From: Tom Lane <tgl@sss.pgh.pa.us>
To: pgsql-hackers@lists.postgresql.org
Subject: CONSTANT/NOT NULL/initializer properties for plpgsql record variables
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Date: Fri, 29 Dec 2017 22:47:30 -0500
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I said a couple of times in recent threads that it wouldn't be too hard
to implement $SUBJECT given the other patches I've been working on.
Attached is proof of the pudding.  This needs to be applied on top of
the patches in
https://postgr.es/m/23537.1514589378@sss.pgh.pa.us
and
https://postgr.es/m/11986.1514407114@sss.pgh.pa.us

It's pretty straightforward really.  Worth noting is that this also
fixes the null-domain-value issues I mentioned as being a loose end
in the first of the above-referenced messages.  Also, I created a
new plpgsql test file for these features, and moved the one relevant
existing test case into that file.

I was a bit disappointed to find that no documentation changes seem
needed, because the SGML docs fail to acknowledge that these cases
didn't work ...

			regards, tom lane


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diff --git a/src/pl/plpgsql/src/Makefile b/src/pl/plpgsql/src/Makefile
index f9a3616..ad93e3e 100644
*** a/src/pl/plpgsql/src/Makefile
--- b/src/pl/plpgsql/src/Makefile
*************** DATA =3D plpgsql.control plpgsql--1.0.sql =

