Bug#37039354 Backport Bug#36559642 FTS cleanup on DROP INDEX issue when adding a FULLTEXT index in same transaction

Cause:
When all FULLTEXT indexes are dropped from a table, but another one
is added in the same transaction using INPLACE algorithm, the logic for
dropping the last FULLTEXT index performs cleanup on the assumption
that the in-memeory and on-disk FTS infrastructure is not needed any
more. Because of the way the INPLACE algorithm works, creation of said
infrastructure for the index being added and related checks will have
already been done at this point - the index is already added but not
yet published (the in-memory fts_t structure is not updated) and thus
not detected. This leaves the infrastructure in an inconsistent state,
leading to incorrect behavior.

Fix:
When dropping a FULLTEXT index, do not perform the cleanup if another
FULLTEXT index is to be added in the same transaction.

Change-Id: Iceed9f4c755d2cd44d2cf7b301fc0f3a18a521cc

Author: Andrzej Jarzabek

storage/innobase/fts/fts0fts.cc

@@ -812,17 +812,21 @@ fts_drop_index(
 /*===========*/
 	dict_table_t*	table,	/*!< in: Table where indexes are dropped */
 	dict_index_t*	index,	/*!< in: Index to be dropped */
-	trx_t*		trx)	/*!< in: Transaction for the drop */
+	trx_t*		trx,	/*!< in: Transaction for the drop */
+        bool            adding_another) /*! in: Another FTS index is to be
+                                            added as part of the same
+                                            transaction */
 {
 	ib_vector_t*	indexes = table->fts->indexes;
 	dberr_t		err = DB_SUCCESS;
 
 	ut_a(indexes);
 
-	if ((ib_vector_size(indexes) == 1
+	const bool last_index = (ib_vector_size(indexes) == 1
 	    && (index == static_cast<dict_index_t*>(
 			ib_vector_getp(table->fts->indexes, 0))))
-	   || ib_vector_is_empty(indexes)) {
+	   || ib_vector_is_empty(indexes);
+        if (last_index && !adding_another) {
 		doc_id_t	current_doc_id;
 		doc_id_t	first_doc_id;
 

storage/innobase/handler/handler0alter.cc

@@ -1,6 +1,6 @@
 /*****************************************************************************
 
-Copyright (c) 2005, 2023, Oracle and/or its affiliates.
+Copyright (c) 2005, 2024, Oracle and/or its affiliates.
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License, version 2.0,
@@ -8019,12 +8019,17 @@ commit_cache_norebuild(
 		}
 	}
 
+        bool adding_fts_index = false;
+
 	for (ulint i = 0; i < ctx->num_to_add_index; i++) {
 		dict_index_t*	index = ctx->add_index[i];
 		assert(dict_index_get_online_status(index)
 		       == ONLINE_INDEX_COMPLETE);
 		assert(!index->is_committed());
 		index->set_committed(true);
+                if (index->type & DICT_FTS) {
+                  adding_fts_index = true;
+                }
 	}
 
 	if (ctx->num_to_drop_index) {
@@ -8071,7 +8076,7 @@ commit_cache_norebuild(
 				       || (index->type
 					   & DICT_CORRUPT));
 				assert(index->table->fts);
-				fts_drop_index(index->table, index, trx);
+				fts_drop_index(index->table, index, trx, adding_fts_index);
 			}
 
 			dict_index_remove_from_cache(index->table, index);
@@ -8858,9 +8863,6 @@ ha_innobase::commit_inplace_alter_table(
 
 			if (index->type & DICT_FTS) {
 				assert(index->type == DICT_FTS);
-				/* We reset DICT_TF2_FTS here because the bit
-				is left unset when a drop proceeds the add. */
-				DICT_TF2_FLAG_SET(ctx->new_table, DICT_TF2_FTS);
 				fts_add_index(index, ctx->new_table);
 			}
 		}

storage/innobase/include/fts0fts.h

@@ -1,6 +1,6 @@
 /*****************************************************************************
 
-Copyright (c) 2011, 2023, Oracle and/or its affiliates.
+Copyright (c) 2011, 2024, Oracle and/or its affiliates.
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License, version 2.0,
@@ -1047,7 +1047,10 @@ fts_drop_index(
 /*===========*/
 	dict_table_t*	table,	/*!< in: Table where indexes are dropped */
 	dict_index_t*	index,	/*!< in: Index to be dropped */
-	trx_t*		trx);	/*!< in: Transaction for the drop */
+	trx_t*		trx,	/*!< in: Transaction for the drop */
+        bool            adding_another = false); /*!< in: Another FTS index is
+                                                      to be added as part of
+                                                      the same transaction */
 
 /****************************************************************//**
 Rename auxiliary tables for all fts index for a table