of effort put into something that's not as easily available yet. A gap exists, and the article doesn't mention at all, about actually configuring solutions like litestream, rqlite, dqlite (not the same!) to build HA, cross region replicated SQLite using purely OSS software provided you architect your software around it. Now that would be a really good "Modern SQLite: Features You Didn't Know It Had" article! Another interesting discussion point is how far self hosted PostgreSQL and pgBackRest can get you to a near-zero data loss high RPO, RTO setup. It just blows my mind that we can self host all this on consumer grade hardware without having to touch a DC or "the cloud" at all.
- 123abcdef 7mo agoI’m afraid you overestimated my knowledge
- esafak 7mo agohttps://www.explainxkcd.com/wiki/index.php/2501:_Average_Familiarity https://www.explainxkcd.com/wiki/index.php/2501:_Average_Fam...
- a96 7mo agohttps://xkcd.com/1053/ https://xkcd.com/1053/
- faizshah 7mo agoTheres also spellfix1 which is an extension you can enable to get fuzzy search. And ON CONFLICT which can help dedupe among other things in a simple and performant way.
- somat 7mo agoI was trying to port a small program I wrote from postgres to a sqlite backend(mainly to make it easier to install) and was pleased to find out sqlite supported "on conflict" I was less pleased to find out that apperently I abuse CTE's to insert foreign keys all the time and sqlite was not happy doing that. with thing_key as ( insert into item(key, description) values('thing', 'a thing') on conflict do nothing ) insert into user_note(uid, key, note) values (123, 'thing', 'I like this thing') on conflict (uid, thing) do update set note = 'I like this thing');
- cloudpeaklabs 7mo ago[flagged]
- Animats 7mo agoEverybody has a JSON extension, and they're all slightly different. I just got hit badly by Dreamhost, which is still running MySQL 8.0. That version has a "JSON extension" which is almost totally useless. I designed something before discovering how different MySQL 8.4 and MySQL 8.0 are.
- MoonWalk 7mo agoThat does seem cool. So there are sufficient functions to iterate through collections that might be stored in a single row of a JSON column?
- duskwuff 7mo agoYes, using the table-valued JSON functions like JSON_EACH and JSON_TREE (which works recursively). Details: https://sqlite.org/json1.html#table_valued_functions_for_parsing_json_json_each_jsonb_each_json_tree_and_jsonb_tree_ https://sqlite.org/json1.html#table_valued_functions_for_par...
- duskwuff 7mo agoOne handy bit of SQLite's JSON features which isn't called out in this article is the short syntax, e.g. SELECT payload->>'$.user.id' AS user_id FROM events ... This works a little more consistently than JSON_EXTRACT - the -> operator always returns a JSON string; the ->> operator (used here) always returns a SQL scalar (text, number, or null). More details: https://sqlite.org/json1.html#jptr https://sqlite.org/json1.html#jptr
- FooBarWidget 7mo agoI've found FTSE5 not useful for serious fuzzy or subword full text search. For example I have documents saying "DaemonSet". But if the user searches for "Daemon" then there will be no results.
- nikisweeting 7mo agoI have found this as well, FTSE5 is convenient to have as an option, but it's not as versatile as postgres or sonic or other full-text search solutions. Does anyone have any other favorite modern bloom-filter-based search solutions that dont need to store copies of all the documents in the search db? Ideally something that can run in WASM too so we can ship a tiny search index to the browser. I found https://github.com/tinysearch/tinysearch https://github.com/tinysearch/tinysearch but haven't tried it yet.
- yomismoaqui 7mo agoDoesn't this work ok? https://www.sqlite.org/fts5.html#fts5_prefix_queries https://www.sqlite.org/fts5.html#fts5_prefix_queries
- ers35 7mo agoUse the trigram tokenizer: https://www.sqlite.org/fts5.html#the_trigram_tokenizer https://www.sqlite.org/fts5.html#the_trigram_tokenizer
- krylon 7mo agoSTRICT tables are something I appreciate very much, even though I cannot recall running into a problem that would have prevented by its presence in the before-time. But it's good to have all the same. I don't think I've ever done much with SQLite's JSON functions, but I have on one or two occasions used a constraint to enforce a TEXT column contains valid JSON, which would have been very tedious to do otherwise.
