Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Ronan Dunklau
Maybe you could set some options on the foreign table before selecting from it ? Another way you could achieve the same result would be to give some column a special meaning (like it is done in the twitter_fdw for example). If you don't mind, do you have a specific use-case for this ? -- Ronan

Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Dimitri Fontaine
Jeff Davis pg...@j-davis.com writes: Take something as simple as generate_series: right now, it materializes the entire thing if it's in the FROM clause, but it wouldn't need to if it could use the foreign table mechanism. So, my understanding of your proposal is that a good way to implement

Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Simon Riggs
On 6 November 2012 06:09, Jeff Davis pg...@j-davis.com wrote: On Sun, 2012-11-04 at 15:13 -0500, Tom Lane wrote: Jeff Davis pg...@j-davis.com writes: Is there any fundamental or philosophical reason why a foreign table can't accept arguments? That isn't a table; it's some sort of function.

Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Tom Lane
Dimitri Fontaine dimi...@2ndquadrant.fr writes: Jeff Davis pg...@j-davis.com writes: Take something as simple as generate_series: right now, it materializes the entire thing if it's in the FROM clause, but it wouldn't need to if it could use the foreign table mechanism. So, my understanding

Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Tom Lane
Simon Riggs si...@2ndquadrant.com writes: (On another thought: why do Foreign Scans get to avoid the materialization we hate with SRFs?) [ shrug... ] That works both ways. If it would be convenient for an FDW to return a tuplestore, which is hardly unlikely, it's out of luck; it has to do the

Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Jeff Davis
On Tue, 2012-11-06 at 08:35 +, Simon Riggs wrote: Tom is complaining about conflating the two features, which does seem unnecessary. But we can still merge code. That's a good way to put it. Providing run-time parameters or table-level options to Foreign Scans seems sensible. I can see

Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Jeff Davis
On Tue, 2012-11-06 at 09:39 +0100, Dimitri Fontaine wrote: Jeff Davis pg...@j-davis.com writes: Take something as simple as generate_series: right now, it materializes the entire thing if it's in the FROM clause, but it wouldn't need to if it could use the foreign table mechanism. So, my

Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Jeff Davis
On Tue, 2012-11-06 at 09:19 +0100, Ronan Dunklau wrote: Maybe you could set some options on the foreign table before selecting from it ? Another way you could achieve the same result would be to give some column a special meaning (like it is done in the twitter_fdw for example). If you

Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Pavel Stehule
2012/11/6 Jeff Davis pg...@j-davis.com: On Tue, 2012-11-06 at 09:19 +0100, Ronan Dunklau wrote: Maybe you could set some options on the foreign table before selecting from it ? Another way you could achieve the same result would be to give some column a special meaning (like it is done in the

Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Jeff Davis
On Tue, 2012-11-06 at 10:55 -0500, Tom Lane wrote: I'd also opine that the FDW APIs are pretty darn heavyweight for an SRF. There might be a small number of SRFs for which it's actually worth dealing with the planner in full generality, but surely not very many. I was not suggesting that we

Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Tom Lane
Jeff Davis pg...@j-davis.com writes: On Tue, 2012-11-06 at 10:55 -0500, Tom Lane wrote: I'd also opine that the FDW APIs are pretty darn heavyweight for an SRF. There might be a small number of SRFs for which it's actually worth dealing with the planner in full generality, but surely not very

Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Tom Lane
Jeff Davis pg...@j-davis.com writes: On Tue, 2012-11-06 at 09:19 +0100, Ronan Dunklau wrote: If you don't mind, do you have a specific use-case for this ? Let's say that your remote data source is a stream of data that is not actually being stored anywhere, e.g. network events. The data you

Re: [HACKERS] Arguments to foreign tables?

2012-11-06 Thread Jeff Davis
On Tue, 2012-11-06 at 12:57 -0500, Tom Lane wrote: That particular example can be handled perfectly well today, with select * from stream_table where tscol 'whatever'; The FDW could be coded to throw an error if the query doesn't provide a WHERE clause that constrains the timestamp

Re: [HACKERS] Arguments to foreign tables?

2012-11-05 Thread Jeff Davis
On Sun, 2012-11-04 at 15:13 -0500, Tom Lane wrote: Jeff Davis pg...@j-davis.com writes: Is there any fundamental or philosophical reason why a foreign table can't accept arguments? That isn't a table; it's some sort of function. Now that we have LATERAL, there is no good reason to

[HACKERS] Arguments to foreign tables?

2012-11-04 Thread Jeff Davis
Is there any fundamental or philosophical reason why a foreign table can't accept arguments? Should that be a TODO? Right now, to accept arguments to a from-clause item, you have to use an SRF, which is much more limited than a foreign table. If foreign tables could accept arguments, then SRFs

Re: [HACKERS] Arguments to foreign tables?

2012-11-04 Thread Tom Lane
Jeff Davis pg...@j-davis.com writes: Is there any fundamental or philosophical reason why a foreign table can't accept arguments? That isn't a table; it's some sort of function. Now that we have LATERAL, there is no good reason to contort SQL's syntax and semantics in the direction you

Re: [HACKERS] Arguments to foreign tables?

2012-11-04 Thread Willem Leenen
] Arguments to foreign tables? From: pg...@j-davis.com To: pgsql-hackers@postgresql.org Date: Sun, 4 Nov 2012 11:59:20 -0800 Is there any fundamental or philosophical reason why a foreign table can't accept arguments? Should that be a TODO? Right now, to accept arguments to a from-clause item

Re: [HACKERS] Arguments to foreign tables?

2012-11-04 Thread John R Pierce
On 11/04/12 11:59 AM, Jeff Davis wrote: Is there any fundamental or philosophical reason why a foreign table can't accept arguments? Should that be a TODO? what does that even mean?how would 'data' accept 'arguments' ??! -- john r pierceN 37, W 122 santa cruz

Re: [HACKERS] Arguments to foreign tables?

2012-11-04 Thread Willem Leenen
what does that even mean?how would 'data' accept 'arguments' ??! That's Sherlock Holmes! Don't argue with your data