--- title: Postgres Checkpoint Followup and Collation Visualization... description: Follow-up piece covering three threads: why an HA replica doesn't fully protect you from a large checkpoint_timeout setting (since restartpoints on a promoted... canonical: https://daily.dev/posts/postgres-checkpoint-followup-and-collation-visualization-and-codex-luna-tgnq8cmgw twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Postgres Checkpoint Followup and Collation Visualization and Codex Luna | daily.dev og:description: Follow-up piece covering three threads: why an HA replica doesn't fully protect you from a large checkpoint_timeout setting (since restartpoints on a promoted... og:url: https://daily.dev/posts/postgres-checkpoint-followup-and-collation-visualization-and-codex-luna-tgnq8cmgw og:image: https://api.daily.dev/og/posts/TGNQ8cMgw.png og:image:alt: Postgres Checkpoint Followup and Collation Visualization and Codex Luna og:image:width: 1200 og:image:height: 630 og:locale: 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. # Postgres Checkpoint Followup and Collation Visualization and Codex Luna **[Planet PostgreSQL](https://daily.dev/sources/planet-postgresql)** · 11 min read · 0 upvotes · 0 comments ## Summary Follow-up piece covering three threads: why an HA replica doesn't fully protect you from a large checkpoint_timeout setting (since restartpoints on a promoted replica take just as long to replay), a major update to the author's glibc/Postgres collation research including a new visual fingerprint grid across OS/language combinations (revealing glibc 2.28+ causes catastrophic sort performance regressions, up to 2 hours for 25 million strings), and a hands-on report of using OpenAI's low-cost Codex 'Luna' model to complete a complex automation project for under $2 after switching away from Claude due to spurious security guardrail triggers. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Can promoting a Postgres HA replica protect me from downtime if I increase checkpoint_timeout beyond the default 5 minutes? Not reliably, because checkpoints on the primary directly translate into restartpoints on the replica since they share the same WAL stream. If the replica itself restarts, it will take just as long to start up and replay WAL as the primary would, undermining the availability benefit of increasing checkpoint_timeout. _Explore how daily.dev surfaces Postgres availability tradeoffs like checkpoint tuning versus replica failover._ ### Why did Postgres sort order change after upgrading to RHEL8, Debian10, or Ubuntu 20.04? Glibc 2.28, shipped in these OS releases, made significant changes to collation sort ordering, which silently corrupted indexes and sort-dependent data in existing Postgres databases when the underlying OS was upgraded. The same corruption risk applies whenever a Postgres container image is updated to a newer base image using the updated glibc. _daily.dev helps developers track glibc and collation gotchas before an OS upgrade corrupts a database._ ### How much does OpenAI Codex's Luna model cost compared to Terra for agentic coding tasks? On a $20 Codex Plus subscription, 71 million tokens consumed only $1.99 of quota on Luna versus 5 million tokens costing $1.78 on Terra, making Luna dramatically cheaper per token. A complex collation-testing project that previously cost hundreds of dollars on models like Sonnet or Opus was completed on Luna-Low effort while leaving 95% of the weekly quota remaining. _Developers comparing AI coding agent costs can follow real-world pricing breakdowns like this on daily.dev._ ## Similar posts on daily.dev - [Happiness Hint: Alarm on Checkpoint Time](https://daily.dev/posts/happiness-hint-alarm-on-checkpoint-time-8r64jnswx) · Planet PostgreSQL · 0 upvotes · 0 comments - [Google Cloud: Investing in the future of PostgreSQL — 2026 highlights](https://daily.dev/posts/google-cloud-investing-in-the-future-of-postgresql-2026-highlights-t1wyfbzsp) · Google Open Source Blog · 7 upvotes · 2 comments --- Tags: [#linux](https://daily.dev/tags/linux), [#ai-agents](https://daily.dev/tags/ai-agents), [#postgresql](https://daily.dev/tags/postgresql) [View this post on daily.dev](https://daily.dev/posts/postgres-checkpoint-followup-and-collation-visualization-and-codex-luna-tgnq8cmgw) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Postgres Checkpoint Followup and Collation Visualization and Codex Luna","url":"https://daily.dev/posts/postgres-checkpoint-followup-and-collation-visualization-and-codex-luna-tgnq8cmgw","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/postgres-checkpoint-followup-and-collation-visualization-and-codex-luna-tgnq8cmgw"},"datePublished":"2026-08-12T21:16:32.054Z","dateModified":"2026-09-14T07:42:31.738Z","description":"Follow-up piece covering three threads: why an HA replica doesn't fully protect you from a large checkpoint_timeout setting (since restartpoints on a promoted...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/d5a4142ddde0ebd8a264b595eca8455e?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/d5a4142ddde0ebd8a264b595eca8455e?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Planet PostgreSQL","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Planet PostgreSQL","logo":"https://media.daily.dev/image/upload/logos/placeholder.jpg","url":"https://daily.dev/sources/planet-postgresql"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/postgres-checkpoint-followup-and-collation-visualization-and-codex-luna-tgnq8cmgw","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"linux,ai-agents,postgresql","timeRequired":"PT11M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Planet PostgreSQL","item":"https://daily.dev/sources/planet-postgresql"},{"@type":"ListItem","position":3,"name":"Postgres Checkpoint Followup and Collation Visualization and Codex Luna"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/postgres-checkpoint-followup-and-collation-visualization-and-codex-luna-tgnq8cmgw#faq","mainEntity":[{"@type":"Question","name":"Can promoting a Postgres HA replica protect me from downtime if I increase checkpoint_timeout beyond the default 5 minutes?","acceptedAnswer":{"@type":"Answer","text":"Not reliably, because checkpoints on the primary directly translate into restartpoints on the replica since they share the same WAL stream. 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