- crazygringo 7mo ago> even though I cannot recall running into a problem that would have prevented by its presence in the before-time I very, very much did. I was using a Python package that used a lot of NumPy internally, and sometimes its return values would be Python integers, and sometimes they'd be NumPy integers. The Python integers would get written to SQLite as SQLite integers. The NumPy integers would get written to SQLite as SQLite binary blobs. Preventing you from doing simple things like even comparing for equal values. Setting to STRICT caused an error whenever my code tried to insert a binary blob into an integer column, so I knew where in the code I needed to explicitly convert the values to Python integers when necessary.
- nikisweeting 7mo agoSurprised no one has mentioned Turso yet! They recently landed multi-writer support for their rust SQLite re-implementation, which is personally the biggest issue I've had with using SQLite for high concurrency applications. `PRAGMA journal_mode = 'mvcc';` https://docs.turso.tech/tursodb/concurrent-writes https://docs.turso.tech/tursodb/concurrent-writes Very excited to see if SQLite responds by adding native support, I'm hoping competition here will spur improvements on both sides.
- ncruces 7mo agoIncredible that a database company writes that page and doesn't document the isolation level of the feature.
- nikisweeting 7mo agoI believe the full docs are here: https://github.com/tursodatabase/turso/blob/main/docs/manual.md#:~:text=The%20transaction%20isolation%20level%20provided%20by%20concurrent%20transactions%20is%20snapshot%20isolation https://github.com/tursodatabase/turso/blob/main/docs/manual...
- malkia 7mo agoIn the past I've used the backup API - https://sqlite.org/backup.html https://sqlite.org/backup.html - in order to load in memory a copy of sqlite db, and have another live one. I would do this after certain user action, and then by doing a diff, I would know what changed... I guess poor way of implementing PostgreSQL events... but it worked! Granted it was small DB (few megabytes), I also wanted to avoid collecting changes one by one, I simply wanted a diff over last time.
- tombert 7mo agoFor a long time I absolutely hated SQLite because of how terribly it was implemented in Emby, which made it so you couldn't load balance an Emby server because they kept a global lock on the database for exactly one process, but at this point I've grown a kind of begrudging respect for it, simply because it is the easiest way to shoehorn something (roughly) like journaling in terrible filesystems like exFAT. I did this recently for a fork of the main MiSTer executable because of a few disagreements with how Sorg runs the project, and it was actually pretty easy to change out the save file features to use SQLite, and now things are a little more resistant to crashes and sudden power loss than you'd get with the terrible raw-dogged writing that it was doing before. It's fast, well documented, and easy to use, and yeah it has a lot more features than people realize.
- 101008 7mo agoNot sure if people interested, but since I use sqlite in a lot of my own projects, I am working on a lightweight monitoring and safety layer for production SQLite. The idea is pretty simple: SQLite is amazing, but once it’s running in production you basically have zero observability. If something weird happens (unexpected writes, schema changes, background jobs touching tables, etc.) you only find out after the fact. It tries to solve that without touching application code. It's a Rust agent that runs next to your sqlite file, and connects to the server where everything is logged in. My current challenge right now is encryption and trust, mostly. Curious if others here are running SQLite in production and if you would be interested in something like this.
- mandeepj 7mo agocheckout https://newrelic.com/instant-observability/sqlite https://newrelic.com/instant-observability/sqlite
- kherud 7mo agoSQLite seems very powerful for building FTS (user enters free text, expects high precision/recall results). Still, I feel like it's non-trivial to get good search quality. I think the naive approach is to tokenize the input and append "*" for prefix matching. I'm not too experienced and this can probably be improved a lot. There are many settings like different tokenizers, stemming, etc. Additionally, a lot can be built on top like weighting, boosting exact matches, etc. Does anyone know good resources for this to learn and draw inspiration from?
- fizx 7mo agoI mean you can use sqlite as an index and then rebuild all of Lucene on top of it. It's non-trivial to build search quality on top of actual search libraries too. O'Reilly's "Relevant Search" isn't the worst here, but you'll be porting/writing a bit yourself.
- subhobroto 7mo ago> Does anyone know good resources for this to learn and draw inspiration from? Is there a reason why something more custom built, like ParadeDB Community edition won't meet your needs? I understand you're speaking about SQLite, while ParadeDB is PostgreSQL but as you know, it's non-trivial to get good search quality, so I'm trying to understand your situation and needs.