*** 26,32 ****
  =

  REGRESS_OPTS =3D --dbname=3D$(PL_TESTDB)
  =

! REGRESS =3D plpgsql_call plpgsql_record
  =

  all: all-lib
  =

--- 26,32 ----
  =

  REGRESS_OPTS =3D --dbname=3D$(PL_TESTDB)
  =

! REGRESS =3D plpgsql_call plpgsql_record plpgsql_varprops
  =

  all: all-lib
  =

diff --git a/src/pl/plpgsql/src/expected/plpgsql_varprops.out b/src/pl/plp=
gsql/src/expected/plpgsql_varprops.out
index ...109056c .
*** a/src/pl/plpgsql/src/expected/plpgsql_varprops.out
--- b/src/pl/plpgsql/src/expected/plpgsql_varprops.out
***************
*** 0 ****
--- 1,300 ----
+ --
+ -- Tests for PL/pgSQL variable properties: CONSTANT, NOT NULL, initializ=
ers
+ --
+ create type var_record as (f1 int4, f2 int4);
+ create domain int_nn as int not null;
+ create domain var_record_nn as var_record not null;
+ create domain var_record_colnn as var_record check((value).f2 is not nul=
l);
+ -- CONSTANT
+ do $$
+ declare x constant int :=3D 42;
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ NOTICE:  x =3D 42
+ do $$
+ declare x constant int;
+ begin
+   x :=3D 42;  -- fail
+ end$$;
+ ERROR:  variable "x" is declared CONSTANT
+ LINE 4:   x :=3D 42;  -- fail
+           ^
+ do $$
+ declare x constant int; y int;
+ begin
+   for x, y in select 1, 2 loop  -- fail
+   end loop;
+ end$$;
+ ERROR:  variable "x" is declared CONSTANT
+ LINE 4:   for x, y in select 1, 2 loop  -- fail
+               ^
+ do $$
+ declare x constant int[];
+ begin
+   x[1] :=3D 42;  -- fail
+ end$$;
+ ERROR:  variable "x" is declared CONSTANT
+ LINE 4:   x[1] :=3D 42;  -- fail
+           ^
+ do $$
+ declare x constant int[]; y int;
+ begin
+   for x[1], y in select 1, 2 loop  -- fail (currently, unsupported synta=
x)
+   end loop;
+ end$$;
+ ERROR:  syntax error at or near "["
+ LINE 4:   for x[1], y in select 1, 2 loop  -- fail (currently, unsup...
+                ^
+ do $$
+ declare x constant var_record;
+ begin
+   x.f1 :=3D 42;  -- fail
+ end$$;
+ ERROR:  variable "x" is declared CONSTANT
+ LINE 4:   x.f1 :=3D 42;  -- fail
+           ^
+ do $$
+ declare x constant var_record; y int;
+ begin
+   for x.f1, y in select 1, 2 loop  -- fail
+   end loop;
+ end$$;
+ ERROR:  variable "x" is declared CONSTANT
+ LINE 4:   for x.f1, y in select 1, 2 loop  -- fail
+               ^
+ -- initializer expressions
+ do $$
+ declare x int :=3D sin(0);
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ NOTICE:  x =3D 0
+ do $$
+ declare x int :=3D 1/0;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  division by zero
+ CONTEXT:  SQL statement "SELECT 1/0"
+ PL/pgSQL function inline_code_block line 3 during statement block local =
variable initialization
+ do $$
+ declare x bigint[] :=3D array[1,3,5];
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ NOTICE:  x =3D {1,3,5}
+ do $$
+ declare x record :=3D row(1,2,3);
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ NOTICE:  x =3D (1,2,3)
+ do $$
+ declare x var_record :=3D row(1,2);
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ NOTICE:  x =3D (1,2)
+ -- NOT NULL
+ do $$
+ declare x int not null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  variable "x" must have a default value, since it's declared NOT =
NULL
+ LINE 2: declare x int not null;  -- fail
+                       ^
+ do $$
+ declare x int not null :=3D 42;
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D null;  -- fail
+ end$$;
+ NOTICE:  x =3D 42
+ ERROR:  null value cannot be assigned to variable "x" declared NOT NULL
+ CONTEXT:  PL/pgSQL function inline_code_block line 5 at assignment
+ do $$
+ declare x int not null :=3D null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  null value cannot be assigned to variable "x" declared NOT NULL
+ CONTEXT:  PL/pgSQL function inline_code_block line 3 during statement bl=
ock local variable initialization
+ do $$
+ declare x record not null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  variable "x" must have a default value, since it's declared NOT =
NULL
+ LINE 2: declare x record not null;  -- fail
+                          ^
+ do $$
+ declare x record not null :=3D row(42);
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D row(null);  -- ok
+   raise notice 'x =3D %', x;
+   x :=3D null;  -- fail
+ end$$;
+ NOTICE:  x =3D (42)
+ NOTICE:  x =3D ()
+ ERROR:  null value cannot be assigned to variable "x" declared NOT NULL
+ CONTEXT:  PL/pgSQL function inline_code_block line 7 at assignment
+ do $$
+ declare x record not null :=3D null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  null value cannot be assigned to variable "x" declared NOT NULL
+ CONTEXT:  PL/pgSQL function inline_code_block line 3 during statement bl=
ock local variable initialization
+ do $$
+ declare x var_record not null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  variable "x" must have a default value, since it's declared NOT =
NULL
+ LINE 2: declare x var_record not null;  -- fail
+                              ^
+ do $$
+ declare x var_record not null :=3D row(41,42);
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D row(null,null);  -- ok
+   raise notice 'x =3D %', x;
+   x :=3D null;  -- fail
+ end$$;
+ NOTICE:  x =3D (41,42)
+ NOTICE:  x =3D (,)
+ ERROR:  null value cannot be assigned to variable "x" declared NOT NULL
+ CONTEXT:  PL/pgSQL function inline_code_block line 7 at assignment
+ do $$
+ declare x var_record not null :=3D null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  null value cannot be assigned to variable "x" declared NOT NULL
+ CONTEXT:  PL/pgSQL function inline_code_block line 3 during statement bl=
ock local variable initialization
+ -- Check that variables are reinitialized on block re-entry.
+ \set VERBOSITY terse   \\ -- needed for output stability
+ do $$
+ begin
+   for i in 1..3 loop
+     declare
+       x int;
+       y int :=3D i;
+       r record;
+       c var_record;
+     begin
+       if i =3D 1 then
+         x :=3D 42;
+         r :=3D row(i, i+1);
+         c :=3D row(i, i+1);
+       end if;
+       raise notice 'x =3D %', x;
+       raise notice 'y =3D %', y;
+       raise notice 'r =3D %', r;
+       raise notice 'c =3D %', c;
+     end;
+   end loop;
+ end$$;
+ NOTICE:  x =3D 42
+ NOTICE:  y =3D 1
+ NOTICE:  r =3D (1,2)
+ NOTICE:  c =3D (1,2)
+ NOTICE:  x =3D <NULL>
+ NOTICE:  y =3D 2
+ NOTICE:  r =3D <NULL>
+ NOTICE:  c =3D <NULL>
+ NOTICE:  x =3D <NULL>
+ NOTICE:  y =3D 3
+ NOTICE:  r =3D <NULL>
+ NOTICE:  c =3D <NULL>
+ \set VERBOSITY default
+ -- Check enforcement of domain constraints during initialization
+ do $$
+ declare x int_nn;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  domain int_nn does not allow null values
+ CONTEXT:  PL/pgSQL function inline_code_block line 3 during statement bl=
ock local variable initialization
+ do $$
+ declare x int_nn :=3D null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  domain int_nn does not allow null values
+ CONTEXT:  PL/pgSQL function inline_code_block line 3 during statement bl=
ock local variable initialization
+ do $$
+ declare x int_nn :=3D 42;
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D null;  -- fail
+ end$$;
+ NOTICE:  x =3D 42
+ ERROR:  domain int_nn does not allow null values
+ CONTEXT:  PL/pgSQL function inline_code_block line 5 at assignment
+ do $$
+ declare x var_record_nn;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  domain var_record_nn does not allow null values
+ CONTEXT:  PL/pgSQL function inline_code_block line 3 during statement bl=
ock local variable initialization
+ do $$
+ declare x var_record_nn :=3D null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  domain var_record_nn does not allow null values
+ CONTEXT:  PL/pgSQL function inline_code_block line 3 during statement bl=
ock local variable initialization
+ do $$
+ declare x var_record_nn :=3D row(1,2);
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D row(null,null);  -- ok
+   x :=3D null;  -- fail
+ end$$;
+ NOTICE:  x =3D (1,2)
+ ERROR:  domain var_record_nn does not allow null values
+ CONTEXT:  PL/pgSQL function inline_code_block line 6 at assignment
+ do $$
+ declare x var_record_colnn;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  value for domain var_record_colnn violates check constraint "var=
_record_colnn_check"
+ CONTEXT:  PL/pgSQL function inline_code_block line 3 during statement bl=
ock local variable initialization
+ do $$
+ declare x var_record_colnn :=3D null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  value for domain var_record_colnn violates check constraint "var=
_record_colnn_check"
+ CONTEXT:  PL/pgSQL function inline_code_block line 3 during statement bl=
ock local variable initialization
+ do $$
+ declare x var_record_colnn :=3D row(1,null);  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ ERROR:  value for domain var_record_colnn violates check constraint "var=
_record_colnn_check"
+ CONTEXT:  PL/pgSQL function inline_code_block line 3 during statement bl=
ock local variable initialization
+ do $$
+ declare x var_record_colnn :=3D row(1,2);
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D null;  -- fail
+ end$$;
+ NOTICE:  x =3D (1,2)
+ ERROR:  value for domain var_record_colnn violates check constraint "var=
_record_colnn_check"
+ CONTEXT:  PL/pgSQL function inline_code_block line 5 at assignment
+ do $$
+ declare x var_record_colnn :=3D row(1,2);
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D row(null,null);  -- fail
+ end$$;
+ NOTICE:  x =3D (1,2)
+ ERROR:  value for domain var_record_colnn violates check constraint "var=
_record_colnn_check"
+ CONTEXT:  PL/pgSQL function inline_code_block line 5 at assignment
diff --git a/src/pl/plpgsql/src/pl_comp.c b/src/pl/plpgsql/src/pl_comp.c
index 5c2e463..576924f 100644
*** a/src/pl/plpgsql/src/pl_comp.c
--- b/src/pl/plpgsql/src/pl_comp.c
*************** do_compile(FunctionCallInfo fcinfo,
*** 594,604 ****
  						 errhint("The arguments of the trigger can be accessed through TG_=
NARGS and TG_ARGV instead.")));
  =

