--- title: Postgres JIT internals get a debugging map, AlloyDB's... description: Today's posts skew toward Postgres internals and hard architectural lessons rather than product launches. A deep-dive on jit_expressions and... canonical: https://daily.dev/posts/postgres-jit-internals-get-a-debugging-map-alloydb-s-postgres-claim-gets-a-year-long-stress-test-2bbgxb1h1 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Postgres JIT internals get a debugging map, AlloyDB's Postgres claim gets a year-long stress test | daily.dev og:description: Today's posts skew toward Postgres internals and hard architectural lessons rather than product launches. A deep-dive on jit_expressions and... og:url: https://daily.dev/posts/postgres-jit-internals-get-a-debugging-map-alloydb-s-postgres-claim-gets-a-year-long-stress-test-2bbgxb1h1 og:image: https://api.daily.dev/og/posts/2BBGXb1H1.png og:image:alt: Postgres JIT internals get a debugging map, AlloyDB's Postgres claim gets a year-long stress test 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 JIT internals get a debugging map, AlloyDB's Postgres claim gets a year-long stress test **[Databases Digest](https://daily.dev/sources/databases_digest)** · 3 min read · 0 upvotes · 0 comments ## Summary Today's posts skew toward Postgres internals and hard architectural lessons rather than product launches. A deep-dive on jit_expressions and jit_tuple_deforming gives operators a way to bisect JIT bugs without restarting the server. A year-long AlloyDB evaluation finds Google's 'fully compatible with PostgreSQL' claim only holds at the wire protocol level. And a retrospective on an autonomous agent project concludes the real lesson wasn't about agent design at all, it was that Postgres should have been the coordination layer from day one. ## Content **TLDR:** Today's posts skew toward Postgres internals and hard architectural lessons rather than product launches. A deep-dive on jit_expressions and jit_tuple_deforming gives operators a way to bisect JIT bugs without restarting the server. A year-long AlloyDB evaluation finds Google's 'fully compatible with PostgreSQL' claim only holds at the wire protocol level. And a retrospective on an autonomous agent project concludes the real lesson wasn't about agent design at all, it was that Postgres should have been the coordination layer from day one. --- ## AlloyDB's PostgreSQL compatibility claim breaks down below the wire protocol A year-long independent evaluation of Google's AlloyDB finds the 'fully compatible with PostgreSQL' pitch holds at the wire protocol level but not below it: storage, VACUUM scheduling, and the write path all diverge from stock Postgres. The in-memory columnar store shows up to 311x speedups on selective TPC-H scans but near-zero benefit on point lookups, and adaptive autovacuum reschedules vacuum work rather than eliminating it. The verdict is narrow but useful: AlloyDB fits GCP-native HTAP workloads with bursty reads, but extension allowlists, storage opacity, and compute costs rule it out for small apps or teams that need deep Postgres tooling access. [Read more](https://daily.dev/posts/m5GVQQ6dx) ## Two Postgres JIT GUCs let you bisect compiler bugs without a restart jit_expressions and jit_tuple_deforming are both boolean, on by default since Postgres 11, and asymmetric in a useful way: disabling jit_tuple_deforming still shows a JIT block minus the deform functions, but disabling jit_expressions removes the JIT block entirely, since deform code only ever gets generated while compiling expressions. That asymmetry means you can narrow a suspected JIT bug to either the deform compiler or the expression compiler by flipping one setting, no restart required. Worth noting: these are explicitly debugging knobs, not something to tune for performance. [Read more](https://daily.dev/posts/YFhFHzFg1) ## An autonomous agent project concludes Postgres should be the system, not the agents A retrospective on building Looper, an experimental agent hierarchy with project heads, warrants, and escalations, found that most of its loops were observe-only and a code-fixing agent had a success predicate nobody could actually satisfy. Critical safety gates, including warrant checks and kill switches, were silently broken or missing entirely. The proposed fix scraps the org-chart model in favor of treating agents as replaceable stateless workers while Postgres holds durable state, using leases, fencing tokens, a trigger-enforced state machine, and stored functions as the only write path. It's a plan, not a shipped system, with a defined test protocol of seven days running with zero human intervention. [Read more](https://daily.dev/posts/HqVMC46rn) ## Rails' after_commit still can't guarantee job delivery on its own A deep dive into Rails after_save callbacks explains why enqueueing a background job before the surrounding transaction commits causes intermittent ActiveRecord::RecordNotFound errors when a worker connects on a separate database connection. Rails 7.2's Account.current_transaction.after_commit and Active Job's enqueue_after_transaction_commit setting (off by default even in Rails 8.1.3) fix the ordering problem, but the piece is blunt that after_commit still can't guarantee delivery if the process dies right after commit. For anything billing-critical, it recommends a durable outbox pattern instead, and flags a testing gotcha where transactional test wrappers let after_commit callbacks fire even though the DB change gets rolled back at teardown. [Read more](https://daily.dev/posts/JmpytyRLH) --- ## Also notable - **Enterprise NoSQL migrations fail on planning, not tooling:** Six recurring gaps sink NoSQL modernization projects: treating schema translation as a data-move instead of an architectural redesign, underscoping query and driver rewrites, skipping phased rollout for risky single cutovers, and neglecting rollback plans with bidirectional sync. [Read more](https://daily.dev/posts/kMAd5Bb1n) ## Similar posts on daily.dev - [The curious case of Google's AlloyDB](https://daily.dev/posts/the-curious-case-of-google-s-alloydb-m5gvqq6dx) · Planet PostgreSQL · 0 upvotes · 0 comments - [Announcing PostgreSQL for agents in AlloyDB](https://daily.dev/posts/announcing-postgresql-for-agents-in-alloydb-dyzuabrfv) · Google Cloud · 2 upvotes · 0 comments - [The agent is not the system. Postgres is.](https://daily.dev/posts/the-agent-is-not-the-system-postgres-is--hqvmc46rn) · Planet PostgreSQL · 1 upvotes · 0 comments --- Tags: [#ai-agents](https://daily.dev/tags/ai-agents), [#alloydb](https://daily.dev/tags/alloydb), [#compiler-optimization](https://daily.dev/tags/compiler-optimization), [#database](https://daily.dev/tags/database), [#postgresql](https://daily.dev/tags/postgresql) [View this post on daily.dev](https://daily.dev/posts/postgres-jit-internals-get-a-debugging-map-alloydb-s-postgres-claim-gets-a-year-long-stress-test-2bbgxb1h1) ```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":"DiscussionForumPosting","mainEntityOfPage":"https://daily.dev/posts/postgres-jit-internals-get-a-debugging-map-alloydb-s-postgres-claim-gets-a-year-long-stress-test-2bbgxb1h1","headline":"Postgres JIT internals get a debugging map, AlloyDB's Postgres claim gets a year-long stress test","text":"Today's posts skew toward Postgres internals and hard architectural lessons rather than product launches. 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