Bug #14676111 WRONG PAGE_LEVEL WRITTEN FOR UPPER THAN FATHER PAGE AT BTR_LIFT_PAGE_UP()

btr_lift_page_up() writes wrong page number (different by -1) for upper than father page.
But in almost all of the cases, the father page should be root page, no upper
pages. It is very rare path.

In addition the leaf page should not be lifted unless the father page is root.
Because the branch pages should not become the leaf pages.

rb://1336 approved by Marko Makela.

18 files changed, 213 insertions, 7 deletions

diff --git a/storage/innobase/btr/btr0btr.c b/storage/innobase/btr/btr0btr.c
index 5079757272a..fc4e07d7169 100644
--- a/storage/innobase/btr/btr0btr.c
+++ b/storage/innobase/btr/btr0btr.c
@@ -1973,6 +1973,7 @@ btr_lift_page_up(
 	ulint		root_page_no;
 	ulint		ancestors;
 	ulint		i;
+	ibool		lift_father_up	= FALSE;
 
 	ut_ad(btr_page_get_prev(page, mtr) == FIL_NULL);
 	ut_ad(btr_page_get_next(page, mtr) == FIL_NULL);
@@ -2007,6 +2008,27 @@ btr_lift_page_up(
 		pages[ancestors++] = iter_page;
 	}
 
+	if (ancestors > 1 && page_level == 0) {
+		/* The father page also should be the only on its level (not
+		root). We should lift up the father page at first.
+		Because the leaf page should be lifted up only for root page.
+		The freeing page is based on page_level (==0 or !=0)
+		to choose segment. If the page_level is changed ==0 from !=0,
+		later freeing of the page doesn't find the page allocation
+		to be freed.*/
+
+		lift_father_up = TRUE;
+		page = father_page;
+		page_level = btr_page_get_level(page, mtr);
+
+		ut_ad(btr_page_get_prev(page, mtr) == FIL_NULL);
+		ut_ad(btr_page_get_next(page, mtr) == FIL_NULL);
+		ut_ad(mtr_memo_contains(mtr, buf_block_align(page),
+					MTR_MEMO_PAGE_X_FIX));
+
+		father_page = pages[1];
+	}
+
 	btr_search_drop_page_hash_index(page);
 
 	/* Make the father empty */
@@ -2018,7 +2040,7 @@ btr_lift_page_up(
 	lock_update_copy_and_discard(father_page, page);
 
 	/* Go upward to root page, decreasing levels by one. */
-	for (i = 0; i < ancestors; i++) {
+	for (i = lift_father_up ? 1 : 0; i < ancestors; i++) {
 		iter_page = pages[i];
 
 		ut_ad(btr_page_get_level(iter_page, mtr) == (page_level + 1));
diff --git a/storage/innobase/btr/btr0cur.c b/storage/innobase/btr/btr0cur.c
index 389e95bcb0a..8dc0a92408b 100644
--- a/storage/innobase/btr/btr0cur.c
+++ b/storage/innobase/btr/btr0cur.c
@@ -49,6 +49,10 @@ ulint	btr_cur_n_sea		= 0;
 ulint	btr_cur_n_non_sea_old	= 0;
 ulint	btr_cur_n_sea_old	= 0;
 
+#ifdef UNIV_DEBUG
+uint	btr_cur_limit_optimistic_insert_debug = 0;
+#endif /* UNIV_DEBUG */
+
 /* In the optimistic insert, if the insert does not fit, but this much space
 can be released by page reorganize, then it is reorganized */
 