  			/* Add the record for referencing NEW ROW */
! 			rec =3D plpgsql_build_record("new", 0, RECORDOID, true);
  			function->new_varno =3D rec->dno;
  =

  			/* Add the record for referencing OLD ROW */
! 			rec =3D plpgsql_build_record("old", 0, RECORDOID, true);
  			function->old_varno =3D rec->dno;
  =

  			/* Add the variable tg_name */
--- 594,604 ----
  						 errhint("The arguments of the trigger can be accessed through TG_=
NARGS and TG_ARGV instead.")));
  =

  			/* Add the record for referencing NEW ROW */
! 			rec =3D plpgsql_build_record("new", 0, NULL, RECORDOID, true);
  			function->new_varno =3D rec->dno;
  =

  			/* Add the record for referencing OLD ROW */
! 			rec =3D plpgsql_build_record("old", 0, NULL, RECORDOID, true);
  			function->old_varno =3D rec->dno;
  =

  			/* Add the variable tg_name */
*************** plpgsql_build_variable(const char *refna
*** 1811,1817 ****
  				var->refname =3D pstrdup(refname);
  				var->lineno =3D lineno;
  				var->datatype =3D dtype;
! 				/* other fields might be filled by caller */
  =

  				/* preset to NULL */
  				var->value =3D 0;
--- 1811,1817 ----
  				var->refname =3D pstrdup(refname);
  				var->lineno =3D lineno;
  				var->datatype =3D dtype;
! 				/* other fields are left as 0, might be changed by caller */
  =

  				/* preset to NULL */
  				var->value =3D 0;
*************** plpgsql_build_variable(const char *refna
*** 1831,1837 ****
  				/* Composite type -- build a record variable */
  				PLpgSQL_rec *rec;
  =

! 				rec =3D plpgsql_build_record(refname, lineno, dtype->typoid,
  										   add2namespace);
  				result =3D (PLpgSQL_variable *) rec;
  				break;
--- 1831,1838 ----
  				/* Composite type -- build a record variable */
  				PLpgSQL_rec *rec;
  =

! 				rec =3D plpgsql_build_record(refname, lineno,
! 										   dtype, dtype->typoid,
  										   add2namespace);
  				result =3D (PLpgSQL_variable *) rec;
  				break;
*************** plpgsql_build_variable(const char *refna
*** 1856,1862 ****
   * Build empty named record variable, and optionally add it to namespace
   */
  PLpgSQL_rec *
! plpgsql_build_record(const char *refname, int lineno, Oid rectypeid,
  					 bool add2namespace)
  {
  	PLpgSQL_rec *rec;
--- 1857,1864 ----
   * Build empty named record variable, and optionally add it to namespace
   */
  PLpgSQL_rec *
! plpgsql_build_record(const char *refname, int lineno,
! 					 PLpgSQL_type *dtype, Oid rectypeid,
  					 bool add2namespace)
  {
  	PLpgSQL_rec *rec;
*************** plpgsql_build_record(const char *refname
*** 1865,1870 ****
--- 1867,1874 ----
  	rec->dtype =3D PLPGSQL_DTYPE_REC;
  	rec->refname =3D pstrdup(refname);
  	rec->lineno =3D lineno;
+ 	/* other fields are left as 0, might be changed by caller */
+ 	rec->datatype =3D dtype;
  	rec->rectypeid =3D rectypeid;
  	rec->firstfield =3D -1;
  	rec->erh =3D NULL;
*************** build_row_from_vars(PLpgSQL_variable **v
*** 1899,1904 ****
--- 1903,1911 ----
  		int32		typmod;
  		Oid			typcoll;
  =

