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Add FAQ_CVS.
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Bruce Momjian
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# PGLIB is probably /usr/local/pgsql/lib
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PGINCLUDE=${PGLIB}/../include
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CFLAGS+=-I${PGINCLUDE}
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install-earthdistance: ${PGLIB}/earthdistance.so
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${PGLIB}/earthdistance.so: earthdistance.so
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sudo install -C -g bin -o bin earthdistance.so ${PGLIB}
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earthdistance.so: earthdistance.o
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$(LD) -o $@ -Bshareable $<
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earthdistance.o: earthdistance.c
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$(CC) -o $@ -c $(CFLAGS) $<
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Date: Wed, 1 Apr 1998 15:19:32 -0600 (CST)
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From: Hal Snyder <hal@vailsys.com>
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To: vmehr@ctp.com
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Subject: [QUESTIONS] Re: Spatial data, R-Trees
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> From: Vivek Mehra <vmehr@ctp.com>
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> Date: Wed, 1 Apr 1998 10:06:50 -0500
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> Am just starting out with PostgreSQL and would like to learn more about
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> the spatial data handling ablilities of postgreSQL - in terms of using
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> R-tree indexes, user defined types, operators and functions.
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>
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> Would you be able to suggest where I could find some code and SQL to
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> look at to create these?
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Here's the setup for adding an operator '<@>' to give distance in
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statute miles between two points on the earth's surface. Coordinates
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are in degrees. Points are taken as (longitude, latitude) and not vice
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versa as longitude is closer to the intuitive idea of x-axis and
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latitude to y-axis.
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There's C source, Makefile for FreeBSD, and SQL for installing and
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testing the function.
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Let me know if anything looks fishy!
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A note on testing C extensions - it seems not enough to drop a function
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and re-create it - if I change a function, I have to stop and restart
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the backend for the new version to be seen. I guess it would be too
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messy to track which functions are added from a .so and do a dlclose
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when the last one is dropped.
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@ -0,0 +1,65 @@
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#include <math.h>
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#include <stdio.h>
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#include <string.h>
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#include <postgres.h>
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#include <utils/geo_decls.h> /* for Pt */
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#include <utils/palloc.h> /* for palloc */
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/* Earth's radius is in statute miles. */
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const EARTH_RADIUS = 3958.747716;
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const TWO_PI = 2.0 * M_PI;
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/******************************************************
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*
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* degtorad - convert degrees to radians
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*
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* arg: double, angle in degrees
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*
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* returns: double, same angle in radians
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******************************************************/
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static double
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degtorad (double degrees) {
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return (degrees / 360.0) * TWO_PI;
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}
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/******************************************************
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*
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* geo_distance - distance between points
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*
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* args:
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* a pair of points - for each point,
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* x-coordinate is longitude in degrees west of Greenwich
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* y-coordinate is latitude in degrees above equator
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*
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* returns: double
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* distance between the points in miles on earth's surface
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******************************************************/
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double *
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geo_distance (Point *pt1, Point *pt2) {
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double long1, lat1, long2, lat2;
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double longdiff;
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double * resultp = palloc (sizeof(double));
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/* convert degrees to radians */
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long1 = degtorad (pt1->x);
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lat1 = degtorad (pt1->y);
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long2 = degtorad (pt2->x);
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lat2 = degtorad (pt2->y);
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/* compute difference in longitudes - want < 180 degrees */
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longdiff = fabs (long1 - long2);
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if (longdiff > M_PI)
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longdiff = TWO_PI - longdiff;
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* resultp = EARTH_RADIUS * acos
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(sin (lat1) * sin (lat2) + cos (lat1) * cos (lat2) * cos (longdiff));
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return resultp;
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}
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@ -0,0 +1,23 @@
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--------------- geo_distance
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DROP FUNCTION geo_distance (point, point);
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CREATE FUNCTION geo_distance (point, point) RETURNS float8
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AS '/usr/local/pgsql/lib/earthdistance.so' LANGUAGE 'c';
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SELECT geo_distance ('(1,2)'::point, '(3,4)'::point);
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--------------- geo_distance as operator <@>
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DROP OPERATOR <@> (point, point);
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CREATE OPERATOR <@> (
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leftarg = point,
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rightarg = point,
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procedure = geo_distance,
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commutator = <@>
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);
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-- ( 87.6, 41.8) is in Chicago
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-- (106.7, 35.1) is in Albuquerque
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-- The cities are about 1100 miles apart
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SELECT '(87.6,41.8)'::point <@> '(106.7,35.1)'::point;
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@ -0,0 +1,84 @@
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<html>
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<head>
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<title>PostgreSQL: Getting the source via CVS</title>
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</head>
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<body bgcolor=white text=black link=blue vlink=purple>
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<font size="+3">Getting the source via CVS</font>
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<p>If you would like to keep up with the current sources on a regular
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basis, you can fetch them from our CVS server and then use CVS to
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retrieve updates from time to time.