- momo_dev 7mo agothe JSON functions are genuinely useful even for simple apps. i use sqlite as a dev database and being able to query JSON columns without a preprocessing step saves a lot of time. STRICT tables are also great, caught a bug where I was accidentally inserting the wrong type and it just silently worked in regular mode
- subhobroto 7mo ago> caught a bug where I was accidentally inserting the wrong type and it just silently worked in regular mode Typically one would design their "DTO"s to catch such errors right in the application layer, way before it even made it into the DB. Different people call this serialization-deserialization layer different names (DTO being the most ubiquitous I think) but in general, one programs the serialization-deserialization layer to catch structural issues (age is "O" instead of 0). The DB is then delegated to catch unchanging ground truths and domain consistency issues (people who have a DOB into the future are signing up or humans who don't have any email or address at all when the business needs it). In your case, it's great the DB caught gaps in the application layer but one would handle it way before it even made it there. The way I think about DB types are: 1. unexpected gaps/bugs: "What did I miss in my application layer?" 2. expected and unchanging constraints: "What are some unchanging ground truth constraints in my business?", "What are the absolute physical limits of my data?" - while I check for a negative age in my DTOs to provide fast errors to the user, I put these constraints in the DB because it's an unchanging rule of reality. Crucially, by keeping volatile business rules out of the database and restricting it only to these ground truths, I avoid being dragged down by constant DB migrations in a fast-evolving business
- momo_dev 7mo agoyeah fair point, validation should ideally happen at the app layer first. in my case it was a quick prototype where i skipped the proper serialization step and STRICT caught it before it became a real problem. definitely not a substitute for proper DTOs in production
- devnotes77 7mo ago[dead]
- QuadrupleA 7mo agoLove SQLite and most of these features. On the STRICT mode, I've asked this elsewhere and never gotten an answer: does anyone have a loose-typing example application where SQLite's non-strict, different-type-allowed-for-each-row has been a big benefit? I love the simplicity of SQLite's small number of column types, but the any-type-allowed-anywhere design always seemed a little strange.
- lateforwork 7mo agoWhen your application's design changes, you may need to store a slightly different type of data. Relational databases traditionally require explicit schema changes for this, whereas NoSQL databases allow more flexible, schema-less data. SQLite sits somewhere in between: it remains a relational database, but its dynamic typing allows you to store different types of values in a column without immediately migrating data to a new table. This flexibility is convenient when only one application reads and writes to the table. But if multiple applications access the same tables, the lack of a strictly enforced schema becomes a liability. The same is true when using generic tools to process data in SQLite tables, because such tools don't know what type of data to expect. The column type may be X but the actual data may be of type Y.
- irq-1 7mo ago> the any-type-allowed-anywhere design always seemed a little strange. Sqlite came from TCL which is all strings. https://www.tcl-lang.org/ https://www.tcl-lang.org/ An example of where this would be a benefit is if you stored date/times in different formats (changing as an app evolved.)
- SQLite 7mo agoFlexible typing works really well with JSON, which is also flexibly typed. Are you familiar with the ->> operator that extracts a value from JSON object or array? If jjj is a column that holds a JSON object, then jjj->>'xyz' is the value of the "xyz" field of that object. I copied the idea for the ->> operator from PostgreSQL. But in PostgreSQL, the ->> operator always returns a text rendering of the value from the JSON, even if the value is really an integer or floating point number. PG is rigidly typed, so that's all it can do. But SQLite is flexibly typed, so the ->> operator can return anything - text, integer, floating-point, NULL - whatever value if finds in the JSON.
- mpyne 7mo agoI actually needed that exact window function example earlier this week when I needed to figure out why our shared YNAB budget somehow got out of balance with the bank. SQLite to load the different CSVs and lay out the bank's view of the world against YNAB's with running totals was what I turned to.
- aaviator42 7mo agoSQLite is insanely robust. I have developed websites serving hundreds of thousands of daily users where the storage layer is entirely handle by SQLite, via an abstraction layer I built that gives you a handy key-value interface so I don't have to craft queries when I just need data storage/retrieval: https://github.com/aaviator42/StorX https://github.com/aaviator42/StorX
- arunix 7mo agoDoes StorX have any special handling of concurrent writes, or would the user need to take care of that?