+ 		/* Member vars of a row should never be const */
+ 		Assert(!var->isconst);
+ =

  		switch (var->dtype)
  		{
  			case PLPGSQL_DTYPE_VAR:
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index c9fbd83..e97be40 100644
*** a/src/pl/plpgsql/src/pl_exec.c
--- b/src/pl/plpgsql/src/pl_exec.c
*************** plpgsql_exec_function(PLpgSQL_function *
*** 461,467 ****
  					}
  					else
  					{
! 						/* If arg is null, treat it as an empty row */
  						exec_move_row(&estate, (PLpgSQL_variable *) rec,
  									  NULL, NULL);
  					}
--- 461,467 ----
  					}
  					else
  					{
! 						/* If arg is null, set variable to null */
  						exec_move_row(&estate, (PLpgSQL_variable *) rec,
  									  NULL, NULL);
  					}
*************** exec_stmt_block(PLpgSQL_execstate *estat
*** 1461,1471 ****
  					{
  						/*
  						 * If needed, give the datatype a chance to reject
! 						 * NULLs, by assigning a NULL to the variable. We
  						 * claim the value is of type UNKNOWN, not the var's
! 						 * datatype, else coercion will be skipped. (Do this
! 						 * before the notnull check to be consistent with
! 						 * exec_assign_value.)
  						 */
  						if (var->datatype->typtype =3D=3D TYPTYPE_DOMAIN)
  							exec_assign_value(estate,
--- 1461,1469 ----
  					{
  						/*
  						 * If needed, give the datatype a chance to reject
! 						 * NULLs, by assigning a NULL to the variable.  We
  						 * claim the value is of type UNKNOWN, not the var's
! 						 * datatype, else coercion will be skipped.
  						 */
  						if (var->datatype->typtype =3D=3D TYPTYPE_DOMAIN)
  							exec_assign_value(estate,
*************** exec_stmt_block(PLpgSQL_execstate *estat
*** 1475,1485 ****
  											  UNKNOWNOID,
  											  -1);
  =

! 						if (var->notnull)
! 							ereport(ERROR,
! 									(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
! 									 errmsg("variable \"%s\" declared NOT NULL cannot default to NU=
LL",
! 											var->refname)));
  					}
  					else
  					{
--- 1473,1480 ----
  											  UNKNOWNOID,
  											  -1);
  =

! 						/* parser should have rejected NOT NULL */
! 						Assert(!var->notnull);
  					}
  					else
  					{
*************** exec_stmt_block(PLpgSQL_execstate *estat
*** 1493,1501 ****
  				{
  					PLpgSQL_rec *rec =3D (PLpgSQL_rec *) datum;
  =

! 					if (rec->erh)
! 						DeleteExpandedObject(ExpandedRecordGetDatum(rec->erh));
! 					rec->erh =3D NULL;
  				}
  				break;
  =

--- 1488,1515 ----
  				{
  					PLpgSQL_rec *rec =3D (PLpgSQL_rec *) datum;
  =

! 					/*
! 					 * Deletion of any existing object will be handled during
! 					 * the assignments below, and in some cases it's more
! 					 * efficient for us not to get rid of it beforehand.
! 					 */
! 					if (rec->default_val =3D=3D NULL)
! 					{
! 						/*
! 						 * If needed, give the datatype a chance to reject
! 						 * NULLs, by assigning a NULL to the variable.
! 						 */
! 						exec_move_row(estate, (PLpgSQL_variable *) rec,
! 									  NULL, NULL);
! =

! 						/* parser should have rejected NOT NULL */
! 						Assert(!rec->notnull);
! 					}
! 					else
! 					{
! 						exec_assign_expr(estate, (PLpgSQL_datum *) rec,
! 										 rec->default_val);
! 					}
  				}
  				break;
  =

*************** exec_assign_value(PLpgSQL_execstate *est
*** 4739,4745 ****
  =

  				if (isNull)
  				{
! 					/* If source is null, just assign nulls to the record */
  					exec_move_row(estate, (PLpgSQL_variable *) rec,
  								  NULL, NULL);
  				}
--- 4753,4765 ----
  =

  				if (isNull)
  				{
! 					if (rec->notnull)
! 						ereport(ERROR,
! 								(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
! 								 errmsg("null value cannot be assigned to variable \"%s\" declar=
ed NOT NULL",
! 										rec->refname)));
! =

! 					/* Set variable to a simple NULL */
  					exec_move_row(estate, (PLpgSQL_variable *) rec,
  								  NULL, NULL);
  				}
*************** exec_move_row(PLpgSQL_execstate *estate,
*** 6442,6450 ****
  		 */
  		if (tupdesc =3D=3D NULL)
  		{
! 			if (rec->erh)
! 				DeleteExpandedObject(ExpandedRecordGetDatum(rec->erh));
! 			rec->erh =3D NULL;
  			return;
  		}
  =

--- 6462,6488 ----
  		 */
  		if (tupdesc =3D=3D NULL)
  		{
! 			if (rec->datatype &&
! 				rec->datatype->typtype =3D=3D TYPTYPE_DOMAIN)
! 			{
! 				/*
! 				 * If it's a composite domain, NULL might not be a legal
! 				 * value, so we instead need to make an empty expanded record
! 				 * and ensure that domain type checking gets done.  If there
! 				 * is already an expanded record, piggyback on its lookups.
! 				 */
! 				newerh =3D make_expanded_record_for_rec(estate, rec,
! 													  NULL, rec->erh);
! 				expanded_record_set_tuple(newerh, NULL, false);
! 				assign_record_var(estate, rec, newerh);
! 			}
! 			else
! 			{
! 				/* Just clear it to NULL */
! 				if (rec->erh)
! 					DeleteExpandedObject(ExpandedRecordGetDatum(rec->erh));
! 				rec->erh =3D NULL;
! 			}
  			return;
  		}
  =

diff --git a/src/pl/plpgsql/src/pl_funcs.c b/src/pl/plpgsql/src/pl_funcs.c
index f499d96..a2634c4 100644
*** a/src/pl/plpgsql/src/pl_funcs.c
--- b/src/pl/plpgsql/src/pl_funcs.c
*************** plpgsql_free_function_memory(PLpgSQL_fun
*** 718,723 ****
--- 718,728 ----
  			case PLPGSQL_DTYPE_ROW:
  				break;
  			case PLPGSQL_DTYPE_REC:
+ 				{
+ 					PLpgSQL_rec *rec =3D (PLpgSQL_rec *) d;
+ =

