Fix MaxHeapTupleSize: take HeapPageSpecialData into account.

Author: Alexander Korotkov

src/include/access/htup_details.h

@@ -601,7 +601,7 @@ do { \
  * ItemIds and tuples have different alignment requirements, don't assume that
  * you can, say, fit 2 tuples of size MaxHeapTupleSize/2 on the same page.
  */
-#define MaxHeapTupleSize  (BLCKSZ - MAXALIGN(SizeOfPageHeaderData + sizeof(ItemIdData)))
+#define MaxHeapTupleSize  (BLCKSZ - MAXALIGN(SizeOfPageHeaderData + sizeof(ItemIdData)) - MAXALIGN(sizeof(HeapPageSpecialData)))
 #define MinHeapTupleSize  MAXALIGN(SizeofHeapTupleHeader)
 
 /*

src/test/regress/expected/insert.out

@@ -694,3 +694,17 @@ insert into returningwrtest values (2, 'foo') returning returningwrtest;
 (1 row)
 
 drop table returningwrtest;
+-- Check for MaxHeapTupleSize
+create table maxheaptuplesize_test(value text);
+alter table maxheaptuplesize_test alter column value set storage external;
+insert into maxheaptuplesize_test values (repeat('x', 8104));
+insert into maxheaptuplesize_test values (repeat('x', 8112));
+insert into maxheaptuplesize_test values (repeat('x', 8120));
+insert into maxheaptuplesize_test values (repeat('x', 8128));
+insert into maxheaptuplesize_test values (repeat('x', 8136));
+insert into maxheaptuplesize_test values (repeat('x', 8144));
+insert into maxheaptuplesize_test values (repeat('x', 8152));
+insert into maxheaptuplesize_test values (repeat('x', 8160));
+insert into maxheaptuplesize_test values (repeat('x', 8168));
+insert into maxheaptuplesize_test values (repeat('x', 8176));
+drop table maxheaptuplesize_test;

src/test/regress/sql/insert.sql

@@ -419,3 +419,18 @@ alter table returningwrtest2 drop c;
 alter table returningwrtest attach partition returningwrtest2 for values in (2);
 insert into returningwrtest values (2, 'foo') returning returningwrtest;
 drop table returningwrtest;
+
+-- Check for MaxHeapTupleSize
+create table maxheaptuplesize_test(value text);
+alter table maxheaptuplesize_test alter column value set storage external;
+insert into maxheaptuplesize_test values (repeat('x', 8104));
+insert into maxheaptuplesize_test values (repeat('x', 8112));
+insert into maxheaptuplesize_test values (repeat('x', 8120));
+insert into maxheaptuplesize_test values (repeat('x', 8128));
+insert into maxheaptuplesize_test values (repeat('x', 8136));
+insert into maxheaptuplesize_test values (repeat('x', 8144));
+insert into maxheaptuplesize_test values (repeat('x', 8152));
+insert into maxheaptuplesize_test values (repeat('x', 8160));
+insert into maxheaptuplesize_test values (repeat('x', 8168));
+insert into maxheaptuplesize_test values (repeat('x', 8176));
+drop table maxheaptuplesize_test;