Re: PostgreSQL function to create index from parent table.

(This doesn't really have anything to do with the ODBC driver. But see
answer below.)

On 07/25/2016 12:58 PM, Venkatesan, Sekhar wrote:
> I want to copy indexes to child table from parent table, something like this:
>
> CREATE OR REPLACE FUNCTION CREATE_INDEX_FOR_CHILD()
> RETURNS void AS
> $$
> DECLARE
> formal_table text;
> BEGIN
> FOR formal_table IN
> SELECT 'CREATE '
> || CASE
> WHEN i.indisunique THEN 'UNIQUE '
> ELSE ''
> END
> || 'INDEX '
> || 'P1_m7_s_'
> || c2.relname
> || ' ON '
> ||
> 'P1_m7_s'
> || ' USING btree ( '
> || split_part(split_part(pg_catalog.pg_get_indexdef(i.indexrelid, 0, true), '(', 2), ')', 1)
> || ' ); '
> FROM pg_catalog.pg_class c
> JOIN pg_catalog.pg_index i
> ON(c.oid = i.indrelid)
> JOIN pg_catalog.pg_class c2
> ON(i.indexrelid = c2.oid)
> JOIN pg_namespace nr
> ON(nr.oid = c.relnamespace)
> WHERE c.relname = 'm7_s'
> loop
> EXECUTE formal_table;
> END LOOP;
> END
> $$ LANGUAGE plpgsql;
>
> When I execute this function "SELECT CREATE_INDEX_FOR_CHILD();", it fails with the below error.
>
> INFO: Exception occurred : state : 42601 message : query has no destination for result data detail : hint : If you want to discard the results of a SELECT, use PERFORM instead. context : PL/pgSQL function inline_code_block line 90 at SQL statement
> Query returned successfully with no result in 156 ms.
>
> Can someone help me understand what is the problem with this code ? How to resolve it?

PL/pgSQL requires using PERFORM instead of SELECT, when the query
doesn't return a result set, or you don't plain "SELECT ..." queries.
For example, this doesn't work:

do $$
begin
SELECT pg_sleep(1);
end;
$$;
ERROR: query has no destination for result data
HINT: If you want to discard the results of a SELECT, use PERFORM instead.
CONTEXT: PL/pgSQL function inline_code_block line 3 at SQL statement

But this works:

begin
PERFORM call_functio();
end;

Now, I'm not sure where in your query or application you have that
situation. The function you pasted above seems OK in that regard. I
think there's something more involved, because the error said "context :
PL/pgSQL function inline_code_block line 90 at SQL statement", but there
aren't 90 lines in that snippet.

- Heikki