Bug#55832: selects crash too easily when innodb_force_recovery>3

dict_update_statistics_low(): Create bogus statistics for those
indexes that cannot be accessed because of the innodb_force_recovery
setting.

ha_innobase::info(): Calculate statistics for each index, even if
innodb_force_recovery is set. Fill in bogus data for those indexes
that are not accessed because of the innodb_force_recovery setting.

storage/innobase/dict/dict0dict.c

@@ -3753,7 +3753,6 @@ dict_update_statistics_low(
 					dictionary mutex */
 {
 	dict_index_t*	index;
-	ulint		size;
 	ulint		sum_of_index_sizes	= 0;
 
 	if (table->ibd_file_missing) {
@@ -3769,14 +3768,6 @@ dict_update_statistics_low(
 		return;
 	}
 
-	/* If we have set a high innodb_force_recovery level, do not calculate
-	statistics, as a badly corrupted index can cause a crash in it. */
-
-	if (srv_force_recovery >= SRV_FORCE_NO_IBUF_MERGE) {
-
-		return;
-	}
-
 	/* Find out the sizes of the indexes and how many different values
 	for the key they approximately have */
 
@@ -3788,26 +3779,48 @@ dict_update_statistics_low(
 		return;
 	}
 
-	while (index) {
-		size = btr_get_size(index, BTR_TOTAL_SIZE);
 
-		index->stat_index_size = size;
+	do {
+		if (UNIV_LIKELY
+		    (srv_force_recovery < SRV_FORCE_NO_IBUF_MERGE
+		     || (srv_force_recovery < SRV_FORCE_NO_LOG_REDO
+			 && (index->type & DICT_CLUSTERED)))) {
+			ulint	size;
+			size = btr_get_size(index, BTR_TOTAL_SIZE);
 
-		sum_of_index_sizes += size;
+			index->stat_index_size = size;
 
-		size = btr_get_size(index, BTR_N_LEAF_PAGES);
+			sum_of_index_sizes += size;
 
-		if (size == 0) {
-			/* The root node of the tree is a leaf */
-			size = 1;
-		}
+			size = btr_get_size(index, BTR_N_LEAF_PAGES);
+
+			if (size == 0) {
+				/* The root node of the tree is a leaf */
+				size = 1;
+			}
+
+			index->stat_n_leaf_pages = size;
+
+			btr_estimate_number_of_different_key_vals(index);
+		} else {
+			/* If we have set a high innodb_force_recovery
+			level, do not calculate statistics, as a badly
+			corrupted index can cause a crash in it.
+			Initialize some bogus index cardinality
+			statistics, so that the data can be queried in
+			various means, also via secondary indexes. */
+			ulint	i;
 
-		index->stat_n_leaf_pages = size;
+			sum_of_index_sizes++;
+			index->stat_index_size = index->stat_n_leaf_pages = 1;
 
-		btr_estimate_number_of_different_key_vals(index);
+			for (i = dict_index_get_n_unique(index); i; ) {
+				index->stat_n_diff_key_vals[i--] = 1;
+			}
+		}
 
 		index = dict_table_get_next_index(index);
-	}
+	} while (index);
 
 	index = dict_table_get_first_index(table);
 

storage/innobase/handler/ha_innodb.cc

@@ -6365,8 +6365,6 @@ ha_innobase::info(
 	dict_index_t*	index;
 	ha_rows		rec_per_key;
 	ib_longlong	n_rows;
-	ulong		j;
-	ulong		i;
 	char		path[FN_REFLEN];
 	os_file_stat_t	stat_info;
 
@@ -6376,16 +6374,6 @@ ha_innobase::info(
 	statistics calculation on tables, because that may crash the
 	server if an index is badly corrupted. */
 
-	if (srv_force_recovery >= SRV_FORCE_NO_IBUF_MERGE) {
-
-		/* We return success (0) instead of HA_ERR_CRASHED,
-		because we want MySQL to process this query and not
-		stop, like it would do if it received the error code
-		HA_ERR_CRASHED. */
-
-		DBUG_RETURN(0);
-	}
-
 	/* We do not know if MySQL can call this function before calling
 	external_lock(). To be safe, update the thd of the current table
 	handle. */
@@ -6480,11 +6468,18 @@ ha_innobase::info(
 		acquiring latches inside InnoDB, we do not call it if we
 		are asked by MySQL to avoid locking. Another reason to
 		avoid the call is that it uses quite a lot of CPU.
-		See Bug#38185.
-		We do not update delete_length if no locking is requested
-		so the "old" value can remain. delete_length is initialized
-		to 0 in the ha_statistics' constructor. */
-		if (!(flag & HA_STATUS_NO_LOCK)) {
+		See Bug#38185. */
+		if (flag & HA_STATUS_NO_LOCK) {
+			/* We do not update delete_length if no
+			locking is requested so the "old" value can
+			remain. delete_length is initialized to 0 in
+			the ha_statistics' constructor. */
+		} else if (UNIV_UNLIKELY
+			   (srv_force_recovery >= SRV_FORCE_NO_IBUF_MERGE)) {
+			/* Avoid accessing the tablespace if
+			innodb_crash_recovery is set to a high value. */
+			stats.delete_length = 0;
+		} else {
 			ullint	avail_space;
 
 			avail_space = fsp_get_available_space_in_free_extents(
@@ -6522,6 +6517,7 @@ ha_innobase::info(
 	}
 
 	if (flag & HA_STATUS_CONST) {
+		ulong	i = 0;
 		index = dict_table_get_first_index_noninline(ib_table);
 
 		if (prebuilt->clust_index_was_generated) {
@@ -6529,6 +6525,8 @@ ha_innobase::info(
 		}
 
 		for (i = 0; i < table->s->keys; i++) {
+			ulong	j;
+
 			if (index == NULL) {
 				sql_print_error("Table %s contains fewer "
 						"indexes inside InnoDB than "
@@ -6585,6 +6583,11 @@ ha_innobase::info(
 		}
 	}
 
+	if (srv_force_recovery >= SRV_FORCE_NO_IBUF_MERGE) {
+
+		goto func_exit;
+	}
+
 	if (flag & HA_STATUS_ERRKEY) {
 		ut_a(prebuilt->trx);
 		ut_a(prebuilt->trx->magic_n == TRX_MAGIC_N);
@@ -6597,6 +6600,7 @@ ha_innobase::info(
  		stats.auto_increment_value = innobase_peek_autoinc();
 	}
 
+func_exit:
 	prebuilt->trx->op_info = (char*)"";
 
   	DBUG_RETURN(0);