Re: [HACKERS] [PATCH] Generic type subscripting
| От | Oleksandr Shulgin |
|---|---|
| Тема | Re: [HACKERS] [PATCH] Generic type subscripting |
| Дата | |
| Msg-id | CACACo5Sioo62z8RdXHvRqJtFZf8=D+EzwEXDueXnOpgnNbU3uw@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: [HACKERS] [PATCH] Generic type subscripting (Dmitry Dolgov <9erthalion6@gmail.com>) |
| Ответы |
Re: [HACKERS] [PATCH] Generic type subscripting
|
| Список | pgsql-hackers |
On Tue, Mar 6, 2018 at 6:21 PM, Dmitry Dolgov <9erthalion6@gmail.com> wrote:
One more small update after fd1a421fe6 in attachments.
Before looking at the code I have a few comments about documentation:
in json.sgml:
+-- Extract value by key
+SELECT ('{"a": 1}'::jsonb)['a'];
What is the result of running this query? What is the resulting data type?
+-- Extract nested value by key path
+SELECT ('{"a": {"b": {"c": 1}}}'::jsonb)['a']['b']['c'];
+
+-- Extract element by index
+SELECT ('[1, "2", null]'::jsonb)['1'];
What is the result here? Why subscript is a string and not a number? Are subscription indexes 0- or 1-based?
+-- Update value by key
+UPDATE table_name set jsonb_field['key'] = 1;
+
+-- Select records using where clause with subscripting
+SELECT * from table_name where jsonb_field['key'] = '"value"';
Please capitalize: SET, FROM, WHERE.
Use of double quotes around "value" requires some explanation, I think.
Should the user expect that a suitable index is used by the query planner for this query?
In other words, I would like to see this part of documentation to be extended beyond just showcasing the syntax.
Regards,
-- Oleksandr "Alex" Shulgin | Database Engineer | Zalando SE | Tel: +49 176 127-59-707
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