# Community **URL:** https://community.questdb.com/c/community/4.md?page=2 [Latest](https://community.questdb.com/latest.md) · [Categories](https://community.questdb.com/categories.md) · [Tags](https://community.questdb.com/tags.md) **Page:** 3 --- ## [Efficient Querying of Multiple Time Ranges from High-Volume Sensor Data in QuestDB](https://community.questdb.com/t/efficient-querying-of-multiple-time-ranges-from-high-volume-sensor-data-in-questdb/867)
**Author:** [@Sam](https://community.questdb.com/u/Sam)\ **Replies:** 3\ **Last updated:** [June 18, 2025, 5:10pm UTC](https://community.questdb.com/t/efficient-querying-of-multiple-time-ranges-from-high-volume-sensor-data-in-questdb/867 "2025-06-18T17:10:18Z")
Dear QuestDB community, We are currently evaluating QuestDB for our company, and I need some help determining the most suitable table structure for our use case. Our application consists of 30 sensors in total, each co… --- ## [Is there a way to have timezoned day partitions?](https://community.questdb.com/t/is-there-a-way-to-have-timezoned-day-partitions/870)
**Author:** [@SJC](https://community.questdb.com/u/SJC)\ **Replies:** 1\ **Last updated:** [June 18, 2025, 2:24pm UTC](https://community.questdb.com/t/is-there-a-way-to-have-timezoned-day-partitions/870 "2025-06-18T14:24:06Z")
Hi, I am currently developing an app that handles iot data in a local facility. I have tables that store iot data that is partitioned by day. The partition is kept for a month and expired partitions are dropped by our s… --- ## [Query data delay](https://community.questdb.com/t/query-data-delay/866)
**Author:** [@Oldman](https://community.questdb.com/u/Oldman)\ **Replies:** 3\ **Last updated:** [June 17, 2025, 5:14pm UTC](https://community.questdb.com/t/query-data-delay/866 "2025-06-17T17:14:07Z")
Hi, I recently use the questdb to store trades and candlestick data, the “candlestick” table works well, However, the data inserted into the “trades” table cannot be queried immediately. seems it will delay for few hour… --- ## [Math operations with lag()](https://community.questdb.com/t/math-operations-with-lag/820)
**Author:** [@vins](https://community.questdb.com/u/vins)\ **Replies:** 21\ **Last updated:** [June 17, 2025, 12:07pm UTC](https://community.questdb.com/t/math-operations-with-lag/820 "2025-06-17T12:07:16Z")
i have a questdb 8.3.0 and i want to graph a typical snmp counter containing network incoming traffic (ifHCInOctets). if i run this query: SELECT timestamp, ifDescr, ifHCInOctets, (LAG(ifHCInOctets,1)… --- ## [Mutiple paritions for the same hour](https://community.questdb.com/t/mutiple-paritions-for-the-same-hour/856)
**Author:** [@mbathla](https://community.questdb.com/u/mbathla)\ **Replies:** 3\ **Last updated:** [June 11, 2025, 2:50pm UTC](https://community.questdb.com/t/mutiple-paritions-for-the-same-hour/856 "2025-06-11T14:50:07Z")
We have a table which is partition by HOUR. However, QuestDB is creating multiple partitions for the same hour. It seems questdb is partitioning further by 20GB size. Can someone explain why 20GB is the limit and if ther… --- ## [Is there a way to LAG() with VARCHAR data?](https://community.questdb.com/t/is-there-a-way-to-lag-with-varchar-data/855)
**Author:** [@germsvel](https://community.questdb.com/u/germsvel)\ **Replies:** 2\ **Last updated:** [June 11, 2025, 2:39pm UTC](https://community.questdb.com/t/is-there-a-way-to-lag-with-varchar-data/855 "2025-06-11T14:39:02Z")
:waving\_hand: hi there, I’m trying out QuestDB for the first time, so this testing is in dev (i.e. not sure if the enterprise edition has differences). One of the things I’m trying to do is find rows in a dataset whose… --- ## [Is there a way to work with encrypted data?](https://community.questdb.com/t/is-there-a-way-to-work-with-encrypted-data/846)
**Author:** [@BepTheWolf](https://community.questdb.com/u/BepTheWolf)\ **Replies:** 3\ **Last updated:** [June 6, 2025, 12:13pm UTC](https://community.questdb.com/t/is-there-a-way-to-work-with-encrypted-data/846 "2025-06-06T12:13:07Z")
Hi, is there a way to work with encrypted data in QuestDB? Or is it planned for the future? --- ## [Using a materialized view as another materialized view as base timeout / OOM](https://community.questdb.com/t/using-a-materialized-view-as-another-materialized-view-as-base-timeout-oom/839)