@@ -1022,6 +1026,9 @@ calculate_sizes_again:
 		goto calculate_sizes_again;
 	}
 
+	LIMIT_OPTIMISTIC_INSERT_DEBUG(page_get_n_recs(page),
+				      goto fail);
+
 	/* If there have been many consecutive inserts, and we are on the leaf
 	level, check if we have to split the page to reserve enough free space
 	for future updates of records. */
@@ -1034,7 +1041,9 @@ calculate_sizes_again:
 	    && (0 == level)
 	    && (btr_page_get_split_rec_to_right(cursor, &dummy_rec)
 		|| btr_page_get_split_rec_to_left(cursor, &dummy_rec))) {
-
+#ifdef UNIV_DEBUG
+fail:
+#endif /* UNIV_DEBUG */
 		if (big_rec_vec) {
 			dtuple_convert_back_big_rec(index, entry, big_rec_vec);
 		}
diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index bcb903d22bf..28262f02551 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -495,6 +495,10 @@ static SHOW_VAR innodb_status_variables[]= {
   (char*) &export_vars.innodb_rows_read,		  SHOW_LONG},
   {"rows_updated",
   (char*) &export_vars.innodb_rows_updated,		  SHOW_LONG},
+#ifdef UNIV_DEBUG
+  {"purge_trx_id_age",
+  (char*) &export_vars.innodb_purge_trx_id_age,		  SHOW_LONG},
+#endif /* UNIV_DEBUG */
   {NullS, NullS, SHOW_LONG}
 };
 
@@ -9274,6 +9278,11 @@ static MYSQL_SYSVAR_UINT(trx_rseg_n_slots_debug, trx_rseg_n_slots_debug,
   PLUGIN_VAR_RQCMDARG,
   "Debug flags for InnoDB to limit TRX_RSEG_N_SLOTS for trx_rsegf_undo_find_free()",
   NULL, NULL, 0, 0, 1024, 0);
+
+static MYSQL_SYSVAR_UINT(limit_optimistic_insert_debug,
+  btr_cur_limit_optimistic_insert_debug, PLUGIN_VAR_RQCMDARG,
+  "Artificially limit the number of records per B-tree page (0=unlimited).",
+  NULL, NULL, 0, 0, UINT_MAX32, 0);
 #endif /* UNIV_DEBUG */
 
 static struct st_mysql_sys_var* innobase_system_variables[]= {
@@ -9323,6 +9332,7 @@ static struct st_mysql_sys_var* innobase_system_variables[]= {
 #endif /* UNIV_DEBUG || UNIV_IBUF_DEBUG */
 #ifdef UNIV_DEBUG
   MYSQL_SYSVAR(trx_rseg_n_slots_debug),
+  MYSQL_SYSVAR(limit_optimistic_insert_debug),
 #endif /* UNIV_DEBUG */
   NULL
 };
diff --git a/storage/innobase/include/btr0cur.h b/storage/innobase/include/btr0cur.h
index 341d628c6dc..c2b81d0ae91 100644
--- a/storage/innobase/include/btr0cur.h
+++ b/storage/innobase/include/btr0cur.h
@@ -703,6 +703,11 @@ extern ulint	btr_cur_n_sea;
 extern ulint	btr_cur_n_non_sea_old;
 extern ulint	btr_cur_n_sea_old;
 
+#ifdef UNIV_DEBUG
+/* Flag to limit optimistic insert records */
+extern uint	btr_cur_limit_optimistic_insert_debug;
+#endif /* UNIV_DEBUG */
+
 #ifndef UNIV_NONINL
 #include "btr0cur.ic"
 #endif
diff --git a/storage/innobase/include/btr0cur.ic b/storage/innobase/include/btr0cur.ic
index bd2c46eb734..d894f0546d9 100644
--- a/storage/innobase/include/btr0cur.ic
+++ b/storage/innobase/include/btr0cur.ic
@@ -8,6 +8,16 @@ Created 10/16/1994 Heikki Tuuri
 
 #include "btr0btr.h"
 
+#ifdef UNIV_DEBUG
+# define LIMIT_OPTIMISTIC_INSERT_DEBUG(NREC, CODE)\
+if (btr_cur_limit_optimistic_insert_debug\
+    && (NREC) >= (ulint)btr_cur_limit_optimistic_insert_debug) {\
+        CODE;\
+}
+#else
+# define LIMIT_OPTIMISTIC_INSERT_DEBUG(NREC, CODE)
+#endif /* UNIV_DEBUG */
+
 /*************************************************************
 Returns the page cursor component of a tree cursor. */
 UNIV_INLINE
@@ -100,6 +110,9 @@ btr_cur_compress_recommendation(
 
 	page = btr_cur_get_page(cursor);
 
