QuestDB

One of the convenient SQL extensions you can find in QuestDB is the `IN` syntax for ranges. Find every trade at midnight Jan 1st 2024 and 1 minute afterwards, then repeat for the same range for 2 years. SELECT * FROM trades WHERE timestamp IN '2024-01-01T00:00:00;1m;1y;2';

Writing a performant database means worrying about the small details, like how to efficiently store VARCHARS, so short strings (below 9 bytes) can be fully inlined within the header and save disk and memory space. Varchar header (column file): +------------+--------------+------------------+ | 32 bits   | 48 bits      | 48 bits     | len + flags | prefix     | offset       +------------+---------------+-----------------+                     │ +------------------------------------+ points to │ ▼ Varchar data (column file): +---+---+---+---+---+---+---+---+---+---+---+ | H | e | l | l | o |   | w | o | r | l | d | +---+---+---+---+---+---+---+---+---+---+---+

Sometimes you just want to quickly check if two tables, or two queries, have any rows in common. select * from btc_trades4 INTERSECT select * from btc_trades3; If you want to get only rows which are present in one but not in the other, try `EXCEPT`

Have you ever tried to implement parallel group by/sample by aggregations? We did, and we didn't get it right at the first time. But now they are blazingly fast! To learn more about our journey read this fantastic post by Andrei Pechkurov https://lnkd.in/d--g4BZj

One of our frequently requested features is soon to be released. Do you have any use cases for PIVOT/UNPIVOT? (SELECT * FROM trades WHERE timestamp in today()) PIVOT ( avg(price), count(price) FOR symbol IN ('BTC-USD', 'ETH-USD') GROUP BY side );

Software is shaped by decisions—big and small. Managing decision fatigue helps us build not just better software, but a better dev experience. A few ways to combat it: ✅ Explore before committing ✅ Document key choices ✅ Refactor with intent ✅ Use tools & automation How do you handle decision fatigue in your projects? See the full blog post by one of our engineers: https://lnkd.in/ecEr6Szg #engineering #questdb #opensource

Did you know you can add a label to your QuestDB Web Console, so it is easier to identify instances and environments? export QDB_INSTANCE_NAME="🐧 Dev 🐧 Market Data" export QDB_INSTANCE_RGB=g

#QuestDB is introducing an #array type, making it easier to store and query order book snapshots efficiently. Perfect for handling tick data. 📈 Stay tuned!

Perspective (https://lnkd.in/eF5ATqSS) is a data visualization tool designed for large and streaming data under the FINOS umbrella. We found their demos quite impressive and wanted to make them even more impressive by adding QuestDB as the backend for the demo data. In this short video you can see a cool blotter updating every 50ms with market data coming from QuestDB.

𝗔𝗻𝗱 𝘁𝗵𝗮𝘁, 𝗸𝗶𝗱𝘀, 𝗶𝘀 𝗵𝗼𝘄 𝗣𝗛𝗣 𝗺𝗮𝗱𝗲 𝗶𝘁 𝗶𝗻𝘁𝗼 𝗼𝘂𝗿 𝗰𝗼𝗱𝗲𝗯𝗮𝘀𝗲. I’d like to open a small window into how we introduce incremental improvements in a mature #timeseries #database used by thousands of users—and how that journey led us to add PHP code to our main repository (primarily Java, with some C++ and Rust). We recently enhanced QuestDB’s Postgres protocol for better performance by adding features like query pipelining. Knowing this could break some existing clients, we built in a safeguard: a legacy compatibility flag that reverts to the previous protocol implementation. Most users never needed it—but for a small few, enabling that flag was enough to solve any issues. A few days ago, a PHP user upgraded to the latest version and encountered a brand-new error. While we don’t officially use or provide a PHP client, we know many in our community rely on QuestDB + PHP. We suggested using the legacy flag as an immediate workaround, which got them running again. However, since the old protocol implementation won’t be there forever, we had to fix the root cause. Armed with a reproduction script from the user, our developer Jaromir Hamala pinpointed the problem and delivered a permanent fix—just 11 days after the initial report. We also added a new PHP test runner to give PHP coverage on par with Python and Rust. That’s open-source incremental development at its best, powered by real user collaboration.