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Questions tagged [questdb]

QuestDB is a high-performance, open-source SQL database used in financial services, IoT, machine learning, DevOps and observability.

QuestDB is an open-source SQL database for applications in financial services, IoT, machine learning, DevOps and observability. Questions with this tag should be about compatibility with the main interfaces:

  • queries and ingestion using PostgreSQL wire protocol
  • ingestion over InfluxDB Line Protocol
  • REST API for queries, bulk imports, and exports

Questions with this tag may also focus on SQL syntax and usage for time-oriented language features. For questions with language compatibility, add these tags where appropriate (e.g. [python-2.7] or [python-3.x]).

215 questions
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How do I get the most recent value from a table in QuestDB?

I have a table that looks something like the following: loc temp timestamp xyz 22.4 2021-03-03T16:51:56.915000Z xyz 21.4 2021-03-03T16:51:56.915000Z abc 22.4 2021-03-03T17:05:38.238413Z abc 21.4 2021-03-03T17:05:38.238478Z What…
funnymay
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How to reduce notification duration time?

When running a query via the Web Console, a notification appears. However, I feel that it lasts too much time, and it impedes my view and performing other tasks. How do I configure the amount of time after which notifications in the Web Console must…
spongebob
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Can I replace null values in returned rows in QuestDB?

Some aggregate queries are returning null values, is there a way to handle this? select time, avg(temp_f) from sensor_data sample by 1h If some records are missing, can the aggregate be set to something other than null?
Doncarleone512
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How do I insert a timestamp in a prepared statement via postgres?

I'm sending records to a table in QuestDB and so far I have the following: #include #include #include #include #include void do_exit(PGconn* conn) { PQfinish(conn); exit(1); } int…
Brian Smith
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How do I write influx line protocol records to QuestDB using Python?

How can I send influx line protocol messages to QuestDB from python? Should I be using a library or should I write to the socket? The node example looks like const net = require("net") const client = new net.Socket() const HOST = "localhost" const…
funnymay
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Is there a way to change the type of a column in QuestDB?

I have a table with sensor data and I'd like to change the type for a column, is there a quick way to do this?
funnymay
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How do I persist data in a QuestDB docker container?

I'm running QuestDB from the Docker image but when I stop it, the data is not persisted on restart: docker run -p 9000:9000 -p 8812:8812 questdb/questdb What's a good strategy for keeping the tables / records when restarting this?
djbobo
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How to downsample timeseries in QuestDb?

I have a table with metrics per box in QuestDb with columns Timestamp (designated timestamp) Machine (Symbol) CPU (double) and I want to downsample the results to 2 min interval taking average per machine so that output is same columns but with 1…
allnau
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Expected 'tables' during Flyway migration

I'm moving over to QuestDB using the postgres connection and my flyway migration fails with a FlywaySqlException. I can see this in the logs: SQL State : null Error Code : 0 Message : ERROR: expected 'tables' or 'columns' ... Caused by:…
funnymay
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How to read big rows from questdb with postgre jdbc driver?

I can read 1800 rows from the db,but if I want read more there throw the error "An I/O error occurred while sending to the backend.". And I also can't use the PreparedStatement to insert message to db. This is my pg configure for…
roycyz
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How do I delete records older than 90 days in QuestDB

I am storing IoT sensor data streaming from mutltiple sources into a few tables in QuestDb and because of the huge size of data, I want to keep only the last 90 days. I can see a few ways on their documentation for deleting, but I don't want to…
djbobo
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Manually setting timestamp format with user defined schema in QuestDB import

I want to import some data with curl to the rest endpoint. I need to use a user defined schema described in the docs, but I have some issues with specifying timestamp format. This is a minimal example of what I'm sending: curl -i \ -F…
funnymay
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SQL wildcard matching column name in QuestDB

I'm trying to do a wildcard match on a column name, but it looks like there is no support for LIKE and there is no reference to wildcard matching in the documentation. How can I get the following to work if I have some boards with device names with…
funnymay
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How do I make sure I can keep ingestion client running if I have heavy read operations on a table?

I am using influx line to insert records into a table in Questdb at a constant and high rate. I have multiple postgres clients attached performing read operations, some are Grafana dashboards which do some heavy aggregations across the table. It…
djbobo
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Create a table by putting data from psycopg2 on QuestDB

Can QuestDB create a table by putting data from psycopg2 in it? I want to initial table using psycopg2
0xKoios
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