MDEV-26826 The guess in buf_page_get_gen() may not be helpfulbb-10.5-MDEV-26826

buf_page_get_low(), buf_page_get_gen(): Remove the parameter "guess".
We will have to access the buf_pool.page_hash anyway, in order to
acquire the page_hash_latch. So, knowing the block upfront might only
help us in case the block is behind a deep hash bucket.

We will also remove the build option WITH_INNODB_ROOT_GUESS,
any references to the preprocessor symbol BTR_CUR_ADAPT,
as well as the data fields
trx_undo_t::guess_block and btr_search_t::root_guess.

25 files changed, 67 insertions, 158 deletions

diff --git a/storage/innobase/btr/btr0btr.cc b/storage/innobase/btr/btr0btr.cc
index 4c832eb77e8..34d3f0c7e40 100644
--- a/storage/innobase/btr/btr0btr.cc
+++ b/storage/innobase/btr/btr0btr.cc
@@ -360,7 +360,7 @@ btr_root_adjust_on_import(
 
 	buf_block_t* block = buf_page_get_gen(
 		page_id_t(table->space->id, index->page),
-		table->space->zip_size(), RW_X_LATCH, NULL, BUF_GET,
+		table->space->zip_size(), RW_X_LATCH, BUF_GET,
 		__FILE__, __LINE__,
 		&mtr, &err);
 	if (!block) {
diff --git a/storage/innobase/btr/btr0bulk.cc b/storage/innobase/btr/btr0bulk.cc
index 9004064a1b9..83285e9bb7f 100644
--- a/storage/innobase/btr/btr0bulk.cc
+++ b/storage/innobase/btr/btr0bulk.cc
@@ -856,13 +856,13 @@ PageBulk::latch()
 
 	ut_ad(m_block->page.buf_fix_count());
 
-	/* In case the block is S-latched by page_cleaner. */
+	/* In case the block is U-latched by page_cleaner. */
 	if (!buf_page_optimistic_get(RW_X_LATCH, m_block, m_modify_clock,
 				     __FILE__, __LINE__, &m_mtr)) {
+		/* FIXME: avoid another lookup */
 		m_block = buf_page_get_gen(page_id_t(m_index->table->space_id,
 						     m_page_no),
-					   0, RW_X_LATCH,
-					   m_block, BUF_GET_IF_IN_POOL,
+					   0, RW_X_LATCH, BUF_GET_IF_IN_POOL,
 					   __FILE__, __LINE__, &m_mtr, &m_err);
 
 		if (m_err != DB_SUCCESS) {
diff --git a/storage/innobase/btr/btr0cur.cc b/storage/innobase/btr/btr0cur.cc
index cfff322f547..7e5a6912c1e 100644
--- a/storage/innobase/btr/btr0cur.cc
+++ b/storage/innobase/btr/btr0cur.cc
@@ -807,7 +807,7 @@ btr_cur_optimistic_latch_leaves(
 				page_id_t(cursor->index->table->space_id,
 					  left_page_no),
 				cursor->index->table->space->zip_size(),
-				mode, nullptr, BUF_GET_POSSIBLY_FREED,
+				mode, BUF_GET_POSSIBLY_FREED,
 				__FILE__, __LINE__, mtr, &err);
 
 			if (!cursor->left_block) {
@@ -1264,7 +1264,6 @@ btr_cur_search_to_nth_level_func(
 {
 	page_t*		page = NULL; /* remove warning */
 	buf_block_t*	block;
-	buf_block_t*	guess;
 	ulint		height;
 	ulint		up_match;
 	ulint		up_bytes;
@@ -1302,9 +1301,6 @@ btr_cur_search_to_nth_level_func(
 
 	DBUG_ENTER("btr_cur_search_to_nth_level");
 
-#ifdef BTR_CUR_ADAPT
-	btr_search_t*	info;
-#endif /* BTR_CUR_ADAPT */
 	mem_heap_t*	heap		= NULL;
 	rec_offs	offsets_[REC_OFFS_NORMAL_SIZE];
 	rec_offs*	offsets		= offsets_;
@@ -1402,13 +1398,8 @@ btr_cur_search_to_nth_level_func(
 	cursor->flag = BTR_CUR_BINARY;
 	cursor->index = index;
 
-#ifndef BTR_CUR_ADAPT
-	guess = NULL;
-#else
-	info = btr_search_get_info(index);
-	guess = info->root_guess;
-
 #ifdef BTR_CUR_HASH_ADAPT
+	btr_search_t*	info = btr_search_get_info(index);
 
 # ifdef UNIV_SEARCH_PERF_STAT
 	info->n_searches++;
@@ -1446,14 +1437,12 @@ btr_cur_search_to_nth_level_func(
 
 		DBUG_RETURN(err);
 	}
-# endif /* BTR_CUR_HASH_ADAPT */
-#endif /* BTR_CUR_ADAPT */
+
 	btr_cur_n_non_sea++;
 
