MDEV-20950 Reduce size of record offsetsbb-10.2-MDEV-20950-stack-offsets

offset_t: this is a type which represents one record offset.
It's unsigned short int.

a lot of functions: replace ulint with offset_t

btr_pcur_restore_position_func(),
page_validate(),
row_ins_scan_sec_index_for_duplicate(),
row_upd_clust_rec_by_insert_inherit_func(),
row_vers_impl_x_locked_low(),
trx_undo_prev_version_build():
  allocate record offsets on the stack instead of waiting for rec_get_offsets()
  to allocate it from mem_heap_t. So, reducing  memory allocations.

RECORD_OFFSET, INDEX_OFFSET:
  now it's less convenient to store pointers in offset_t*
  array. One pointer occupies now several offset_t. And those constant are start
  indexes into array to places where to store pointer values

REC_OFFS_HEADER_SIZE: adjusted for the new reality

REC_OFFS_NORMAL_SIZE:
  increase size from 100 to 300 which means less heap allocations.
  And sizeof(offset_t[REC_OFFS_NORMAL_SIZE]) now is 600 bytes which
  is smaller than previous 800 bytes.

REC_OFFS_SEC_INDEX_SIZE: adjusted for the new reality

rem0rec.h, rem0rec.ic, rem0rec.cc:
  various arguments, return values and local variables types were changed to
  fix numerous integer conversions issues.

enum field_type_t:
  offset types concept was introduces which replaces old offset flags stuff.
  Like in earlier version, 2 upper bits are used to store offset type.
  And this enum represents those types.

REC_OFFS_SQL_NULL, REC_OFFS_MASK: removed

get_type(), set_type(), get_value(), combine():
  these are convenience functions to work with offsets and it's types

rec_offs_base()[0]:
  still uses an old scheme with flags REC_OFFS_COMPACT and REC_OFFS_EXTERNAL

rec_offs_base()[i]:
  these have type offset_t now. Two upper bits contains type.

1 files changed, 4 insertions, 4 deletions

diff --git a/storage/innobase/row/row0umod.cc b/storage/innobase/row/row0umod.cc
index 3d4065cbab6..4598e8959d6 100644
--- a/storage/innobase/row/row0umod.cc
+++ b/storage/innobase/row/row0umod.cc
@@ -75,7 +75,7 @@ dberr_t
 row_undo_mod_clust_low(
 /*===================*/
 	undo_node_t*	node,	/*!< in: row undo node */
-	ulint**		offsets,/*!< out: rec_get_offsets() on the record */
+	offset_t**	offsets,/*!< out: rec_get_offsets() on the record */
 	mem_heap_t**	offsets_heap,
 				/*!< in/out: memory heap that can be emptied */
 	mem_heap_t*	heap,	/*!< in/out: memory heap */
@@ -184,7 +184,7 @@ row_undo_mod_remove_clust_low(
 	if (!trx_id_offset) {
 		mem_heap_t*	heap	= NULL;
 		ulint		trx_id_col;
-		const ulint*	offsets;
+		const offset_t*	offsets;
 		ulint		len;
 
 		trx_id_col = dict_index_get_sys_col_pos(
@@ -285,7 +285,7 @@ row_undo_mod_clust(
 
 	mem_heap_t*	heap		= mem_heap_create(1024);
 	mem_heap_t*	offsets_heap	= NULL;
-	ulint*		offsets		= NULL;
+	offset_t*	offsets		= NULL;
 	const dtuple_t*	rebuilt_old_pk;
 	byte		sys[DATA_TRX_ID_LEN + DATA_ROLL_PTR_LEN];
 
@@ -665,7 +665,7 @@ try_again:
 	switch (search_result) {
 		mem_heap_t*	heap;
 		mem_heap_t*	offsets_heap;
-		ulint*		offsets;
+		offset_t*	offsets;
 	case ROW_BUFFERED:
 	case ROW_NOT_DELETED_REF:
 		/* These are invalid outcomes, because the mode passed