**Author:** [@JForsaken](https://community.questdb.com/u/JForsaken)\ **Replies:** 29\ **Last updated:** [June 3, 2025, 6:42am UTC](https://community.questdb.com/t/using-a-materialized-view-as-another-materialized-view-as-base-timeout-oom/839 "2025-06-03T06:42:57Z")
Hey guys! Been loving what you guys are doing with QuestDB \<3 The current issue i’m having is with trying to have rollup MVs for a price system. I have a base table that has ~700M rows (between 1-10M rows per partition,… --- ## [Migration from InfluxDB](https://community.questdb.com/t/migration-from-influxdb/842)
**Author:** [@Ingmar](https://community.questdb.com/u/Ingmar)\ **Replies:** 3\ **Last updated:** [June 2, 2025, 7:47pm UTC](https://community.questdb.com/t/migration-from-influxdb/842 "2025-06-02T19:47:01Z")
I’m using Home Assistant’s InfluxDB integration to write data to a time-series database using the Influx Python client. Currently, this writes to an InfluxDB 2.0 installation, but I’m planning to migrate this to QuestDB… --- ## [Deployment test without docker](https://community.questdb.com/t/deployment-test-without-docker/843)
**Author:** [@Thom](https://community.questdb.com/u/Thom)\ **Replies:** 4\ **Last updated:** [June 2, 2025, 4:13pm UTC](https://community.questdb.com/t/deployment-test-without-docker/843 "2025-06-02T16:13:31Z")
Hi, I’m on a setup that does not allow me to use docker, and I have 2 machines (A would launch Questdb and B starts the program that puts data in my db). When I change the http adresse to something else than 0.0.0.0 Qu… --- ## [cant enable wal on my intance in macos or docker](https://community.questdb.com/t/cant-enable-wal-on-my-intance-in-macos-or-docker/837)
**Author:** [@Aviad\_Korakin](https://community.questdb.com/u/Aviad_Korakin)\ **Replies:** 1\ **Last updated:** [May 21, 2025, 7:48pm UTC](https://community.questdb.com/t/cant-enable-wal-on-my-intance-in-macos-or-docker/837 "2025-05-21T19:48:28Z")
i set the config to apply it i tried with bypass wal as well but its just create all my tables as wal disabled, i enabled it in the server.conf and also tried this : CREATE TABLE IF NOT EXISTS motion ( ts TIMESTAMP, ax… --- ## [Update with a sub-query](https://community.questdb.com/t/update-with-a-sub-query/835)
**Author:** [@BepTheWolf](https://community.questdb.com/u/BepTheWolf)\ **Replies:** 2\ **Last updated:** [May 19, 2025, 4:53pm UTC](https://community.questdb.com/t/update-with-a-sub-query/835 "2025-05-19T16:53:04Z")
Hi, I’m trying a query to perform an update from a sub-query, but it gives me an error. The query is as follows: WITH up AS (select index\_time, ColA, ColB from MyTabTmp) UPDATE MyTab mt SET mt.ColA = up.ColA, mt.ColB… --- ## [Null in greatest() function](https://community.questdb.com/t/null-in-greatest-function/829)
**Author:** [@BepTheWolf](https://community.questdb.com/u/BepTheWolf)\ **Replies:** 5\ **Last updated:** [May 16, 2025, 3:01pm UTC](https://community.questdb.com/t/null-in-greatest-function/829 "2025-05-16T15:01:04Z")
Hi, doing some testing, I noticed that if one of the arguments of greatest() function is null, this is considered the greatest value. --- ## [Know when rows are ready for select?](https://community.questdb.com/t/know-when-rows-are-ready-for-select/834)
**Author:** [@BepTheWolf](https://community.questdb.com/u/BepTheWolf)\ **Replies:** 3\ **Last updated:** [May 16, 2025, 11:42am UTC](https://community.questdb.com/t/know-when-rows-are-ready-for-select/834 "2025-05-16T11:42:22Z")
Hi, I’m here again… When I insert some rows and immediately after I do a select, it return the rows without the last insert. If I wait 1 seconds before doing the select the result is correct. Is there any way to know … --- ## [Node-Red MQTT to QuestDB](https://community.questdb.com/t/node-red-mqtt-to-questdb/832)
**Author:** [@ajay100](https://community.questdb.com/u/ajay100)\ **Replies:** 6\ **Last updated:** [May 15, 2025, 11:08am UTC](https://community.questdb.com/t/node-red-mqtt-to-questdb/832 "2025-05-15T11:08:26Z")
Hello again! I am converting some sensor data from Ecowitt2MQTT to QuestDB in Node-Red using the Node.js ingestion client. I am wondering if the method I am using is best practice, as it seems restrictive when trying t… --- ## [A little problem that I don't know how to solve](https://community.questdb.com/t/a-little-problem-that-i-dont-know-how-to-solve/828)
