创建物化视图时如何指示列不可为空? [英] How to indicate that a column is not nullable when creating a materialized view?

问题描述

我正在使用以下查询创建物化视图:

I am creating a materialized view using the following query:

CREATE MATERIALIZED VIEW article_view AS
SELECT
  id,
  alternative_headline,
  article_author_id,
  created_at,
  description,
  headline,
  preview_paragraph_image_id,
  published_at,
  updated_at
FROM article
WHERE
  published_at IS NOT NULL
WITH NO DATA;

CREATE UNIQUE INDEX ON article_view (id);

我希望它在 实体化视图表明published_at列不可为空.

I want it to be represented in the materialized-view that the published_at column is not nullable.

想要将 published_at 列表示为不可为空的原因是因为我使用的是 脚手架工具 根据数据库模式生成数据库查询和类型.在这种特殊情况下，published_at 被错误地表示为触发严格类型检查错误的可空列.

The reason for wanting to represent the published_at column as not nullable, is because I am using a scaffolding tool that generates database queries and types based on the database schema. In this particular case, the published_at is being falsely represented as a nullable column triggering strict type checking errors.

上述脚手架工具使用以下查询来描述数据库:

The said scaffolding tool is using the following query to describe the database:

SELECT
  pc1.relname AS "tableName",
  pa1.attname AS "columnName",
  pg_catalog.format_type (pa1.atttypid, NULL) "dataType",
  pc1.relkind = 'm' "isMaterializedView",
  NOT(pa1.attnotnull) "isNullable"
FROM
  pg_class pc1
JOIN pg_namespace pn1 ON pn1.oid = pc1.relnamespace
JOIN
  pg_attribute pa1 ON pa1.attrelid = pc1.oid
  AND pa1.attnum > 0
  AND NOT pa1.attisdropped
WHERE
  pn1.nspname = 'public' AND
  pc1.relkind IN ('r', 'm')

推荐答案

目前的语法不支持 CREATE 或 ALTER 形式.我在猜测，但由于 CREATE MATERIALIZED VIEW 语句接受任何查询，它无法可靠地从引用的表中复制非空约束.

The syntax doesn't support it in CREATE or ALTER forms as it stands today. I am guessing, but since the CREATE MATERIALIZED VIEW statement accepts any query, it cannot reliably copy the not null constraints from the referenced table.

然而，您可以更新 pg_catalog.pg_attribute 本身以执行您想要的操作.

You can however UPDATE the pg_catalog.pg_attribute itself to do what you want.

UPDATE pg_catalog.pg_attribute 
SET attnotnull = true
WHERE attrelid = the_oid_of_the_published_at_column;

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