+ 					free_expr(rec->default_val);
+ 				}
  				break;
  			case PLPGSQL_DTYPE_RECFIELD:
  				break;
*************** plpgsql_dumptree(PLpgSQL_function *func)
*** 1589,1594 ****
--- 1594,1609 ----
  				printf("REC %-16s typoid %u\n",
  					   ((PLpgSQL_rec *) d)->refname,
  					   ((PLpgSQL_rec *) d)->rectypeid);
+ 				if (((PLpgSQL_rec *) d)->isconst)
+ 					printf("                                  CONSTANT\n");
+ 				if (((PLpgSQL_rec *) d)->notnull)
+ 					printf("                                  NOT NULL\n");
+ 				if (((PLpgSQL_rec *) d)->default_val !=3D NULL)
+ 				{
+ 					printf("                                  DEFAULT ");
+ 					dump_expr(((PLpgSQL_rec *) d)->default_val);
+ 					printf("\n");
+ 				}
  				break;
  			case PLPGSQL_DTYPE_RECFIELD:
  				printf("RECFIELD %-16s of REC %d\n",
diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y
index df88ba3..e37f548 100644
*** a/src/pl/plpgsql/src/pl_gram.y
--- b/src/pl/plpgsql/src/pl_gram.y
*************** decl_statement	: decl_varname decl_const
*** 502,538 ****
  =

  						var =3D plpgsql_build_variable($1.name, $1.lineno,
  													 $3, true);
! 						if ($2)
! 						{
! 							if (var->dtype =3D=3D PLPGSQL_DTYPE_VAR)
! 								((PLpgSQL_var *) var)->isconst =3D $2;
! 							else
! 								ereport(ERROR,
! 										(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 										 errmsg("record variable cannot be CONSTANT"),
! 										 parser_errposition(@2)));
! 						}
! 						if ($5)
! 						{
! 							if (var->dtype =3D=3D PLPGSQL_DTYPE_VAR)
! 								((PLpgSQL_var *) var)->notnull =3D $5;
! 							else
! 								ereport(ERROR,
! 										(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 										 errmsg("record variable cannot be NOT NULL"),
! 										 parser_errposition(@4)));
  =

! 						}
! 						if ($6 !=3D NULL)
! 						{
! 							if (var->dtype =3D=3D PLPGSQL_DTYPE_VAR)
! 								((PLpgSQL_var *) var)->default_val =3D $6;
! 							else
! 								ereport(ERROR,
! 										(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
! 										 errmsg("default value for record variable is not supported"),
! 										 parser_errposition(@5)));
! 						}
  					}
  				| decl_varname K_ALIAS K_FOR decl_aliasitem ';'
  					{
--- 502,521 ----
  =

  						var =3D plpgsql_build_variable($1.name, $1.lineno,
  													 $3, true);
! 						var->isconst =3D $2;
! 						var->notnull =3D $5;
! 						var->default_val =3D $6;
  =

! 						/*
! 						 * The combination of NOT NULL without an initializer
! 						 * can't work, so let's reject it at compile time.
! 						 */
! 						if (var->notnull && var->default_val =3D=3D NULL)
! 							ereport(ERROR,
! 									(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
! 									 errmsg("variable \"%s\" must have a default value, since it's =
declared NOT NULL",
! 											var->refname),
! 									 parser_errposition(@5)));
  					}
  				| decl_varname K_ALIAS K_FOR decl_aliasitem ';'
  					{
*************** decl_cursor_args :
*** 632,637 ****
--- 615,621 ----
  						foreach (l, $2)
  						{
  							PLpgSQL_variable *arg =3D (PLpgSQL_variable *) lfirst(l);
+ 							Assert(!arg->isconst);
  							new->fieldnames[i] =3D arg->refname;
  							new->varnos[i] =3D arg->dno;
  							i++;
*************** for_control		: for_variable K_IN
*** 1378,1383 ****
--- 1362,1368 ----
  							new->var =3D (PLpgSQL_variable *)
  								plpgsql_build_record($1.name,
  													 $1.lineno,
+ 													 NULL,
  													 RECORDOID,
  													 true);
  =

*************** exception_sect	:
*** 2205,2211 ****
  																			-1,
  																			plpgsql_curr_compile->fn_input_collation),
  													 true);
! 						((PLpgSQL_var *) var)->isconst =3D true;
  						new->sqlstate_varno =3D var->dno;
  =

  						var =3D plpgsql_build_variable("sqlerrm", lineno,
--- 2190,2196 ----
  																			-1,
  																			plpgsql_curr_compile->fn_input_collation),
  													 true);
! 						var->isconst =3D true;
  						new->sqlstate_varno =3D var->dno;
  =

  						var =3D plpgsql_build_variable("sqlerrm", lineno,
*************** exception_sect	:
*** 2213,2219 ****
  																			-1,
  																			plpgsql_curr_compile->fn_input_collation),
  													 true);
! 						((PLpgSQL_var *) var)->isconst =3D true;
  						new->sqlerrm_varno =3D var->dno;
  =

