Re: Patch for 8.5, transformationHook
От | Pavel Stehule |
---|---|
Тема | Re: Patch for 8.5, transformationHook |
Дата | |
Msg-id | 162867790907260629w48328b02y1e7873cedb5b2056@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: Patch for 8.5, transformationHook (Robert Haas <robertmhaas@gmail.com>) |
Ответы |
Re: Patch for 8.5, transformationHook
(Pavel Stehule <pavel.stehule@gmail.com>)
Re: Patch for 8.5, transformationHook (Robert Haas <robertmhaas@gmail.com>) Re: Patch for 8.5, transformationHook (Jeff Davis <pgsql@j-davis.com>) |
Список | pgsql-hackers |
Hello new patch add new contrib "transformations" with three modules anotation, decode and json. These modules are ported from my older work. Before applying this patch, please use named-fixed patch too. The hook doesn't need it, but modules anotation and json depend on it. Regards Pavel Stehule 2009/7/26 Robert Haas <robertmhaas@gmail.com>: > On Sat, Jul 25, 2009 at 11:38 PM, Pavel Stehule<pavel.stehule@gmail.com> wrote: >> Hello >> >> 2009/7/25 Robert Haas <robertmhaas@gmail.com>: >>> On Mon, Apr 20, 2009 at 8:45 AM, Pavel Stehule<pavel.stehule@gmail.com> wrote: >>>> 2009/4/18 Tom Lane <tgl@sss.pgh.pa.us>: >>>>> Pavel Stehule <pavel.stehule@gmail.com> writes: >>>>>> 2009/4/11 Tom Lane <tgl@sss.pgh.pa.us>: >>>>>>> No, I was complaining that a hook right there is useless and expensive. >>>>>>> transformExpr() is executed multiple times per query, potentially a very >>>>>>> large number of times per query; so even testing to see if a hook exists >>>>>>> is not a negligible cost. >>>>> >>>>>> I did some tests based on pgbench. >>>>> >>>>> The queries done by pgbench are completely trivial and do not stress >>>>> parser performance. Even if they did (consider cases likw an IN with a >>>>> few thousand list items), the parser is normally not a bottleneck >>>>> compared to transaction overhead, network round trips, and pgbench >>>>> itself. >>>>> >>>>>> I though about different position of hook, but only in this place the >>>>>> hook is useful (because expressions are recursive). >>>>> >>>>> As I keep saying, a hook there is useless, at least by itself. You >>>>> have no control over the grammar and no ability to modify what the >>>>> rest of the system understands. The only application I can think of is >>>>> to fool with the transformation of FuncCall nodes, which you could do in >>>>> a much lower-overhead way by hooking into transformFuncCall. Even that >>>>> seems pretty darn marginal for real-world problems. >>>>> >>>> >>>> I am sending modified patch - it hooking parser via transformFuncCall >>> >>> I am reviewing this patch. It seems to me upon rereading the thread >>> that the objections Tom and Peter had to inserting a hook into >>> transformExpr() mostly still apply to a hook in transformFuncCall(): >>> namely, that there's no proof that putting a hook here is actually >>> useful. I think we should apply the same criteria to this that we >>> have to some other patches that have been rejected (like the >>> extensible-rmgr patch Simon submitted for CommitFest 2008-11), namely, >>> requiring that the extension mechanism be submitted together with at >>> least two examples of how it can be used to interesting and useful >>> things, bundled as one or more contrib modules. >> >> I have in my plan add to contrib JSON support similar to Bauman design: >> >> http://www.mysqludf.org/lib_mysqludf_json/index.php >> >> It's will be sample of "smart" functions. Because this need more then >> less work I am waiting on commit. >> >> Other simple intrduction contrib module should be real Oracle decode >> function - I sent source code some time ago. But this code needs some >> modification. I should send this code if you need it. > > Sure, post it and let's discuss. > > ...Robert >
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