[GENERAL] Syntax error in spi_prepare usage

[dipti shah]

I am using SPI_Prepare from trigger like below. I have some minor issue with
$query syntax. I have tried almost all combination but I am not able to
resolve. Could anyone please help me out.

CREATE OR REPLACE FUNCTION insert_history_info()
RETURNS VOID AS
$BODY$
 my $query = (<<ENDQUERY);
  INSERT INTO changelogtest(id, txid, txtime)
  SELECT  (\$1, \$2, \$3) --> there is some issue here.
  EXCEPT
  SELECT (id, txid, txtime)
  FROM changelogtest
  WHERE id = \$1
  AND txid = \$2
  AND txtime = \$3;
 ENDQUERY

 # Always use the prepared query if available
 if (not exists($_SHARED{$query})) {
  $_SHARED{$query} = spi_prepare($query, 'INTEGER', 'INTEGER', 'TIMESTAMP');
 }

 spi_exec_prepared($_SHARED{$query}, 5, 123, now());

 return;
$BODY$
  LANGUAGE 'plperl' VOLATILE SECURITY DEFINER

techdb=# SELECT insert_history_info();
ERROR:  error from Perl function "insert_history_info": INSERT has more
target columns than expressions at line 15.

If I remove the braces from (\$1, \$2, \$3) then it gives below error.
 my $query = (<<ENDQUERY);
  INSERT INTO changelogtest(id, txid, txtime)
  SELECT  \$1, \$2, \$3
  EXCEPT
  SELECT (id, txid, txtime)
  FROM changelogtest
  WHERE id = \$1
  AND txid = \$2
  AND txtime = \$3;
 ENDQUERY

techdb=# SELECT insert_history_info();
ERROR:  error from Perl function "insert_history_info": each EXCEPT query
must have the same number of columns at line 15.

My table Definitation:

 techdb=# \d changelogtest
...
                               Table "techdb.changelogtest"
     Column     |            Type             |                Modifiers
----------------+-----------------------------+------------------------------------------
 id             | integer                     | not null
 txid           | integer                     | not null default
txid_current()
 txtime         | timestamp without time zone | not null default
transaction_timestamp()
Foreign-key constraints:
    "changelogtest_id_fkey" FOREIGN KEY (id) REFERENCES logtable(id)

Thanks,
Dipti