  						$<exception_block>$ =3D new;
--- 2198,2204 ----
  																			-1,
  																			plpgsql_curr_compile->fn_input_collation),
  													 true);
! 						var->isconst =3D true;
  						new->sqlerrm_varno =3D var->dno;
  =

  						$<exception_block>$ =3D new;
*************** check_assignable(PLpgSQL_datum *datum, i
*** 3287,3310 ****
  	{
  		case PLPGSQL_DTYPE_VAR:
  		case PLPGSQL_DTYPE_PROMISE:
! 			if (((PLpgSQL_var *) datum)->isconst)
  				ereport(ERROR,
  						(errcode(ERRCODE_ERROR_IN_ASSIGNMENT),
! 						 errmsg("\"%s\" is declared CONSTANT",
! 								((PLpgSQL_var *) datum)->refname),
  						 parser_errposition(location)));
  			break;
  		case PLPGSQL_DTYPE_ROW:
! 			/* always assignable?  Shouldn't we check member vars? */
! 			break;
! 		case PLPGSQL_DTYPE_REC:
! 			/* always assignable?  What about NEW/OLD? */
  			break;
  		case PLPGSQL_DTYPE_RECFIELD:
! 			/* always assignable? */
  			break;
  		case PLPGSQL_DTYPE_ARRAYELEM:
! 			/* always assignable? */
  			break;
  		default:
  			elog(ERROR, "unrecognized dtype: %d", datum->dtype);
--- 3272,3297 ----
  	{
  		case PLPGSQL_DTYPE_VAR:
  		case PLPGSQL_DTYPE_PROMISE:
! 		case PLPGSQL_DTYPE_REC:
! 			if (((PLpgSQL_variable *) datum)->isconst)
  				ereport(ERROR,
  						(errcode(ERRCODE_ERROR_IN_ASSIGNMENT),
! 						 errmsg("variable \"%s\" is declared CONSTANT",
! 								((PLpgSQL_variable *) datum)->refname),
  						 parser_errposition(location)));
  			break;
  		case PLPGSQL_DTYPE_ROW:
! 			/* always assignable; member vars were checked at compile time */
  			break;
  		case PLPGSQL_DTYPE_RECFIELD:
! 			/* assignable if parent record is */
! 			check_assignable(plpgsql_Datums[((PLpgSQL_recfield *) datum)->recpare=
ntno],
! 							 location);
  			break;
  		case PLPGSQL_DTYPE_ARRAYELEM:
! 			/* assignable if parent array is */
! 			check_assignable(plpgsql_Datums[((PLpgSQL_arrayelem *) datum)->arrayp=
arentno],
! 							 location);
  			break;
  		default:
  			elog(ERROR, "unrecognized dtype: %d", datum->dtype);
*************** read_into_scalar_list(char *initial_name
*** 3429,3437 ****
  	 */
  	plpgsql_push_back_token(tok);
  =

! 	row =3D palloc(sizeof(PLpgSQL_row));
  	row->dtype =3D PLPGSQL_DTYPE_ROW;
- 	row->refname =3D pstrdup("*internal*");
  	row->lineno =3D plpgsql_location_to_lineno(initial_location);
  	row->rowtupdesc =3D NULL;
  	row->nfields =3D nfields;
--- 3416,3423 ----
  	 */
  	plpgsql_push_back_token(tok);
  =

! 	row =3D palloc0(sizeof(PLpgSQL_row));
  	row->dtype =3D PLPGSQL_DTYPE_ROW;
  	row->lineno =3D plpgsql_location_to_lineno(initial_location);
  	row->rowtupdesc =3D NULL;
  	row->nfields =3D nfields;
*************** make_scalar_list1(char *initial_name,
*** 3464,3472 ****
  =

  	check_assignable(initial_datum, location);
  =

! 	row =3D palloc(sizeof(PLpgSQL_row));
  	row->dtype =3D PLPGSQL_DTYPE_ROW;
- 	row->refname =3D pstrdup("*internal*");
  	row->lineno =3D lineno;
  	row->rowtupdesc =3D NULL;
  	row->nfields =3D 1;
--- 3450,3457 ----
  =

  	check_assignable(initial_datum, location);
  =

! 	row =3D palloc0(sizeof(PLpgSQL_row));
  	row->dtype =3D PLPGSQL_DTYPE_ROW;
  	row->lineno =3D lineno;
  	row->rowtupdesc =3D NULL;
  	row->nfields =3D 1;
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index 96e92b2..c1c2b40 100644
*** a/src/pl/plpgsql/src/plpgsql.h
--- b/src/pl/plpgsql/src/plpgsql.h
*************** typedef struct PLpgSQL_variable
*** 262,267 ****
--- 262,270 ----
  	int			dno;
  	char	   *refname;
  	int			lineno;
+ 	bool		isconst;
+ 	bool		notnull;
+ 	PLpgSQL_expr *default_val;
  } PLpgSQL_variable;
  =

  /*
*************** typedef struct PLpgSQL_var
*** 281,292 ****
  	int			dno;
  	char	   *refname;
  	int			lineno;
- 	/* end of PLpgSQL_variable fields */
- =

  	bool		isconst;
  	bool		notnull;
- 	PLpgSQL_type *datatype;
  	PLpgSQL_expr *default_val;
  =

