I have a plpgslq function which does some data processing and would like to write a for loop, however my table name is not known at design time. Is there any possible way to achieve this? Here is sample code snippet of what I want to achieve:
-- Function: check_data()
-- DROP FUNCTION check_data();
CREATE OR REPLACE FUNCTION check_data()
RETURNS character varying AS
$BODY$declare
dyn_rec record;
tbl_name record;
begin
-- sample dynamic tables
tbl_name := 'cars';
tbl_name := 'trucks';
tbl_name := 'bicycles';
for dyn_rec in select * from format($$s%$$,tbl_name) loop
raise notice 'item is %',dyn_rec.item_no;
end loop;
return 'Processing Ok';
end;$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
ALTER FUNCTION check_data()
OWNER TO postgres;
You cannot use a variable as table or column identifier in plpgsql embedded SQL ever. A solution is dynamic SQL - EXECUTE or FOR IN EXECUTE statements:
DO $$
DECLARE
tables text[] = ARRAY['table1','table2'];
table_name text;
rec record;
BEGIN
FOREACH table_name IN ARRAY tables
LOOP
FOR r IN EXECUTE format('SELECT * FROM %I', table_name)
LOOP
RAISE NOTICE '%', rec;
END LOOP;
END LOOP;
END; $$
Related
I am trying create this script where if it matches the current database , then do a chunk of work inside a sub block. As this is my first attempt, i cannot get this to work. Any thoughts?
DO
$do$
DECLARE
database CONSTANT text[] := array['prd1', 'prd2'];
BEGIN
IF current_database() = any(database)
THEN
**--execute the below sub block**
DECLARE
v_sql text;
BEGIN
v_sql :=
IF NOT EXISTS (
SELECT FROM pg_catalog.pg_roles -- SELECT list can be empty for this
WHERE rolname = 'dave') THEN
create role dave encrypted password 'md502bbddbc560b6470b360219ac95c13e2';
create schema authorization dave;
END IF;
END
);
-- end of sub block
END IF;
END
$do$;
SQL Error [42601]: ERROR: syntax error at or near "NOT" Position:
231
What i want do is a like where it does alot of actions in a sub block:
DO
$do$
DECLARE
database CONSTANT text[] := array['prd1', 'prd2'];
BEGIN
IF current_database() = any(database)
THEN
**--execute the below sub block**
DECLARE
v_sql text;
BEGIN
v_sql :=
IF NOT EXISTS (
SELECT FROM pg_catalog.pg_roles -- SELECT list can be empty for this
WHERE rolname = 'dave') THEN
create role dave encrypted password 'md502bbddbc560b6470b360219ac95c13e2';
create schema authorization dave;
END IF;
END
do
$$
begin
execute format('grant connect, temporary on database %I to %I', current_database(), 'user_monitor');
end;
$$;
CREATE OR REPLACE FUNCTION test.log_ddl()
RETURNS event_trigger AS $$
DECLARE
audit_query TEXT;
r RECORD;
BEGIN
[...]
END;
$$ LANGUAGE plpgsql;
**-- end of sub block**
END IF;
END
$do$;
Why use sub-block when you can use the IF conditional? 2) Why v_sql := ...? I see no point in assigning the query to a variable. Again all you want is to take CREATE actions based on the IF condition. –
Adrian Klaver
I have a stored procedure(P1) that returns a refcursor and few other text datatype values.
I have another procedure(P2) where I need to the fetch P1's refcursor output and insert it into a temporary table. The temporary table has matching columns and datatypes.
create or replace procedure P1(inout rfcur refcursor, in dtl text)
as
$$
begin
open rfcur for select * from tst_dump where ident = dtl;
end;
$$
language plpgsql;
create or replace P2(inout rfc refcursor, in dt_array text[])
as
$$
declare
i record;
cur refcursor;
begin
for i in array_lower(dt_array, 1)..array_upper(dt_array, 1) loop
call P1(cur, i);
--I need to fetch the result set from `cur` and store into a temp table `t_tab1`.
end loop;
end;
$$
language plpgsql;
Is it possible to achieve this in Postgres?
NOTE: I'm not supposed to make any changes to the procedure P1.
p2 could look like this:
CREATE PROCEDURE p2(IN dt_array text[])
LANGUAGE plpgsql AS
$$DECLARE
r record;
i integer;
cur refcursor;
BEGIN
FOR i IN array_lower(dt_array, 1)..array_upper(dt_array, 1) LOOP
CALL p1(cur, i::text);
LOOP
FETCH cur INTO r;
EXIT WHEN NOT FOUND;
INSERT INTO t_tab1 (...) VALUES (r.col1, r.col2, ...;
END LOOP;
END LOOP;
END;$$;
You should indent your code. That's the basic requirement when you program.
It seems to me that you are doing something the wrong way. Using procedures and cursors complicates everything and makes it slower.
You should do something like
INSERT INTO t_tab
SELECT /* your original query */;
I have a question: how to add multiple table for one trigger?
Is that possible, or should I just make another 2 triggers for 2 different tables?
