From 7f20a5920123066918a627029ad8ae7f7b55cf10 Mon Sep 17 00:00:00 2001 From: Bruce Momjian Date: Wed, 1 Dec 2004 17:21:58 +0000 Subject: [PATCH] Update with Gavin's additions. --- doc/FAQ_DEV | 340 +++++---- doc/src/FAQ/FAQ_DEV.html | 1453 ++++++++++++++++++++------------------ 2 files changed, 938 insertions(+), 855 deletions(-) diff --git a/doc/FAQ_DEV b/doc/FAQ_DEV index d251b9f35f..665e65ee90 100644 --- a/doc/FAQ_DEV +++ b/doc/FAQ_DEV @@ -1,7 +1,7 @@ Developer's Frequently Asked Questions (FAQ) for PostgreSQL - Last updated: Sat Nov 27 01:02:35 EST 2004 + Last updated: Wed Dec 1 16:11:11 EST 2006 Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us) @@ -12,19 +12,24 @@ General Questions 1.1) How do I get involved in PostgreSQL development? - 1.2) How do I add a feature or fix a bug? - 1.3) How do I download/update the current source tree? - 1.4) How do I test my changes? - 1.5) What tools are available for developers? - 1.6) What books are good for developers? - 1.7) What is configure all about? - 1.8) How do I add a new port? - 1.9) Why don't you use threads/raw devices/async-I/O, ? - 1.10) How are RPM's packaged? - 1.11) How are CVS branches handled? - 1.12) Where can I get a copy of the SQL standards? - 1.1) How do I get involved in PostgreSQL web site development? + 1.14) How are RPM's packaged? + 1.15) How are CVS branches handled? + 1.16) Where can I get a copy of the SQL standards? + 1.17) Where can I get technical assistance? + 1.18) How do I get involved in PostgreSQL web site development? Technical Questions @@ -43,150 +48,157 @@ 1.1) How go I get involved in PostgreSQL development? - This was written by Lamar Owen: + Download the code and have a look around. See 1.7. - 2001-06-22 - What open source development process is used by the PostgreSQL team? + Subscribe to and read the pgsql-hackers mailing list (often termed + 'hackers'). This is where the major contributors and core members of + the project discuss development. - Read HACKERS for six months (or a full release cycle, whichever is - longer). Really. HACKERS _is_the process. The process is not well - documented (AFAIK -- it may be somewhere that I am not aware of) -- - and it changes continually. - What development environment (OS, system, compilers, etc) is required - to develop code? - - Developers Corner on the website has links to this information. The - distribution tarball itself includes all the extra tools and documents - that go beyond a good Unix-like development environment. In general, a - modern unix with a modern gcc, GNU make or equivalent, autoconf (of a - particular version), and good working knowledge of those tools are - required. - What areas need support? - - The TODO list. - - You've made the first step, by finding and subscribing to HACKERS. - Once you find an area to look at in the TODO, and have read the - documentation on the internals, etc, then you check out a current - CVS,write what you are going to write (keeping your CVS checkout up to - date in the process), and make up a patch (as a context diff only) and - send to the PATCHES list, prefereably. - - Discussion on the patch typically happens here. If the patch adds a - major feature, it would be a good idea to talk about it first on the - HACKERS list, in order to increase the chances of it being accepted, - as well as toavoid duplication of effort. Note that experienced - developers with a proven track record usually get the big jobs -- for - more than one reason. Also note that PostgreSQL is highly portable -- - nonportable code will likely be dismissed out of hand. - - Once your contributions get accepted, things move from there. - Typically, you would be added as a developer on the list on the - website when one of the other developers recommends it. Membership on - the steering committee is by invitation only, by the other steering - committee members, from what I have gathered watching froma distance. - - I make these statements from having watched the process for over two - years. - - To see a good example of how one goes about this, search the archives - for the name 'Tom Lane' and see what his first post consisted of, and - where he took things. In particular, note that this hasn't been _that_ - long ago -- and his bugfixing and general deep knowledge with this - codebase is legendary. Take a few days to read after him. And pay - special attention to both the sheer quantity as well as the - painstaking quality of his work. Both are in high demand. - - 1.2) How do I add a feature or fix a bug? + 1.2) What development environment is required to develop code? - The source code is over 350,000 lines. Many fixes/features are - isolated to one specific area of the code. Others require knowledge of - much of the source. If you are confused about where to start, ask the - hackers list, and they will be glad to assess the complexity and give - pointers on where to start. + PostgreSQL is developed mostly in the C programming language. It also + makes use of Yacc and Lex. - Another thing to keep in mind is that many fixes and features can be - added with surprisingly little code. I often start by adding code, - then looking at other areas in the code where similar things are done, - and by the time I am finished, the patch is quite small and compact. + The source code is targeted at most of the popular Unix platforms and + the Windows environment (XP, Windows 2000, and up). - When adding code, keep in mind that it should use the existing - facilities in the source, for performance reasons and for simplicity. - Often a review of existing code doing similar things is helpful. + Most developers make use of the open source development tool chain. If + you have contributed to open source software before, you will probably + be familiar with these tools. They include: GCC (http://gcc.gnu.org, + GDB (www.gnu.org/software/gdb/gdb.html), autoconf + (www.gnu.org/software/autoconf/) AND GNU make + (www.gnu.org/software/make/make.html. - The usual process for source additions is: - * Review the TODO list. - * Discuss hackers the desirability of the fix/feature. - * How should it behave in complex circumstances? - * How should it be implemented? - * Submit the patch to the patches list. - * Answer email questions. - * Wait for the patch to be applied. - - 1.3) How do I download/update the current source tree? + Developers using this tool chain on Windows make use of MingW (see + http://www.mingw.org/). + + Some developers use compilers from other software vendors with mixed + results. + + Developers who are regularly rebuilding the source often pass the + --enable-depend flag to configure. The result is that when you make a + modification to a C header file, all files depend upon that file are + also rebuilt. + + 1.3) What areas need work? + + Outstanding features are detailed in the TODO list. This is located in + doc/TODO in the source distribution or at + http://developer.postgresql.org/todo.php. + + You can learn more about these features by consulting the archives, + the SQL standards and the recommend texts (see 1.10). + + 1.4) What do I do after choosing an item to work on? + + Send an email to pgsql-hackers with a proposal for what you want to do + (assuming your contribution is not trivial). Working in isolation is + not advisable: others may be working on the same TODO item; you may + have misunderstood the TODO item; your approach may benefit from the + review of others. + + 1.5) Where can I learn more about the code? + + Other than documentation in the source tree itself, you can find some + papers/presentations discussing the code at + http://developers.postgresql.org. + + 1.6) I've developed a patch, what next? + + Generate the patch in contextual diff format. If you are unfamiliar + with this, you may find the script src/tools/makediff/difforig useful. + + Ensure that your patch is generated against the most recent version of + the code. If it is a patch adding new functionality, the most recent + version is cvs HEAD; if it is a bug fix, this will be the most + recently version of the branch which suffers from the bug (for more on + branches in PostgreSQL, see 1.15). + + Finally, submit the patch to pgsql-patches@postgresql.org. It will be + reviewed by other contributors to the project and may be either + accepted or sent back for further work. + + 1.7) How do I download/update the current source tree? There are several ways to obtain the source tree. Occasional developers can just get the most recent source tree snapshot from - ftp.postgresql.org. For regular developers, you can use CVS. CVS - allows you to download the source tree, then occasionally update your - copy of the source tree with any new changes. Using CVS, you don't - have to download the entire source each time, only the changed files. - Anonymous CVS does not allows developers to update the remote source - tree, though privileged developers can do this. There is a CVS section - (http://developer.postgresql.org/docs/postgres/cvs.html) in our - documentation that describes how to use remote CVS. You can also use - CVSup, which has similarly functionality, and is available from - ftp.postgresql.org. + ftp://ftp.postgresql.org. - To update the source tree, there are two ways. You can generate a - patch against your current source tree, perhaps using the make_diff - tools mentioned above, and send them to the patches list. They will be - reviewed, and applied in a timely manner. If the patch is major, and - we are in beta testing, the developers may wait for the final release - before applying your patches. + Regular developers may want to take advantage of anonymous access to + our source code management system. The source tree is currently hosted + in CVS. For details of how to obtain the source from CVS see + http://developer.postgresql.org/docs/postgres/cvs.html. - For hard-core developers, Marc(scrappy@postgresql.org) will give you a - Unix shell account on postgresql.org, so you can use CVS to update the - main source tree, or you can ftp your files into your account, patch, - and cvs install the changes directly into the source tree. - - 1.4) How do I test my changes? + 1.8) How do I test my changes? - First, use