 	/* If the hash search did not succeed, do binary search down the
 	tree */
 
-#ifdef BTR_CUR_HASH_ADAPT
 	if (ahi_latch) {
 		/* Release possible search latch to obey latching order */
 		rw_lock_s_unlock(ahi_latch);
@@ -1613,7 +1602,7 @@ search_loop:
 retry_page_get:
 	ut_ad(n_blocks < BTR_MAX_LEVELS);
 	tree_savepoints[n_blocks] = mtr_set_savepoint(mtr);
-	block = buf_page_get_gen(page_id, zip_size, rw_latch, guess,
+	block = buf_page_get_gen(page_id, zip_size, rw_latch,
 				 buf_mode, file, line, mtr, &err,
 				 height == 0 && !index->is_clust());
 	tree_blocks[n_blocks] = block;
@@ -1729,7 +1718,7 @@ retry_page_get:
 				= mtr_set_savepoint(mtr);
 			get_block = buf_page_get_gen(
 				page_id_t(page_id.space(), left_page_no),
-				zip_size, rw_latch, NULL, buf_mode,
+				zip_size, rw_latch, buf_mode,
 				file, line, mtr, &err);
 			prev_tree_blocks[prev_n_blocks] = get_block;
 			prev_n_blocks++;
@@ -1760,7 +1749,7 @@ retry_page_get:
 
 		tree_savepoints[n_blocks] = mtr_set_savepoint(mtr);
 		block = buf_page_get_gen(page_id, zip_size,
-					 rw_latch, NULL, buf_mode,
+					 rw_latch, buf_mode,
 					 file, line, mtr, &err);
 		tree_blocks[n_blocks] = block;
 
@@ -1838,10 +1827,6 @@ retry_page_get:
 			cursor->rtr_info->thr = cursor->thr;
 			rtr_get_mbr_from_tuple(tuple, &cursor->rtr_info->mbr);
 		}
-
-#ifdef BTR_CUR_ADAPT
-		info->root_guess = block;
-#endif
 	}
 
 	if (height == 0) {
@@ -2038,7 +2023,6 @@ retry_page_get:
 		ut_ad(height > 0);
 
 		height--;
-		guess = NULL;
 
 		node_ptr = page_cur_get_rec(page_cursor);
 
@@ -2381,8 +2365,6 @@ need_opposite_intention:
 		/* btr_insert_into_right_sibling() might cause
 		deleting node_ptr at upper level */
 
-		guess = NULL;
-
 		if (height == 0) {
 			/* release the leaf pages if latched */
 			for (uint i = 0; i < 3; i++) {
@@ -2638,7 +2620,7 @@ btr_cur_open_at_index_side_func(
 			&& (latch_mode != BTR_MODIFY_TREE || height == level)
 			? upper_rw_latch : RW_NO_LATCH;
 		buf_block_t* block = buf_page_get_gen(page_id, zip_size,
-						      rw_latch, NULL, BUF_GET,
+						      rw_latch, BUF_GET,
 						      file, line, mtr, &err,
 						      height == 0
 						      && !index->is_clust());
@@ -2979,7 +2961,7 @@ btr_cur_open_at_rnd_pos_func(
 			&& latch_mode != BTR_MODIFY_TREE
 			? upper_rw_latch : RW_NO_LATCH;
 		buf_block_t* block = buf_page_get_gen(page_id, zip_size,
-						      rw_latch, NULL, BUF_GET,
+						      rw_latch, BUF_GET,
 						      file, line, mtr, &err,
 						      height == 0
 						      && !index->is_clust());
@@ -6076,7 +6058,7 @@ btr_estimate_n_rows_in_range_on_level(
 		the B-tree. We pass BUF_GET_POSSIBLY_FREED in order to
 		silence a debug assertion about this. */
 		block = buf_page_get_gen(page_id, zip_size, RW_S_LATCH,
-					 NULL, BUF_GET_POSSIBLY_FREED,
+					 BUF_GET_POSSIBLY_FREED,
 					 __FILE__, __LINE__, &mtr, &err);
 
 		ut_ad((block != NULL) == (err == DB_SUCCESS));
diff --git a/storage/innobase/btr/btr0sea.cc b/storage/innobase/btr/btr0sea.cc
index 2f75f567933..2e7332f8b56 100644
--- a/storage/innobase/btr/btr0sea.cc
+++ b/storage/innobase/btr/btr0sea.cc
@@ -1436,7 +1436,6 @@ void btr_search_drop_page_hash_when_freed(const page_id_t page_id)
 {
 	buf_block_t*	block;
 	mtr_t		mtr;
-	dberr_t		err = DB_SUCCESS;
 
 	mtr_start(&mtr);
 
@@ -1446,9 +1445,9 @@ void btr_search_drop_page_hash_when_freed(const page_id_t page_id)
 	are possibly holding, we cannot s-latch the page, but must
 	(recursively) x-latch it, even though we are only reading. */
 
-	block = buf_page_get_gen(page_id, 0, RW_X_LATCH, NULL,
+	block = buf_page_get_gen(page_id, 0, RW_X_LATCH,
 				 BUF_PEEK_IF_IN_POOL, __FILE__, __LINE__,
-				 &mtr, &err);
+				 &mtr);
 
 	if (block) {
 
diff --git a/storage/innobase/buf/buf0buf.cc b/storage/innobase/buf/buf0buf.cc
index 1c126191df3..c944d9b7044 100644
--- a/storage/innobase/buf/buf0buf.cc
+++ b/storage/innobase/buf/buf0buf.cc
@@ -2844,7 +2844,6 @@ done:
 @param[in]	page_id			page id
 @param[in]	zip_size		ROW_FORMAT=COMPRESSED page size, or 0
 @param[in]	rw_latch		RW_S_LATCH, RW_X_LATCH, RW_NO_LATCH
-@param[in]	guess			guessed block or NULL
 @param[in]	mode			BUF_GET, BUF_GET_IF_IN_POOL,
 BUF_PEEK_IF_IN_POOL, BUF_GET_NO_LATCH, or BUF_GET_IF_IN_POOL_OR_WATCH
 @param[in]	file			file name
@@ -2861,7 +2860,6 @@ buf_page_get_low(
 	const page_id_t		page_id,
 	ulint			zip_size,
 	ulint			rw_latch,
-	buf_block_t*		guess,
 	ulint			mode,
 	const char*		file,
 	unsigned		line,
@@ -2924,31 +2922,11 @@ buf_page_get_low(
 	buf_pool.stat.n_page_gets++;
 loop:
 	buf_block_t* fix_block;
-	block = guess;
 
 	page_hash_latch* hash_lock = buf_pool.page_hash.lock<false>(fold);
 