**Author:** [@BepTheWolf](https://community.questdb.com/u/BepTheWolf)\ **Replies:** 5\ **Last updated:** [May 12, 2025, 8:55am UTC](https://community.questdb.com/t/a-little-problem-that-i-dont-know-how-to-solve/828 "2025-05-12T08:55:13Z")
Hi, I have a little problem that I don’t know how to solve. A query that I will have to put into a union, but first I have to solve it. Let me give you an example. CREATE TABLE ‘Log\_80003’ ( dateStart TIMESTAMP, dat… --- ## [High Dimensional Tables](https://community.questdb.com/t/high-dimensional-tables/817)
**Author:** [@A\_G](https://community.questdb.com/u/A_G)\ **Replies:** 2\ **Last updated:** [May 8, 2025, 5:50pm UTC](https://community.questdb.com/t/high-dimensional-tables/817 "2025-05-08T17:50:41Z")
Hello, we are currently evaluating QuestDB to adopt it as a timeseries database for our company. We are interested in testing it out to store IoT sensor data for up to 5000 sensors that are typically recorded at 10 Hz. W… --- ## [QuestDB High CPU Usage with Table-Per-Metric Approach (Ex-InfluxDB Refugee)](https://community.questdb.com/t/questdb-high-cpu-usage-with-table-per-metric-approach-ex-influxdb-refugee/826)
**Author:** [@kowen](https://community.questdb.com/u/kowen)\ **Replies:** 4\ **Last updated:** [May 2, 2025, 8:24pm UTC](https://community.questdb.com/t/questdb-high-cpu-usage-with-table-per-metric-approach-ex-influxdb-refugee/826 "2025-05-02T20:24:15Z")
Background We’re enterprise users who recently started considering our options after InfluxData limited features in their V3 core offering. Our application tracks system metrics in a radar control system, writing data at… --- ## [Influxdb migration idea](https://community.questdb.com/t/influxdb-migration-idea/823)
**Author:** [@David\_Goadby](https://community.questdb.com/u/David_Goadby)\ **Replies:** 2\ **Last updated:** [May 2, 2025, 1:05am UTC](https://community.questdb.com/t/influxdb-migration-idea/823 "2025-05-02T01:05:36Z")
Like a lot of Influxdb users I am pi\*\*ed of about their new policies. I am still on V1 and was looking forward to upgrading to V3. Time for a change… I did look at TDengine and they have a perfect way of migrating as th… --- ## [Calculate data reception frequency table](https://community.questdb.com/t/calculate-data-reception-frequency-table/821)
**Author:** [@BepTheWolf](https://community.questdb.com/u/BepTheWolf)\ **Replies:** 2\ **Last updated:** [April 29, 2025, 12:48am UTC](https://community.questdb.com/t/calculate-data-reception-frequency-table/821 "2025-04-29T00:48:17Z")
I needed to calculate a table of data reception frequencies. This is the schema: CREATE TABLE ‘measurements’ ( index\_time TIMESTAMP, val DOUBLE ) timestamp(index\_time) PARTITION BY DAY WAL DEDUP UPSERT KEYS(index\_t… --- ## [Which strategy with this Use Case](https://community.questdb.com/t/which-strategy-with-this-use-case/811)
**Author:** [@alb](https://community.questdb.com/u/alb)\ **Replies:** 6\ **Last updated:** [April 22, 2025, 5:52pm UTC](https://community.questdb.com/t/which-strategy-with-this-use-case/811 "2025-04-22T17:52:25Z")
Hi all, I’m a beginner with QuestDB, and I found it very interesting!! I would like to understand if can solve issues in huge archiving data and performance quering I have data file CSV with 230 Million of rows daily … --- ## [Heavy ZFS flush activity impacting QuestDB performance?](https://community.questdb.com/t/heavy-zfs-flush-activity-impacting-questdb-performance/812)
**Author:** [@Aditya\_Rawat](https://community.questdb.com/u/Aditya_Rawat)\ **Replies:** 6\ **Last updated:** [April 22, 2025, 10:01am UTC](https://community.questdb.com/t/heavy-zfs-flush-activity-impacting-questdb-performance/812 "2025-04-22T10:01:19Z")
Hi all, I’m running QuestDB on ZFS and noticed extremely high disk write activity (almost ~1 GB/s) from a kernel thread: \[flush-zfs-2\]. due to whcih my disk util is always 100%. Is this level of ZFS background flushi… --- ## [Null, -2147483648 or what am I doing wrong?](https://community.questdb.com/t/null-2147483648-or-what-am-i-doing-wrong/807)