psql to make sure it is working as you expect. Then run - src/test/regress and get the output of src/test/regress/checkresults - with and without your changes, to see that your patch does not change - the regression test in unexpected ways. This practice has saved me - many times. The regression tests test the code in ways I would never - do, and has caught many bugs in my patches. By finding the problems - now, you save yourself a lot of debugging later when things are - broken, and you can't figure out when it happened. + Basic system testing - 1.5) What tools are available for developers? + The easiest way to test your code is to ensure that it builds against + the latest verion of the code and that it does not generate compiler + warnings. + + It is worth advised that you pass --enable-cassert to configure. This + will turn on assertions with in the source which will often show us + bugs because they cause data corruption of segmentation violations. + This generally makes debugging much easier. + + Then, perform run time testing via psql. + + Regression test suite + + The next step is to test your changes against the existing regression + test suite. To do this, issue "make check" in the root directory of + the source tree. If any tests failure, investigate. + + If you've deliberately changed existing behaviour, this change may + cause a regression test failure but not any actual regression. If so, + you should also patch the regression test suite. + + Other run time testing + + Some developers make use of tools such as valgrind + (http://valgrind.kde.org) for memory testing, gprof (which comes with + the GNU binutils suite) and oprofile + (http://oprofile.sourceforge.net/) for profiling and other related + tools. + + What about unit testing, static analysis, model checking...? + + There have been a number of discussions about other testing frameworks + and some developers are exploring these ideas. + + 1.9) What tools are available for developers? - Aside from the User documentation mentioned in the regular FAQ, there - are several development tools available. First, all the files in the - /tools directory are designed for developers. + First, all the files in the src/tools directory are designed for + developers. RELEASE_CHANGES changes we have to make for each release - SQL_keywords standard SQL'92 keywords backend description/flowchart of the backend directories ccsym find standard defines made by your compiler + copyright fixes copyright notices + entab converts tabs to spaces, used by pgindent find_static finds functions that could be made static find_typedef finds typedefs in the source code find_badmacros finds macros that use braces incorrectly + fsync a script to provide information about the cost of cache + syncing system calls make_ctags make vi 'tags' file in each directory make_diff make *.orig and diffs of source make_etags make emacs 'etags' files make_keywords make comparison of our keywords and SQL'92 make_mkid make mkid ID files - mkldexport create AIX exports file - pgindent indents C source files - pgjindent indents Java source files + pgcvslog used to generate a list of changes for each release pginclude scripts for adding/removing include files - unused_oids in pgsql/src/include/catalog + pgindent indents source files + pgtest a semi-automated build system + thread a thread testing script - Let me note some of these. If you point your browser at the - file:/usr/local/src/pgsql/src/tools/backend/index.html directory, you + In src/include/catalog: + unused_oids a script which generates unused OIDs for use in system + catalogs + duplicate_oids finds duplicate OIDs in system catalog definitions + + If you point your browser at the tools/backend/index.html file, you will see few paragraphs describing the data flow, the backend components in a flow chart, and a description of the shared memory area. You can click on any flowchart box to see a description. If you @@ -203,18 +215,18 @@ back out twice to return to the original function. Most editors support this via tags or etags files. - Third, you need to get id-utils from: - ftp://alpha.gnu.org/gnu/id-utils-3.2d.tar.gz - ftp://tug.org/gnu/id-utils-3.2d.tar.gz - ftp://ftp.enst.fr/pub/gnu/gnits/id-utils-3.2d.tar.gz - - By running tools/make_mkid, an archive of source symbols can be - created that can be rapidly queried like grep or edited. Others prefer - glimpse. + Third, you need to get id-utils from ftp://ftp.gnu.org/gnu/id-utils/ - make_diff has tools to create patch diff files that can be applied to - the distribution. This produces context diffs, which is our preferred - format. + By running tools/make_mkid, an archive of source symbols can be + created that can be rapidly queried. + + Some developers make use of cscope, which can be found at + http://cscope.sf.net/. Others use glimpse, which can be found at + http://webglimpse.net/. + + tools/make_diff has tools to create patch diff files that can be + applied to the distribution. This produces context diffs, which is our + preferred format. Our standard format is to indent each code level with one tab, where each tab is four spaces. You will need to set your editor to display @@ -262,7 +274,7 @@ pgindent will the format code by specifying flags to your operating system's utility indent. This article describes the value of a - constent coding style. + consistent coding style. pgindent is run on all source files just before each beta test period. It auto-formats all source files to make them consistent. Comment @@ -277,7 +289,7 @@ is also a script called unused_oids in pgsql/src/include/catalog that shows the unused oids. - 1.6) What books are good for developers? + 1.10) What books are good for developers? I have four good books, An Introduction to Database Systems, by C.J. Date, Addison, Wesley, A Guide to the SQL Standard, by C.J. Date, et. @@ -285,9 +297,9 @@ Navathe, and Transaction Processing, by Jim Gray, Morgan, Kaufmann There is also a database performance site, with a handbook on-line - written by Jim Gray at http://www.benchmarkresources.com. + written by Jim Gray at http://www.benchmarkresources.com.. - 1.7) What is configure all about? + 1.11) What is configure all about? The files configure and configure.in are part of the GNU autoconf package. Configure allows us to test for various capabilities of the @@ -309,7 +321,7 @@ removed, so you see only the file contained in the source distribution. - 1.8) How do I add a new port? + 1.12) How do I add a new port? There are a variety of places that need to be modified to add a new port. First, start in the src/template directory. Add an appropriate @@ -326,7 +338,7 @@ src/makefiles directory for port-specific Makefile handling. There is a backend/port directory if you need special files for your OS. - 1.9) Why don't you use threads/raw devices/async-I/O, ? There is always a temptation to use the newest operating system @@ -352,7 +364,7 @@ cautious about their adoption. The TODO list often contains links to discussions showing our reasoning in these areas. - 1.10) How are RPM's packaged? + 1.14) How are RPMs packaged? This was written by Lamar Owen: @@ -447,7 +459,7 @@ Of course, there are many projects that DO include all the files necessary to build RPMs from their Official Tarball (TM). - 1.11) How are CVS branches managed? + 1.15) How are CVS branches managed? This was written by Tom Lane: @@ -506,7 +518,7 @@ tree right away after a major release --- we wait for a dot-release or two, so that we won't have to double-patch the first wave of fixes. - 1.12) Where can I get a copy of the SQL standards? + 1.16) Where can I get a copy of the SQL standards? There are three versions of the SQL standard: SQL-92, SQL:1999, and SQL:2003. They are endorsed by ANSI and ISO. Draft versions can be @@ -523,7 +535,20 @@ * http://www.contrib.andrew.cmu.edu/~shadow/sql.html#syntax (SQL-92) * http://dbs.uni-leipzig.de/en/lokal/standards.pdf (paper) - 1.13) How go I get involved in PostgreSQL web site development? + 1.17) Where can I get technical assistance? + + Many technical questions held by those new to the code have been + answered on the pgsql-hackers mailing list - the archives of which can + be found at http://archives.postgresql.org/pgsql-hackers/. + + If you cannot find discussion or your particular question, feel free + to put it to the list. + + Major contributors also answer technical questions, including + questions about development of new features, on IRC at + irc.freenode.net in the #postgresql channel. + + 1.18) How go I get involved in PostgreSQL web site development? PostgreSQL website development is discussed on the pgsql-www@postgresql.org mailing list. The is a project page where the @@ -627,8 +652,9 @@ typedef struct nameData Here are some of the List manipulation commands: - lfirst(i) - return the data at list element i. + lfirst(i), lfirst_int(i), lfirst_oid(i) + return the data (a point, inteter and OID respectively) at list + element i. lnext(i) return the next list element after i. @@ -640,7 +666,8 @@ typedef struct nameData a typical code snippet that loops through a List containing Var *'s and processes each one: -List *i, *list; + List *list; + ListCell *i; foreach(i, list) { @@ -689,9 +716,10 @@ List *i, *list; The structures passing around from the parser, rewrite, optimizer, and executor require quite a bit of support. Most structures have support routines in src/backend/nodes used to create, copy, read, and output - those structures. Make sure you add support for your new field to - these files. Find any other places the structure may need code for - your new field. mkid is helpful with this (see above). + those structures (in particular, the files copyfuncs.c and + equalfuncs.c. Make sure you add support for your new field to these + files. Find any other places the structure may need code for your new + field. mkid is helpful with this (see 1.9). 2.5) Why do we use palloc() and pfree() to allocate memory? diff --git a/doc/src/FAQ/FAQ_DEV.html b/doc/src/FAQ/FAQ_DEV.html index ad34a74768..ab898d6dd6 100644 --- a/doc/src/FAQ/FAQ_DEV.html +++ b/doc/src/FAQ/FAQ_DEV.html @@ -1,279 +1,304 @@ + + + +PostgreSQL Developers FAQ + + +