+	LIMIT_OPTIMISTIC_INSERT_DEBUG(page_get_n_recs(page) * 2,
+				      return(FALSE));
+
 	if ((page_get_data_size(page) < BTR_CUR_PAGE_COMPRESS_LIMIT)
 	    || ((btr_page_get_next(page, mtr) == FIL_NULL)
 		&& (btr_page_get_prev(page, mtr) == FIL_NULL))) {
diff --git a/storage/innobase/include/srv0srv.h b/storage/innobase/include/srv0srv.h
index aa6c88e0538..e79d352d1e6 100644
--- a/storage/innobase/include/srv0srv.h
+++ b/storage/innobase/include/srv0srv.h
@@ -569,6 +569,9 @@ struct export_var_struct{
 	ulint innodb_rows_inserted;
 	ulint innodb_rows_updated;
 	ulint innodb_rows_deleted;
+#ifdef UNIV_DEBUG
+	ulint innodb_purge_trx_id_age;
+#endif /* UNIV_DEBUG */
 };
 
 /* The server system struct */
diff --git a/storage/innobase/include/trx0purge.h b/storage/innobase/include/trx0purge.h
index fbae7eb9a6d..fc9ff021920 100644
--- a/storage/innobase/include/trx0purge.h
+++ b/storage/innobase/include/trx0purge.h
@@ -133,6 +133,10 @@ struct trx_purge_struct{
 					than this */
 	dulint		purge_undo_no;	/* Purge has advanced past all records
 					whose undo number is less than this */
+#ifdef UNIV_DEBUG
+	dulint		done_trx_no;	/* Indicate 'purge pointer' which have
+					purged already accurately. */
+#endif /* UNIV_DEBUG */
 	/*-----------------------------*/
 	ibool		next_stored;	/* TRUE if the info of the next record
 					to purge is stored below: if yes, then
diff --git a/storage/innobase/srv/srv0srv.c b/storage/innobase/srv/srv0srv.c
index 3f6f1982992..46d5b6ad274 100644
--- a/storage/innobase/srv/srv0srv.c
+++ b/storage/innobase/srv/srv0srv.c
@@ -1913,6 +1913,15 @@ srv_export_innodb_status(void)
 	export_vars.innodb_rows_updated = srv_n_rows_updated;
 	export_vars.innodb_rows_deleted = srv_n_rows_deleted;
 
+#ifdef UNIV_DEBUG
+	if (ut_dulint_cmp(trx_sys->max_trx_id, purge_sys->done_trx_no) < 0) {
+		export_vars.innodb_purge_trx_id_age = 0;
+	} else {
+		export_vars.innodb_purge_trx_id_age =
+		  ut_dulint_minus(trx_sys->max_trx_id, purge_sys->done_trx_no);
+	}
+#endif /* UNIV_DEBUG */
+
 	mutex_exit(&srv_innodb_monitor_mutex);
 }
 
@@ -2387,6 +2396,29 @@ loop:
 			+ buf_pool->n_pages_written;
 		srv_main_thread_op_info = "sleeping";
 
+#ifdef UNIV_DEBUG
+		if (btr_cur_limit_optimistic_insert_debug) {
+			/* If btr_cur_limit_optimistic_insert_debug is enabled
+			and no purge_threads, purge opportunity is increased
+			by x100 (1purge/100msec), to speed up debug scripts
+			which should wait for purged. */
+
+			if (!skip_sleep) {
+				os_thread_sleep(100000);
+			}
+
+			do {
+				if (srv_fast_shutdown
+				    && srv_shutdown_state > 0) {
+					goto background_loop;
+				}
+
+				srv_main_thread_op_info = "purging";
+				n_pages_purged = trx_purge();
+
+			} while (n_pages_purged);
+		} else
+#endif /* UNIV_DEBUG */
 		if (!skip_sleep) {
 
