Re: create unique constraint on jsonb->filed during create table
| От | David G. Johnston |
|---|---|
| Тема | Re: create unique constraint on jsonb->filed during create table |
| Дата | |
| Msg-id | CAKFQuwbGEE-vVnFvtY-xQ7pHkQ=PAP9W-z=1TKe_VFL0yKgqKg@mail.gmail.com обсуждение исходный текст |
| Ответ на | create unique constraint on jsonb->filed during create table (Andy Fan <zhihui.fan1213@gmail.com>) |
| Ответы |
Re: create unique constraint on jsonb->filed during create table
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| Список | pgsql-general |
On Wednesday, February 27, 2019, Andy Fan <zhihui.fan1213@gmail.com> wrote:
The following way works with 2 commands:zhifan=# create table t1 (a jsonb);CREATE TABLEzhifan=# create unique index t1_a_name on t1 ((a->'name'));CREATE INDEXbut know I want to merge them into 1 command, is it possible?zhifan=# create table t2 (a jsonb, constraint uk_t2_a_name unique((a->'name')));ERROR: syntax error at or near "("LINE 1: ...table t2 (a jsonb, constraint uk_t2_a_name unique((a->'name'...
Not according to the documentation. Unique table constraints can only reference columns in the table as a whole. An expression index must be created separately from the table to which it is attached.
Or add a trigger to the table, populate an actual second column (making it unique), and add a table check constraint that that column and the expression are equal. I suspect you’ll be happier having the PK as actual column data anyway.
David J.
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