Re: Multiple inserts with two levels of foreign keys

Have you considered writing a stored procedure to process records that have
been written to temporary tables?

0. Create temporary tables tmp_farms, tmp_crops and tmp_deliveries, which
don't have id columns.
1. Truncate the three temporary tables
2. Insert into the temp tables a "set" of prod data.
3. Call a stored procedure in the dev database that does INSERT INTO ...,
using RETURNING to get the relevant id values for the subsequent tables.
4. goto 1.

On 10/4/23 21:15, Dow Drake wrote:
> I see.  That would definitely work, but part of this for me is to get a
> better understanding of PostgreSQL's capabilities.  I'm going to keep
> working on a minimal solution that deletes no records from the dev
> database, and only inserts the required records.
>
> On Wed, Oct 4, 2023 at 6:58 PM Ron <ronljohnsonjr(at)gmail(dot)com> wrote:
>
> Ah.  We'd truncate all of the dev tables, then load a "slice" (for
> example, accounts 10000 to 19999, and all associated records from
> downstream tables; lots and lots of views!!) from the prod database.
>
> On 10/4/23 20:50, Dow Drake wrote:
>> Thanks for the reply, Ron!
>> I'm not sure I see how to make your suggestion work, though.  Suppose
>> I dump the three tables to CSV as you suggest (and write a script to
>> extract the relevant records from those CSV dumps in the correct
>> order).  It might be that in the dev database, the next generated key
>> values are 199 for farm's id, 2145 for crop's id and 10242 for
>> deliveries' id.  The databases are independent.
>>
>> Just inserting the records in the same order doesn't take care of
>> setting the foreign key values correctly -- does it?  I think I'm
>> really looking for a solution more along the lines of the link in my
>> original post.
>>
>> Best,
>> Dow
>>
>> On Wed, Oct 4, 2023 at 6:26 PM Ron <ronljohnsonjr(at)gmail(dot)com> wrote:
>>
>> Frame challenge: why can't you just "\copy to" the dev database
>> tables in the correct order, to satisfy foreign key requirements?
>>
>> On 10/4/23 18:59, Dow Drake wrote:
>>> Hi,
>>>
>>> I'm trying to write a postgresql script to replicate a
>>> hierarchical structure in a live database into my development
>>> database, where I can debug and test more easily.  I can extract
>>> the data from the live database that needs to be inserted, but
>>> I'm having trouble writing the insertion script
>>>
>>> Here's a simplified version of the problem I'm trying to solve:
>>> There are three tables: farms, crops and deliveries where a farm
>>> has many crops and a crop has many deliveries.
>>>
>>> create table farms (
>>>    id bigint NOT NULL GENERATED BY DEFAULT AS IDENTITY,
>>>    name character varying(30)
>>> );
>>> create table crops (
>>>    id bigint NOT NULL GENERATED BY DEFAULT AS IDENTITY,
>>>    farm_id bigint not null
>>>    name character varying(30)
>>> );
>>> create table deliveries (
>>>    id bigint NOT NULL GENERATED BY DEFAULT AS IDENTITY,
>>>    crop_id bigint not null
>>>    ticket character varying(30)
>>> );
>>> I want to insert a farm record, then insert two crops associated
>>> with that farm, then insert two deliveries for each of the the
>>> two crops so that in the end, my tables look like this:
>>> farms
>>> id name
>>> 1 'Happy Valley Farm'
>>>
>>> crops
>>> id farm_id    name
>>> 1 1         'corn'
>>> 2 1         'wheat'
>>>
>>> delvieries
>>> id crop_id    ticket
>>> 1 1          '3124'
>>> 2 2          '3127'
>>> 3 1          '3133'
>>> 4 2          '3140'
>>>
>>> It's important that the deliveries get assigned to the right
>>> crops.  I think this post:
>>> https://dba.stackexchange.com/questions/199916
>>> gets close to what I need, but I haven't been able to figure out
>>> how to adapt it to multiple records.
>>>
>>> Thanks for any help on this!
>>>
>>>
>>
>> --
>> Born in Arizona, moved to Babylonia.
>>
>
> --
> Born in Arizona, moved to Babylonia.
>

--
Born in Arizona, moved to Babylonia.