---
title: "#222: Deferrable SQL Constraints in Depth"
publication: "Postgres Weekly"
issue: 222
published_at: "2017-08-30"
canonical_url: "https://postgresweekly.com/issues/222"
---

Postgres Weekly 222   . 

[Read this on the Web](http://postgresweekly.com/issues/222) 

[Postgres Weekly](http://postgresweekly.com) Issue 222 — August 30, 2017     

[Deferrable SQL Constraints in Depth](https://begriffs.com/posts/2017-08-27-deferrable-sql-constraints.html?utm_source=postgresweekly&utm_medium=email)Automatic constraint enforcement is a useful and powerful feature, but sometimes there are reasons to defer enforcement, as examined in depth here. Joe Nelson [Understanding Tricky Joins and Multi-Table Updates](https://build.affinity.co/understanding-tricky-joins-and-multi-table-updates-in-postgresql-using-boolean-algebra-7b329606ca45?utm_source=postgresweekly&utm_medium=email)Writing a proper SQL UPDATE query involving multiple tables in Postgres can be tricky and counterintuitive. Here’s a look at a particularly tricky example and the overall concepts. Paul Martinez [2ndQPostgres: More Speed. More Reliability. More Scalability](https://www.2ndquadrant.com/en/resources/2ndqpostgres/)Supercharged PostgreSQL for your Enterprise. Offered exclusively to 2ndQuadrant customers, 2ndQPostgres includes quality-assured features not yet available in community PostgreSQL - giving you access to cutting-edge features with no lock-in. 2ndQuadrant PostgreSQL Products#sponsored[![\](https://copm.s3.amazonaws.com/12574ce2.jpg)](https://www.2ndquadrant.com/en/resources/2ndqpostgres/) [Five Sharding Data Models and Which Is Right](https://www.citusdata.com/blog/2017/08/28/five-data-models-for-sharding/?utm_source=postgresweekly&utm_medium=email)A survey of five sharding approaches and what factors could guide you to each approach. Craig Kerstiens [BigSQL Announces Support of pg_hint_plan in Linux](https://www.openscg.com/2017/08/bigsql-announces-support-of-pg_hint_plan-in-linux/?utm_source=postgresweekly&utm_medium=email)A PG distribution integrated with lots of components and includes support for giving Postgres’s query planner ‘hints’ (or demands, really) of which indexes to use. OpenSCG#news [Announcing PGConf US Mini: NYC on September, 14th 2017](http://blog.pgconf.us/2017/08/announcing-pgconf-us-mini-nyc-on.html?utm_source=postgresweekly&utm_medium=email) Joshua Drake#news [What Tables Will Be Vacuumed At The Next Autovacuum Cycle?](http://richyen.com/postgres/2017/08/25/what_will_be_vacuumed_autovacuum.html?utm_source=postgresweekly&utm_medium=email)Which tables will be ‘vacuum’ed soon? Here’s a query that tries to figure it out. Richard Yen [Anatomy of a VACUUM](http://richyen.com/postgres/2017/08/24/anatomy_of_vacuum.html?utm_source=postgresweekly&utm_medium=email)It’s possible to keep an eye on what a lengthy ‘vacuum’ is doing using tools available on most Unix-like systems. Richard Yen [Partition and Conquer Large Data with Postgres 10](https://www.youtube.com/watch?v=1d9HkH0mRBA&utm_source=postgresweekly&utm_medium=email) Amit Langote and Ashutosh Bapat#video [Say hello to PostgreSQL’s perfect match](https://selectstar.io/blog/3-strategies-to-improve-postgresql-performance-schemas/?utm_source=sponsored&utm_medium=email&utm_campaign=08+30+2017+Postgres+Weekly)Start a free trial to see how SelectStar’s comprehensive monitoring can compliment your Postgres environment. SelectStar#sponsored    

Postgres Weekly is curated by [Craig Kerstiens](https://twitter.com/craigkerstiens) [Read this issue on the Web](http://postgresweekly.com/issues/222) [See our archives](http://postgresweekly.com/issues) [Change your email address](*|UPDATE_PROFILE|*)  [Stop getting this newsletter](*|UNSUB|*)  

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