-	if (block) {
-
-		/* If the guess is a compressed page descriptor that
-		has been allocated by buf_page_alloc_descriptor(),
-		it may have been freed by buf_relocate(). */
-
-		if (!buf_pool.is_uncompressed(block)
-		    || page_id != block->page.id()
-		    || block->page.state() != BUF_BLOCK_FILE_PAGE) {
-			/* Our guess was bogus or things have changed
-			since. */
-			guess = nullptr;
-			goto lookup;
-		} else {
-			ut_ad(!block->page.in_zip_hash);
-		}
-	} else {
-lookup:
-		block = reinterpret_cast<buf_block_t*>(
-			buf_pool.page_hash_get_low(page_id, fold));
-	}
+	block = reinterpret_cast<buf_block_t*>(
+		buf_pool.page_hash_get_low(page_id, fold));
 
 	if (!block || buf_pool.watch_is_sentinel(block->page)) {
 		hash_lock->read_unlock();
@@ -3284,15 +3262,12 @@ re_evict:
 				: buf_pool.page_hash_get_low(page_id, fold));
 			hash_lock->write_unlock();
 
-			if (block != NULL) {
+			if (block) {
 				/* Either the page has been read in or
 				a watch was set on that in the window
 				where we released the buf_pool.mutex
 				and before we acquire the hash_lock
 				above. Try again. */
-				guess = block;
-
-				goto loop;
 			}
 
 			return(NULL);
@@ -3409,7 +3384,6 @@ get_latch:
 @param[in]	page_id			page id
 @param[in]	zip_size		ROW_FORMAT=COMPRESSED page size, or 0
 @param[in]	rw_latch		RW_S_LATCH, RW_X_LATCH, RW_NO_LATCH
-@param[in]	guess			guessed block or NULL
 @param[in]	mode			BUF_GET, BUF_GET_IF_IN_POOL,
 BUF_PEEK_IF_IN_POOL, BUF_GET_NO_LATCH, or BUF_GET_IF_IN_POOL_OR_WATCH
 @param[in]	file			file name
@@ -3424,7 +3398,6 @@ buf_page_get_gen(
 	const page_id_t		page_id,
 	ulint			zip_size,
 	ulint			rw_latch,
-	buf_block_t*		guess,
 	ulint			mode,
 	const char*		file,
 	unsigned		line,
@@ -3461,7 +3434,7 @@ buf_page_get_gen(
   }
 
   return buf_page_get_low(page_id, zip_size, rw_latch,
-                          guess, mode, file, line, mtr, err, allow_ibuf_merge);
+                          mode, file, line, mtr, err, allow_ibuf_merge);
 }
 
 /********************************************************************//**
diff --git a/storage/innobase/dict/dict0dict.cc b/storage/innobase/dict/dict0dict.cc
index 9c1750c588f..6c98e4d599a 100644
--- a/storage/innobase/dict/dict0dict.cc
+++ b/storage/innobase/dict/dict0dict.cc
@@ -1291,7 +1291,7 @@ dict_index_t *dict_index_t::clone() const
   ut_ad(!rtr_track);
 
   const size_t size= sizeof *this + n_fields * sizeof(*fields) +
-#ifdef BTR_CUR_ADAPT
+#ifdef BTR_CUR_HASH_ADAPT
     sizeof *search_info +
 #endif
     1 + strlen(name) +
@@ -1308,9 +1308,9 @@ dict_index_t *dict_index_t::clone() const
   index->name= mem_heap_strdup(heap, name);
   index->fields= static_cast<dict_field_t*>
     (mem_heap_dup(heap, fields, n_fields * sizeof *fields));
-#ifdef BTR_CUR_ADAPT
+#ifdef BTR_CUR_HASH_ADAPT
   index->search_info= btr_search_info_create(index->heap);
-#endif /* BTR_CUR_ADAPT */
+#endif /* BTR_CUR_HASH_ADAPT */
   index->stat_n_diff_key_vals= static_cast<ib_uint64_t*>
     (mem_heap_zalloc(heap, n_uniq * sizeof *stat_n_diff_key_vals));
   index->stat_n_sample_sizes= static_cast<ib_uint64_t*>
@@ -2156,9 +2156,9 @@ dict_index_add_to_cache(
 	/* Add the new index as the last index for the table */
 
 	UT_LIST_ADD_LAST(new_index->table->indexes, new_index);
-#ifdef BTR_CUR_ADAPT
+#ifdef BTR_CUR_HASH_ADAPT
 	new_index->search_info = btr_search_info_create(new_index->heap);
-#endif /* BTR_CUR_ADAPT */
+#endif /* BTR_CUR_HASH_ADAPT */
 
 	new_index->page = unsigned(page_no);
 	rw_lock_create(index_tree_rw_lock_key, &new_index->lock,
diff --git a/storage/innobase/dict/dict0stats.cc b/storage/innobase/dict/dict0stats.cc
index 42f75252cee..998d6e26917 100644
--- a/storage/innobase/dict/dict0stats.cc
+++ b/storage/innobase/dict/dict0stats.cc
@@ -1519,7 +1519,7 @@ dict_stats_analyze_index_below_cur(
 		dberr_t err = DB_SUCCESS;
 