**Author:** [@BepTheWolf](https://community.questdb.com/u/BepTheWolf)\ **Replies:** 5\ **Last updated:** [April 14, 2025, 3:25pm UTC](https://community.questdb.com/t/null-2147483648-or-what-am-i-doing-wrong/807 "2025-04-14T15:25:11Z")
Hi, I have a question: I make a table: CREATE TABLE ‘MyTab’ ( index\_time TIMESTAMP, ColA DOUBLE NULL, ColB DOUBLE NULL, ColC DOUBLE NULL, ColD DOUBLE NULL ) timestamp(index\_time) PARTITION BY DAY WAL DEDUP UPSER… --- ## [INSERT or UPDATE with DEDUP UPSERT](https://community.questdb.com/t/insert-or-update-with-dedup-upsert/802)
**Author:** [@BepTheWolf](https://community.questdb.com/u/BepTheWolf)\ **Replies:** 5\ **Last updated:** [April 11, 2025, 4:00pm UTC](https://community.questdb.com/t/insert-or-update-with-dedup-upsert/802 "2025-04-11T16:00:56Z")
Hi to everyone, I have a problem to solve. Is there a way to ignore omitted columns in case of update during an insert with dedup upsert? For example: CREATE TABLE ‘MyTab’ ( index\_time TIMESTAMP, ColA DOUBLE, ColB … --- ## [How to compute and expand average power over time?](https://community.questdb.com/t/how-to-compute-and-expand-average-power-over-time/799)
**Author:** [@alexcode](https://community.questdb.com/u/alexcode)\ **Replies:** 6\ **Last updated:** [April 11, 2025, 4:00pm UTC](https://community.questdb.com/t/how-to-compute-and-expand-average-power-over-time/799 "2025-04-11T16:00:52Z")
I’m working with a dataset where an IoT device sends a wh (watt-hour) value at discrete timestamps, identified by an operationId. I want to visualize this data by plotting the sum of average power per operation, broken d… --- ## [Timeout on export query](https://community.questdb.com/t/timeout-on-export-query/801)
**Author:** [@Thom](https://community.questdb.com/u/Thom)\ **Replies:** 5\ **Last updated:** [April 10, 2025, 12:26pm UTC](https://community.questdb.com/t/timeout-on-export-query/801 "2025-04-10T12:26:40Z")
Hello, I have a program on which I need to make changes and so on each version I generates the results and put them on QuestDB to compare them in order to check that there is no regression. The problem is that each run… --- ## [Disabling O3 Engine for Ordered Data Ingestion](https://community.questdb.com/t/disabling-o3-engine-for-ordered-data-ingestion/793)
**Author:** [@CS-Aditya-Rawat](https://community.questdb.com/u/CS-Aditya-Rawat)\ **Replies:** 1\ **Last updated:** [April 1, 2025, 2:41pm UTC](https://community.questdb.com/t/disabling-o3-engine-for-ordered-data-ingestion/793 "2025-04-01T14:41:28Z")
I’m working with a scenario where my data is guaranteed to arrive in strict timestamp order. Therefore, I believe the out-of-order (O3) engine’s functionality is redundant and potentially adds unnecessary overhead in my … --- ## [Material View & Disk access](https://community.questdb.com/t/material-view-disk-access/788)
**Author:** [@Gabriel](https://community.questdb.com/u/Gabriel)\ **Replies:** 1\ **Last updated:** [March 31, 2025, 7:51am UTC](https://community.questdb.com/t/material-view-disk-access/788 "2025-03-31T07:51:02Z")
Hello, I have created a materialized view and the query performances is great. We were waiting for it and it will help us a lot. On the other hand, it is writing a lot on the disk and I would like to see if there are an… --- ## [Bug: Random tables are created](https://community.questdb.com/t/bug-random-tables-are-created/791)
**Author:** [@ThomasJaeger](https://community.questdb.com/u/ThomasJaeger)\ **Replies:** 1\ **Last updated:** [March 30, 2025, 3:55pm UTC](https://community.questdb.com/t/bug-random-tables-are-created/791 "2025-03-30T15:55:49Z")
I’m using the latest version with he Go client on an AWS EC2 instance. I see more and more random tables created based on what looks like some of the payload/column values. This is happening random. Here is the Go code … --- ## [Importing CSV with timestamps in milliseconds](https://community.questdb.com/t/importing-csv-with-timestamps-in-milliseconds/789)
**Author:** [@Soren\_Martius](https://community.questdb.com/u/Soren_Martius)\ **Replies:** 3\ **Last updated:** [March 28, 2025, 1:35pm UTC](https://community.questdb.com/t/importing-csv-with-timestamps-in-milliseconds/789 "2025-03-28T13:35:28Z")
I am trying to import a CSV file to an existing table. The timestamps defined in the CSV file are in milliseconds. If I try to importing using the REST API or web interface I get an error on all timestamp columns. This … [Previous page](https://community.questdb.com/c/community/4.md?page=1) [Next page](https://community.questdb.com/c/community/4.md?page=3)