Re: [HACKERS] Which file does the SELECT?
Yeah that is what seems to be the best way. The thing is that I am looking in the PostgreSQL code for the first time and I am not fully aware of the data structures or the methods / algos implemented in the project. This makes the work of finding out whats and whys much more difficult. So I asked it on the list. Thanks anyways for the reply. -Vaibhav (*_*) On Wed, Nov 10, 2010 at 9:38 AM, Robert Haas robertmh...@gmail.com wrote: On Mon, Nov 8, 2010 at 9:55 PM, Vaibhav Kaushal vaibhavkaushal...@gmail.com wrote: I have started with the work and am using Eclipse and it helps quite a lot. I can find the declarations quite easily. Thanks to open Source. BTW, I am encountering too many (just too many) data types as I try to understand the backend (specifically the executor). I do think that its normal because the executor has to consider almost everything that the other parts of the DB can possibly command it to do. Is there some documentation available on the data types / structures which are in use at the backend? There's less than one might hope. I think you pretty much have to look through the README files and source code comments. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
Re: [HACKERS] Which file does the SELECT?
On Mon, Nov 8, 2010 at 9:55 PM, Vaibhav Kaushal vaibhavkaushal...@gmail.com wrote: I have started with the work and am using Eclipse and it helps quite a lot. I can find the declarations quite easily. Thanks to open Source. BTW, I am encountering too many (just too many) data types as I try to understand the backend (specifically the executor). I do think that its normal because the executor has to consider almost everything that the other parts of the DB can possibly command it to do. Is there some documentation available on the data types / structures which are in use at the backend? There's less than one might hope. I think you pretty much have to look through the README files and source code comments. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Fwd: [HACKERS] Which file does the SELECT?
-- Forwarded message -- From: Vaibhav Kaushal vaibhavkaushal...@gmail.com Date: Tue, Nov 9, 2010 at 8:24 AM Subject: Re: [HACKERS] Which file does the SELECT? To: Dimitri Fontaine dimi...@2ndquadrant.fr I have started with the work and am using Eclipse and it helps quite a lot. I can find the declarations quite easily. Thanks to open Source. BTW, I am encountering too many (just too many) data types as I try to understand the backend (specifically the executor). I do think that its normal because the executor has to consider almost everything that the other parts of the DB can possibly command it to do. Is there some documentation available on the data types / structures which are in use at the backend? -Vaibhav (*_*) On Wed, Oct 13, 2010 at 1:20 AM, Dimitri Fontaine dimi...@2ndquadrant.frwrote: David Fetter da...@fetter.org writes: On Mon, Oct 11, 2010 at 04:14:04PM +0530, Vaibhav Kaushal wrote: Is there something like that in Kdevelop? I dont use CLI editors much. KDevelop is listed as one of the editors that support ctags. I've just developed some code for the backend and used cscope (from Emacs directly) which is excellent. http://cscope.sourceforge.net/ http://kscope.sourceforge.net/ http://www.ziplink.net/~felaco/cbrowser/http://www.ziplink.net/%7Efelaco/cbrowser/ Unfortunately the KDE GUI for it seems unmaintained now. Regards, -- Dimitri Fontaine http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support
Fwd: [HACKERS] Which file does the SELECT?
I have started with the work and am using Eclipse and it helps quite a lot. I can find the declarations quite easily. Thanks to open Source. BTW, I am encountering too many (just too many) data types as I try to understand the backend (specifically the executor). I do think that its normal because the executor has to consider almost everything that the other parts of the DB can possibly command it to do. Is there some documentation available on the data types / structures which are in use at the backend? -Vaibhav (*_*) On Wed, Oct 13, 2010 at 1:20 AM, Dimitri Fontaine dimi...@2ndquadrant.frwrote: David Fetter da...@fetter.org writes: On Mon, Oct 11, 2010 at 04:14:04PM +0530, Vaibhav Kaushal wrote: Is there something like that in Kdevelop? I dont use CLI editors much. KDevelop is listed as one of the editors that support ctags. I've just developed some code for the backend and used cscope (from Emacs directly) which is excellent. http://cscope.sourceforge.net/ http://kscope.sourceforge.net/ http://www.ziplink.net/~felaco/cbrowser/http://www.ziplink.net/%7Efelaco/cbrowser/ Unfortunately the KDE GUI for it seems unmaintained now. Regards, -- Dimitri Fontaine http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support
Re: [HACKERS] Which file does the SELECT?