 		block = buf_page_get_gen(page_id, zip_size,
-					 RW_S_LATCH, NULL, BUF_GET,
+					 RW_S_LATCH, BUF_GET,
 					 __FILE__, __LINE__, &mtr, &err,
 					 !index->is_clust()
 					 && 1 == btr_page_get_level(page));
diff --git a/storage/innobase/fil/fil0crypt.cc b/storage/innobase/fil/fil0crypt.cc
index 240a2682efc..a26d62749cd 100644
--- a/storage/innobase/fil/fil0crypt.cc
+++ b/storage/innobase/fil/fil0crypt.cc
@@ -1004,7 +1004,6 @@ fil_crypt_read_crypt_data(fil_space_t* space)
 	mtr.start();
 	if (buf_block_t* block = buf_page_get_gen(page_id_t(space->id, 0),
 						  zip_size, RW_S_LATCH,
-						  nullptr,
 						  BUF_GET_POSSIBLY_FREED,
 						  __FILE__, __LINE__, &mtr)) {
 		if (block->page.status == buf_page_t::FREED) {
@@ -1065,11 +1064,10 @@ static bool fil_crypt_start_encrypting_space(fil_space_t* space)
 	mtr.start();
 
 	/* 2 - get page 0 */
-	dberr_t err = DB_SUCCESS;
 	if (buf_block_t* block = buf_page_get_gen(
 		    page_id_t(space->id, 0), space->zip_size(),
-		    RW_X_LATCH, NULL, BUF_GET_POSSIBLY_FREED,
-		    __FILE__, __LINE__, &mtr, &err)) {
+		    RW_X_LATCH, BUF_GET_POSSIBLY_FREED,
+		    __FILE__, __LINE__, &mtr)) {
 		if (block->page.status == buf_page_t::FREED) {
 			goto abort;
 		}
@@ -1812,11 +1810,9 @@ fil_crypt_get_page_throttle_func(
 		return NULL;
 	}
 
-	dberr_t err = DB_SUCCESS;
 	buf_block_t* block = buf_page_get_gen(page_id, zip_size, RW_X_LATCH,
-					      NULL,
 					      BUF_PEEK_IF_IN_POOL, file, line,
-					      mtr, &err);
+					      mtr);
 	if (block != NULL) {
 		/* page was in buffer pool */
 		state->crypt_stat.pages_read_from_cache++;
@@ -1835,10 +1831,8 @@ fil_crypt_get_page_throttle_func(
 	state->crypt_stat.pages_read_from_disk++;
 
 	const ulonglong start = my_interval_timer();
-	block = buf_page_get_gen(page_id, zip_size,
-				 RW_X_LATCH,
-				 NULL, BUF_GET_POSSIBLY_FREED,
-				file, line, mtr, &err);
+	block = buf_page_get_gen(page_id, zip_size, RW_X_LATCH,
+				 BUF_GET_POSSIBLY_FREED, file, line, mtr);
 	const ulonglong end = my_interval_timer();
 
 	state->cnt_waited++;
@@ -2082,7 +2076,7 @@ fil_crypt_flush_space(
 
 	if (buf_block_t* block = buf_page_get_gen(
 		    page_id_t(space->id, 0), space->zip_size(),
-		    RW_X_LATCH, NULL, BUF_GET_POSSIBLY_FREED,
+		    RW_X_LATCH, BUF_GET_POSSIBLY_FREED,
 		    __FILE__, __LINE__, &mtr)) {
 		if (block->page.status != buf_page_t::FREED) {
 			mtr.set_named_space(space);
diff --git a/storage/innobase/fsp/fsp0fsp.cc b/storage/innobase/fsp/fsp0fsp.cc
index 962d18d8081..62af5f81c66 100644
--- a/storage/innobase/fsp/fsp0fsp.cc
+++ b/storage/innobase/fsp/fsp0fsp.cc
@@ -412,7 +412,6 @@ xdes_get_descriptor_const(
 
 	if (buf_block_t* block = buf_page_get_gen(page_id_t(space->id, page),
 						  zip_size, RW_S_LATCH,
-						  nullptr,
 						  BUF_GET_POSSIBLY_FREED,
 						  __FILE__, __LINE__, mtr)) {
 		buf_block_dbg_add_level(block, SYNC_FSP_PAGE);
diff --git a/storage/innobase/gis/gis0sea.cc b/storage/innobase/gis/gis0sea.cc
index 1c22aab4d00..4ab41055874 100644
--- a/storage/innobase/gis/gis0sea.cc
+++ b/storage/innobase/gis/gis0sea.cc
@@ -265,12 +265,10 @@ rtr_pcur_getnext_from_path(
 					btr_cur->page_cur.block)));
 #endif /* UNIV_RTR_DEBUG */
 
-		dberr_t err = DB_SUCCESS;
-
 		block = buf_page_get_gen(
 			page_id_t(index->table->space_id,
 				  next_rec.page_no), zip_size,
-			rw_latch, NULL, BUF_GET, __FILE__, __LINE__, mtr, &err);
+			rw_latch, BUF_GET, __FILE__, __LINE__, mtr);
 
 		if (block == NULL) {
 			continue;
@@ -1353,12 +1351,9 @@ rtr_cur_restore_position(
 	ut_ad(r_cursor == node->cursor);
 
 search_again:
-	dberr_t err = DB_SUCCESS;
-
 	block = buf_page_get_gen(
 		page_id_t(index->table->space_id, page_no),
-		zip_size, RW_X_LATCH, NULL,
-		BUF_GET, __FILE__, __LINE__, mtr, &err);
+		zip_size, RW_X_LATCH, BUF_GET, __FILE__, __LINE__, mtr);
 
 	ut_ad(block);
 
