--- title: "Real-Time Data Classification with Generated Column" url: https://daily.dev/posts/real-time-data-classification-with-generated-column-wh0q0cd09 source_url: https://cratedb.com/blog/real-time-data-classification-with-generated-column type: article source: "CrateDB" published: 2026-08-24T14:56:50.247Z updated: 2026-08-24T14:57:13.037Z tags: ["sql", "cratedb"] reading_time: 6 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Real-Time Data Classification with Generated Column **[CrateDB](https://daily.dev/sources/cratedb)** · 6 min read · 0 upvotes · 0 comments ## Summary CrateDB's generated columns let you classify and index streaming data at insert time rather than in a separate cleanup pass. A worked example models baggage-handling events at Heathrow Terminal 5 using five generated columns: an oversize boolean flag from a CASE expression, a reported_late flag comparing event timestamps to catch upstream lag, a geo_location field converting raw lat/long into a GEO_POINT, an in_t5 boolean from a within() polygon check, and an event_week timestamp used to auto-partition the table by week. Because these values are computed once on write and stored/indexed like any other column, later queries become cheap boolean filters instead of repeated computations, and old data can be dropped by removing entire weekly partitions. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How can I flag oversize bags or records automatically as they are inserted into a database instead of computing it at query time? Use a generated column with a CASE expression that evaluates the business rule on every insert. For example, a CrateDB BOOLEAN column defined as GENERATED ALWAYS AS a CASE statement over length, width, and height columns computes an oversize flag automatically, so any application inserting rows gets the same consistent result without repeating logic in every query. _Explore how developers apply generated columns for consistent data rules on daily.dev._ ### How do I automatically partition a time-series table by week without the application knowing about partitions? Create a generated column that truncates the event timestamp to the start of its week using date_trunc('week', conveyer_timestamp), and partition the table by that column. Rows then route themselves into weekly partitions automatically, and dropping data older than a retention window becomes a matter of dropping whole partitions instead of deleting millions of rows individually. _Developers designing time-series retention strategies can track database techniques like this on daily.dev._ ### How do I convert raw latitude and longitude fields into a usable geo point for mapping and geo queries in CrateDB? Define a generated column typed as GEO_POINT that is computed from the raw lat and long fields, for example GENERATED ALWAYS AS [reported_location['long'], reported_location['lat']]. This produces a proper GEO_POINT value stored and indexed on every insert, enabling CrateDB's geo functions and direct plotting on tools like Grafana without any query-time conversion. _Anyone building geospatial dashboards can follow database and mapping patterns like this on daily.dev._ ## Similar posts on daily.dev - [What Is a Columnar Database? Understanding the Power Behind Real-Time Analytics](https://daily.dev/posts/what-is-a-columnar-database-understanding-the-power-behind-real-time-analytics-ddxxul0dj) · CrateDB · 0 upvotes · 0 comments - [Inside CrateDB: How Storage Optimization Powers Real-Time Analytics at Scale](https://daily.dev/posts/inside-cratedb-how-storage-optimization-powers-real-time-analytics-at-scale-3iozebt7s) · CrateDB · 0 upvotes · 0 comments - [Inside CrateDB’s Real-Time Query Engine: Aggregations, Ad-Hoc Queries, Hybrid Search, and AI](https://daily.dev/posts/inside-cratedb-s-real-time-query-engine-aggregations-ad-hoc-queries-hybrid-search-and-ai-sl7jvqmbr) · CrateDB · 1 upvotes · 0 comments --- Tags: [#sql](https://daily.dev/tags/sql), [#cratedb](https://daily.dev/tags/cratedb) [View this post on daily.dev](https://daily.dev/posts/real-time-data-classification-with-generated-column-wh0q0cd09)