Developer's Frequently Asked Questions (FAQ) for +PostgreSQL

- - - +

Last updated: Wed Dec 1 16:11:11 EST 2006

- PostgreSQL Developers FAQ - +

Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
+

- -

Developer's Frequently Asked Questions (FAQ) for - PostgreSQL

+

The most recent version of this document can be viewed at http://www.PostgreSQL.org/docs/faqs/FAQ_DEV.html.

-

Last updated: Sat Nov 27 01:02:35 EST 2004

+
+
+ +
+

General Questions

+
-

Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
-

+1.1) How do I get involved in PostgreSQL +development?
+ 1.2) What development environment is required +to develop code?
+ 1.3) What areas need work?
+ 1.4) What do I do after choosing an item to +work on?
+ 1.5) Where can I learn more about the code?
+ 1.6) I've developed a patch, what next?
+ 1.7) How do I download/update the current +source tree?
+ 1.8) How do I test my changes?
+ 1.9) What tools are available for +developers?
+ 1.10) What books are good for developers?
+ 1.11) What is configure all about?
+ 1.12) How do I add a new port?
+ 1.13) Why don't you use threads/raw +devices/async-I/O, <insert your favorite wizz-bang feature +here>?
+ 1.14) How are RPM's packaged?
+ 1.15) How are CVS branches handled?
+ 1.16) Where can I get a copy of the SQL +standards?
+ 1.17) Where can I get technical +assistance?
+ 1.18) How do I get involved in PostgreSQL web +site development?
+ +
+

Technical Questions

+
-

The most recent version of this document can be viewed at http://www.PostgreSQL.org/docs/faqs/FAQ_DEV.html.

+2.1) How do I efficiently access information in +tables from the backend code?
+ 2.2) Why are table, column, type, function, +view names sometimes referenced as Name or NameData, +and sometimes as char *?
+ 2.3) Why do we use Node and List +to make data structures?
+ 2.4) I just added a field to a structure. What +else should I do?
+ 2.5) Why do we use palloc() and +pfree() to allocate memory?
+ 2.6) What is ereport()?
+ 2.7) What is CommandCounterIncrement()?
+
+ +
+
+

General Questions

+
-
-
- +

1.1) How go I get involved in PostgreSQL +development?

-
-

General Questions

-
- 1.1) How do I get involved in PostgreSQL - development?
- 1.2) How do I add a feature or fix a bug?
- 1.3) How do I download/update the current source - tree?
- 1.4) How do I test my changes?
- 1.5) What tools are available for developers?
- 1.6) What books are good for developers?
- 1.7) What is configure all about?
- 1.8) How do I add a new port?
- 1.9) Why don't you use threads/raw - devices/async-I/O, <insert your favorite wizz-bang feature - here>?
- 1.10) How are RPM's packaged?
- 1.11) How are CVS branches handled?
- 1.12) Where can I get a copy of the SQL - standards?
- 1.1) How do I get involved in PostgreSQL - web site development?
+

Download the code and have a look around. See 1.7.

-
-

Technical Questions

-
- 2.1) How do I efficiently access information in - tables from the backend code?
- 2.2) Why are table, column, type, function, view - names sometimes referenced as Name or NameData, and - sometimes as char *?
- 2.3) Why do we use Node and List to - make data structures?
- 2.4) I just added a field to a structure. What else - should I do?
- 2.5) Why do we use palloc() and - pfree() to allocate memory?
- 2.6) What is ereport()?
- 2.7) What is CommandCounterIncrement()?
-
- -
+

Subscribe to and read the pgsql-hackers +mailing list (often termed 'hackers'). This is where the major +contributors and core members of the project discuss +development.

-
-

General Questions

-
+

1.2) What development environment is required +to develop code?

-

1.1) How go I get involved in PostgreSQL - development?

+

PostgreSQL is developed mostly in the C programming language. It +also makes use of Yacc and Lex.

-

This was written by Lamar Owen:

+

The source code is targeted at most of the popular Unix +platforms and the Windows environment (XP, Windows 2000, and +up).

-

2001-06-22

+

Most developers make use of the open source development tool +chain. If you have contributed to open source software before, you +will probably be familiar with these tools. They include: GCC (http://gcc.gnu.org, GDB (www.gnu.org/software/gdb/gdb.html), +autoconf (www.gnu.org/software/autoconf/) +AND GNU make (www.gnu.org/software/make/make.html.

- What open source development process is used by the PostgreSQL - team? +

Developers using this tool chain on Windows make use of MingW +(see http://www.mingw.org/).

-

Read HACKERS for six months (or a full release cycle, whichever - is longer). Really. HACKERS _is_the process. The process is not - well documented (AFAIK -- it may be somewhere that I am not aware - of) -- and it changes continually.

+

Some developers use compilers from other software vendors with +mixed results.

- What development environment (OS, system, compilers, etc) is - required to develop code? +

Developers who are regularly rebuilding the source often pass +the --enable-depend flag to configure. The result is that +when you make a modification to a C header file, all files depend +upon that file are also rebuilt.

-

Developers Corner on the - website has links to this information. The distribution tarball - itself includes all the extra tools and documents that go beyond a - good Unix-like development environment. In general, a modern unix - with a modern gcc, GNU make or equivalent, autoconf (of a - particular version), and good working knowledge of those tools are - required.

+

1.3) What areas need work?

- What areas need support? +Outstanding features are detailed in the TODO list. This is located +in doc/TODO in the source distribution or at http://developer.postgresql.org/todo.php. -

The TODO list.

+

You can learn more about these features by consulting the +archives, the SQL standards and the recommend texts (see 1.10).

-

You've made the first step, by finding and subscribing to - HACKERS. Once you find an area to look at in the TODO, and have - read the documentation on the internals, etc, then you check out a - current CVS,write what you are going to write (keeping your CVS - checkout up to date in the process), and make up a patch (as a - context diff only) and send to the PATCHES list, prefereably.

+

1.4) What do I do after choosing an item to +work on?

-

Discussion on the patch typically happens here. If the patch - adds a major feature, it would be a good idea to talk about it - first on the HACKERS list, in order to increase the chances of it - being accepted, as well as toavoid duplication of effort. Note that - experienced developers with a proven track record usually get the - big jobs -- for more than one reason. Also note that PostgreSQL is - highly portable -- nonportable code will likely be dismissed out of - hand.

+

Send an email to pgsql-hackers with a proposal for what you want +to do (assuming your contribution is not trivial). Working in +isolation is not advisable: others may be working on the same TODO +item; you may have misunderstood the TODO item; your approach may +benefit from the review of others.

-

Once your contributions get accepted, things move from there. - Typically, you would be added as a developer on the list on the - website when one of the other developers recommends it. Membership - on the steering committee is by invitation only, by the other - steering committee members, from what I have gathered watching - froma distance.

+

1.5) Where can I learn more about the +code?

-

I make these statements from having watched the process for over - two years.

+

Other than documentation in the source tree itself, you can find +some papers/presentations discussing the code at http://developers.postgresql.org.

-

To see a good example of how one goes about this, search the - archives for the name 'Tom Lane' and see what his first post - consisted of, and where he took things. In particular, note that - this hasn't been _that_ long ago -- and his bugfixing and general - deep knowledge with this codebase is legendary. Take a few days to - read after him. And pay special attention to both the sheer - quantity as well as the painstaking quality of his work. Both are - in high demand.

+

1.6) I've developed a patch, what next?

-

1.2) How do I add a feature or fix a bug?

+

Generate the patch in contextual diff format. If you are +unfamiliar with this, you may find the script +src/tools/makediff/difforig useful.

-

The source code is over 350,000 lines. Many fixes/features - are isolated to one specific area of the code. Others require - knowledge of much of the source. If you are confused about where to - start, ask the hackers list, and they will be glad to assess the - complexity and give pointers on where to start.

+

Ensure that your patch is generated against the most recent +version of the code. If it is a patch adding new functionality, the +most recent version is cvs HEAD; if it is a bug fix, this will be +the most recently version of the branch which suffers from the bug +(for more on branches in PostgreSQL, see 1.15).

-

Another thing to keep in mind is that many fixes and features - can be added with surprisingly little code. I often start by adding - code, then looking at other areas in the code where similar things - are done, and by the time I am finished, the patch is quite small - and compact.

+

Finally, submit the patch to pgsql-patches@postgresql.org. It +will be reviewed by other contributors to the project and may be +either accepted or sent back for further work.

-

When adding code, keep in mind that it should use the existing - facilities in the source, for performance reasons and for - simplicity. Often a review of existing code doing similar things is - helpful.

+

1.7) How do I download/update the current +source tree?

-

The usual process for source additions is: -

    -
  • Review the TODO list.
    • -
  • Discuss hackers the desirability of the fix/feature.
    • -
  • How should it behave in complex circumstances?
    • -
  • How should it be implemented?
    • -
  • Submit the patch to the patches list.
    • -
  • Answer email questions.
    • -
  • Wait for the patch to be applied.
    • -

-

1.3) How do I download/update the current source - tree?

+

There are several ways to obtain the source tree. Occasional +developers can just get the most recent source tree snapshot from +ftp://ftp.postgresql.org.

-

There are several ways to obtain the source tree. Occasional - developers can just get the most recent source tree snapshot from - ftp.postgresql.org. For regular developers, you can use CVS. CVS - allows you to download the source tree, then occasionally update - your copy of the source tree with any new changes. Using CVS, you - don't have to download the entire source each time, only the - changed files. Anonymous CVS does not allows developers to update - the remote source tree, though privileged developers can do this. - There is a CVS section (http://developer.postgresql.org/docs/postgres/cvs.html) - in our documentation that describes how to use remote CVS. You can - also use CVSup, which has similarly functionality, and is available - from ftp.postgresql.org.