 			os_thread_sleep(1000000);
diff --git a/storage/innobase/trx/trx0purge.c b/storage/innobase/trx/trx0purge.c
index 6fe5855ebfa..e783f14c1ee 100644
--- a/storage/innobase/trx/trx0purge.c
+++ b/storage/innobase/trx/trx0purge.c
@@ -209,6 +209,7 @@ trx_purge_sys_create(void)
 	purge_sys->purge_trx_no = ut_dulint_zero;
 	purge_sys->purge_undo_no = ut_dulint_zero;
 	purge_sys->next_stored = FALSE;
+	ut_d(purge_sys->done_trx_no = ut_dulint_zero);
 
 	rw_lock_create(&purge_sys->latch, SYNC_PURGE_LATCH);
 
@@ -576,6 +577,7 @@ trx_purge_truncate_if_arr_empty(void)
 	ut_ad(mutex_own(&(purge_sys->mutex)));
 
 	if (purge_sys->arr->n_used == 0) {
+		ut_d(purge_sys->done_trx_no = purge_sys->purge_trx_no);
 
 		trx_purge_truncate_history();
 
diff --git a/storage/innodb_plugin/btr/btr0btr.c b/storage/innodb_plugin/btr/btr0btr.c
index 9fef7843f9a..04f3a79866e 100644
--- a/storage/innodb_plugin/btr/btr0btr.c
+++ b/storage/innodb_plugin/btr/btr0btr.c
@@ -3072,6 +3072,8 @@ btr_lift_page_up(
 	buf_block_t*	blocks[BTR_MAX_LEVELS];
 	ulint		n_blocks;	/*!< last used index in blocks[] */
 	ulint		i;
+	ibool		lift_father_up	= FALSE;
+	buf_block_t*	block_orig	= block;
 
 	ut_ad(btr_page_get_prev(page, mtr) == FIL_NULL);
 	ut_ad(btr_page_get_next(page, mtr) == FIL_NULL);
@@ -3082,11 +3084,13 @@ btr_lift_page_up(
 
 	{
 		btr_cur_t	cursor;
-		mem_heap_t*	heap	= mem_heap_create(100);
-		ulint*		offsets;
+		ulint*		offsets	= NULL;
+		mem_heap_t*	heap	= mem_heap_create(
+			sizeof(*offsets)
+			* (REC_OFFS_HEADER_SIZE + 1 + 1 + index->n_fields));
 		buf_block_t*	b;
 
-		offsets = btr_page_get_father_block(NULL, heap, index,
+		offsets = btr_page_get_father_block(offsets, heap, index,
 						    block, mtr, &cursor);
 		father_block = btr_cur_get_block(&cursor);
 		father_page_zip = buf_block_get_page_zip(father_block);
@@ -3110,6 +3114,29 @@ btr_lift_page_up(
 			blocks[n_blocks++] = b = btr_cur_get_block(&cursor);
 		}
 
+		if (n_blocks && page_level == 0) {
+			/* The father page also should be the only on its level (not
+			root). We should lift up the father page at first.
+			Because the leaf page should be lifted up only for root page.
+			The freeing page is based on page_level (==0 or !=0)
+			to choose segment. If the page_level is changed ==0 from !=0,
+			later freeing of the page doesn't find the page allocation
+			to be freed.*/
+
+			lift_father_up = TRUE;
+			block = father_block;
+			page = buf_block_get_frame(block);
+			page_level = btr_page_get_level(page, mtr);
+
+			ut_ad(btr_page_get_prev(page, mtr) == FIL_NULL);
+			ut_ad(btr_page_get_next(page, mtr) == FIL_NULL);
+			ut_ad(mtr_memo_contains(mtr, block, MTR_MEMO_PAGE_X_FIX));
+
+			father_block = blocks[0];
+			father_page_zip = buf_block_get_page_zip(father_block);
+			father_page = buf_block_get_frame(father_block);
+		}
+
 		mem_heap_free(heap);
 	}
 