diff --git a/storage/innobase/ibuf/ibuf0ibuf.cc b/storage/innobase/ibuf/ibuf0ibuf.cc
index 9288a496735..9f5ff39b0eb 100644
--- a/storage/innobase/ibuf/ibuf0ibuf.cc
+++ b/storage/innobase/ibuf/ibuf0ibuf.cc
@@ -479,9 +479,9 @@ ibuf_init_at_db_start(void)
 	ibuf.index->n_uniq = REC_MAX_N_FIELDS;
 	rw_lock_create(index_tree_rw_lock_key, &ibuf.index->lock,
 		       SYNC_IBUF_INDEX_TREE);
-#ifdef BTR_CUR_ADAPT
+#ifdef BTR_CUR_HASH_ADAPT
 	ibuf.index->search_info = btr_search_info_create(ibuf.index->heap);
-#endif /* BTR_CUR_ADAPT */
+#endif /* BTR_CUR_HASH_ADAPT */
 	ibuf.index->page = FSP_IBUF_TREE_ROOT_PAGE_NO;
 	ut_d(ibuf.index->cached = TRUE);
 
@@ -690,8 +690,7 @@ ibuf_bitmap_get_map_page_func(
 {
 	buf_block_t* block = buf_page_get_gen(
 		ibuf_bitmap_page_no_calc(page_id, zip_size),
-		zip_size, RW_X_LATCH, NULL, BUF_GET_POSSIBLY_FREED,
-		file, line, mtr);
+		zip_size, RW_X_LATCH, BUF_GET_POSSIBLY_FREED, file, line, mtr);
 
 	if (block) {
 		buf_block_dbg_add_level(block, SYNC_IBUF_BITMAP);
@@ -997,7 +996,7 @@ ibuf_page_low(
 
 		buf_block_t* block = buf_page_get_gen(
 			ibuf_bitmap_page_no_calc(page_id, zip_size),
-			zip_size, RW_NO_LATCH, NULL, BUF_GET_NO_LATCH,
+			zip_size, RW_NO_LATCH, BUF_GET_NO_LATCH,
 			file, line, &local_mtr, &err);
 
 		ret = ibuf_bitmap_page_get_bits_low(
@@ -2325,7 +2324,7 @@ tablespace_deleted:
 			mtr.start();
 			dberr_t err;
 			buf_page_get_gen(page_id_t(space_id, page_nos[i]),
-					 zip_size, RW_X_LATCH, nullptr,
+					 zip_size, RW_X_LATCH,
 					 BUF_GET_POSSIBLY_FREED,
 					 __FILE__, __LINE__, &mtr, &err, true);
 			mtr.commit();
diff --git a/storage/innobase/include/btr0btr.h b/storage/innobase/include/btr0btr.h
index 8b2859bd770..d68ad8225a9 100644
--- a/storage/innobase/include/btr0btr.h
+++ b/storage/innobase/include/btr0btr.h
@@ -236,7 +236,7 @@ inline buf_block_t* btr_block_get_func(const dict_index_t& index,
 
 	if (buf_block_t* block = buf_page_get_gen(
 		    page_id_t(index.table->space->id, page),
-		    index.table->space->zip_size(), mode, NULL, BUF_GET,
+		    index.table->space->zip_size(), mode, BUF_GET,
 		    file, line, mtr, &err, merge && !index.is_clust())) {
 		ut_ad(err == DB_SUCCESS);
 		if (mode != RW_NO_LATCH) {
diff --git a/storage/innobase/include/btr0sea.h b/storage/innobase/include/btr0sea.h
index 1e6b667c324..dbf28eb8a59 100644
--- a/storage/innobase/include/btr0sea.h
+++ b/storage/innobase/include/btr0sea.h
@@ -159,19 +159,6 @@ static inline bool btr_search_own_any();
 /** Unlock all search latches from shared mode. */
 static inline void btr_search_s_unlock_all();
 
-#else /* BTR_CUR_HASH_ADAPT */
-# define btr_search_sys_create()
-# define btr_search_sys_free()
-# define btr_search_drop_page_hash_index(block)
-# define btr_search_s_lock_all(index)
-# define btr_search_s_unlock_all(index)
-# define btr_search_info_update(index, cursor)
-# define btr_search_move_or_delete_hash_entries(new_block, block)
-# define btr_search_update_hash_on_insert(cursor, ahi_latch)
-# define btr_search_update_hash_on_delete(cursor)
-#endif /* BTR_CUR_HASH_ADAPT */
-
-#ifdef BTR_CUR_ADAPT
 /** Create and initialize search info.
 @param[in,out]	heap		heap where created
 @return own: search info struct */
@@ -183,16 +170,12 @@ static inline btr_search_t* btr_search_get_info(dict_index_t* index)
 {
 	return(index->search_info);
 }
-#endif /* BTR_CUR_ADAPT */
 
 /** The search info struct in an index */
 struct btr_search_t{
 	/* @{ The following fields are not protected by any latch.
 	Unfortunately, this means that they must be aligned to
 	the machine word, i.e., they cannot be turned into bit-fields. */
-	buf_block_t* root_guess;/*!< the root page frame when it was last time
-				fetched, or NULL */
-#ifdef BTR_CUR_HASH_ADAPT
 	ulint	hash_analysis;	/*!< when this exceeds
 				BTR_SEARCH_HASH_ANALYSIS, the hash
 				analysis starts; this is reset if no
@@ -234,7 +217,6 @@ struct btr_search_t{
 				far */
 	ulint	n_searches;	/*!< number of searches */
 #endif /* UNIV_SEARCH_PERF_STAT */
-#endif /* BTR_CUR_HASH_ADAPT */
 #ifdef UNIV_DEBUG
 	ulint	magic_n;	/*!< magic number @see BTR_SEARCH_MAGIC_N */
 /** value of btr_search_t::magic_n, used in assertions */
@@ -242,7 +224,6 @@ struct btr_search_t{
 #endif /* UNIV_DEBUG */
 };
 
