--- title: "PostGIS Performance: Data Sampling" url: https://daily.dev/posts/postgis-performance-data-sampling-98rbh0w9f source_url: https://www.crunchydata.com/blog/postgis-performance-data-sampling type: article source: "Crunchy Data" published: 2025-11-21T19:25:01.919Z updated: 2025-11-21T19:25:19.525Z tags: ["database", "sql", "postgresql", "data-analysis"] reading_time: 4 upvotes: 2 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. # PostGIS Performance: Data Sampling **[Crunchy Data](https://daily.dev/sources/crunchydata)** · 4 min read · 2 upvotes · 0 comments ## Summary Learn how to use PostgreSQL's TABLESAMPLE feature to dramatically speed up queries on large datasets by analyzing representative samples instead of full table scans. The technique leverages the Law of Large Numbers to provide accurate estimates in milliseconds rather than seconds, reducing query time by up to 97% in spatial data examples. The approach works best when data is randomly distributed across database pages, making it ideal for statistical aggregations and spatial queries over large geographic areas. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [PostGIS Performance: Indexing and EXPLAIN](https://daily.dev/posts/postgis-performance-indexing-and-explain-fmb4tskgj) · Crunchy Data · 1 upvotes · 0 comments - [PostGIS Performance: Improve Bounding Boxes...](https://daily.dev/posts/postgis-performance-improve-bounding-boxes--zcjfqb3vi) · Crunchy Data · 1 upvotes · 0 comments --- Tags: [#database](https://daily.dev/tags/database), [#sql](https://daily.dev/tags/sql), [#postgresql](https://daily.dev/tags/postgresql), [#data-analysis](https://daily.dev/tags/data-analysis) [View this post on daily.dev](https://daily.dev/posts/postgis-performance-data-sampling-98rbh0w9f)