- aaviator42 7mo agoWe use SQLite IMMEDIATE transactions, which lock files for writes for a few milliseconds while commiting data to the file. This is not a problem in practice until you reach more than dozens of concurrent writers. StorX configures a default busy timeout of 1.5s, but it can be configured as per your needs. You can also get a lot more out of it by being smart about how you spread your data over DB files (eg: one file per user instead of one for multiple/all users), and also by considering when you call openFile() and closeFile() (eg: keep write transactions short, don't leave a file handler open while running long calculations).
- andrewstuart 7mo agoDisturbing. I did not know SQLite allows writing data that does not match the column type. Yuck. Now I need to review anything I built and fix it. I understand why they wouldn’t, but STRICT should be the default.
- lateforwork 7mo agoSTRICT has severe limitations, for example it does not have date data type. Why is it a problem that it allows data that does not match the column type? SQLite is intended for embedded databases, where only your application reads and writes from the tables. In this scenario, as long as you write data that matches the column's data type, data in the table does match the column type.
- subhobroto 7mo ago> Why is it a problem that it allows data that does not match the column type? SQLite is intended for embedded databases I'm afraid people forget that SQLite is (or was?) designed to be a superior `open()` replacement. It's great that modern SQLite has all these nice features, but if Dr. Hipp was reading this thread, I would assume he would be having very mixed feelings about the ways people mention using SQLite here.
- SQLite 7mo agoNo, I think that people can use SQLite anyway they want. I'm glad people find it useful. I do remain perplexed, though, about how people continue to think that rigid typing helps reliability in a scripting language (like SQL or JSON) where all values are subclasses of a single superclass. I have never seen that in my own practice. I don't know of any objective research that supports the idea that rigid typing is helpful in that context. Maybe I missed something...
- lateforwork 7mo ago> where all values are subclasses of a single superclass I don't understand this. By values do you mean a row (in database terms)? I don't understand what that has to do with rigid typing. Lack of rigid typing has two issues, in my opinion: First, when two or more applications have to read data from a single database, lack of an agreed-upon-and-enforced schema is a limitation. Second, when you use generic tools to process data, the tools have no idea what type of data to expect in a column, if they can't rely on the table schema.
- kristianp 7mo agoThere's table valued functions over json as well, as mentioned by [1]. https://sqlite.org/json1.html#table_valued_functions_for_parsing_json_json_each_jsonb_each_json_tree_and_jsonb_tree_ https://sqlite.org/json1.html#table_valued_functions_for_par... [1] https://news.ycombinator.com/item?id=47618597 https://news.ycombinator.com/item?id=47618597
- captn3m0 7mo agoYou can shorten your JSON queries using arrow notation in sqlite. SELECT settings -> '$.languages' languages FROM user_settings WHERE settings ->> '$.languages' LIKE '%"en"%'; I use them heavily with my jekyll-sqlite projects. See https://github.com/blr-today/website/blob/main/_config.yml#L82-L86 https://github.com/blr-today/website/blob/main/_config.yml#L... for example.
- fushihara 7mo agoI wish SQLite would add a bool type and proper date/time types. Is there really no plan to add them? For bool, it could just be an alias of a numeric type. Something equivalent to number check(col = 0 or col = 1) would be perfectly fine. Date/time handling is pretty weak. Having to store values as GMT text is just inconvenient. When retrieving values in Node.js, I ended up using new Date(val), which caused the classic bug where a GMT-stored value gets interpreted in the local timezone. The correct approach was new Date(val + ".Z"), but I really don’t want to deal with that kind of hassle anymore.
- malkia 7mo agoOne more "hidden" fact - Windows uses sqlite a lot, for a lot of tables. There is even "C:\Windows\System32\winsqlite3.dll" and "C:\Program Files (x86)\Windows Kits\10\Include\10.0.27975.0\um\winsqlite\winsqlite3.h" "C:\Program Files (x86)\Windows Kits\10\Include\10.0.27975.0\um\winsqlite\winsqlite3ext.h" Well it's compiled in it's own way, which may not be to your liking, but it's there to use :)
- mastermage 7mo agoSqlite is pretty great I personaly would appreciate abit more expressive types though.
- mergisi 7mo ago[dead]