-#ifdef BTR_CUR_HASH_ADAPT
 /** The hash index system */
 struct btr_search_sys_t
 {
@@ -385,8 +366,17 @@ the hash index */
 over calls from MySQL. If we notice someone waiting for the latch, we
 again set this much timeout. This is to reduce contention. */
 #define BTR_SEA_TIMEOUT			10000
+# include "btr0sea.ic"
+#else /* BTR_CUR_HASH_ADAPT */
+# define btr_search_sys_create()
+# define btr_search_sys_free()
+# define btr_search_drop_page_hash_index(block)
+# define btr_search_s_lock_all(index)
+# define btr_search_s_unlock_all(index)
+# define btr_search_info_update(index, cursor)
+# define btr_search_move_or_delete_hash_entries(new_block, block)
+# define btr_search_update_hash_on_insert(cursor, ahi_latch)
+# define btr_search_update_hash_on_delete(cursor)
 #endif /* BTR_CUR_HASH_ADAPT */
 
-#include "btr0sea.ic"
-
 #endif
diff --git a/storage/innobase/include/btr0sea.ic b/storage/innobase/include/btr0sea.ic
index 40eb5d86ead..76316458c1c 100644
--- a/storage/innobase/include/btr0sea.ic
+++ b/storage/innobase/include/btr0sea.ic
@@ -28,6 +28,7 @@ Created 2/17/1996 Heikki Tuuri
 #include "btr0cur.h"
 #include "buf0buf.h"
 
+#ifdef BTR_CUR_HASH_ADAPT
 /** Create and initialize search info.
 @param[in,out]	heap		heap where created
 @return own: search info struct */
@@ -36,14 +37,11 @@ static inline btr_search_t* btr_search_info_create(mem_heap_t* heap)
 	btr_search_t*	info = static_cast<btr_search_t*>(
 		mem_heap_zalloc(heap, sizeof(btr_search_t)));
 	ut_d(info->magic_n = BTR_SEARCH_MAGIC_N);
-#ifdef BTR_CUR_HASH_ADAPT
 	info->n_fields = 1;
 	info->left_side = TRUE;
-#endif /* BTR_CUR_HASH_ADAPT */
 	return(info);
 }
 
-#ifdef BTR_CUR_HASH_ADAPT
 /** Updates the search info.
 @param[in,out]	info	search info
 @param[in,out]	cursor	cursor which was just positioned */
diff --git a/storage/innobase/include/buf0buf.h b/storage/innobase/include/buf0buf.h
index e5e15730253..e4aa1c4a7f7 100644
--- a/storage/innobase/include/buf0buf.h
+++ b/storage/innobase/include/buf0buf.h
@@ -210,7 +210,7 @@ NOTE! The following macros should be used instead of buf_page_get_gen,
 to improve debugging. Only values RW_S_LATCH and RW_X_LATCH are allowed
 in LA! */
 #define buf_page_get(ID, SIZE, LA, MTR)					\
-	buf_page_get_gen(ID, SIZE, LA, NULL, BUF_GET, __FILE__, __LINE__, MTR)
+	buf_page_get_gen(ID, SIZE, LA, BUF_GET, __FILE__, __LINE__, MTR)
 
 /**************************************************************//**
 Use these macros to bufferfix a page with no latching. Remember not to
@@ -219,7 +219,7 @@ the contents of the page! We have separated this case, because it is
 error-prone programming not to set a latch, and it should be used
 with care. */
 #define buf_page_get_with_no_latch(ID, SIZE, MTR)	\
-	buf_page_get_gen(ID, SIZE, RW_NO_LATCH, NULL, BUF_GET_NO_LATCH, \
+	buf_page_get_gen(ID, SIZE, RW_NO_LATCH, BUF_GET_NO_LATCH, \
 			 __FILE__, __LINE__, MTR)
 /********************************************************************//**
 This is the general function used to get optimistic access to a database
@@ -275,7 +275,6 @@ buf_page_t* buf_page_get_zip(const page_id_t page_id, ulint zip_size);
 @param[in]	page_id			page id
 @param[in]	zip_size		ROW_FORMAT=COMPRESSED page size, or 0
 @param[in]	rw_latch		RW_S_LATCH, RW_X_LATCH, RW_NO_LATCH
-@param[in]	guess			guessed block or NULL
 @param[in]	mode			BUF_GET, BUF_GET_IF_IN_POOL,
 BUF_PEEK_IF_IN_POOL, BUF_GET_NO_LATCH, or BUF_GET_IF_IN_POOL_OR_WATCH
 @param[in]	file			file name
@@ -290,7 +289,6 @@ buf_page_get_gen(
 	const page_id_t		page_id,
 	ulint			zip_size,
 	ulint			rw_latch,
-	buf_block_t*		guess,
 	ulint			mode,
 	const char*		file,
 	unsigned		line,
@@ -302,7 +300,6 @@ buf_page_get_gen(
 @param[in]	page_id			page id
 @param[in]	zip_size		ROW_FORMAT=COMPRESSED page size, or 0
 @param[in]	rw_latch		RW_S_LATCH, RW_X_LATCH, RW_NO_LATCH
-@param[in]	guess			guessed block or NULL
 @param[in]	mode			BUF_GET, BUF_GET_IF_IN_POOL,
 BUF_PEEK_IF_IN_POOL, BUF_GET_NO_LATCH, or BUF_GET_IF_IN_POOL_OR_WATCH
 @param[in]	file			file name
@@ -319,7 +316,6 @@ buf_page_get_low(
 	const page_id_t		page_id,
 	ulint			zip_size,
 	ulint			rw_latch,
-	buf_block_t*		guess,
 	ulint			mode,
 	const char*		file,
 	unsigned		line,
diff --git a/storage/innobase/include/dict0mem.h b/storage/innobase/include/dict0mem.h
index a039776dfbf..aaad328ef33 100644
--- a/storage/innobase/include/dict0mem.h
+++ b/storage/innobase/include/dict0mem.h
@@ -1074,10 +1074,10 @@ struct dict_index_t {
 	dict_add_v_col_info* new_vcol_info;
 	UT_LIST_NODE_T(dict_index_t)
 			indexes;/*!< list of indexes of the table */
-#ifdef BTR_CUR_ADAPT
+#ifdef BTR_CUR_HASH_ADAPT
 	btr_search_t*	search_info;
 				/*!< info used in optimistic searches */
-#endif /* BTR_CUR_ADAPT */
+#endif /* BTR_CUR_HASH_ADAPT */
 	row_log_t*	online_log;
 				/*!< the log of modifications
 				during online index creation;
diff --git a/storage/innobase/include/trx0undo.h b/storage/innobase/include/trx0undo.h
index 319ea4ee8d9..f4ef8b69f29 100644
--- a/storage/innobase/include/trx0undo.h
+++ b/storage/innobase/include/trx0undo.h
@@ -317,8 +317,6 @@ struct trx_undo_t {
 					log if we think of it as a stack */
 	undo_no_t	top_undo_no;	/*!< undo number of the latest record
 					(IB_ID_MAX if the undo log is empty) */
-	buf_block_t*	guess_block;	/*!< guess for the buffer block where
-					the top page might reside */
 