David Fetter da...@fetter.org writes: On Mon, Oct 11, 2010 at 04:14:04PM +0530, Vaibhav Kaushal wrote: Is there something like that in Kdevelop? I dont use CLI editors much. KDevelop is listed as one of the editors that support ctags. I've just developed some code for the backend and used cscope (from Emacs directly) which is excellent. http://cscope.sourceforge.net/ http://kscope.sourceforge.net/ http://www.ziplink.net/~felaco/cbrowser/ Unfortunately the KDE GUI for it seems unmaintained now. Regards, -- Dimitri Fontaine http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Which file does the SELECT?
Is there something like that in Kdevelop? I dont use CLI editors much. On Mon, Oct 11, 2010 at 7:55 AM, David Christensen da...@endpoint.comwrote: On Oct 10, 2010, at 12:21 PM, Vaibhav Kaushal wrote: Thanks to both hitoshi and tom for your replies. I think I need to look into the Postgres code itself (I am better at code than documentation). But since I have not been touch with C lately (these days I am programming on PHP) I think I have forgot a few rules of game (afterall PHP is so much more easy than C :P ). Moreover, postgres is the first Open Source software whose code I am interested in. I have never looked into other OSS codes much except correcting a few compilation errors here and there on beta / alpha releases. I have had the chance and success to compile my own Linux OS and it was fun to do so... but I guess development is a tougher job. With an idea in mind, and a thankful feeling towards postgres is what drives me to do this tougher job. When I was designing my database for a web app, I found so many problems in MySQL that I could not continue (the best of all, I can't use the commands written in my DB book to create a foreign key, it does not natively support foreign keys, confusing storage engines and so on).. and then I got postgres which I am a fan of. I hope I will not be flamed when I will ask those questions (some of them are actually very silly ones). I will look inside the code now and will get back after i get some progress with it. However, I find too many references to the Data structure datum what is it and where is it defined? Can someone tell me please? Also, what role does it play? Thanks to you all for your replies. -Vaibhav Depending on your text editor, you may be able to utilize TAGS files; see src/tools/make_(e|c)tags for creating TAGS files for your editor of choice (emacs/vim, although other editors may support specific formats). This will allow you to navigate to the specific definition of the type/function/macro, and can be very enlightening and help answer some of these questions. `git grep` will also come in handy if you're working directly from a git checkout. Regards, David -- David Christensen End Point Corporation da...@endpoint.com
Re: [HACKERS] Which file does the SELECT?
On Mon, Oct 11, 2010 at 04:14:04PM +0530, Vaibhav Kaushal wrote: Is there something like that in Kdevelop? I dont use CLI editors much. KDevelop is listed as one of the editors that support ctags. http://en.wikipedia.org/wiki/Ctags Cheers, David. -- David Fetter da...@fetter.org http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fet...@gmail.com iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
[HACKERS] Which file does the SELECT?
I have gone through the source code a bit but I wanted to know that which file contains the code that performs the final SLECTION after the optimizer has created the final plan? I mean which part of the executor is responsible for the SELCT to be run? Can someone tell me the file which governs it? Thanks for any help in advance.
Re: [HACKERS] Which file does the SELECT?
On sön, 2010-10-10 at 13:32 +0530, Vaibhav Kaushal wrote: I have gone through the source code a bit but I wanted to know that which file contains the code that performs the final SLECTION after the optimizer has created the final plan? I mean which part of the executor is responsible for the SELCT to be run? That depends on what plan was chosen for the SELECT, since the executor is primarily organized by plan node type, independent of which statement caused the plan to be generated. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Which file does the SELECT?
Thanks for the reply. So if I am not wrong, I will have to understand the whole querying process in detail? If it is so, then where do I start from? -Vaibhav On Sun, Oct 10, 2010 at 1:41 PM, Peter Eisentraut pete...@gmx.net wrote: On sön, 2010-10-10 at 13:32 +0530, Vaibhav Kaushal wrote: I have gone through the source code a bit but I wanted to know that which file contains the code that performs the final SLECTION after the optimizer has created the final plan? I mean which part of the executor is responsible for the SELCT to be run? That depends on what plan was chosen for the SELECT, since the executor is primarily organized by plan node type, independent of which statement caused the plan to be generated.