+

Regular developers may want to take advantage of anonymous +access to our source code management system. The source tree is +currently hosted in CVS. For details of how to obtain the source +from CVS see http://developer.postgresql.org/docs/postgres/cvs.html.

-

To update the source tree, there are two ways. You can generate - a patch against your current source tree, perhaps using the - make_diff tools mentioned above, and send them to the patches list. - They will be reviewed, and applied in a timely manner. If the patch - is major, and we are in beta testing, the developers may wait for - the final release before applying your patches.

+

1.8) How do I test my changes?

-

For hard-core developers, Marc(scrappy@postgresql.org) will give - you a Unix shell account on postgresql.org, so you can use CVS to - update the main source tree, or you can ftp your files into your - account, patch, and cvs install the changes directly into the - source tree.

+

Basic system testing

-

1.4) How do I test my changes?

+

The easiest way to test your code is to ensure that it builds +against the latest verion of the code and that it does not generate +compiler warnings.

-

First, use psql to make sure it is working as you expect. - Then run src/test/regress and get the output of - src/test/regress/checkresults with and without your changes, - to see that your patch does not change the regression test in - unexpected ways. This practice has saved me many times. The - regression tests test the code in ways I would never do, and has - caught many bugs in my patches. By finding the problems now, you - save yourself a lot of debugging later when things are broken, and - you can't figure out when it happened.

+

It is worth advised that you pass --enable-cassert to +configure. This will turn on assertions with in the source +which will often show us bugs because they cause data corruption of +segmentation violations. This generally makes debugging much +easier.

-

1.5) What tools are available for - developers?

+

Then, perform run time testing via psql.

-

Aside from the User documentation mentioned in the regular FAQ, - there are several development tools available. First, all the files - in the /tools directory are designed for developers.

-
+
Regression test suite

+
+
The next step is to test your changes against the existing
+regression test suite. To do this, issue "make check" in the root
+directory of the source tree. If any tests failure,
+investigate.

+
+
If you've deliberately changed existing behaviour, this change
+may cause a regression test failure but not any actual regression.
+If so, you should also patch the regression test suite.

+
+
Other run time testing

+
+
Some developers make use of tools such as valgrind (http://valgrind.kde.org) for memory
+testing, gprof (which comes with the GNU binutils suite) and
+oprofile (http://oprofile.sourceforge.net/)
+for profiling and other related tools.

+
+
What about unit testing, static analysis, model
+checking...?

+
+
There have been a number of discussions about other testing
+frameworks and some developers are exploring these ideas.

+
+
1.9) What tools are available for
+developers?

+
+
First, all the files in the src/tools directory are
+designed for developers.

+
+
     RELEASE_CHANGES changes we have to make for each release
-    SQL_keywords    standard SQL'92 keywords
     backend         description/flowchart of the backend directories
     ccsym           find standard defines made by your compiler
+     copyright       fixes copyright notices
+
     entab           converts tabs to spaces, used by pgindent
     find_static     finds functions that could be made static
     find_typedef    finds typedefs in the source code
     find_badmacros  finds macros that use braces incorrectly
+    fsync           a script to provide information about the cost of cache
+                     syncing system calls
     make_ctags      make vi 'tags' file in each directory
     make_diff       make *.orig and diffs of source
     make_etags      make emacs 'etags' files
     make_keywords   make comparison of our keywords and SQL'92
     make_mkid       make mkid ID files
-    mkldexport      create AIX exports file
-    pgindent        indents C source files
-    pgjindent       indents Java source files
+    pgcvslog        used to generate a list of changes for each release
     pginclude       scripts for adding/removing include files
-    unused_oids     in pgsql/src/include/catalog
-

-    Let me note some of these. If you point your browser at the
-    file:/usr/local/src/pgsql/src/tools/backend/index.html
-    directory, you will see few paragraphs describing the data flow,
-    the backend components in a flow chart, and a description of the
-    shared memory area. You can click on any flowchart box to see a
-    description. If you then click on the directory name, you will be
-    taken to the source directory, to browse the actual source code
-    behind it. We also have several README files in some source
-    directories to describe the function of the module. The browser
-    will display these when you enter the directory also. The
-    tools/backend directory is also contained on our web page
-    under the title How PostgreSQL Processes a Query. 
+    pgindent        indents source files
+    pgtest          a semi-automated build system
+    thread          a thread testing script
+
-

Second, you really should have an editor that can handle tags, - so you can tag a function call to see the function definition, and - then tag inside that function to see an even lower-level function, - and then back out twice to return to the original function. Most - editors support this via tags or etags files.

+

In src/include/catalog:

-

Third, you need to get id-utils from:

-
-    ftp://alpha.gnu.org/gnu/id-utils-3.2d.tar.gz
-    ftp://tug.org/gnu/id-utils-3.2d.tar.gz
-    ftp://ftp.enst.fr/pub/gnu/gnits/id-utils-3.2d.tar.gz
-
- By running tools/make_mkid, an archive of source symbols can - be created that can be rapidly queried like grep or edited. - Others prefer glimpse. +
+    unused_oids     a script which generates unused OIDs for use in system
+                     catalogs
+    duplicate_oids  finds duplicate OIDs in system catalog definitions
+
-

make_diff has tools to create patch diff files that can - be applied to the distribution. This produces context diffs, which - is our preferred format.

+If you point your browser at the tools/backend/index.html +file, you will see few paragraphs describing the data flow, the +backend components in a flow chart, and a description of the shared +memory area. You can click on any flowchart box to see a +description. If you then click on the directory name, you will be +taken to the source directory, to browse the actual source code +behind it. We also have several README files in some source +directories to describe the function of the module. The browser +will display these when you enter the directory also. The +tools/backend directory is also contained on our web page +under the title How PostgreSQL Processes a Query. +

Second, you really should have an editor that can handle tags, +so you can tag a function call to see the function definition, and +then tag inside that function to see an even lower-level function, +and then back out twice to return to the original function. Most +editors support this via tags or etags files.

-

Our standard format is to indent each code level with one tab, - where each tab is four spaces. You will need to set your editor to - display tabs as four spaces:
-

-
+
Third, you need to get id-utils from ftp://ftp.gnu.org/gnu/id-utils/

+
+
By running tools/make_mkid, an archive of source symbols
+can be created that can be rapidly queried.

+
+
Some developers make use of cscope, which can be found at http://cscope.sf.net/. Others use
+glimpse, which can be found at http://webglimpse.net/.

+
+
tools/make_diff has tools to create patch diff files that
+can be applied to the distribution. This produces context diffs,
+which is our preferred format.

+
+
Our standard format is to indent each code level with one tab,
+where each tab is four spaces. You will need to set your editor to
+display tabs as four spaces:

+

+
+
     vi in ~/.exrc:
             set tabstop=4
             set sw=4
@@ -286,26 +311,26 @@
 
         or
 
-	(c-add-style "pgsql"
-		'("bsd"
-			(indent-tabs-mode . t)
-			(c-basic-offset   . 4)
-			(tab-width . 4)
-			(c-offsets-alist .
-				((case-label . +)))
-		)
-		nil ) ; t = set this style, nil = don't
+        (c-add-style "pgsql"
+                '("bsd"
+                        (indent-tabs-mode . t)
+                        (c-basic-offset   . 4)
+                        (tab-width . 4)
+                        (c-offsets-alist .
+                                ((case-label . +)))
+                )
+                nil ) ; t = set this style, nil = don't
 
-	(defun pgsql-c-mode ()
-      		(c-mode)
-		(c-set-style "pgsql")
-	)
+        (defun pgsql-c-mode ()
+                (c-mode)
+                (c-set-style "pgsql")
+        )
 
         and add this to your autoload list (modify file path in macro):
 
-	(setq auto-mode-alist
-		(cons '("\\`/home/andrew/pgsql/.*\\.[chyl]\\'" . pgsql-c-mode)
-		auto-mode-alist))
+        (setq auto-mode-alist
+                (cons '("\\`/home/andrew/pgsql/.*\\.[chyl]\\'" . pgsql-c-mode)
+                auto-mode-alist))
         or
             /*
              * Local variables:
@@ -314,473 +339,498 @@
              *  c-basic-offset: 4
              * End:
              */
-

-    

-     pgindent will the format code by specifying flags to your
-    operating system's utility indent.  This 
-    
-    article describes the value of a constent coding style.
+
-

pgindent is run on all source files just before each beta - test period. It auto-formats all source files to make them - consistent. Comment blocks that need specific line breaks should be - formatted as block comments, where the comment starts as - /*------. These comments will not be reformatted in - any way.

+
+ pgindent will the format code by specifying flags to your +operating system's utility indent. This article +describes the value of a consistent coding style. +

pgindent is run on all source files just before each beta +test period. It auto-formats all source files to make them +consistent. Comment blocks that need specific line breaks should be +formatted as block comments, where the comment starts as +/*------. These comments will not be reformatted in +any way.