@@ -3117,6 +3144,7 @@ btr_lift_page_up(
 
 	/* Make the father empty */
 	btr_page_empty(father_block, father_page_zip, index, page_level, mtr);
+	page_level++;
 
 	/* Copy the records to the father page one by one. */
 	if (0
@@ -3149,7 +3177,7 @@ btr_lift_page_up(
 	lock_update_copy_and_discard(father_block, block);
 
 	/* Go upward to root page, decrementing levels by one. */
-	for (i = 0; i < n_blocks; i++, page_level++) {
+	for (i = lift_father_up ? 1 : 0; i < n_blocks; i++, page_level++) {
 		page_t*		page	= buf_block_get_frame(blocks[i]);
 		page_zip_des_t*	page_zip= buf_block_get_page_zip(blocks[i]);
 
@@ -3171,7 +3199,7 @@ btr_lift_page_up(
 	ut_ad(page_validate(father_page, index));
 	ut_ad(btr_check_node_ptr(index, father_block, mtr));
 
-	return(father_block);
+	return(lift_father_up ? block_orig : father_block);
 }
 
 /*************************************************************//**
diff --git a/storage/innodb_plugin/btr/btr0cur.c b/storage/innodb_plugin/btr/btr0cur.c
index 6c67d27ffec..e38b8a9bf53 100644
--- a/storage/innodb_plugin/btr/btr0cur.c
+++ b/storage/innodb_plugin/btr/btr0cur.c
@@ -86,6 +86,11 @@ srv_refresh_innodb_monitor_stats().  Referenced by
 srv_printf_innodb_monitor(). */
 UNIV_INTERN ulint	btr_cur_n_sea_old	= 0;
 
+#ifdef UNIV_DEBUG
+/* Flag to limit optimistic insert records */
+UNIV_INTERN uint	btr_cur_limit_optimistic_insert_debug = 0;
+#endif /* UNIV_DEBUG */
+
 /** In the optimistic insert, if the insert does not fit, but this much space
 can be released by page reorganize, then it is reorganized */
 #define BTR_CUR_PAGE_REORGANIZE_LIMIT	(UNIV_PAGE_SIZE / 32)
@@ -1171,6 +1176,9 @@ btr_cur_optimistic_insert(
 		}
 	}
 
+	LIMIT_OPTIMISTIC_INSERT_DEBUG(page_get_n_recs(page),
+				      goto fail);
+
 	/* If there have been many consecutive inserts, and we are on the leaf
 	level, check if we have to split the page to reserve enough free space
 	for future updates of records. */
diff --git a/storage/innodb_plugin/handler/ha_innodb.cc b/storage/innodb_plugin/handler/ha_innodb.cc
index bbdf5680e30..9ed452d9809 100644
--- a/storage/innodb_plugin/handler/ha_innodb.cc
+++ b/storage/innodb_plugin/handler/ha_innodb.cc
@@ -577,6 +577,10 @@ static SHOW_VAR innodb_status_variables[]= {
   (char*) &export_vars.innodb_rows_read,		  SHOW_LONG},
   {"rows_updated",
   (char*) &export_vars.innodb_rows_updated,		  SHOW_LONG},
+#ifdef UNIV_DEBUG
+  {"purge_trx_id_age",
+  (char*) &export_vars.innodb_purge_trx_id_age,		  SHOW_LONG},
+#endif /* UNIV_DEBUG */
   {NullS, NullS, SHOW_LONG}
 };
 
@@ -11262,6 +11266,11 @@ static MYSQL_SYSVAR_UINT(trx_rseg_n_slots_debug, trx_rseg_n_slots_debug,
   PLUGIN_VAR_RQCMDARG,
   "Debug flags for InnoDB to limit TRX_RSEG_N_SLOTS for trx_rsegf_undo_find_free()",
   NULL, NULL, 0, 0, 1024, 0);
+
+static MYSQL_SYSVAR_UINT(limit_optimistic_insert_debug,
+  btr_cur_limit_optimistic_insert_debug, PLUGIN_VAR_RQCMDARG,
+  "Artificially limit the number of records per B-tree page (0=unlimited).",
+  NULL, NULL, 0, 0, UINT_MAX32, 0);
 #endif /* UNIV_DEBUG */
 
