Use zic's new "-b slim" option to generate smaller timezone files.

tglsfdc · tglsfdc · commit a12079109686 · 2019-08-19T13:17:02.000-04:00
IANA tzcode release 2019b adds an option that tells zic not to emit the old 32-bit section of the timezone files, and to skip some other space-wasting hacks needed for compatibility with old timezone client libraries. Since we only expect our own code to use the timezone data we install, and our code is up-to-date with 2019b, there's no apparent reason not to generate the smallest possible files. Unfortunately, while the individual zone files do get significantly smaller in many cases, they were not that big to begin with; which means that no real space savings ensues on filesystems that don't optimize small files. (For instance, on ext4 with 4K block size, "du" says the installed timezone tree is the same size as before.) Still, it seems worth making the change, if only because this is presumably the wave of the future. At the very least, we'll save some cycles while reading a zone file. But given the marginal value and the fact that this is a new code path, it doesn't seem worth the risk of back-patching this change into stable branches. Hence, unlike most of our timezone-related changes, apply to HEAD only. Discussion: https://postgr.es/m/24998.1563403327@sss.pgh.pa.us
diff --git a/src/timezone/Makefile b/src/timezone/Makefile
@@ -55,7 +55,7 @@ zic: $(ZICOBJS) | submake-libpgport
 
 install: all installdirs
 ifeq (,$(with_system_tzdata))
-	$(ZIC) -d '$(DESTDIR)$(datadir)/timezone' -p '$(POSIXRULES)' $(ZIC_OPTIONS) $(TZDATAFILES)
+	$(ZIC) -d '$(DESTDIR)$(datadir)/timezone' -p '$(POSIXRULES)' -b slim $(ZIC_OPTIONS) $(TZDATAFILES)
 endif
 	$(MAKE) -C tznames $@
 
diff --git a/src/tools/msvc/Install.pm b/src/tools/msvc/Install.pm
@@ -365,8 +365,9 @@ sub GenerateTimezoneFiles
 
 	print "Generating timezone files...";
 
-	my @args =
-	  ("$conf/zic/zic", '-d', "$target/share/timezone", '-p', "$posixrules");
+	my @args = (
+		"$conf/zic/zic", '-d', "$target/share/timezone", '-p',
+		"$posixrules",   '-b', 'slim');
 	foreach (@tzfiles)
 	{
 		my $tzfile = $_;
