Merge 10.2 into 10.3

Author: dr-m

mysql-test/suite/innodb/r/blob_cmp_empty.result

@@ -0,0 +1,19 @@
+connect prevent_purge,localhost,root,,;
+start transaction with consistent snapshot;
+connection default;
+SET @fill_amount = (@@innodb_page_size / 2 ) + 1;
+CREATE TABLE t1 (col_text TEXT NOT NULL, KEY (col_text(9))) ENGINE=InnoDB;
+INSERT INTO t1 (col_text) VALUES (REPEAT('x', @fill_amount));
+UPDATE t1 SET col_text='';
+UPDATE t1 SET col_text=REPEAT('y', @fill_amount);
+connect con1,localhost,root,,;
+SET @fill_amount = (@@innodb_page_size / 2 ) + 1;
+BEGIN;
+INSERT INTO t1 (col_text) VALUES (REPEAT('z', @fill_amount));
+connection default;
+CHECK TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+disconnect con1;
+disconnect prevent_purge;
+DROP TABLE t1;

mysql-test/suite/innodb/t/blob_cmp_empty.test

@@ -0,0 +1,26 @@
+--source include/innodb_row_format.inc
+--source include/count_sessions.inc
+--connect(prevent_purge,localhost,root,,)
+start transaction with consistent snapshot;
+
+--connection default
+SET @fill_amount = (@@innodb_page_size / 2 ) + 1;
+CREATE TABLE t1 (col_text TEXT NOT NULL, KEY (col_text(9))) ENGINE=InnoDB;
+
+INSERT INTO t1 (col_text) VALUES (REPEAT('x', @fill_amount));
+UPDATE t1 SET col_text='';
+UPDATE t1 SET col_text=REPEAT('y', @fill_amount);
+
+--connect(con1,localhost,root,,)
+SET @fill_amount = (@@innodb_page_size / 2 ) + 1;
+BEGIN;
+INSERT INTO t1 (col_text) VALUES (REPEAT('z', @fill_amount));
+
+--connection default
+# If the bug is not fixed, CHECK TABLE will complain about wrong secondary index
+# rows count
+CHECK TABLE t1;
+--disconnect con1
+--disconnect prevent_purge
+DROP TABLE t1;
+--source include/wait_until_count_sessions.inc

mysql-test/suite/innodb_gis/disabled.def

@@ -12,3 +12,4 @@
 
 rtree_concurrent_srch : MDEV-15284 COUNT(*) mismatch
 rtree_recovery : MDEV-15284 COUNT(*) mismatch
+rtree_compress2 : MDEV-16269 CHECK TABLE reports wrong count

storage/innobase/row/row0sel.cc

@@ -354,11 +354,16 @@ row_sel_sec_rec_is_for_clust_rec(
 }
 
 len = clust_len;
+ulint prefix_len = ifield->prefix_len;
 if (rec_offs_nth_extern(clust_offs, clust_pos)) {
+/* BLOB can contain prefix. */
 len -= BTR_EXTERN_FIELD_REF_SIZE;
+if (!len) {
+goto compare_blobs;
+}
 }
 
-if (ulint prefix_len = ifield->prefix_len) {
+if (prefix_len) {
 len = dtype_get_at_most_n_mbchars(
 col->prtype, col->mbminlen,
 col->mbmaxlen, prefix_len, len,
@@ -371,6 +376,7 @@ row_sel_sec_rec_is_for_clust_rec(
 check_for_blob:
 if (rec_offs_nth_extern(clust_offs,
 clust_pos)) {
+compare_blobs:
 if (!row_sel_sec_rec_is_for_blob(
  col->mtype, col->prtype,
  col->mbminlen,