-

pginclude contains scripts used to add needed - #include's to include files, and removed unneeded - #include's.

+

pginclude contains scripts used to add needed +#include's to include files, and removed unneeded +#include's.

-

When adding system types, you will need to assign oids to them. - There is also a script called unused_oids in - pgsql/src/include/catalog that shows the unused oids.

+

When adding system types, you will need to assign oids to them. +There is also a script called unused_oids in +pgsql/src/include/catalog that shows the unused oids.

-

1.6) What books are good for developers?

+

1.10) What books are good for +developers?

-

I have four good books, An Introduction to Database - Systems, by C.J. Date, Addison, Wesley, A Guide to the SQL - Standard, by C.J. Date, et. al, Addison, Wesley, - Fundamentals of Database Systems, by Elmasri and Navathe, - and Transaction Processing, by Jim Gray, Morgan, - Kaufmann

+

I have four good books, An Introduction to Database +Systems, by C.J. Date, Addison, Wesley, A Guide to the SQL +Standard, by C.J. Date, et. al, Addison, Wesley, +Fundamentals of Database Systems, by Elmasri and Navathe, +and Transaction Processing, by Jim Gray, Morgan, +Kaufmann

-

There is also a database performance site, with a handbook - on-line written by Jim Gray at http://www.benchmarkresources.com.

+

There is also a database performance site, with a handbook +on-line written by Jim Gray at http://www.benchmarkresources.com..

-

1.7) What is configure all about?

+

1.11) What is configure all about?

-

The files configure and configure.in are part of - the GNU autoconf package. Configure allows us to test for - various capabilities of the OS, and to set variables that can then - be tested in C programs and Makefiles. Autoconf is installed on the - PostgreSQL main server. To add options to configure, edit - configure.in, and then run autoconf to generate - configure.

+

The files configure and configure.in are part of +the GNU autoconf package. Configure allows us to test for +various capabilities of the OS, and to set variables that can then +be tested in C programs and Makefiles. Autoconf is installed on the +PostgreSQL main server. To add options to configure, edit +configure.in, and then run autoconf to generate +configure.

-

When configure is run by the user, it tests various OS - capabilities, stores those in config.status and - config.cache, and modifies a list of *.in files. For - example, if there exists a Makefile.in, configure generates - a Makefile that contains substitutions for all @var@ - parameters found by configure.

+

When configure is run by the user, it tests various OS +capabilities, stores those in config.status and +config.cache, and modifies a list of *.in files. For +example, if there exists a Makefile.in, configure generates +a Makefile that contains substitutions for all @var@ +parameters found by configure.

-

When you need to edit files, make sure you don't waste time - modifying files generated by configure. Edit the *.in - file, and re-run configure to recreate the needed file. If - you run make distclean from the top-level source directory, - all files derived by configure are removed, so you see only the - file contained in the source distribution.

+

When you need to edit files, make sure you don't waste time +modifying files generated by configure. Edit the *.in +file, and re-run configure to recreate the needed file. If +you run make distclean from the top-level source directory, +all files derived by configure are removed, so you see only the +file contained in the source distribution.

-

1.8) How do I add a new port?

+

1.12) How do I add a new port?

-

There are a variety of places that need to be modified to add a - new port. First, start in the src/template directory. Add an - appropriate entry for your OS. Also, use src/config.guess to - add your OS to src/template/.similar. You shouldn't match - the OS version exactly. The configure test will look for an - exact OS version number, and if not found, find a match without - version number. Edit src/configure.in to add your new OS. - (See configure item above.) You will need to run autoconf, or patch - src/configure too.

+

There are a variety of places that need to be modified to add a +new port. First, start in the src/template directory. Add an +appropriate entry for your OS. Also, use src/config.guess to +add your OS to src/template/.similar. You shouldn't match +the OS version exactly. The configure test will look for an +exact OS version number, and if not found, find a match without +version number. Edit src/configure.in to add your new OS. +(See configure item above.) You will need to run autoconf, or patch +src/configure too.

-

Then, check src/include/port and add your new OS file, - with appropriate values. Hopefully, there is already locking code - in src/include/storage/s_lock.h for your CPU. There is also - a src/makefiles directory for port-specific Makefile - handling. There is a backend/port directory if you need - special files for your OS.

+

Then, check src/include/port and add your new OS file, +with appropriate values. Hopefully, there is already locking code +in src/include/storage/s_lock.h for your CPU. There is also +a src/makefiles directory for port-specific Makefile +handling. There is a backend/port directory if you need +special files for your OS.

-

1.9) Why don't you use threads/raw - devices/async-I/O, <insert your favorite wizz-bang feature - here>?

+

1.13) Why don't you use threads/raw +devices/async-I/O, <insert your favorite wizz-bang feature +here>?

-

There is always a temptation to use the newest operating system - features as soon as they arrive. We resist that temptation.

+

There is always a temptation to use the newest operating system +features as soon as they arrive. We resist that temptation.

-

First, we support 15+ operating systems, so any new feature has - to be well established before we will consider it. Second, most new - wizz-bang features don't provide dramatic - improvements. Third, they usually have some downside, such as - decreased reliability or additional code required. Therefore, we - don't rush to use new features but rather wait for the feature to be - established, then ask for testing to show that a measurable - improvement is possible.

+

First, we support 15+ operating systems, so any new feature has +to be well established before we will consider it. Second, most new +wizz-bang features don't provide dramatic +improvements. Third, they usually have some downside, such as +decreased reliability or additional code required. Therefore, we +don't rush to use new features but rather wait for the feature to +be established, then ask for testing to show that a measurable +improvement is possible.

-

As an example, threads are not currently used in the backend code - because:

+

As an example, threads are not currently used in the backend +code because:

-
    -
  • Historically, threads were unsupported and buggy.
    • +
      +
    • Historically, threads were unsupported and buggy.
      • -
    • An error in one backend can corrupt other backends.
      • +
    • An error in one backend can corrupt other backends.
      • -
    • Speed improvements using threads are small compared to the - remaining backend startup time.
      • +
    • Speed improvements using threads are small compared to the +remaining backend startup time.
      • -
    • The backend code would be more complex.
      • -
    +
  • The backend code would be more complex.
    • +
-

So, we are not ignorant of new features. It is just that - we are cautious about their adoption. The TODO list often - contains links to discussions showing our reasoning in - these areas.

+

So, we are not ignorant of new features. It is just that we are +cautious about their adoption. The TODO list often contains links +to discussions showing our reasoning in these areas.

-

1.10) How are RPM's packaged?

+

1.14) How are RPMs packaged?

-

This was written by Lamar Owen:

+

This was written by Lamar Owen:

-

2001-05-03

+

2001-05-03

-

As to how the RPMs are built -- to answer that question sanely - requires me to know how much experience you have with the whole RPM - paradigm. 'How is the RPM built?' is a multifaceted question. The - obvious simple answer is that I maintain:

+

As to how the RPMs are built -- to answer that question sanely +requires me to know how much experience you have with the whole RPM +paradigm. 'How is the RPM built?' is a multifaceted question. The +obvious simple answer is that I maintain:

-
    -
  1. A set of patches to make certain portions of the source tree - 'behave' in the different environment of the RPMset;
    2. +
      +
    1. A set of patches to make certain portions of the source tree +'behave' in the different environment of the RPMset;
      2. -
    2. The initscript;
      3. +
    3. The initscript;
      4. -
    4. Any other ancilliary scripts and files;
      5. +
    5. Any other ancilliary scripts and files;
      6. -
    6. A README.rpm-dist document that tries to adequately document - both the differences between the RPM build and the WHY of the - differences, as well as useful RPM environment operations (like, - using syslog, upgrading, getting postmaster to start at OS boot, - etc);
      7. +
    7. A README.rpm-dist document that tries to adequately document +both the differences between the RPM build and the WHY of the +differences, as well as useful RPM environment operations (like, +using syslog, upgrading, getting postmaster to start at OS boot, +etc);
      8. -
    8. The spec file that throws it all together. This is not a - trivial undertaking in a package of this size.
      9. -
    +
  2. The spec file that throws it all together. This is not a +trivial undertaking in a package of this size.
    3. +
-

I then download and build on as many different canonical - distributions as I can -- currently I am able to build on Red Hat - 6.2, 7.0, and 7.1 on my personal hardware. Occasionally I receive - opportunity from certain commercial enterprises such as Great - Bridge and PostgreSQL, Inc. to build on other distributions.

+

I then download and build on as many different canonical +distributions as I can -- currently I am able to build on Red Hat +6.2, 7.0, and 7.1 on my personal hardware. Occasionally I receive +opportunity from certain commercial enterprises such as Great +Bridge and PostgreSQL, Inc. to build on other distributions.

-

I test the build by installing the resulting packages and - running the regression tests. Once the build passes these tests, I - upload to the postgresql.org ftp server and make a release - announcement. I am also responsible for maintaining the RPM - download area on the ftp site.

+

I test the build by installing the resulting packages and +running the regression tests. Once the build passes these tests, I +upload to the postgresql.org ftp server and make a release +announcement. I am also responsible for maintaining the RPM +download area on the ftp site.

