Remove dead code in ATExecSetDistributedBy

This commit is the first step to refactor ATExecSetDistributedBy. Its
main purpose is to remove some dead code in this function and during
the process we find some helper functions can also be simplified so
the simplification is also in this commit.

According to MPP-7770, we should disable changing storage options for now.
It is ugly to just throw an error when encounter `appendonly` option but
without removing the code. In this commit remove all related logic.

Because of with clause can only contain reshuffle|reorganize, we only
new_rel_opts if the table itself is ao|aoco. No need to deduce it from with
clause.

We also remove the unnecessary checks at the start of this function. Because
These checks have been already done in the function `ATPrepCmd`.

Co-authored-by: Shuejie Zhang <shzhang@pivotal.io >

src/backend/nodes/copyfuncs.c

@@ -3318,7 +3318,6 @@ _copySetDistributionCmd(const SetDistributionCmd *from)
 
 	COPY_SCALAR_FIELD(backendId);
 	COPY_NODE_FIELD(relids);
-	COPY_NODE_FIELD(indexOidMap);
 	COPY_NODE_FIELD(hiddenTypes);
 
 	return newnode;

src/backend/nodes/equalfuncs.c

@@ -1048,7 +1048,6 @@ _equalSetDistributionCmd(const SetDistributionCmd *a, const SetDistributionCmd *
 {
 	COMPARE_SCALAR_FIELD(backendId);
 	COMPARE_NODE_FIELD(relids);
-	COMPARE_NODE_FIELD(indexOidMap);
 	COMPARE_NODE_FIELD(hiddenTypes);
 
 	return true;

src/backend/nodes/outfuncs.c

@@ -2779,13 +2779,12 @@ _outAlterTableCmd(StringInfo str, const AlterTableCmd *node)
 }
 
 static void
-_outSetDistributionCmd(StringInfo str, const SetDistributionCmd*node)
+_outSetDistributionCmd(StringInfo str, const SetDistributionCmd *node)
 {
 	WRITE_NODE_TYPE("SETDISTRIBUTIONCMD");
 
 	WRITE_INT_FIELD(backendId);
 	WRITE_NODE_FIELD(relids);
-	WRITE_NODE_FIELD(indexOidMap);
 	WRITE_NODE_FIELD(hiddenTypes);
 }
 

src/backend/nodes/readfast.c

@@ -591,7 +591,6 @@ _readSetDistributionCmd(void)
 
 	READ_INT_FIELD(backendId);
 	READ_NODE_FIELD(relids);
-	READ_NODE_FIELD(indexOidMap);
 	READ_NODE_FIELD(hiddenTypes);
 
 	READ_DONE();

src/backend/nodes/readfuncs.c

@@ -1033,7 +1033,6 @@ _readSetDistributionCmd(void)
 
 	READ_INT_FIELD(backendId);
 	READ_NODE_FIELD(relids);
-	READ_NODE_FIELD(indexOidMap);
 	READ_NODE_FIELD(hiddenTypes);
 
 	READ_DONE();

src/include/nodes/parsenodes.h

@@ -1547,7 +1547,6 @@ typedef struct SetDistributionCmd
 	NodeTag		type;
 	int	        backendId;     /* backend ID on QD */
 	List	   *relids;            /* oid of relations(partitions) which have related temporary table */
-	List	   *indexOidMap;       /* the map between relation oid and index oid */
 	List	   *hiddenTypes;       /* the types need to build for dropped column */
 } SetDistributionCmd;
 

src/test/regress/expected/alter_distribution_policy.out

@@ -356,7 +356,7 @@ select * from distcheck where rel = 'atsdb';
 
 alter table atsdb drop column n;
 alter table atsdb set with(appendonly = true, compresslevel = 3);
-ERROR:  option "appendonly" not supported
+ERROR:  cannot specify more than one option in WITH clause
 select relname, segrelid != 0, reloptions from pg_class, pg_appendonly where pg_class.oid =
 'atsdb'::regclass and relid = pg_class.oid;
  relname | ?column? | reloptions 
@@ -600,7 +600,7 @@ alter table atsdb set with (fgdfgef = asds);
 ERROR:  option "fgdfgef" not supported
 alter table atsdb set with(reorganize = true, reorganize = false) distributed
 randomly;
-ERROR:  "reorganize" specified more than once
+ERROR:  cannot specify more than one option in WITH clause
 drop table atsdb;
 -- check distribution after dropping distribution key column.
 create table atsdb (i int, j int, t text, n numeric) distributed by (i, j);
@@ -823,7 +823,7 @@ NOTICE:  Table doesn't have 'DISTRIBUTED BY' clause -- Using column named 'c' as
 HINT:  The 'DISTRIBUTED BY' clause determines the distribution of data. Make sure column(s) chosen are the optimal data distribution key to minimize skew.
 insert into mpp5746 select array[i], i from generate_series(1, 100) i;
 alter table mpp5746 set with (reorganize=true, appendonly = true);
-ERROR:  option "appendonly" not supported
+ERROR:  cannot specify more than one option in WITH clause
 select * from mpp5746 order by 1;
    c   |  t  
 -------+-----
@@ -1036,7 +1036,7 @@ select * from mpp5746 order by 1;
 (100 rows)
 
 alter table mpp5746 set with (reorganize=true, appendonly = false);
-ERROR:  option "appendonly" not supported
+ERROR:  cannot specify more than one option in WITH clause
 select * from mpp5746 order by 1;
    c   
 -------