Postgres Trigger function performance issue - postgresql

Question

Postgres 9.3 x64 bit ,I am using a history table with user log.huge data insertion occurring on every second till now the data is is around 90 millions and still counting
I partitioned the table using date column for every month and I used a trigger where for each insert it will check weather for the particular month table is there or not, if there it will directly insert else it will try to create and insert the data. but the trigger taking soo much time to execute is there any way to improvise the performance
CREATE OR REPLACE FUNCTION history_master_part_trigger()
RETURNS TRIGGER AS $$
DECLARE
yr int;
mnth int;
tbname character varying;
sdate character varying;
edate character varying;
cnt int;
Begin
raise notice '%','something';
EXECUTE 'select EXTRACT(YEAR FROM DATE '''||NEW.hm_date||''')' INTO yr;
EXECUTE 'select EXTRACT(month FROM DATE '''||NEW.hm_date||''')' INTO mnth;
tbname := 'history_master_part_y'||yr||'m'||mnth;
sdate :=yr||'-'||mnth||'-01';
IF mnth = 12 THEN
edate :=yr+1||'-'||'01-01';
ELSE
edate :=yr||'-'||mnth+1||'-01';
END IF;
--raise notice 'table-----', tbname;
raise notice '%', sdate;
raise notice '%', edate;
raise notice '%',yr;
If(SELECT EXISTS (
SELECT 1
FROM pg_catalog.pg_class c
JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE n.nspname = 'public'
AND c.relname = tbname
AND c.relkind = 'r' -- only tables(?)
)) THEN
--INSERT INTO ||tbname|| VALUES ||NEW'.*)';
raise notice '%','inserting into'||tbname;
EXECUTE format('INSERT INTO ' || tbname || ' SELECT ($1).*')
USING NEW;
ELSE
EXECUTE 'CREATE TABLE '|| tbname||'(
CHECK ( hm_date >= DATE '''||sdate||''' AND hm_date < DATE '''||edate||''' )
) INHERITS (history_master_part)';
EXECUTE format('INSERT INTO ' || tbname || ' SELECT ($1).*')
USING NEW;
--RAISE EXCEPTION 'Caution Caution Caution Amit is getting angry';
END IF;
Return NULL;
End;
$$
LANGUAGE 'plpgsql'