  	/*
  	 * Variables declared as CURSOR FOR <query> are mostly like ordinary
--- 284,295 ----
  	int			dno;
  	char	   *refname;
  	int			lineno;
  	bool		isconst;
  	bool		notnull;
  	PLpgSQL_expr *default_val;
+ 	/* end of PLpgSQL_variable fields */
+ =

+ 	PLpgSQL_type *datatype;
  =

  	/*
  	 * Variables declared as CURSOR FOR <query> are mostly like ordinary
*************** typedef struct PLpgSQL_var
*** 318,323 ****
--- 321,331 ----
   *
   * Note that there's no way to name the row as such from PL/pgSQL code,
   * so many functions don't need to support these.
+  *
+  * refname, isconst, notnull, and default_val are unsupported (and hence
+  * always zero/null) for a row.  The member variables of a row should ha=
ve
+  * been checked to be writable at compile time, so isconst is correctly =
set
+  * to false.  notnull and default_val aren't applicable.
   */
  typedef struct PLpgSQL_row
  {
*************** typedef struct PLpgSQL_row
*** 325,330 ****
--- 333,341 ----
  	int			dno;
  	char	   *refname;
  	int			lineno;
+ 	bool		isconst;
+ 	bool		notnull;
+ 	PLpgSQL_expr *default_val;
  	/* end of PLpgSQL_variable fields */
  =

  	/*
*************** typedef struct PLpgSQL_rec
*** 348,358 ****
--- 359,376 ----
  	int			dno;
  	char	   *refname;
  	int			lineno;
+ 	bool		isconst;
+ 	bool		notnull;
+ 	PLpgSQL_expr *default_val;
  	/* end of PLpgSQL_variable fields */
  =

+ 	PLpgSQL_type *datatype;		/* can be NULL, if rectypeid is RECORDOID */
  	Oid			rectypeid;		/* declared type of variable */
  	/* RECFIELDs for this record are chained together for easy access */
  	int			firstfield;		/* dno of first RECFIELD, or -1 if none */
+ =

+ 	/* Fields below here can change at runtime */
+ =

  	/* We always store record variables as "expanded" records */
  	ExpandedRecordHeader *erh;
  } PLpgSQL_rec;
*************** extern PLpgSQL_variable *plpgsql_build_v
*** 1121,1127 ****
  					   PLpgSQL_type *dtype,
  					   bool add2namespace);
  extern PLpgSQL_rec *plpgsql_build_record(const char *refname, int lineno=
,
! 					 Oid rectypeid, bool add2namespace);
  extern PLpgSQL_recfield *plpgsql_build_recfield(PLpgSQL_rec *rec,
  					   const char *fldname);
  extern int plpgsql_recognize_err_condition(const char *condname,
--- 1139,1146 ----
  					   PLpgSQL_type *dtype,
  					   bool add2namespace);
  extern PLpgSQL_rec *plpgsql_build_record(const char *refname, int lineno=
,
! 					 PLpgSQL_type *dtype, Oid rectypeid,
! 					 bool add2namespace);
  extern PLpgSQL_recfield *plpgsql_build_recfield(PLpgSQL_rec *rec,
  					   const char *fldname);
  extern int plpgsql_recognize_err_condition(const char *condname,
diff --git a/src/pl/plpgsql/src/sql/plpgsql_varprops.sql b/src/pl/plpgsql/=
src/sql/plpgsql_varprops.sql
index ...c0e7f95 .
*** a/src/pl/plpgsql/src/sql/plpgsql_varprops.sql
--- b/src/pl/plpgsql/src/sql/plpgsql_varprops.sql
***************
*** 0 ****
--- 1,249 ----
+ --
+ -- Tests for PL/pgSQL variable properties: CONSTANT, NOT NULL, initializ=
ers
+ --
+ =

+ create type var_record as (f1 int4, f2 int4);
+ create domain int_nn as int not null;
+ create domain var_record_nn as var_record not null;
+ create domain var_record_colnn as var_record check((value).f2 is not nul=
l);
+ =

+ -- CONSTANT
+ =

+ do $$
+ declare x constant int :=3D 42;
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x constant int;
+ begin
+   x :=3D 42;  -- fail
+ end$$;
+ =

+ do $$
+ declare x constant int; y int;
+ begin
+   for x, y in select 1, 2 loop  -- fail
+   end loop;
+ end$$;
+ =

+ do $$
+ declare x constant int[];
+ begin
+   x[1] :=3D 42;  -- fail
+ end$$;
+ =

+ do $$
+ declare x constant int[]; y int;
+ begin
+   for x[1], y in select 1, 2 loop  -- fail (currently, unsupported synta=
x)
+   end loop;
+ end$$;
+ =

+ do $$
+ declare x constant var_record;
+ begin
+   x.f1 :=3D 42;  -- fail
+ end$$;
+ =

+ do $$
+ declare x constant var_record; y int;
+ begin
+   for x.f1, y in select 1, 2 loop  -- fail
+   end loop;
+ end$$;
+ =

+ -- initializer expressions
+ =

+ do $$
+ declare x int :=3D sin(0);
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x int :=3D 1/0;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x bigint[] :=3D array[1,3,5];
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x record :=3D row(1,2,3);
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x var_record :=3D row(1,2);
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ -- NOT NULL
+ =

