Hitoshi Harada wrote: >I made up my mind to scratch former window functions and redesigned >completely new execution model, based on the discussion with Heikki. >Attached is the v06 against HEAD today. >http://umitanuki.net/pgsql/wfv06/design.html
First off, fantastic work! In my eyes this and WITH RECURSIVE are a big step for both Postgres and open source RBDMS'. Only, one small query with LEAD() and LAG() Going by http://www.wiscorp.com/sql200n.zip "The lead and lag functions each take three arguments, a <value expression> VE, an <exact numeric literal> OFFSET, and a <value expression> DEFAULT. For each row R within the window partition P of R defined by a window structure descriptor, the lag function returns the value of VE evaluated on a row that is OFFSET number of rows before R within P, and the lead function returns the value of VE evaluated on a row that is OFFSET number of rows after R within P. The value of DEFAULT is returned as the result if there is no row corresponding to the OFFSET number of rows before R within P (for the lag function) or after R within P (for the lead function). In addition, RESPECT NULLS or IGNORE NULLS can be specified to indicate whether the rows within P for which VE evaluates to the null value are preserved or eliminated" So going by that: SELECT name,LAG(name,1,'None') OVER (ORDER BY employeeid) FROM employee; Would use 'None' for rows that would be out of the bounds of the window. The current patch only seems to accept 2 arguments. ERROR: function lag(character varying, integer, unknown) does not exist -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