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<P>To do this you first need a local copy of CVS (Concurrent Version Control
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System), which you can get from
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<A HREF="http://www.cyclic.com/">http://www.cyclic.com/</A> or
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any GNU software archive site. Currently we recommend version 1.9.
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<P>Once you have installed the CVS software, do this:
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<PRE>
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cvs -d :pserver:anoncvs@postgresql.org:/usr/local/cvsroot login
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</PRE>
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You will be prompted for a password; enter '<tt>postgresql</tt>'.
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You should only need to do this once, since the password will be
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saved in <tt>.cvspass</tt> in your home directory.
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<P>Having logged in, you are ready to fetch the PostgreSQL sources.
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Do this:
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<PRE>
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cvs -z3 -d :pserver:anoncvs@postgresql.org:/usr/local/cvsroot co -P pgsql
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</PRE>
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which will install the PostgreSQL sources into a subdirectory <tt>pgsql</tt>
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of the directory you are currently in.
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<P>(If you have a fast link to the Internet, you may not need <tt>-z3</tt>,
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which instructs CVS to use gzip compression for transferred data. But
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on a modem-speed link, it's a very substantial win.)
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<P>This initial checkout is a little slower than simply downloading
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a <tt>tar.gz</tt> file; expect it to take 40 minutes or so if you
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have a 28.8K modem. The advantage of CVS doesn't show up until you
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want to update the file set later on.
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<P>Whenever you want to update to the latest CVS sources, <tt>cd</tt> into
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the <tt>pgsql</tt> subdirectory, and issue
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<PRE>
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cvs -z3 update -d -P
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</PRE>
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This will fetch only the changes since the last time you updated.
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You can update in just a couple of minutes, typically, even over
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a modem-speed line.
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<P>You can save yourself some typing by making a file <tt>.cvsrc</tt>
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in your home directory that contains
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<PRE>
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cvs -z3
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update -d -P
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</PRE>
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This supplies the <tt>-z3</tt> option to all cvs commands, and the
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<tt>-d</tt> and <tt>-P</tt> options to cvs update. Then you just have
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to say
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<PRE>
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cvs update
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</PRE>
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to update your files.
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<P><strong>CAUTION:</strong> some versions of CVS have a bug that
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causes all checked-out files to be stored world-writable in your
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directory. If you see that this has happened, you can do something like
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<PRE>
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chmod -R go-w pgsql
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</PRE>
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to set the permissions properly. This bug is allegedly fixed in the
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latest beta version of CVS, 1.9.28 ... but it may have other, less
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predictable bugs.
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<P>CVS can do a lot of other things, such as fetching prior revisions
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of the PostgreSQL sources rather than the latest development version.
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For more info consult the manual that comes with CVS, or see the online
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documentation at <A HREF="http://www.cyclic.com/">http://www.cyclic.com/</A>.
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</body>
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</html>
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@ -113,12 +113,15 @@ existing code doing similar things is helpful.
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There are several ways to obtain the source tree. Occasional developers can
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just get the most recent source tree snapshot from ftp.postgresql.org. For
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regular developers, you can get CVSup, which is available from
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regular developers, you can use CVSup, which is available from
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ftp.postgresql.org too. CVSup allows you to download the source tree, then
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occasionally update your copy of the source tree with any new changes. Using
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CVSup, you don't have to download the entire source each time, only the
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changed files. CVSup does not allow developers to update the source tree.
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Anonymous CVS is available too. See the doc/FAQ_CVS file for more
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information.
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To update the source tree, there are two ways. You can generate a patch
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against your current source tree, perhaps using the make_diff tools
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mentioned above, and send them to the patches list. They will be reviewed,
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