Re: query multiple schemas

Em dom., 21 de abr. de 2024 às 17:12, Norbert Sándor <
sandor(dot)norbert(at)erinors(dot)com> escreveu:

> Hello,
>
> I have a database with multiple tenants with a separate schema for each
> tenant.
> The structure of each schema is identical, the tenant ID is the name of
> the schema.
>
> What I would like to achieve is to able to query tables in all schemas at
> once with the tenant IDs added to the result set.
>
I have a similar structure and do my multi tenant queries this way.
The only problem I see is that we have to define every result type, because
I return a record, but it runs fine.

create function sql_per_tenant(sql text, tenants text[]) returns setof
record language plpgsql AS $function$
declare
Result record;
schemas text;
begin
for schemas in select unnest(tenants) loop
execute Format('set local search_path to %s, public;', schemas);
for Result in execute Format('select $$%1$s$$ tenant, * from (%2$s) x',
schemas, sql) loop
return next Result;
end loop;
end loop;
end;$function$;

select * from sql_per_tenant('select Order_ID, sum(Value) from Orders inner
join Items using(Order_ID)
where Due_Date = Current_Date','{cus_001,cus_035,cus_175}')
as (SchemaName text, Order_ID integer, sum_of_items Numeric)

regards
Marcos