MDEV-17697 Broken versioning info after instant drop column

Closes #986

mysql-test/suite/versioning/r/online.result

@@ -124,5 +124,16 @@ alter table t add index idx(a), lock=none;
 alter table t drop column s, drop column e;
 alter table t drop system versioning, lock=none;
 ERROR 0A000: LOCK=NONE is not supported. Reason: Not implemented for system-versioned operations. Try LOCK=SHARED
+#
+# MDEV-17697 Broken versioning info after instant drop column
+#
+set @@system_versioning_alter_history= keep;
+create or replace table t1 (a int, b int) with system versioning;
+insert into t1 values (1, 1);
+alter table t1 drop column b, algorithm=instant;
+alter table t1 drop system versioning;
+create or replace table t1 (a int, b int) with system versioning;
+insert into t1 values (1, 1);
+alter table t1 drop system versioning;
 drop database test;
 create database test;

mysql-test/suite/versioning/t/online.test

@@ -148,5 +148,29 @@ alter table t drop column s, drop column e;
 --error ER_ALTER_OPERATION_NOT_SUPPORTED_REASON
 alter table t drop system versioning, lock=none;
 
+--echo #
+--echo # MDEV-17697 Broken versioning info after instant drop column
+--echo #
+set @@system_versioning_alter_history= keep;
+create or replace table t1 (a int, b int) with system versioning;
+insert into t1 values (1, 1);
+alter table t1 drop column b, algorithm=instant;
+alter table t1 drop system versioning;
+
+create or replace table t1 (a int, b int) with system versioning;
+insert into t1 values (1, 1);
+
+if ($have_debug) {
+--disable_query_log
+--disable_result_log
+set debug_dbug='+d,ib_commit_inplace_fail_1';
+--error ER_INTERNAL_ERROR
+alter table t1 drop column b, algorithm=instant;
+set debug_dbug= default;
+--enable_query_log
+--enable_result_log
+}
+alter table t1 drop system versioning;
+
 drop database test;
 create database test;

storage/innobase/handler/handler0alter.cc

@@ -538,6 +538,14 @@ inline bool dict_table_t::instant_column(const dict_table_t& table,
 				      & ~(DATA_NOT_NULL | DATA_VERSIONED)));
 			DBUG_ASSERT(c.mtype == o->mtype);
 			DBUG_ASSERT(c.len >= o->len);
+
+			if (o->vers_sys_start()) {
+				ut_ad(o->ind == vers_start);
+				vers_start = i;
+			} else if (o->vers_sys_end()) {
+				ut_ad(o->ind == vers_end);
+				vers_end = i;
+			}
 			continue;
 		}
 
@@ -786,6 +794,16 @@ inline void dict_table_t::rollback_instant(
 	n_v_def = n_v_cols = old_n_v_cols;
 	n_t_def = n_t_cols = n_cols + n_v_cols;
 
+	if (versioned()) {
+		for (unsigned i = 0; i < n_cols; ++i) {
+			if (cols[i].vers_sys_start()) {
+				vers_start = i;
+			} else if (cols[i].vers_sys_end()) {
+				vers_end = i;
+			}
+		}
+	}
+
 	index->fields = old_fields;
 	mtr.commit();
 
@@ -4116,7 +4134,7 @@ innobase_build_col_map(
 	Alter_inplace_info*	ha_alter_info,
 	const TABLE*		altered_table,
 	const TABLE*		table,
-	const dict_table_t*	new_table,
+	dict_table_t*		new_table,
 	const dict_table_t*	old_table,
 	dtuple_t*		defaults,
 	mem_heap_t*		heap)
@@ -4190,6 +4208,13 @@ innobase_build_col_map(
 				}
 
 				col_map[old_i - num_old_v] = i;
+				if (old_table->versioned()) {
+					if (old_i == old_table->vers_start) {
+						new_table->vers_start = i;
+					} else if (old_i == old_table->vers_end) {
+						new_table->vers_end = i;
+					}
+				}
 				goto found_col;
 			}
 		}

storage/innobase/include/dict0mem.h

@@ -618,7 +618,8 @@ struct dict_col_t{
 		ut_ad(mtype == DATA_INT || mtype == DATA_FIXBINARY);
 		return mtype == DATA_INT;
 	}
-	/** @return whether this is system versioned */
+	/** @return whether this user column (not row_start, row_end)
+		    has System Versioning property */
 	bool is_versioned() const { return !(~prtype & DATA_VERSIONED); }
 	/** @return whether this is the system version start */
 	bool vers_sys_start() const