 static struct st_mysql_sys_var* innobase_system_variables[]= {
@@ -11327,6 +11336,7 @@ static struct st_mysql_sys_var* innobase_system_variables[]= {
   MYSQL_SYSVAR(io_capacity),
 #ifdef UNIV_DEBUG
   MYSQL_SYSVAR(trx_rseg_n_slots_debug),
+  MYSQL_SYSVAR(limit_optimistic_insert_debug),
 #endif /* UNIV_DEBUG */
   NULL
 };
diff --git a/storage/innodb_plugin/include/btr0cur.h b/storage/innodb_plugin/include/btr0cur.h
index 1c421167828..7744d2d1ee2 100644
--- a/storage/innodb_plugin/include/btr0cur.h
+++ b/storage/innodb_plugin/include/btr0cur.h
@@ -795,6 +795,11 @@ srv_printf_innodb_monitor(). */
 extern ulint	btr_cur_n_sea_old;
 #endif /* !UNIV_HOTBACKUP */
 
+#ifdef UNIV_DEBUG
+/* Flag to limit optimistic insert records */
+extern uint	btr_cur_limit_optimistic_insert_debug;
+#endif /* UNIV_DEBUG */
+
 #ifndef UNIV_NONINL
 #include "btr0cur.ic"
 #endif
diff --git a/storage/innodb_plugin/include/btr0cur.ic b/storage/innodb_plugin/include/btr0cur.ic
index e31f77c77eb..5fc4651ca13 100644
--- a/storage/innodb_plugin/include/btr0cur.ic
+++ b/storage/innodb_plugin/include/btr0cur.ic
@@ -27,6 +27,16 @@ Created 10/16/1994 Heikki Tuuri
 #include "btr0btr.h"
 
 #ifdef UNIV_DEBUG
+# define LIMIT_OPTIMISTIC_INSERT_DEBUG(NREC, CODE)\
+if (btr_cur_limit_optimistic_insert_debug\
+    && (NREC) >= (ulint)btr_cur_limit_optimistic_insert_debug) {\
+        CODE;\
+}
+#else
+# define LIMIT_OPTIMISTIC_INSERT_DEBUG(NREC, CODE)
+#endif /* UNIV_DEBUG */
+
+#ifdef UNIV_DEBUG
 /*********************************************************//**
 Returns the page cursor component of a tree cursor.
 @return	pointer to page cursor component */
@@ -146,6 +156,9 @@ btr_cur_compress_recommendation(
 
 	page = btr_cur_get_page(cursor);
 
+	LIMIT_OPTIMISTIC_INSERT_DEBUG(page_get_n_recs(page) * 2,
+				      return(FALSE));
+
 	if ((page_get_data_size(page) < BTR_CUR_PAGE_COMPRESS_LIMIT)
 	    || ((btr_page_get_next(page, mtr) == FIL_NULL)
 		&& (btr_page_get_prev(page, mtr) == FIL_NULL))) {
diff --git a/storage/innodb_plugin/include/srv0srv.h b/storage/innodb_plugin/include/srv0srv.h
index 1a9f54882c5..089a4c1c777 100644
--- a/storage/innodb_plugin/include/srv0srv.h
+++ b/storage/innodb_plugin/include/srv0srv.h
@@ -650,6 +650,9 @@ struct export_var_struct{
 	ulint innodb_rows_inserted;		/*!< srv_n_rows_inserted */
 	ulint innodb_rows_updated;		/*!< srv_n_rows_updated */
 	ulint innodb_rows_deleted;		/*!< srv_n_rows_deleted */
+#ifdef UNIV_DEBUG
+	ulint innodb_purge_trx_id_age;		/*!< max_trx_id - purged trx_id */
+#endif /* UNIV_DEBUG */
 };
 