 	/** @return whether the undo log is empty */
 	bool empty() const { return top_undo_no == IB_ID_MAX; }
diff --git a/storage/innobase/innodb.cmake b/storage/innobase/innodb.cmake
index cd8ba4f04d3..1a897b7fcd8 100644
--- a/storage/innobase/innodb.cmake
+++ b/storage/innobase/innodb.cmake
@@ -87,19 +87,10 @@ ADD_FEATURE_INFO(INNODB_COMPILER_HINTS INNODB_COMPILER_HINTS "InnoDB compiled wi
 SET(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -DUNIV_DEBUG")
 
 OPTION(WITH_INNODB_AHI "Include innodb_adaptive_hash_index" ON)
-OPTION(WITH_INNODB_ROOT_GUESS "Cache index root block descriptors" ON)
 IF(WITH_INNODB_AHI)
-  ADD_DEFINITIONS(-DBTR_CUR_HASH_ADAPT -DBTR_CUR_ADAPT)
-  IF(NOT WITH_INNODB_ROOT_GUESS)
-    MESSAGE(WARNING "WITH_INNODB_AHI implies WITH_INNODB_ROOT_GUESS")
-    SET(WITH_INNODB_ROOT_GUESS ON)
-  ENDIF()
-ELSEIF(WITH_INNODB_ROOT_GUESS)
-  ADD_DEFINITIONS(-DBTR_CUR_ADAPT)
+  ADD_DEFINITIONS(-DBTR_CUR_HASH_ADAPT)
 ENDIF()
 ADD_FEATURE_INFO(INNODB_AHI WITH_INNODB_AHI "InnoDB Adaptive Hash Index")
-ADD_FEATURE_INFO(INNODB_ROOT_GUESS WITH_INNODB_ROOT_GUESS
-                 "Cache index root block descriptors in InnoDB")
 
 OPTION(WITH_INNODB_EXTRA_DEBUG "Enable extra InnoDB debug checks" OFF)
 IF(WITH_INNODB_EXTRA_DEBUG)
diff --git a/storage/innobase/lock/lock0lock.cc b/storage/innobase/lock/lock0lock.cc
index d7ec5736826..a7df9dafdcd 100644
--- a/storage/innobase/lock/lock0lock.cc
+++ b/storage/innobase/lock/lock0lock.cc
@@ -5000,7 +5000,7 @@ static void lock_rec_block_validate(const page_id_t page_id)
 		block = buf_page_get_gen(
 			page_id,
 			space->zip_size(),
-			RW_X_LATCH, NULL,
+			RW_X_LATCH,
 			BUF_GET_POSSIBLY_FREED,
 			__FILE__, __LINE__, &mtr, &err);
 
diff --git a/storage/innobase/log/log0recv.cc b/storage/innobase/log/log0recv.cc
index eb34fd8ede9..4f48006ff8b 100644
--- a/storage/innobase/log/log0recv.cc
+++ b/storage/innobase/log/log0recv.cc
@@ -688,7 +688,7 @@ public:
 				continue;
 			}
 			if (buf_block_t* block = buf_page_get_low(
-				    i.first, 0, RW_X_LATCH, nullptr,
+				    i.first, 0, RW_X_LATCH,
 				    BUF_GET_IF_IN_POOL, __FILE__, __LINE__,
 				    &mtr, nullptr, false)) {
 				if (UNIV_LIKELY_NULL(block->page.zip.data)) {
@@ -2700,7 +2700,7 @@ next_page:
         mtr.start();
         mtr.set_log_mode(MTR_LOG_NO_REDO);
         if (buf_block_t *block= buf_page_get_low(page_id, 0, RW_X_LATCH,
-                                                 nullptr, BUF_GET_IF_IN_POOL,
+                                                 BUF_GET_IF_IN_POOL,
                                                  __FILE__, __LINE__,
                                                  &mtr, nullptr, false))
         {
diff --git a/storage/innobase/row/row0import.cc b/storage/innobase/row/row0import.cc
index 7fe5cc1802c..e5436a0bb20 100644
--- a/storage/innobase/row/row0import.cc
+++ b/storage/innobase/row/row0import.cc
@@ -2159,8 +2159,8 @@ dberr_t PageConverter::operator()(buf_block_t* block) UNIV_NOTHROW
 	in the buffer pool, evict it now, because
 	we no longer evict the pages on DISCARD TABLESPACE. */
 	buf_page_get_gen(block->page.id(), get_zip_size(),
-			 RW_NO_LATCH, NULL, BUF_EVICT_IF_IN_POOL,
-			 __FILE__, __LINE__, NULL, NULL);
+			 RW_NO_LATCH, BUF_EVICT_IF_IN_POOL,
+			 __FILE__, __LINE__, nullptr);
 