-

You'll notice I said 'canonical' distributions above. That - simply means that the machine is as stock 'out of the box' as - practical -- that is, everything (except select few programs) on - these boxen are installed by RPM; only official Red Hat released - RPMs are used (except in unusual circumstances involving software - that will not alter the build -- for example, installing a newer - non-RedHat version of the Dia diagramming package is OK -- - installing Python 2.1 on the box that has Python 1.5.2 installed is - not, as that alters the PostgreSQL build). The RPM as uploaded is - built to as close to out-of-the-box pristine as is possible. Only - the standard released 'official to that release' compiler is used - -- and only the standard official kernel is used as well.

+

You'll notice I said 'canonical' distributions above. That +simply means that the machine is as stock 'out of the box' as +practical -- that is, everything (except select few programs) on +these boxen are installed by RPM; only official Red Hat released +RPMs are used (except in unusual circumstances involving software +that will not alter the build -- for example, installing a newer +non-RedHat version of the Dia diagramming package is OK -- +installing Python 2.1 on the box that has Python 1.5.2 installed is +not, as that alters the PostgreSQL build). The RPM as uploaded is +built to as close to out-of-the-box pristine as is possible. Only +the standard released 'official to that release' compiler is used +-- and only the standard official kernel is used as well.

-

For a time I built on Mandrake for RedHat consumption -- no - more. Nonstandard RPM building systems are worse than useless. - Which is not to say that Mandrake is useless! By no means is - Mandrake useless -- unless you are building Red Hat RPMs -- and Red - Hat is useless if you're trying to build Mandrake or SuSE RPMs, for - that matter. But I would be foolish to use 'Lamar Owen's Super - Special RPM Blend Distro 0.1.2' to build for public consumption! - :-)

+

For a time I built on Mandrake for RedHat consumption -- no +more. Nonstandard RPM building systems are worse than useless. +Which is not to say that Mandrake is useless! By no means is +Mandrake useless -- unless you are building Red Hat RPMs -- and Red +Hat is useless if you're trying to build Mandrake or SuSE RPMs, for +that matter. But I would be foolish to use 'Lamar Owen's Super +Special RPM Blend Distro 0.1.2' to build for public consumption! +:-)

-

I _do_ attempt to make the _source_ RPM compatible with as many - distributions as possible -- however, since I have limited - resources (as a volunteer RPM maintainer) I am limited as to the - amount of testing said build will get on other distributions, - architectures, or systems.

+

I _do_ attempt to make the _source_ RPM compatible with as many +distributions as possible -- however, since I have limited +resources (as a volunteer RPM maintainer) I am limited as to the +amount of testing said build will get on other distributions, +architectures, or systems.

-

And, while I understand people's desire to immediately upgrade - to the newest version, realize that I do this as a side interest -- - I have a regular, full-time job as a broadcast - engineer/webmaster/sysadmin/Technical Director which occasionally - prevents me from making timely RPM releases. This happened during - the early part of the 7.1 beta cycle -- but I believe I was pretty - much on the ball for the Release Candidates and the final - release.

+

And, while I understand people's desire to immediately upgrade +to the newest version, realize that I do this as a side interest -- +I have a regular, full-time job as a broadcast +engineer/webmaster/sysadmin/Technical Director which occasionally +prevents me from making timely RPM releases. This happened during +the early part of the 7.1 beta cycle -- but I believe I was pretty +much on the ball for the Release Candidates and the final +release.

-

I am working towards a more open RPM distribution -- I would - dearly love to more fully document the process and put everything - into CVS -- once I figure out how I want to represent things such - as the spec file in a CVS form. It makes no sense to maintain a - changelog, for instance, in the spec file in CVS when CVS does a - better job of changelogs -- I will need to write a tool to generate - a real spec file from a CVS spec-source file that would add version - numbers, changelog entries, etc to the result before building the - RPM. IOW, I need to rethink the process -- and then go through the - motions of putting my long RPM history into CVS one version at a - time so that version history information isn't lost.

+

I am working towards a more open RPM distribution -- I would +dearly love to more fully document the process and put everything +into CVS -- once I figure out how I want to represent things such +as the spec file in a CVS form. It makes no sense to maintain a +changelog, for instance, in the spec file in CVS when CVS does a +better job of changelogs -- I will need to write a tool to generate +a real spec file from a CVS spec-source file that would add version +numbers, changelog entries, etc to the result before building the +RPM. IOW, I need to rethink the process -- and then go through the +motions of putting my long RPM history into CVS one version at a +time so that version history information isn't lost.

-

As to why all these files aren't part of the source tree, well, - unless there was a large cry for it to happen, I don't believe it - should. PostgreSQL is very platform-agnostic -- and I like that. - Including the RPM stuff as part of the Official Tarball (TM) would, - IMHO, slant that agnostic stance in a negative way. But maybe I'm - too sensitive to that. I'm not opposed to doing that if that is the - consensus of the core group -- and that would be a sneaky way to - get the stuff into CVS :-). But if the core group isn't thrilled - with the idea (and my instinct says they're not likely to be), I am - opposed to the idea -- not to keep the stuff to myself, but to not - hinder the platform-neutral stance. IMHO, of course.

+

As to why all these files aren't part of the source tree, well, +unless there was a large cry for it to happen, I don't believe it +should. PostgreSQL is very platform-agnostic -- and I like that. +Including the RPM stuff as part of the Official Tarball (TM) would, +IMHO, slant that agnostic stance in a negative way. But maybe I'm +too sensitive to that. I'm not opposed to doing that if that is the +consensus of the core group -- and that would be a sneaky way to +get the stuff into CVS :-). But if the core group isn't thrilled +with the idea (and my instinct says they're not likely to be), I am +opposed to the idea -- not to keep the stuff to myself, but to not +hinder the platform-neutral stance. IMHO, of course.

-

Of course, there are many projects that DO include all the files - necessary to build RPMs from their Official Tarball (TM).

+

Of course, there are many projects that DO include all the files +necessary to build RPMs from their Official Tarball (TM).

-

1.11) How are CVS branches managed?

+

1.15) How are CVS branches managed?

-

This was written by Tom Lane:

+

This was written by Tom Lane:

-

2001-05-07

+

2001-05-07

-

If you just do basic "cvs checkout", "cvs update", "cvs commit", - then you'll always be dealing with the HEAD version of the files in - CVS. That's what you want for development, but if you need to patch - past stable releases then you have to be able to access and update - the "branch" portions of our CVS repository. We normally fork off a - branch for a stable release just before starting the development - cycle for the next release.

+

If you just do basic "cvs checkout", "cvs update", "cvs commit", +then you'll always be dealing with the HEAD version of the files in +CVS. That's what you want for development, but if you need to patch +past stable releases then you have to be able to access and update +the "branch" portions of our CVS repository. We normally fork off a +branch for a stable release just before starting the development +cycle for the next release.

-

The first thing you have to know is the branch name for the - branch you are interested in getting at. To do this, look at some - long-lived file, say the top-level HISTORY file, with "cvs status - -v" to see what the branch names are. (Thanks to Ian Lance Taylor - for pointing out that this is the easiest way to do it.) Typical - branch names are:

-
+
The first thing you have to know is the branch name for the
+branch you are interested in getting at. To do this, look at some
+long-lived file, say the top-level HISTORY file, with "cvs status
+-v" to see what the branch names are. (Thanks to Ian Lance Taylor
+for pointing out that this is the easiest way to do it.) Typical
+branch names are:

+
+
     REL7_1_STABLE
     REL7_0_PATCHES
     REL6_5_PATCHES
-

+
-

OK, so how do you do work on a branch? By far the best way is to - create a separate checkout tree for the branch and do your work in - that. Not only is that the easiest way to deal with CVS, but you - really need to have the whole past tree available anyway to test - your work. (And you *better* test your work. Never forget that - dot-releases tend to go out with very little beta testing --- so - whenever you commit an update to a stable branch, you'd better be - doubly sure that it's correct.)

+

OK, so how do you do work on a branch? By far the best way is to +create a separate checkout tree for the branch and do your work in +that. Not only is that the easiest way to deal with CVS, but you +really need to have the whole past tree available anyway to test +your work. (And you *better* test your work. Never forget that +dot-releases tend to go out with very little beta testing --- so +whenever you commit an update to a stable branch, you'd better be +doubly sure that it's correct.)

-

Normally, to checkout the head branch, you just cd to the place - you want to contain the toplevel "pgsql" directory and say

-
+
Normally, to checkout the head branch, you just cd to the place
+you want to contain the toplevel "pgsql" directory and say

+
+
     cvs ... checkout pgsql
-

+
-

To get a past branch, you cd to whereever you want it and - say

-
+
To get a past branch, you cd to whereever you want it and
+say

+
+
     cvs ... checkout -r BRANCHNAME pgsql
-

+
-

For example, just a couple days ago I did

-
+
For example, just a couple days ago I did

+
+
     mkdir ~postgres/REL7_1
     cd ~postgres/REL7_1
     cvs ... checkout -r REL7_1_STABLE pgsql
-

+
-

and now I have a maintenance copy of 7.1.*.

