5 files changed, 241 insertions, 8 deletions
diff --git a/src/timezone/.gitignore b/src/timezone/.gitignore
index f844c9fcf19..673f864b438 100644
--- a/src/timezone/.gitignore
+++ b/src/timezone/.gitignore
@@ -1 +1,2 @@
 /zic
+/abbrevs.txt
diff --git a/src/timezone/Makefile b/src/timezone/Makefile
index 2cecaec5e63..6cfe95019b8 100644
--- a/src/timezone/Makefile
+++ b/src/timezone/Makefile
@@ -55,6 +55,11 @@ ifeq (,$(with_system_tzdata))
 endif
 	$(MAKE) -C tznames $@
 
+abbrevs.txt: zic $(TZDATAFILES)
+	mkdir junkdir
+	$(ZIC) -P -d junkdir -p '$(POSIXRULES)' $(TZDATAFILES) | LANG=C sort | uniq >abbrevs.txt
+	rm -rf junkdir
+
 installdirs:
 	$(MKDIR_P) '$(DESTDIR)$(datadir)'
 
@@ -65,4 +70,4 @@ endif
 	$(MAKE) -C tznames $@
 
 clean distclean maintainer-clean:
-	rm -f zic$(X) $(ZICOBJS)
+	rm -f zic$(X) $(ZICOBJS) abbrevs.txt
diff --git a/src/timezone/README b/src/timezone/README
index 201b2938814..d09b8854a09 100644
--- a/src/timezone/README
+++ b/src/timezone/README
@@ -22,11 +22,17 @@ Since time zone rules change frequently in some parts of the world,
 we should endeavor to update the data files before each PostgreSQL
 release.
 
-At each update, we should check if time zone offsets have changed.
-Just search for the current or previous year and see what has changed.
-Sometimes a country changes its time zone offsets, for example Georgia
-in 2004.  Just grepping in the zic database files for 2004 is enough to
-spot such a change.  Then the files under tznames/ should be updated.
+While the files under data/ can just be duplicated when updating, manual
+effort is needed to update the time zone abbreviation lists under tznames/.
+These need to be changed whenever new abbreviations are invented or the
+UTC offset associated with an existing abbreviation changes.  To detect
+if this has happened, after installing new files under data/ do
+	gmake abbrevs.txt
+which will produce a file showing all abbreviations that are in current
+use according to the data/ files.  Compare this to known_abbrevs.txt,
+which is the list that existed last time the tznames/ files were updated.
+Update tznames/ as seems appropriate, then replace known_abbrevs.txt
+in the same commit.
 
