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+Developer's Frequently Asked Questions (FAQ) for PostgreSQL
+
+Last updated: Wed Feb 11 20:23:01 EST 1998
+
+Current maintainer: Bruce Momjian (maillist@candle.pha.pa.us)
+
+The most recent version of this document can be viewed at the postgreSQL Web
+site, http://postgreSQL.org.
+
+  ------------------------------------------------------------------------
+
+Questions answered:
+
+1) What tools are available for developers?
+2) What books are good for developers?
+3) Why do we use palloc() and pfree() to allocate memory?
+4) Why do we use Node and List to make data structures?
+5) How do I add a feature or fix a bug?
+6) How do I download/update the current source tree?
+7) How do I test my changes?
+
+  ------------------------------------------------------------------------
+
+1) 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
+pgsql/src/tools directory are designed for developers.
+
+        RELEASE_CHANGES         changes we have to make for each release
+        SQL_keywords            standard SQL'92 keywords
+        backend                 web flowchart of the backend directories
+        ccsym                   find standard defines made by your compiler
+        entab                   converts tabs to spaces, used by pgindent
+        find_static             finds functions that could be made static
+        find_typedef            get a list of typedefs in the source code
+        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.README    make comparison of our keywords and SQL'92
+        make_mkid               make mkid ID files
+        mkldexport              create AIX exports file
+        pgindent                indents C source files
+
+Let me note some of these. If you point your browser at the
+pgsql/src/tools/backend directory, you will see all the backend
+components in a flow chart. You can click on any one 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 pgsql/src/tools/backend directory is also
+contained on our web page under the title Backend Flowchart.
+
+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.
+
+Third, you need to get mkid from ftp.postgresql.org. By running
+tools/make_mkid, an archive of source symbols can be created that can be
+rapidly queried like grep or edited.
+
+make_diff has tools to create patch diff files that can be applied to the
+distribution.
+
+pgindent will format source files to match our standard format, which has
+four-space tabs, and an indenting format specified by flags to the your
+operating system's utility indent.
+
+2) What books are good for developers?
+
+I have three 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, and Transaction Processing:  Concepts and Techniques,
+by Jim Gray and Andreas Reuter, Morgan, Kaufmann.
+
+3) Why do we use palloc() and pfree() to allocate memory?
+
+palloc() and pfree() are used in place of malloc() and free() because we
+automatically free all memory allocated when a transaction completes. This
+makes it easier to make sure we free memory that gets allocated in one
+place, but only freed much later. There are several contexts that memory can
+be allocated in, and this controls when the allocated memory is
+automatically freed by the backend.
+
+4) 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 lists of Nodes. lfirst(),
+lnext(), and foreach() are used to get, skip, and traverse through Lists.
+
+5) How do I add a feature or fix a bug?
+
+The source code is over 250,000 lines. Many problems/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.
+
+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.
+
+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.
+
+6) 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 get CVSup, which is available from
+ftp.postgresql.org too. CVSup allows you to download the source tree, then
+occasionally update your copy of the source tree with any new changes. Using
+CVSup, you don't have to download the entire source each time, only the
+changed files. CVSup does not allow developers to update the source tree.
+
+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.
+
+For hard-core developers, Marc(scrappy@postgresql.org) will give you a Unix
+shell account on postgresql.org, and you can ftp your files into your
+account, patch, and cvs install the changes directly into the source tree.
+
+6) 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.