 	uint16_t page_type;
 
diff --git a/storage/innobase/row/row0merge.cc b/storage/innobase/row/row0merge.cc
index 417bf6a4a1f..aa5404550d5 100644
--- a/storage/innobase/row/row0merge.cc
+++ b/storage/innobase/row/row0merge.cc
@@ -46,9 +46,9 @@ Completed by Sunny Bains and Marko Makela
 #include "row0vers.h"
 #include "handler0alter.h"
 #include "btr0bulk.h"
-#ifdef BTR_CUR_ADAPT
+#ifdef BTR_CUR_HASH_ADAPT
 # include "btr0sea.h"
-#endif /* BTR_CUR_ADAPT */
+#endif /* BTR_CUR_HASH_ADAPT */
 #include "ut0stage.h"
 #include "fil0crypt.h"
 
diff --git a/storage/innobase/row/row0sel.cc b/storage/innobase/row/row0sel.cc
index cc82bec475d..5b12b592abd 100644
--- a/storage/innobase/row/row0sel.cc
+++ b/storage/innobase/row/row0sel.cc
@@ -1183,7 +1183,7 @@ re_scan:
 			cur_block = buf_page_get_gen(
 				page_id_t(index->table->space_id, page_no),
 				index->table->space->zip_size(),
-				RW_X_LATCH, NULL, BUF_GET,
+				RW_X_LATCH, BUF_GET,
 				__FILE__, __LINE__, mtr, &err);
 		} else {
 			mtr->start();
@@ -3384,7 +3384,7 @@ Row_sel_get_clust_rec_for_mysql::operator()(
 			buf_block_t*	block = buf_page_get_gen(
 				btr_pcur_get_block(prebuilt->pcur)->page.id(),
 				btr_pcur_get_block(prebuilt->pcur)->zip_size(),
-				RW_NO_LATCH, NULL, BUF_GET,
+				RW_NO_LATCH, BUF_GET,
 				__FILE__, __LINE__, mtr, &err);
 			mem_heap_t*	heap = mem_heap_create(256);
 			dtuple_t*       tuple = dict_index_build_data_tuple(
diff --git a/storage/innobase/trx/trx0rec.cc b/storage/innobase/trx/trx0rec.cc
index 438dfcf9352..6f8ddc5c538 100644
--- a/storage/innobase/trx/trx0rec.cc
+++ b/storage/innobase/trx/trx0rec.cc
@@ -1914,7 +1914,6 @@ dberr_t trx_undo_report_rename(trx_t* trx, const dict_table_t* table)
 				undo->top_page_no = undo->last_page_no;
 				undo->top_offset  = offset;
 				undo->top_undo_no = trx->undo_no++;
-				undo->guess_block = block;
 				ut_ad(!undo->empty());
 
 				err = DB_SUCCESS;
@@ -2077,7 +2076,6 @@ trx_undo_report_row_operation(
 			mtr.commit();
 			undo->top_offset  = offset;
 			undo->top_undo_no = trx->undo_no++;
-			undo->guess_block = undo_block;
 			ut_ad(!undo->empty());
 
 			if (!is_temp) {
diff --git a/storage/innobase/trx/trx0undo.cc b/storage/innobase/trx/trx0undo.cc
index 3d2d9752a42..fd5b10f826e 100644
--- a/storage/innobase/trx/trx0undo.cc
+++ b/storage/innobase/trx/trx0undo.cc
@@ -1009,7 +1009,6 @@ trx_undo_mem_create(
 
 	undo->top_undo_no = IB_ID_MAX;
 	undo->top_page_no = page_no;
-	undo->guess_block = NULL;
 	ut_ad(undo->empty());
 
 	return(undo);
@@ -1185,8 +1184,7 @@ trx_undo_assign(trx_t* trx, dberr_t* err, mtr_t* mtr)
 	if (undo) {
 		return buf_page_get_gen(
 			page_id_t(undo->rseg->space->id, undo->last_page_no),
-			0, RW_X_LATCH, undo->guess_block,
-			BUF_GET, __FILE__, __LINE__, mtr, err);
+			0, RW_X_LATCH, BUF_GET, __FILE__, __LINE__, mtr, err);
 	}
 
 	trx_rseg_t* rseg = trx->rsegs.m_redo.rseg;
@@ -1239,8 +1237,7 @@ trx_undo_assign_low(trx_t* trx, trx_rseg_t* rseg, trx_undo_t** undo,
 	if (*undo) {
 		return buf_page_get_gen(
 			page_id_t(rseg->space->id, (*undo)->last_page_no),
-			0, RW_X_LATCH, (*undo)->guess_block,
-			BUF_GET, __FILE__, __LINE__, mtr, err);
+			0, RW_X_LATCH, BUF_GET, __FILE__, __LINE__, mtr, err);
 	}
 
 	DBUG_EXECUTE_IF(