Create a new function
CREATE OR REPLACE FUNCTION updated_timestamp_func()
RETURNS TRIGGER
LANGUAGE plpgsql AS
'
BEGIN
NEW.updated_at = now();
RETURN NEW;
END;
';
Then create a trigger for each table that has the column updated_at
DO $$
DECLARE
t text;
BEGIN
FOR t IN
SELECT table_name FROM information_schema.columns WHERE column_name = 'updated_at'
LOOP
EXECUTE format('CREATE TRIGGER trigger_update_timestamp
BEFORE UPDATE ON %I
FOR EACH ROW EXECUTE PROCEDURE updated_timestamp_func()', t,t);
END loop;
END;
$$ language 'plpgsql';
Iterate one trigger for all tables
(For Example Foreign Tables)
DO
$$
DECLARE
r RECORD;
BEGIN
FOR r IN SELECT *
FROM information_schema.tables
where table_type = 'FOREIGN TABLE'
and table_schema = 'public'
and table_name <> 'django_migrations'
LOOP
RAISE NOTICE 'CREATE TRIGGER FOR: %', r.table_name::text;
EXECUTE 'CREATE TRIGGER trg_insert_ids
BEFORE INSERT
on ' || r.table_name || ' FOR EACH ROW
EXECUTE PROCEDURE insert_ids();';
END LOOP;
END;
$$ LANGUAGE plpgsql;
You need to define a trigger for each table, so if you have two tables, you need two triggers.
However, multiple triggers can use the same trigger function.
I wrote a PL/pgsql to batch create index on tables
CREATE OR REPLACE FUNCTION create_index() RETURNS void AS
$BODY$
DECLARE
r INTEGER;
BEGIN
FOR r IN 1..1000
LOOP
EXECUTE format(
' CREATE INDEX idx_abc_id_' || r::text ||
' ON abc_id_' || r::text ||
' USING btree
(key);');
END LOOP;
RETURN;
END
$BODY$
LANGUAGE plpgsql;
it has one problem, if partition abc_500 doesn't exist, then the how create index function will fail and do nothing.
How to make loop keep going through even if create_index made an error on one of the table in between?
I think a better approach would be to not hardcode the number for the loop, but iterate over the existing tables:
CREATE OR REPLACE FUNCTION create_index() RETURNS void AS
$BODY$
DECLARE
r record;
BEGIN
FOR r IN select tablename, regexp_replace(tablename, '[^0-9]+','') as idx_nr
from pg_tables
where tablename ~ 'abc_id_[0-9]+'
LOOP
EXECUTE format('CREATE INDEX %I ON %I USING btree (key)',
'idx_abc_id_'||r.idx_nr,
r.tablename);
END LOOP;
RETURN;
END
$BODY$
LANGUAGE plpgsql;
When you use the format() function is better to use the proper place holders for identifiers.
If you also want to ignore any error when creating the index on an existing table, you need to catch the exception and ignore it:
CREATE OR REPLACE FUNCTION create_index() RETURNS void AS
$BODY$
DECLARE
r record;
msg text;
BEGIN
FOR r IN select tablename, regexp_replace(tablename, '[^0-9]+','') as idx_nr
from pg_tables
where tablename ~ 'abc_id_[0-9]+'
LOOP
BEGIN
EXECUTE format('CREATE INDEX %I ON %I USING btree (key)',
'idx_abc_id_'||r.idx_nr,
r.tablename);
EXCEPTION
WHEN OTHERS THEN
GET STACKED DIAGNOSTICS msg = MESSAGE_TEXT;
RAISE NOTICE 'Could not create index for: %, %', r.idx_nr, msg;
END;
END LOOP;
RETURN;
END
$BODY$
LANGUAGE plpgsql;
How can I iterate over integer[] if I have:
operators_ids = string_to_array(operators_ids_g,',')::integer[];
I want iterate over operators_ids.
I can't do it in this way:
FOR oid IN operators_ids LOOP
and this:
FOR oid IN SELECT operators_ids LOOP
oid is integer;
You can iterate over an array like
DO
$body$
DECLARE your_array integer[] := '{1, 2, 3}'::integer[];
BEGIN
FOR i IN array_lower(your_array, 1) .. array_upper(your_array, 1)
LOOP
-- do something with your value
raise notice '%', your_array[i];
END LOOP;
END;
$body$
LANGUAGE plpgsql;
But the main question in my view is: why do you need to do this? There are chances you can solve your problem in better ways, for example:
DO
$body$
DECLARE i record;
BEGIN
FOR i IN (SELECT operators_id FROM your_table)
LOOP
-- do something with your value
raise notice '%', i.operators_id;
END LOOP;
END;
$body$
LANGUAGE plpgsql;
I think Dezso is right. You do not need to use looping the array using an index.
If you make a select statement grouping by person_id in combination with limit 1, you have the result set you wanted:
create or replace function statement_example(p_data text[]) returns int as $$
declare
rw event_log%rowtype;
begin
for rw in select * from "PRD".events_log where (event_type_id = 100 or event_type_id = 101) and person_id = any(operators_id::int[]) and plc_time < begin_date_g order by plc_time desc group by person_id limit 1 loop
raise notice 'interesting log: %', rw.field;
end loop;
return 1;
end;
$$ language plpgsql volatile;
That should perform much better.
If you still prefer looping an integer array and there are a lot of person_ids to look after, then might you consider using the flyweight design pattern:
create or replace function flyweight_example(p_data text[]) returns int as $$
declare
i_id int;
i_min int;
i_max int;
begin
i_min := array_lower(p_data,1);
i_max := array_upper(p_data,1);
for i_id in i_min .. i_max loop
raise notice 'interesting log: %',p_data[i_id];
end loop;
return 1;
end;
$$ language plpgsql volatile;