 When there has been a new release of Windows (probably including Service
 Packs), the list of matching timezones need to be updated. Run the
diff --git a/src/timezone/known_abbrevs.txt b/src/timezone/known_abbrevs.txt
new file mode 100644
index 00000000000..d2c490bea47
--- /dev/null
+++ b/src/timezone/known_abbrevs.txt
@@ -0,0 +1,200 @@
+ACT	-18000
+ADDT	-7200	D
+ADT	-10800	D
+ADT	14400	D
+AFT	16200
+AKST	-32400
+ALMST	25200	D
+AMT	-14400
+AMT	14400
+ANAT	39600
+APT	-10800	D
+AQTT	14400
+AQTT	18000
+ART	-10800
+AST	-14400
+AST	10800
+AWT	-10800	D
+AZOT	-3600
+AZST	18000	D
+BDT	21600
+BEAT	9000
+BEAUT	9885
+BNT	28800
+BOT	-14400
+BRT	-10800
+BTT	21600
+CAST	10800	D
+CAT	7200
+CCT	23400
+CDT	-14400	D
+CDT	-18000	D
+CDT	32400	D
+CEST	7200	D
+CET	3600
+CHAST	45900
+CHOST	36000	D
+CIT	28800
+CKHST	-34200	D
+CLT	-14400
+COT	-18000
+CPT	-18000	D
+CST	-21600
+CST	28800
+CST	34200
+CVT	-3600
+CWT	-18000	D
+CXT	25200
+ChST	36000
+DAVT	25200
+DDUT	36000
+EAST	-21600
+EAT	10800
+ECT	-18000
+EDT	-14400	D
+EEST	10800	D
+EET	7200
+EGST	0	D
+EPT	-14400	D
+EST	-18000
+EST	36000
+FJT	43200
+FKT	-10800
+FNT	-7200
+GALT	-21600
+GAMT	-32400
+GEST	14400	D
+GFT	-10800
+GILT	43200
+GMT	0
+GMT+1	-3600
+GMT+10	-36000
+GMT+11	-39600
+GMT+12	-43200
+GMT+2	-7200
+GMT+3	-10800
+GMT+4	-14400
+GMT+5	-18000
+GMT+6	-21600
+GMT+7	-25200
+GMT+8	-28800
+GMT+9	-32400
+GMT-1	3600
+GMT-10	36000
+GMT-11	39600
+GMT-12	43200
+GMT-13	46800
+GMT-14	50400
+GMT-2	7200
+GMT-3	10800
+GMT-4	14400
+GMT-5	18000
+GMT-6	21600
+GMT-7	25200
+GMT-8	28800
+GMT-9	32400
+GST	-7200
+GST	14400
+GYT	-14400
+HAST	-36000
+HKT	28800
+HOVST	28800	D
+HST	-36000
+ICT	25200
+ICT	28800
+IDDT	14400	D
+IOT	21600
+IRDT	16200	D
+IRKT	25200
+IST	23400	D
+JST	32400
+KDT	36000	D
+KGST	21600	D
+KOST	43200
+KRAT	21600
+KST	28800
+LHST	39600	D
+LINT	50400
+LKT	21600
+MAGT	36000
+MART	-34200
+MAWT	21600
+MDDT	-18000	D
+MDT	-21600	D
+MET	3600
+MHT	43200
+MMT	23400
+MPT	-21600	D
+MST	-25200
+MUT	14400
+MVT	18000
+MWT	-21600	D
+MYT	28800
+NCT	39600
+NDDT	-5400	D
+NFT	41400
+NOVST	25200	D
+NPT	20700
+NRT	43200
+NUT	-39600
+NZST	43200
+OMST	18000
+ORAT	18000
+PET	-18000
+PETT	39600
+PGT	36000
+PHOT	46800
+PKT	18000
+PMDT	-7200	D
+PONT	39600
+PPT	-25200	D
+PST	-28800
+PWT	-25200	D
+PWT	32400
+PYST	-10800	D
+QYZT	21600
+RET	14400
+ROTT	-10800
+SAKT	36000
+SAMT	14400
+SAST	10800	D
+SAST	7200
+SBT	39600
+SCT	14400
+SGT	28800
+SRT	-10800
+SST	-39600
+SYOT	10800
+TAHT	-36000
+TFT	18000
+TJT	18000
+TKT	-36000
+TMT	18000
+TOST	50400	D
+TRUT	36000
+TVT	43200
+UCT	0
+ULAST	32400	D
+UTC	0
+UYHST	-9000	D
+UZT	18000
+VET	-14400
+VLAST	32400
+VOST	21600
+VUT	39600
+WAKT	43200
+WARST	-10800	D
+WART	-14400
+WAST	7200	D
+WAT	-3600
+WAT	0
+WAT	3600
+WEST	3600	D
+WET	0
+WFT	43200
+WGST	-7200	D
+WIT	25200
+WST	-39600
+WST	28800
+YAKT	28800
+YEKT	18000
diff --git a/src/timezone/zic.c b/src/timezone/zic.c
index 0aa90ebfca1..2c34b874e3c 100644
--- a/src/timezone/zic.c
+++ b/src/timezone/zic.c
@@ -181,6 +181,8 @@ static int	max_year;
 static zic_t min_time;
 static int	min_year;
 static int	noise;
+static int	print_abbrevs;
+static zic_t print_cutoff;
 static const char *rfilename;
 static int	rlinenum;
 static const char *progname;
@@ -457,7 +459,7 @@ static void
 usage(FILE *stream, int status)
 {
 	(void) fprintf(stream, _("%s: usage is %s \
-[ --version ] [ --help ] [ -v ] [ -l localtime ] [ -p posixrules ] \\\n\
+[ --version ] [ --help ] [ -v ] [ -P ] [ -l localtime ] [ -p posixrules ] \\\n\
 \t[ -d directory ] [ -L leapseconds ] [ -y yearistype ] [ filename ... ]\n\
 \n\
 Report bugs to tz@elsie.nci.nih.gov.\n"),
@@ -498,7 +500,7 @@ main(int argc, char *argv[])
 		{
 			usage(stdout, EXIT_SUCCESS);
 		}
-	while ((c = getopt(argc, argv, "d:l:p:L:vsy:")) != EOF && c != -1)
+	while ((c = getopt(argc, argv, "d:l:p:L:vPsy:")) != EOF && c != -1)
 		switch (c)
 		{
 			default:
@@ -561,6 +563,10 @@ main(int argc, char *argv[])
 			case 'v':
 				noise = TRUE;
 				break;
+			case 'P':
+				print_abbrevs = TRUE;
+				print_cutoff = time(NULL);
+				break;
 			case 's':
 				(void) printf("%s: -s ignored\n", progname);
 				break;
@@ -1780,6 +1786,21 @@ writezone(const char *name, const char *string)
 				puttzcode(gmtoffs[i], fp);
 				(void) putc(isdsts[i], fp);
 				(void) putc((unsigned char) indmap[abbrinds[i]], fp);
+
+				/* Print current timezone abbreviations if requested */
+				if (print_abbrevs && pass == 2 &&
+					(ats[i] >= print_cutoff || i == typecnt - 1))
+				{
+					char *thisabbrev = &thischars[indmap[abbrinds[i]]];
+
+					/* filter out assorted junk entries */
+					if (strcmp(thisabbrev, GRANDPARENTED) != 0 &&
+						strcmp(thisabbrev, "zzz") != 0)
+						fprintf(stdout, "%s\t%ld%s\n",
+								thisabbrev,
+								gmtoffs[i],
+								isdsts[i] ? "\tD" : "");
+				}
 			}
 		if (thischarcnt != 0)
 			(void) fwrite((void *) thischars,