+

and now I have a maintenance copy of 7.1.*.

-

When you've done a checkout in this way, the branch name is - "sticky": CVS automatically knows that this directory tree is for - the branch, and whenever you do "cvs update" or "cvs commit" in - this tree, you'll fetch or store the latest version in the branch, - not the head version. Easy as can be.

+

When you've done a checkout in this way, the branch name is +"sticky": CVS automatically knows that this directory tree is for +the branch, and whenever you do "cvs update" or "cvs commit" in +this tree, you'll fetch or store the latest version in the branch, +not the head version. Easy as can be.

-

So, if you have a patch that needs to apply to both the head and - a recent stable branch, you have to make the edits and do the - commit twice, once in your development tree and once in your stable - branch tree. This is kind of a pain, which is why we don't normally - fork the tree right away after a major release --- we wait for a - dot-release or two, so that we won't have to double-patch the first - wave of fixes.

+

So, if you have a patch that needs to apply to both the head and +a recent stable branch, you have to make the edits and do the +commit twice, once in your development tree and once in your stable +branch tree. This is kind of a pain, which is why we don't normally +fork the tree right away after a major release --- we wait for a +dot-release or two, so that we won't have to double-patch the first +wave of fixes.

-

1.12) Where can I get a copy of the SQL - standards?

+

1.16) Where can I get a copy of the SQL +standards?

-

There are three versions of the SQL standard: SQL-92, SQL:1999, - and SQL:2003. They are endorsed by ANSI and ISO. Draft versions - can be downloaded from: -

+

There are three versions of the SQL standard: SQL-92, SQL:1999, +and SQL:2003. They are endorsed by ANSI and ISO. Draft versions can +be downloaded from:

-

Some SQL standards web pages are: -

- -

1.13) How go I get involved in PostgreSQL - web site development?

+ -

2.1) How do I efficiently access information in - tables from the backend code?

+

Some SQL standards web pages are:

-

You first need to find the tuples(rows) you are interested in. - There are two ways. First, SearchSysCache() and related - functions allow you to query the system catalogs. This is the - preferred way to access system tables, because the first call to - the cache loads the needed rows, and future requests can return the - results without accessing the base table. The caches use system - table indexes to look up tuples. A list of available caches is - located in src/backend/utils/cache/syscache.c. - src/backend/utils/cache/lsyscache.c contains many - column-specific cache lookup functions.

+
    +
  • http://troels.arvin.dk/db/rdbms/links/#standards
    • -

    The rows returned are cache-owned versions of the heap rows. - Therefore, you must not modify or delete the tuple returned by - SearchSysCache(). What you should do is release it - with ReleaseSysCache() when you are done using it; this - informs the cache that it can discard that tuple if necessary. If - you neglect to call ReleaseSysCache(), then the cache entry - will remain locked in the cache until end of transaction, which is - tolerable but not very desirable.

    +
  • http://www.wiscorp.com/SQLStandards.html
    • -

    If you can't use the system cache, you will need to retrieve the - data directly from the heap table, using the buffer cache that is - shared by all backends. The backend automatically takes care of - loading the rows into the buffer cache.

    +
  • http://www.contrib.andrew.cmu.edu/~shadow/sql.html#syntax +(SQL-92)
    • -

    Open the table with heap_open(). You can then start a - table scan with heap_beginscan(), then use - heap_getnext() and continue as long as - HeapTupleIsValid() returns true. Then do a - heap_endscan(). Keys can be assigned to the - scan. No indexes are used, so all rows are going to be - compared to the keys, and only the valid rows returned.

    +
  • http://dbs.uni-leipzig.de/en/lokal/standards.pdf +(paper)
    • +
-

You can also use heap_fetch() to fetch rows by block - number/offset. While scans automatically lock/unlock rows from the - buffer cache, with heap_fetch(), you must pass a - Buffer pointer, and ReleaseBuffer() it when - completed.

+

1.17) Where can I get technical +assistance?

-

Once you have the row, you can get data that is common to all - tuples, like t_self and t_oid, by merely accessing - the HeapTuple structure entries. If you need a - table-specific column, you should take the HeapTuple pointer, and - use the GETSTRUCT() macro to access the table-specific start - of the tuple. You then cast the pointer as a Form_pg_proc - pointer if you are accessing the pg_proc table, or - Form_pg_type if you are accessing pg_type. You can then - access the columns by using a structure pointer:

-
-((Form_pg_class) GETSTRUCT(tuple))->relnatts
-
-
- You must not directly change live tuples in this way. The - best way is to use heap_modifytuple() and pass it your - original tuple, and the values you want changed. It returns a - palloc'ed tuple, which you pass to heap_replace(). You can - delete tuples by passing the tuple's t_self to - heap_destroy(). You use t_self for - heap_update() too. Remember, tuples can be either system - cache copies, which may go away after you call - ReleaseSysCache(), or read directly from disk buffers, which - go away when you heap_getnext(), heap_endscan, or - ReleaseBuffer(), in the heap_fetch() case. Or it may - be a palloc'ed tuple, that you must pfree() when finished. +

Many technical questions held by those new to the code have been +answered on the pgsql-hackers mailing list - the archives of which +can be found at http://archives.postgresql.org/pgsql-hackers/.

-

2.2) Why are table, column, type, function, view - names sometimes referenced as Name or NameData, and - sometimes as char *?

+

If you cannot find discussion or your particular question, feel +free to put it to the list.

-

Table, column, type, function, and view names are stored in - system tables in columns of type Name. Name is a - fixed-length, null-terminated type of NAMEDATALEN bytes. - (The default value for NAMEDATALEN is 64 bytes.)

-
-typedef struct nameData
+
Major contributors also answer technical questions, including
+questions about development of new features, on IRC at
+irc.freenode.net in the #postgresql channel.

+
+
1.18) How go I get involved in PostgreSQL
+web site development?

+
+
PostgreSQL website development is discussed on the
+pgsql-www@postgresql.org mailing list. The is a project page where
+the source code is available at http://gborg.postgresql.org/project/pgweb/projdisplay.php
+, the code for the next version of the website is under the
+"portal" module. You will al so find code for the "techdocs"
+website if you would like to contribute to that. A temporary todo
+list for current website development issues is available at http://xzilla.postgresql.org/todo

+
+

+
Technical Questions

+

+
+
2.1) How do I efficiently access information
+in tables from the backend code?

+
+
You first need to find the tuples(rows) you are interested in.
+There are two ways. First, SearchSysCache() and related
+functions allow you to query the system catalogs. This is the
+preferred way to access system tables, because the first call to
+the cache loads the needed rows, and future requests can return the
+results without accessing the base table. The caches use system
+table indexes to look up tuples. A list of available caches is
+located in src/backend/utils/cache/syscache.c.
+src/backend/utils/cache/lsyscache.c contains many
+column-specific cache lookup functions.

+
+
The rows returned are cache-owned versions of the heap rows.
+Therefore, you must not modify or delete the tuple returned by
+SearchSysCache(). What you should do is release it
+with ReleaseSysCache() when you are done using it; this
+informs the cache that it can discard that tuple if necessary. If
+you neglect to call ReleaseSysCache(), then the cache entry
+will remain locked in the cache until end of transaction, which is
+tolerable but not very desirable.

+
+
If you can't use the system cache, you will need to retrieve the
+data directly from the heap table, using the buffer cache that is
+shared by all backends. The backend automatically takes care of
+loading the rows into the buffer cache.

+
+
Open the table with heap_open(). You can then start a
+table scan with heap_beginscan(), then use
+heap_getnext() and continue as long as
+HeapTupleIsValid() returns true. Then do a
+heap_endscan(). Keys can be assigned to the
+scan. No indexes are used, so all rows are going to be
+compared to the keys, and only the valid rows returned.

+
+
You can also use heap_fetch() to fetch rows by block
+number/offset. While scans automatically lock/unlock rows from the
+buffer cache, with heap_fetch(), you must pass a
+Buffer pointer, and ReleaseBuffer() it when
+completed.

+
+
Once you have the row, you can get data that is common to all
+tuples, like t_self and t_oid, by merely accessing
+the HeapTuple structure entries. If you need a
+table-specific column, you should take the HeapTuple pointer, and
+use the GETSTRUCT() macro to access the table-specific start
+of the tuple. You then cast the pointer as a Form_pg_proc
+pointer if you are accessing the pg_proc table, or
+Form_pg_type if you are accessing pg_type. You can then
+access the columns by using a structure pointer:

+
+
+((Form_pg_class) GETSTRUCT(tuple))->relnatts
+
+

+
+You must not directly change live tuples in this way. The
+best way is to use heap_modifytuple() and pass it your
+original tuple, and the values you want changed. It returns a
+palloc'ed tuple, which you pass to heap_replace(). You can
+delete tuples by passing the tuple's t_self to
+heap_destroy(). You use t_self for
+heap_update() too. Remember, tuples can be either system
+cache copies, which may go away after you call
+ReleaseSysCache(), or read directly from disk buffers, which
+go away when you heap_getnext(), heap_endscan, or
+ReleaseBuffer(), in the heap_fetch() case. Or it may
+be a palloc'ed tuple, that you must pfree() when finished. 
+
2.2) Why are table, column, type, function,
+view names sometimes referenced as Name or NameData,
+and sometimes as char *?

