Copy postgresql.auto.conf from segment while gpexpand. (#12212)

The config file postgresql.auto.conf might not the same across
QD or QEs. While execute gpexpand, copy this file from master
is not correct. We should copy them from segment for newly added
segments.

gpMgmt/bin/gpexpand

@@ -861,6 +861,14 @@ class SegmentTemplate:
             remoteHost=self.srcSegHostname)
         cpCmd.run(validateAfter=True)
 
+        self.logger.info('Copying postgresql.auto.conf from existing segment into template')
+        cmdName = 'gpexpand copying postgresql.auto.conf to %s:%s/postgresql.auto.conf' \
+                  % (self.srcSegHostname, self.srcSegDataDir)
+        cpCmd = Scp(name=cmdName, srcFile=self.srcSegDataDir + '/postgresql.auto.conf',
+            dstFile=self.tempDir, dstHost=localHostname, ctxt=REMOTE,
+            remoteHost=self.srcSegHostname)
+        cpCmd.run(validateAfter=True)
+
         self.logger.info('Copying pg_hba.conf from existing segment into template')
         cmdName = 'gpexpand copy pg_hba.conf to %s:%s/pg_hba.conf' \
                   % (self.srcSegHostname, self.srcSegDataDir)

gpMgmt/test/behave/mgmt_utils/gpexpand.feature

@@ -529,3 +529,21 @@ Feature: expand the cluster by adding more segments
         When the user runs gpexpand to redistribute
         Then the numsegments of table "public.test_matview" is 4
         And distribution information from table "public.test_matview" and "public.test_matview_base" in "gptest" are the same
+
+    @gpexpand_verify_autoconf_from_qe
+    Scenario: Verify should succeed when expand partition table
+        Given the database is not running
+        And a working directory of the test as '/data/gpdata/gpexpand'
+        And a temporary directory under "/data/gpdata/gpexpand/expandedData" to expand into
+        And the cluster is generated with "1" primaries only
+        And database "gptest" exists
+        And the user change enable_mergejoin to on only on qd by alter system on gptest
+        And the user restart the whole cluster
+        And enable_mergejoin is on on qd and off on all qes
+        And there are no gpexpand_inputfiles
+        And the cluster is setup for an expansion on hosts "localhost"
+        When the user runs gpexpand interview to add 1 new segment and 0 new host "ignored.host"
+        Then the number of segments have been saved
+        When the user runs gpexpand with the latest gpexpand_inputfile with additional parameters "--silent"
+        Then verify that the cluster has 1 new segments
+        Then enable_mergejoin is on on qd and off on all qes

gpMgmt/test/behave/mgmt_utils/steps/mgmt_utils.py

@@ -2422,6 +2422,32 @@ def impl(context, command, target):
     if target not in contents:
         raise Exception("cannot find %s in %s" % (target, filename))
 
+
+@given('the user change enable_mergejoin to on only on qd by alter system on gptest')
+def impl(context):
+    host, port = get_primary_segment_host_port_for_content('-1')
+    query = "alter system set enable_mergejoin to on"
+    psql_cmd = "PGDATABASE=\'%s\' psql -h %s -p %s -c \"%s\"; " % (
+        "gptest", host, port, query)
+    Command(name='Running Remote command: %s' % psql_cmd, cmdStr=psql_cmd).run(validateAfter=True)
+
+@given('the user restart the whole cluster')
+def impl(context):
+    cmd = "gpstop -rai"
+    Command(name='Running Remote command: %s' % cmd, cmdStr=cmd).run(validateAfter=True)
+
+@given('enable_mergejoin is on on qd and off on all qes')
+@then('enable_mergejoin is on on qd and off on all qes')
+def impl(context):
+    cmd = "gpconfig -s enable_mergejoin"
+    c = Command(name='Running Remote command: %s' % cmd, cmdStr=cmd)
+    c.run(validateAfter=True)
+    out = c.get_stdout()
+    if ("Master  value: on" not in out or
+        "Segment value: off" not in out):
+        raise Exception('Guc enable_mergejoin value is not correct')
+
+
 @given('verify that a role "{role_name}" exists in database "{dbname}"')
 @then('verify that a role "{role_name}" exists in database "{dbname}"')
 def impl(context, role_name, dbname):