Re: [HACKERS] Which file does the SELECT?
2010/10/10 Vaibhav Kaushal vaibhavkaushal...@gmail.com: Thanks for the reply. So if I am not wrong, I will have to understand the whole querying process in detail? If it is so, then where do I start from? -Vaibhav On Sun, Oct 10, 2010 at 1:41 PM, Peter Eisentraut pete...@gmx.net wrote: On sön, 2010-10-10 at 13:32 +0530, Vaibhav Kaushal wrote: I have gone through the source code a bit but I wanted to know that which file contains the code that performs the final SLECTION after the optimizer has created the final plan? I mean which part of the executor is responsible for the SELCT to be run? That depends on what plan was chosen for the SELECT, since the executor is primarily organized by plan node type, independent of which statement caused the plan to be generated. So if I am not wrong, I will have to understand the whole querying process in detail? If it is so, then where do I start from? And it depends on what you are interested in. If the executor behavior is your interest, see execMain.c, but your question looks more interested in nodeSeqscan.c which scans rows from a relation. Regards, -- Hitoshi Harada -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Which file does the SELECT?
Vaibhav Kaushal vaibhavkaushal...@gmail.com writes: So if I am not wrong, I will have to understand the whole querying process in detail? If it is so, then where do I start from? If you haven't seen it already, this is a good place to start: http://developer.postgresql.org/pgdocs/postgres/overview.html There's also some stuff in src/tools/backend/ that tries to summarize which subdirectories of the source tree do what. Also, many subsystems have README files in the source tree. It sounds like you might like to look at src/backend/executor/README. But in the end there's no substitute for reading source code... regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Which file does the SELECT?
The PostgreSQL documentation (9.0.1) has the following section in section 44.5.1: The planner preferentially considers joins between any two relations for which there exist a corresponding join clause in the WHERE qualification (i.e., for which a restriction like where rel1.attr1=rel2.attr2 exists). *Join pairs with no join clause are considered only when* there is no other choice, that is, a particular relation has no available join clauses to any other relation. All possible plans are generated for every join pair considered by the planner, and the one that is (estimated to be) the cheapest is chosen. Can someone tell me what are 'Join Pairs with no Join clause' ? I am not able to figure that out! -Vaibhav (*_*) On Sun, Oct 10, 2010 at 1:58 PM, Vaibhav Kaushal vaibhavkaushal...@gmail.com wrote: Thanks for the reply. So if I am not wrong, I will have to understand the whole querying process in detail? If it is so, then where do I start from? -Vaibhav On Sun, Oct 10, 2010 at 1:41 PM, Peter Eisentraut pete...@gmx.net wrote: On sön, 2010-10-10 at 13:32 +0530, Vaibhav Kaushal wrote: I have gone through the source code a bit but I wanted to know that which file contains the code that performs the final SLECTION after the optimizer has created the final plan? I mean which part of the executor is responsible for the SELCT to be run? That depends on what plan was chosen for the SELECT, since the executor is primarily organized by plan node type, independent of which statement caused the plan to be generated.
Re: [HACKERS] Which file does the SELECT?
Vaibhav Kaushal vaibhavkaushal...@gmail.com writes: Can someone tell me what are 'Join Pairs with no Join clause' ? I am not able to figure that out! Consider select * from t1, t2, t3 where t1.a = t2.x and t1.b = t3.y; In theory this query could be done by first joining t2 and t3, then joining that to t1. But the planner won't investigate the possibility because the t2/t3 join would have to be a cartesian product join: there's no WHERE clause relating them. On the other hand, if we have select * from t1, t2, t3 where t1.a = t2.x and t1.a = t3.y; then the planner is able to infer the additional join clause t2.x = t3.y, so it will consider that join sequence. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Which file does the SELECT?
