Hi,
I need a table to hold the last n INSERTs into it.
To keep track of how many entries there are, and to
provide a unique id to order the records in the table,
I use a sequence. A trigger function deletes and entry
on an insert if the table is full.
The number n maybe changed, so I implemented this
PL/PgSQL function:
CREATE OR REPLACE FUNCTION set_max_records(integer)
RETURNS integer AS ' DECLARE new_max_records ALIAS FOR $1; BEGIN DROP SEQUENCE my_sequence;
--CREATESEQUENCE my_sequence MAXVALUE 4
CYCLE; CREATE SEQUENCE my_sequence MAXVALUE
new_max_records CYCLE; RETURN 0; END;
' LANGUAGE 'plpgsql';
(I left out the part where the table is shrunk and
renumbered if n goes down).
rdb=# select set_max_records(3);
LOG: query: CREATE SEQUENCE my_sequence MAXVALUE $1
CYCLE
LOG: statement: select set_max_records(3);
WARNING: Error occurred while executing PL/pgSQL
function set_max_records
LOG: statement: select set_max_records(3);
WARNING: line 6 at SQL statement
LOG: statement: select set_max_records(3);
DEBUG: AbortCurrentTransaction
ERROR: parser: parse error at or near "$1" at
character 39
If I don't use the variable new_max_records, it works
(the commented out line). What could be the problem ?
Also, if there is a better mechanism to implement
this, I'm all ears...
Erik Erkelens.
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