Fix upper limit for vacuum_cleanup_index_scale_factor

6ca33a88 sets upper limit for vacuum_cleanup_index_scale_factor to
DBL_MAX.  DBL_MAX appears to be platform-dependent. That causes
many buildfarm animals to fail, because we check boundaries of
vacuum_cleanup_index_scale_factor in regression tests.

This commit changes upper limit from DBL_MAX to just "large enough"
limit, which was arbitrary selected as 1e10.

Author: Alexander Korotkov
Reported-by: Tom Lane, Darafei Praliaskouski
Discussion: https://postgr.es/m/CAPpHfdvewmr4PcpRjrkstoNn1n2_6dL-iHRB21CCfZ0efZdBTg%40mail.gmail.com
Discussion: https://postgr.es/m/CAC8Q8tLYFOpKNaPS_E7V8KtPdE%3D_TnAn16t%3DA3LuL%3DXjfOO-BQ%40mail.gmail.com

doc/src/sgml/config.sgml

@@ -6989,7 +6989,8 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
        </para>
 
        <para>
-        The value should be non-negative.
+        The value can range from <literal>0</literal> to
+        <literal>10000000000</literal>.
         When <varname>vacuum_cleanup_index_scale_factor</varname> is set to
         <literal>0</literal>, index scans are never skipped during
         <command>VACUUM</command> cleanup. The default value is <literal>0.1</literal>.

src/backend/access/common/reloptions.c

@@ -416,7 +416,7 @@ static relopt_real realRelOpts[] =
 			RELOPT_KIND_BTREE,
 			ShareUpdateExclusiveLock
 		},
-		-1, 0.0, DBL_MAX
+		-1, 0.0, 1e10
 	},
 	/* list terminator */
 	{{NULL}}

src/backend/utils/misc/guc.c

@@ -3253,7 +3253,7 @@ static struct config_real ConfigureNamesReal[] =
 			NULL
 		},
 		&vacuum_cleanup_index_scale_factor,
-		0.1, 0.0, DBL_MAX,
+		0.1, 0.0, 1e10,
 		NULL, NULL, NULL
 	},
 

src/test/regress/expected/btree_index.out

@@ -165,7 +165,7 @@ select reloptions from pg_class WHERE oid = 'btree_idx1'::regclass;
 -- Fail while setting improper values
 create index btree_idx_err on btree_test(a) with (vacuum_cleanup_index_scale_factor = -10.0);
 ERROR:  value -10.0 out of bounds for option "vacuum_cleanup_index_scale_factor"
-DETAIL:  Valid values are between "0.000000" and "179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.000000".
+DETAIL:  Valid values are between "0.000000" and "10000000000.000000".
 create index btree_idx_err on btree_test(a) with (vacuum_cleanup_index_scale_factor = 100.0);
 create index btree_idx_err on btree_test(a) with (vacuum_cleanup_index_scale_factor = 'string');
 ERROR:  invalid value for floating point option "vacuum_cleanup_index_scale_factor": string