- The “col_name_1, col_name_2, …” that are enclosed within a set of parentheses represent the columns on which the unique constraint will be applied. Example: Applying Unique Constraint on Multiple Columns Let’s create a “cp_employee” table and insert the unique constraint...
I enjoy Beta season... reviewing and testing new features is a fun diversion from daily tasks. This post takes a look at an improvement toUNIQUEconstraints on columns withNULLvalues. While the nuances of unique constraints are not as flashy asmaking sorts faster(that's exciting!), improving ...
subject text, target text, success boolean, ... ); CREATE UNIQUE INDEX tests_success_constraint ON tests(subject, target) WHERE success; 该部分索引将只会对success字段值为true的数据进行唯一性约束。在实际的应用中,如果成功的数据较少,而不成功的数据较多时,该实现方法将会非常高效。6.7...
You can also create unique constraint on multiple columns. Suppose you are a SAAS provider and username only needs to be unique in a same customer. Then you can add a `customer_id` column and set unique on `customer_id` and `username`. ```sql create table users (id serial, customer_...
CREATE UNIQUE INDEX CONCURRENTLY dist_id_temp_idx ON distributors (dist_id); ALTER TABLE distributors DROP CONSTRAINT distributors_pkey, ADD CONSTRAINT distributors_pkey PRIMARY KEY USING INDEX dist_id_temp_idx; ###Attach a partition to range partitioned table: ...
Temporal primary, unique and foreign keys (revert: 8aee330a) Planner: remove redundant self-joins (revert: d1d286d8) pg_constraint: NOT NULL constraints (revert: 16f8bb7c1) Now, letʼs get to the new stuff. SQL commands New features of the MERGE command COPY ... FROM: messages ...
For updates and deletes to replicate on other nodes, we must be able to identify the unique rows affected. BDR requires that a table have either a PRIMARY KEY defined, a UNIQUE constraint, or an explicit REPLICA IDENTITY defined on specific columns. If one of those isn't defined, a warni...
This kind of lock is used when either ddl_locking = on or ddl_locking = dml, and the DDL statement might cause in-flight DML statements to fail. These failures can occur when you add or modify a constraint such as a unique constraint, check constraint, or NOT NULL constraint. Relation ...
ERROR: unique constraint on partitioned table must include all partitioning columns,DETAIL: EXCLUDE constraint on table "idxpart" lacks column "a" which is part of the partition key. CREATE TABLE idxpart (a int4range, b int4range, c int4range, EXCLUDE USING GIST (a with =, b with =,...
First of all, we're going to talk about the new unique constraint NULLS NOT DISTINCT option, and then we'll talk about the SELECT DISTINCT performance improvements. Share this episode: Click here to share this episode on twitter, or sign up for our newsletter and check out the newsletter ...