Christophe Pettus: All Your GUCs in a Row: from_collapse_limit
2026-07-22 3 min PostgreSQL All Your GUCs in a Row: from_collapse_limit Almost nobody writes the query shape this parameter governs: Copy1SELECT * FROM x, y, (SELECT * FROM a, b, c WHERE something) AS ss 2WHERE somethingelse; But you produce it constantly without meaning to. Reference a view that contains a join and the view’s definition is inserted in place of the reference, leaving the planner looking at exactly that: a subquery sitting in your FROM list. Nested views, ORM-generated SQL, and anything built out of reusable query fragments all arrive at the planner in this form. from_collapse_limit decides what the planner does with it.
- ▪2026-07-22 3 min PostgreSQL All Your GUCs in a Row: from_collapse_limit Almost nobody writes the query shape this parameter governs: Copy1SELECT * FROM x, y, (SELECT * FROM a, b, c WHERE something) AS ss 2WHERE somethingelse; But you produc
- ▪Reference a view that contains a join and the view’s definition is inserted in place of the reference, leaving the planner looking at exactly that: a subquery sitting in your FROM list.
- ▪Nested views, ORM-generated SQL, and anything built out of reusable query fragments all arrive at the planner in this form. from_collapse_limit decides what the planner does with it.
Planet PostgreSQL files mainly under programming. We currently carry 28 of its stories.
Story provenance
Source · retrieval · rights · ranking — open for full record
inspect →
Story provenance
Attribution is not the same as permission. This drawer separates discovery metadata, excerpts, WeSearch-generated summaries, reuse status, and whether the publisher receives the visit. Nothing here claims a legal grant the publisher has not made.
Record
| Original publisher | Postgr |
| Canonical URL | https://postgr.es/p/9qj |
| Publication time | Thu, 23 Jul 2026 02:30:00 +0000 |
| Retrieval time | 2026-07-26T10:01:46.705Z |
| Last seen | 2026-07-26T10:01:46.705Z |
| Headline source | Publisher (no WeSearch rewrite) |
| Excerpt source | publisher body |
| Excerpt method | First ~120 words (~800 chars) of extracted publisher body, fair-use limited. |
| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
| Citation coverage | Summary is a WeSearch-generated derivative; primary citation is the original publisher URL. |
| Cluster | WLweH_33K9z3 · 5 stories |
| Cluster logic | Grouped by semantic title/content similarity across sources within a rolling window. Same-publisher template collisions are excluded from coverage comparison. |
| Ranking reason | Story pages are not engagement-ranked. Hub feeds use recency, with optional source-diversified chronological ordering (cap consecutive stories per source). No personalized ranking. |
| Publisher visit | Yes — open original |
| Substitutes article? | No — link-out required for full text |
Rights status (four layers)
WeSearch handling by dimension
| Indexing | May the item be indexed (stored, ranked, made findable)? | Allowed |
| Snippet | May a short excerpt of the publisher's text be shown? | Allowed |
| AI summary | May WeSearch generate its own short summary of the article? | Limited |
| Retrieval / RAG | May the content be exposed for third-party retrieval-augmented generation? | Not asserted |
| Model training | May the content be used to train AI models? | Not asserted |
| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
2026-07-22 3 min PostgreSQL All Your GUCs in a Row: from_collapse_limit Almost nobody writes the query shape this parameter governs: Copy1SELECT * FROM x, y, (SELECT * FROM a, b, c WHERE something) AS ss 2WHERE somethingelse; But you produce it constantly without meaning to. Reference a view that contains a join and the view’s definition is inserted in place of the reference, leaving the planner looking at exactly that: a subquery sitting in your FROM list. Nested views, ORM-generated SQL, and anything built out of reusable query fragments all arrive at the planner in this form. from_collapse_limit decides what the planner does with it. Default 8, context user, valid from 1 up to 2147483647.
…
Excerpt limited to ~120 words for fair-use compliance. The full article is at Postgr.
Discussion
0 commentsMore from Postgr