+ do $$
+ declare x int not null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x int not null :=3D 42;
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D null;  -- fail
+ end$$;
+ =

+ do $$
+ declare x int not null :=3D null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x record not null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x record not null :=3D row(42);
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D row(null);  -- ok
+   raise notice 'x =3D %', x;
+   x :=3D null;  -- fail
+ end$$;
+ =

+ do $$
+ declare x record not null :=3D null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x var_record not null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x var_record not null :=3D row(41,42);
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D row(null,null);  -- ok
+   raise notice 'x =3D %', x;
+   x :=3D null;  -- fail
+ end$$;
+ =

+ do $$
+ declare x var_record not null :=3D null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ -- Check that variables are reinitialized on block re-entry.
+ =

+ \set VERBOSITY terse   \\ -- needed for output stability
+ do $$
+ begin
+   for i in 1..3 loop
+     declare
+       x int;
+       y int :=3D i;
+       r record;
+       c var_record;
+     begin
+       if i =3D 1 then
+         x :=3D 42;
+         r :=3D row(i, i+1);
+         c :=3D row(i, i+1);
+       end if;
+       raise notice 'x =3D %', x;
+       raise notice 'y =3D %', y;
+       raise notice 'r =3D %', r;
+       raise notice 'c =3D %', c;
+     end;
+   end loop;
+ end$$;
+ \set VERBOSITY default
+ =

+ -- Check enforcement of domain constraints during initialization
+ =

+ do $$
+ declare x int_nn;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x int_nn :=3D null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x int_nn :=3D 42;
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D null;  -- fail
+ end$$;
+ =

+ do $$
+ declare x var_record_nn;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x var_record_nn :=3D null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x var_record_nn :=3D row(1,2);
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D row(null,null);  -- ok
+   x :=3D null;  -- fail
+ end$$;
+ =

+ do $$
+ declare x var_record_colnn;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x var_record_colnn :=3D null;  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x var_record_colnn :=3D row(1,null);  -- fail
+ begin
+   raise notice 'x =3D %', x;
+ end$$;
+ =

+ do $$
+ declare x var_record_colnn :=3D row(1,2);
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D null;  -- fail
+ end$$;
+ =

+ do $$
+ declare x var_record_colnn :=3D row(1,2);
+ begin
+   raise notice 'x =3D %', x;
+   x :=3D row(null,null);  -- fail
+ end$$;
diff --git a/src/test/regress/expected/plpgsql.out b/src/test/regress/expe=
cted/plpgsql.out
index e38fe90..bb35326 100644
*** a/src/test/regress/expected/plpgsql.out
--- b/src/test/regress/expected/plpgsql.out
*************** select scope_test();
*** 5025,5066 ****
  (1 row)
  =

  drop function scope_test();
- -- Check that variables are reinitialized on block re-entry.
- \set VERBOSITY terse   \\ -- needed for output stability
- do $$
- begin
-   for i in 1..3 loop
-     declare
-       x int;
-       y int :=3D i;
-       r record;
-       c int8_tbl;
-     begin
-       if i =3D 1 then
-         x :=3D 42;
-         r :=3D row(i, i+1);
-         c :=3D row(i, i+1);
-       end if;
-       raise notice 'x =3D %', x;
-       raise notice 'y =3D %', y;
-       raise notice 'r =3D %', r;
-       raise notice 'c =3D %', c;
-     end;
-   end loop;
- end$$;
- NOTICE:  x =3D 42
- NOTICE:  y =3D 1
- NOTICE:  r =3D (1,2)
- NOTICE:  c =3D (1,2)
- NOTICE:  x =3D <NULL>
- NOTICE:  y =3D 2
- NOTICE:  r =3D <NULL>
- NOTICE:  c =3D <NULL>
- NOTICE:  x =3D <NULL>
- NOTICE:  y =3D 3
- NOTICE:  r =3D <NULL>
- NOTICE:  c =3D <NULL>
- \set VERBOSITY default
  -- Check handling of conflicts between plpgsql vars and table columns.
  set plpgsql.variable_conflict =3D error;
  create function conflict_test() returns setof int8_tbl as $$
--- 5025,5030 ----
diff --git a/src/test/regress/sql/plpgsql.sql b/src/test/regress/sql/plpgs=
ql.sql
index 132f912..6620ea6 100644
*** a/src/test/regress/sql/plpgsql.sql
--- b/src/test/regress/sql/plpgsql.sql
*************** select scope_test();
*** 4014,4045 ****
  =

  drop function scope_test();
  =

- -- Check that variables are reinitialized on block re-entry.
- =

- \set VERBOSITY terse   \\ -- needed for output stability
- do $$
- begin
-   for i in 1..3 loop
-     declare
-       x int;
-       y int :=3D i;
-       r record;
-       c int8_tbl;
-     begin
-       if i =3D 1 then
-         x :=3D 42;
-         r :=3D row(i, i+1);
-         c :=3D row(i, i+1);
-       end if;
-       raise notice 'x =3D %', x;
-       raise notice 'y =3D %', y;
-       raise notice 'r =3D %', r;
-       raise notice 'c =3D %', c;
-     end;
-   end loop;
- end$$;
- \set VERBOSITY default
- =

  -- Check handling of conflicts between plpgsql vars and table columns.
  =

  set plpgsql.variable_conflict =3D error;
--- 4014,4019 ----

------- =_aaaaaaaaaa0--