 /** The server system struct */
diff --git a/storage/innodb_plugin/include/trx0purge.h b/storage/innodb_plugin/include/trx0purge.h
index 37d3795efb0..f221a65d076 100644
--- a/storage/innodb_plugin/include/trx0purge.h
+++ b/storage/innodb_plugin/include/trx0purge.h
@@ -153,6 +153,10 @@ struct trx_purge_struct{
 					than this */
 	undo_no_t	purge_undo_no;	/*!< Purge has advanced past all records
 					whose undo number is less than this */
+#ifdef UNIV_DEBUG
+	trx_id_t	done_trx_no;	/* Indicate 'purge pointer' which have
+					purged already accurately. */
+#endif /* UNIV_DEBUG */
 	/*-----------------------------*/
 	ibool		next_stored;	/*!< TRUE if the info of the next record
 					to purge is stored below: if yes, then
diff --git a/storage/innodb_plugin/srv/srv0srv.c b/storage/innodb_plugin/srv/srv0srv.c
index 8ad4c02e322..2d48fcc6b18 100644
--- a/storage/innodb_plugin/srv/srv0srv.c
+++ b/storage/innodb_plugin/srv/srv0srv.c
@@ -1964,6 +1964,15 @@ srv_export_innodb_status(void)
 	export_vars.innodb_rows_updated = srv_n_rows_updated;
 	export_vars.innodb_rows_deleted = srv_n_rows_deleted;
 
+#ifdef UNIV_DEBUG
+	if (ut_dulint_cmp(trx_sys->max_trx_id, purge_sys->done_trx_no) < 0) {
+		export_vars.innodb_purge_trx_id_age = 0;
+	} else {
+		export_vars.innodb_purge_trx_id_age =
+		  ut_dulint_minus(trx_sys->max_trx_id, purge_sys->done_trx_no);
+	}
+#endif /* UNIV_DEBUG */
+
 	mutex_exit(&srv_innodb_monitor_mutex);
 }
 
@@ -2468,6 +2477,30 @@ loop:
 		srv_main_thread_op_info = "sleeping";
 		srv_main_1_second_loops++;
 
+#ifdef UNIV_DEBUG
+		if (btr_cur_limit_optimistic_insert_debug) {
+			/* If btr_cur_limit_optimistic_insert_debug is enabled
+			and no purge_threads, purge opportunity is increased
+			by x100 (1purge/100msec), to speed up debug scripts
+			which should wait for purged. */
+
+			if (!skip_sleep) {
+				os_thread_sleep(100000);
+				srv_main_sleeps++;
+			}
+
+			do {
+				if (srv_fast_shutdown
+				    && srv_shutdown_state > 0) {
+					goto background_loop;
+				}
+
+				srv_main_thread_op_info = "purging";
+				n_pages_purged = trx_purge();
+
+			} while (n_pages_purged);
+		} else
+#endif /* UNIV_DEBUG */
 		if (!skip_sleep) {
 
 			os_thread_sleep(1000000);
diff --git a/storage/innodb_plugin/trx/trx0purge.c b/storage/innodb_plugin/trx/trx0purge.c
index 56607c9ff93..ea508c1003c 100644
--- a/storage/innodb_plugin/trx/trx0purge.c
+++ b/storage/innodb_plugin/trx/trx0purge.c
@@ -226,6 +226,7 @@ trx_purge_sys_create(void)
 	purge_sys->purge_trx_no = ut_dulint_zero;
 	purge_sys->purge_undo_no = ut_dulint_zero;
 	purge_sys->next_stored = FALSE;
+	ut_d(purge_sys->done_trx_no = ut_dulint_zero);
 
 	rw_lock_create(&purge_sys->latch, SYNC_PURGE_LATCH);
 
@@ -637,6 +638,7 @@ trx_purge_truncate_if_arr_empty(void)
 	ut_ad(mutex_own(&(purge_sys->mutex)));
 
 	if (purge_sys->arr->n_used == 0) {
+		ut_d(purge_sys->done_trx_no = purge_sys->purge_trx_no);
 
 		trx_purge_truncate_history();