Fix tablespace inheritance for partitioned rels

Commit ca4103025dfe left a few loose ends.  The most important one
(broken pg_dump output) is already fixed by virtue of commit
3b23552ad8bb, but some things remained:

* When ALTER TABLE rewrites tables, the indexes must remain in the
  tablespace they were originally in.  This didn't work because
  index recreation during ALTER TABLE runs manufactured SQL (yuck),
  which runs afoul of default_tablespace in competition with the parent
  relation tablespace.  To fix, reset default_tablespace to the empty
  string temporarily, and add the TABLESPACE clause as appropriate.

* Setting a partitioned rel's tablespace to the database default is
  confusing; if it worked, it would direct the partitions to that
  tablespace regardless of default_tablespace.  But in reality it does
  not work, and making it work is a larger project.  Therefore, throw
  an error when this condition is detected, to alert the unwary.

Add some docs and tests, too.

Author: Álvaro Herrera
Discussion: https://postgr.es/m/CAKJS1f_1c260nOt_vBJ067AZ3JXptXVRohDVMLEBmudX1YEx-A@mail.gmail.com

3 files changed, 8 insertions, 0 deletions

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 8f51315bee8..780d7ab00b5 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -2919,6 +2919,7 @@ _copyConstraint(const Constraint *from)
 	COPY_NODE_FIELD(options);
 	COPY_STRING_FIELD(indexname);
 	COPY_STRING_FIELD(indexspace);
+	COPY_SCALAR_FIELD(reset_default_tblspc);
 	COPY_STRING_FIELD(access_method);
 	COPY_NODE_FIELD(where_clause);
 	COPY_NODE_FIELD(pktable);
@@ -3475,6 +3476,7 @@ _copyIndexStmt(const IndexStmt *from)
 	COPY_SCALAR_FIELD(transformed);
 	COPY_SCALAR_FIELD(concurrent);
 	COPY_SCALAR_FIELD(if_not_exists);
+	COPY_SCALAR_FIELD(reset_default_tblspc);
 
 	return newnode;
 }
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 68b51f3de71..4f2ebe5118e 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -1347,6 +1347,7 @@ _equalIndexStmt(const IndexStmt *a, const IndexStmt *b)
 	COMPARE_SCALAR_FIELD(transformed);
 	COMPARE_SCALAR_FIELD(concurrent);
 	COMPARE_SCALAR_FIELD(if_not_exists);
+	COMPARE_SCALAR_FIELD(reset_default_tblspc);
 
 	return true;
 }
@@ -2593,6 +2594,7 @@ _equalConstraint(const Constraint *a, const Constraint *b)
 	COMPARE_NODE_FIELD(options);
 	COMPARE_STRING_FIELD(indexname);
 	COMPARE_STRING_FIELD(indexspace);
+	COMPARE_SCALAR_FIELD(reset_default_tblspc);
 	COMPARE_STRING_FIELD(access_method);
 	COMPARE_NODE_FIELD(where_clause);
 	COMPARE_NODE_FIELD(pktable);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 82ca6826ab1..387e4b9b716 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -2649,6 +2649,7 @@ _outIndexStmt(StringInfo str, const IndexStmt *node)
 	WRITE_BOOL_FIELD(transformed);
 	WRITE_BOOL_FIELD(concurrent);
 	WRITE_BOOL_FIELD(if_not_exists);
+	WRITE_BOOL_FIELD(reset_default_tblspc);
 }
 
 static void
@@ -3491,6 +3492,7 @@ _outConstraint(StringInfo str, const Constraint *node)
 			WRITE_NODE_FIELD(options);
 			WRITE_STRING_FIELD(indexname);
 			WRITE_STRING_FIELD(indexspace);
+			WRITE_BOOL_FIELD(reset_default_tblspc);
 			/* access_method and where_clause not currently used */
 			break;
 
@@ -3501,6 +3503,7 @@ _outConstraint(StringInfo str, const Constraint *node)
 			WRITE_NODE_FIELD(options);
 			WRITE_STRING_FIELD(indexname);
 			WRITE_STRING_FIELD(indexspace);
+			WRITE_BOOL_FIELD(reset_default_tblspc);
 			/* access_method and where_clause not currently used */
 			break;
 
@@ -3511,6 +3514,7 @@ _outConstraint(StringInfo str, const Constraint *node)
 			WRITE_NODE_FIELD(options);
 			WRITE_STRING_FIELD(indexname);
 			WRITE_STRING_FIELD(indexspace);
+			WRITE_BOOL_FIELD(reset_default_tblspc);
 			WRITE_STRING_FIELD(access_method);
 			WRITE_NODE_FIELD(where_clause);
 			break;