5 Commits (ec4be2ee6827b6bd85e0813c7a8993cfbb0e6fa7)

Author	SHA1	Message	Date
Tom Lane	ec4be2ee68	Extend the set of frame options supported for window functions. ... This patch allows the frame to start from CURRENT ROW (in either RANGE or ROWS mode), and it also adds support for ROWS n PRECEDING and ROWS n FOLLOWING start and end points. (RANGE value PRECEDING/FOLLOWING isn't there yet --- the grammar works, but that's all.) Hitoshi Harada, reviewed by Pavel Stehule	16 years ago
Tom Lane	bb16dc49ab	Modify the definition of window-function PARTITION BY and ORDER BY clauses ... so that their elements are always taken as simple expressions over the query's input columns. It originally seemed like a good idea to make them act exactly like GROUP BY and ORDER BY, right down to the SQL92-era behavior of accepting output column names or numbers. However, that was not such a great idea, for two reasons: 1. It permits circular references, as exhibited in bug #5018: the output column could be the one containing the window function itself. (We actually had a regression test case illustrating this, but nobody thought twice about how confusing that would be.) 2. It doesn't seem like a good idea for, eg, "lead(foo) OVER (ORDER BY foo)" to potentially use two completely different meanings for "foo". Accordingly, narrow down the behavior of window clauses to use only the SQL99-compliant interpretation that the expressions are simple expressions.	17 years ago
Tom Lane	8e8854daa2	Add some basic support for window frame clauses to the window-functions ... patch. This includes the ability to force the frame to cover the whole partition, and the ability to make the frame end exactly on the current row rather than its last ORDER BY peer. Supporting any more of the full SQL frame-clause syntax will require nontrivial hacking on the window aggregate code, so it'll have to wait for 8.5 or beyond.	17 years ago
Tom Lane	2f806e540f	Tighten up a couple of regression test cases that can have platform-dependent ... results due to underspecified ordering. Per report from buildfarm member pika.	17 years ago
Tom Lane	95b07bc7f5	Support window functions a la SQL:2008. ... Hitoshi Harada, with some kibitzing from Heikki and Tom.	17 years ago