Thanks to both hitoshi and tom for your replies. I think I need to look into the Postgres code itself (I am better at code than documentation). But since I have not been touch with C lately (these days I am programming on PHP) I think I have forgot a few rules of game (afterall PHP is so much more easy than C :P ). Moreover, postgres is the first Open Source software whose code I am interested in. I have never looked into other OSS codes much except correcting a few compilation errors here and there on beta / alpha releases. I have had the chance and success to compile my own Linux OS and it was fun to do so... but I guess development is a tougher job. With an idea in mind, and a thankful feeling towards postgres is what drives me to do this tougher job. When I was designing my database for a web app, I found so many problems in MySQL that I could not continue (the best of all, I can't use the commands written in my DB book to create a foreign key, it does not natively support foreign keys, confusing storage engines and so on).. and then I got postgres which I am a fan of. I hope I will not be flamed when I will ask those questions (some of them are actually very silly ones). I will look inside the code now and will get back after i get some progress with it. However, I find too many references to the Data structure datum what is it and where is it defined? Can someone tell me please? Also, what role does it play? Thanks to you all for your replies. -Vaibhav On Sun, Oct 10, 2010 at 9:29 PM, Tom Lane t...@sss.pgh.pa.us wrote: Vaibhav Kaushal vaibhavkaushal...@gmail.com writes: Can someone tell me what are 'Join Pairs with no Join clause' ? I am not able to figure that out! Consider select * from t1, t2, t3 where t1.a = t2.x and t1.b = t3.y; In theory this query could be done by first joining t2 and t3, then joining that to t1. But the planner won't investigate the possibility because the t2/t3 join would have to be a cartesian product join: there's no WHERE clause relating them. On the other hand, if we have select * from t1, t2, t3 where t1.a = t2.x and t1.a = t3.y; then the planner is able to infer the additional join clause t2.x = t3.y, so it will consider that join sequence. regards, tom lane
Re: [HACKERS] Which file does the SELECT?
On Sun, Oct 10, 2010 at 10:51:54PM +0530, Vaibhav Kaushal wrote: However, I find too many references to the Data structure datum what is it and where is it defined? Can someone tell me please? Also, what role does it play? Datum is the singular form of data. It refers to a single item of any type. So it may be an integer, text type, geometry type, anything. A row is a list of datums. (A datum can also be a composite type). Normally in the planner code you don't need to worry to much about what it explicitly refers to, but if you do, you need to know the type of a datum before you can manipulate it. The type is not stored inside the datum. Have a nice day, -- Martijn van Oosterhout klep...@svana.org http://svana.org/kleptog/ Patriotism is when love of your own people comes first; nationalism, when hate for people other than your own comes first. - Charles de Gaulle signature.asc Description: Digital signature
Re: [HACKERS] Which file does the SELECT?
On Oct 10, 2010, at 12:21 PM, Vaibhav Kaushal wrote: Thanks to both hitoshi and tom for your replies. I think I need to look into the Postgres code itself (I am better at code than documentation). But since I have not been touch with C lately (these days I am programming on PHP) I think I have forgot a few rules of game (afterall PHP is so much more easy than C :P ). Moreover, postgres is the first Open Source software whose code I am interested in. I have never looked into other OSS codes much except correcting a few compilation errors here and there on beta / alpha releases. I have had the chance and success to compile my own Linux OS and it was fun to do so... but I guess development is a tougher job. With an idea in mind, and a thankful feeling towards postgres is what drives me to do this tougher job. When I was designing my database for a web app, I found so many problems in MySQL that I could not continue (the best of all, I can't use the commands written in my DB book to create a foreign key, it does not natively support foreign keys, confusing storage engines and so on).. and then I got postgres which I am a fan of. I hope I will not be flamed when I will ask those questions (some of them are actually very silly ones). I will look inside the code now and will get back after i get some progress with it. However, I find too many references to the Data structure datum what is it and where is it defined? Can someone tell me please? Also, what role does it play? Thanks to you all for your replies. -Vaibhav Depending on your text editor, you may be able to utilize TAGS files; see src/tools/make_(e|c)tags for creating TAGS files for your editor of choice (emacs/vim, although other editors may support specific formats). This will allow you to navigate to the specific definition of the type/function/macro, and can be very enlightening and help answer some of these questions. `git grep` will also come in handy if you're working directly from a git checkout. Regards, David -- David Christensen End Point Corporation da...@endpoint.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