+
+
Table, column, type, function, and view names are stored in
+system tables in columns of type Name. Name is a
+fixed-length, null-terminated type of NAMEDATALEN bytes.
+(The default value for NAMEDATALEN is 64 bytes.)

+
+
+typedef struct nameData
     {
         char        data[NAMEDATALEN];
     } NameData;
     typedef NameData *Name;
-
-

-    Table, column, type, function, and view names that come into the
-    backend via user queries are stored as variable-length,
-    null-terminated character strings. 
+
+
-

Many functions are called with both types of names, ie. - heap_open(). Because the Name type is null-terminated, it is - safe to pass it to a function expecting a char *. Because there are - many cases where on-disk names(Name) are compared to user-supplied - names(char *), there are many cases where Name and char * are used - interchangeably.

+Table, column, type, function, and view names that come into the +backend via user queries are stored as variable-length, +null-terminated character strings. +

Many functions are called with both types of names, ie. +heap_open(). Because the Name type is null-terminated, it is +safe to pass it to a function expecting a char *. Because there are +many cases where on-disk names(Name) are compared to user-supplied +names(char *), there are many cases where Name and char * are used +interchangeably.

-

2.3) Why do we use Node and List to - make data structures?

+

2.3) Why do we use Node and +List to make data structures?

-

We do this because this allows a consistent way to pass data - inside the backend in a flexible way. Every node has a - NodeTag which specifies what type of data is inside the - Node. Lists are groups of Nodes chained together as a - forward-linked list.

+

We do this because this allows a consistent way to pass data +inside the backend in a flexible way. Every node has a +NodeTag which specifies what type of data is inside the +Node. Lists are groups of Nodes chained together as a +forward-linked list.

-

Here are some of the List manipulation commands:

+

Here are some of the List manipulation commands:

-
-
-
lfirst(i)
+
+
+
lfirst(i), lfirst_int(i), lfirst_oid(i)
-
return the data at list element i.
+
return the data (a point, inteter and OID respectively) at list +element i.
-
lnext(i)
+
lnext(i)
-
return the next list element after i.
+
return the next list element after i.
-
foreach(i, list)
+
foreach(i, list)
-
- loop through list, assigning each list element to - i. It is important to note that i is a List *, - not the data in the List element. You need to use - lfirst(i) to get at the data. Here is a typical code - snippet that loops through a List containing Var *'s - and processes each one: -
-List *i, *list;
+
loop through list, assigning each list element to
+i. It is important to note that i is a List *, not
+the data in the List element. You need to use
+lfirst(i) to get at the data. Here is a typical code snippet
+that loops through a List containing Var *'s and processes
+each one: 
+
+   List                *list;
+    ListCell    *i;
     
     foreach(i, list)
     {
@@ -788,109 +838,114 @@
 
         /* process var here */
     }
-
-

-        

+
+
+
-
lcons(node, list)
+
lcons(node, list)
-
add node to the front of list, or create a - new list with node if list is NIL.
+
add node to the front of list, or create a new +list with node if list is NIL.
-
lappend(list, node)
+
lappend(list, node)
-
add node to the end of list. This is more - expensive that lcons.
+
add node to the end of list. This is more +expensive that lcons.
-
nconc(list1, list2)
+
nconc(list1, list2)
-
Concat list2 on to the end of list1.
+
Concat list2 on to the end of list1.
-
length(list)
+
length(list)
-
return the length of the list.
+
return the length of the list.
-
nth(i, list)
+
nth(i, list)
-
return the i'th element in list.
+
return the i'th element in list.
-
lconsi, ...
+
lconsi, ...
-
There are integer versions of these: lconsi, lappendi, - etc. Also versions for OID lists: lconso, lappendo, etc.
-
-
- You can print nodes easily inside gdb. First, to disable - output truncation when you use the gdb print command: -
-(gdb) set print elements 0
-
-
- Instead of printing values in gdb format, you can use the next two - commands to print out List, Node, and structure contents in a - verbose format that is easier to understand. List's are unrolled - into nodes, and nodes are printed in detail. The first prints in a - short format, and the second in a long format: -
-(gdb) call print(any_pointer)
+
There are integer versions of these: lconsi, lappendi,
+etc. Also versions for OID lists: lconso, lappendo,
+etc.

+
+
+ +You can print nodes easily inside gdb. First, to disable +output truncation when you use the gdb print command: +
+(gdb) set print elements 0
+
+
+ +Instead of printing values in gdb format, you can use the next two +commands to print out List, Node, and structure contents in a +verbose format that is easier to understand. List's are unrolled +into nodes, and nodes are printed in detail. The first prints in a +short format, and the second in a long format: +
+(gdb) call print(any_pointer)
     (gdb) call pprint(any_pointer)
-
-
- The output appears in the postmaster log file, or on your screen if - you are running a backend directly without a postmaster. + + -

2.4) I just added a field to a structure. What - else should I do?

+The output appears in the postmaster log file, or on your screen if +you are running a backend directly without a postmaster. +

2.4) I just added a field to a structure. +What else should I do?

-

The structures passing around from the parser, rewrite, - optimizer, and executor require quite a bit of support. Most - structures have support routines in src/backend/nodes used - to create, copy, read, and output those structures. Make sure you - add support for your new field to these files. Find any other - places the structure may need code for your new field. mkid - is helpful with this (see above).

+

The structures passing around from the parser, rewrite, +optimizer, and executor require quite a bit of support. Most +structures have support routines in src/backend/nodes used +to create, copy, read, and output those structures (in particular, +the files copyfuncs.c and equalfuncs.c. Make sure you +add support for your new field to these files. Find any other +places the structure may need code for your new field. mkid +is helpful with this (see 1.9).

-

2.5) Why do we use palloc() and - pfree() to allocate memory?

+

2.5) Why do we use palloc() and +pfree() to allocate memory?

-

palloc() and pfree() are used in place of malloc() - and free() because we find it easier to automatically free all - memory allocated when a query completes. This assures us that all - memory that was allocated gets freed even if we have lost track of - where we allocated it. There are special non-query contexts that - memory can be allocated in. These affect when the allocated memory - is freed by the backend.

+

palloc() and pfree() are used in place of malloc() +and free() because we find it easier to automatically free all +memory allocated when a query completes. This assures us that all +memory that was allocated gets freed even if we have lost track of +where we allocated it. There are special non-query contexts that +memory can be allocated in. These affect when the allocated memory +is freed by the backend.

-

2.6) What is ereport()?

+

2.6) What is ereport()?

-

ereport() is used to send messages to the front-end, and - optionally terminate the current query being processed. The first - parameter is an ereport level of DEBUG (levels 1-5), LOG, - INFO, NOTICE, ERROR, FATAL, or - PANIC. NOTICE prints on the user's terminal and the - postmaster logs. INFO prints only to the user's terminal and - LOG prints only to the server logs. (These can be changed - from postgresql.conf.) ERROR prints in both places, - and terminates the current query, never returning from the call. - FATAL terminates the backend process. The remaining - parameters of ereport are a printf-style set of - parameters to print.

+

ereport() is used to send messages to the front-end, and +optionally terminate the current query being processed. The first +parameter is an ereport level of DEBUG (levels 1-5), +LOG, INFO, NOTICE, ERROR, FATAL, +or PANIC. NOTICE prints on the user's terminal and +the postmaster logs. INFO prints only to the user's terminal +and LOG prints only to the server logs. (These can be +changed from postgresql.conf.) ERROR prints in both +places, and terminates the current query, never returning from the +call. FATAL terminates the backend process. The remaining +parameters of ereport are a printf-style set of +parameters to print.

-

ereport(ERROR) frees most memory and open file descriptors so - you don't need to clean these up before the call.

+

ereport(ERROR) frees most memory and open file +descriptors so you don't need to clean these up before the +call.

-

2.7) What is CommandCounterIncrement()?

+

2.7) What is CommandCounterIncrement()?

-

Normally, transactions can not see the rows they modify. This - allows UPDATE foo SET x = x + 1 to work correctly.

+

Normally, transactions can not see the rows they modify. This +allows UPDATE foo SET x = x + 1 to work correctly.

-

However, there are cases where a transactions needs to see rows - affected in previous parts of the transaction. This is accomplished - using a Command Counter. Incrementing the counter allows - transactions to be broken into pieces so each piece can see rows - modified by previous pieces. CommandCounterIncrement() - increments the Command Counter, creating a new part of the - transaction.

+

However, there are cases where a transactions needs to see rows +affected in previous parts of the transaction. This is accomplished +using a Command Counter. Incrementing the counter allows +transactions to be broken into pieces so each piece can see rows +modified by previous pieces. CommandCounterIncrement() +increments the Command Counter, creating a new part of the +transaction.

+ + - -