2 commits

Author	SHA1	Message	Date
Marko Mäkelä	3cef4f8f0f	MDEV-515 Reduce InnoDB undo logging for insert into empty table ... We implement an idea that was suggested by Michael 'Monty' Widenius in October 2017: When InnoDB is inserting into an empty table or partition, we can write a single undo log record TRX_UNDO_EMPTY, which will cause ROLLBACK to clear the table. For this to work, the insert into an empty table or partition must be covered by an exclusive table lock that will be held until the transaction has been committed or rolled back, or the INSERT operation has been rolled back (and the table is empty again), in lock_table_x_unlock(). Clustered index records that are covered by the TRX_UNDO_EMPTY record will carry DB_TRX_ID=0 and DB_ROLL_PTR=1<<55, and thus they cannot be distinguished from what MDEV-12288 leaves behind after purging the history of row-logged operations. Concurrent non-locking reads must be adjusted: If the read view was created before the INSERT into an empty table, then we must continue to imagine that the table is empty, and not try to read any records. If the read view was created after the INSERT was committed, then all records must be visible normally. To implement this, we introduce the field dict_table_t::bulk_trx_id. This special handling only applies to the very first INSERT statement of a transaction for the empty table or partition. If a subsequent statement in the transaction is modifying the initially empty table again, we must enable row-level undo logging, so that we will be able to roll back to the start of the statement in case of an error (such as duplicate key). INSERT IGNORE will continue to use row-level logging and locking, because implementing it would require the ability to roll back the latest row. Since the undo log that we write only allows us to roll back the entire statement, we cannot support INSERT IGNORE. We will introduce a handler::extra() parameter HA_EXTRA_IGNORE_INSERT to indicate to storage engines that INSERT IGNORE is being executed. In many test cases, we add an extra record to the table, so that during the 'interesting' part of the test, row-level locking and logging will be used. Replicas will continue to use row-level logging and locking until MDEV-24622 has been addressed. Likewise, this optimization will be disabled in Galera cluster until MDEV-24623 enables it. dict_table_t::bulk_trx_id: The latest active or committed transaction that initiated an insert into an empty table or partition. Protected by exclusive table lock and a clustered index leaf page latch. ins_node_t::bulk_insert: Whether bulk insert was initiated. trx_t::mod_tables: Use C++11 style accessors (emplace instead of insert). Unlike earlier, this collection will cover also temporary tables. trx_mod_table_time_t: Add start_bulk_insert(), end_bulk_insert(), is_bulk_insert(), was_bulk_insert(). trx_undo_report_row_operation(): Before accessing any undo log pages, invoke trx->mod_tables.emplace() in order to determine whether undo logging was disabled, or whether this is the first INSERT and we are supposed to write a TRX_UNDO_EMPTY record. row_ins_clust_index_entry_low(): If we are inserting into an empty clustered index leaf page, set the ins_node_t::bulk_insert flag for the subsequent trx_undo_report_row_operation() call. lock_rec_insert_check_and_lock(), lock_prdt_insert_check_and_lock(): Remove the redundant parameter 'flags' that can be checked in the caller. btr_cur_ins_lock_and_undo(): Simplify the logic. Correctly write DB_TRX_ID,DB_ROLL_PTR after invoking trx_undo_report_row_operation(). trx_mark_sql_stat_end(), ha_innobase::extra(HA_EXTRA_IGNORE_INSERT), ha_innobase::external_lock(): Invoke trx_t::end_bulk_insert() so that the next statement will not be covered by table-level undo logging. ReadView::changes_visible(trx_id_t) const: New accessor for the case where the trx_id_t is not read from a potentially corrupted index page but directly from the memory. In this case, we can skip a sanity check. row_sel(), row_sel_try_search_shortcut(), row_search_mvcc(): row_sel_try_search_shortcut_for_mysql(), row_merge_read_clustered_index(): Check dict_table_t::bulk_trx_id. row_sel_clust_sees(): Replaces lock_clust_rec_cons_read_sees(). lock_sec_rec_cons_read_sees(): Replaced with lower-level code. btr_root_page_init(): Refactored from btr_create(). dict_index_t::clear(), dict_table_t::clear(): Empty an index or table, for the ROLLBACK of an INSERT operation. ROW_T_EMPTY, ROW_OP_EMPTY: Note a concurrent ROLLBACK of an INSERT into an empty table. This is joint work with Thirunarayanan Balathandayuthapani, who created a working prototype. Thanks to Matthias Leich for extensive testing.	2021-01-25 18:41:27 +02:00
Andrei Elkin	c8ae357341	MDEV-742 XA PREPAREd transaction survive disconnect/server restart ... Lifted long standing limitation to the XA of rolling it back at the transaction's connection close even if the XA is prepared. Prepared XA-transaction is made to sustain connection close or server restart. The patch consists of - binary logging extension to write prepared XA part of transaction signified with its XID in a new XA_prepare_log_event. The concusion part - with Commit or Rollback decision - is logged separately as Query_log_event. That is in the binlog the XA consists of two separate group of events. That makes the whole XA possibly interweaving in binlog with other XA:s or regular transaction but with no harm to replication and data consistency. Gtid_log_event receives two more flags to identify which of the two XA phases of the transaction it represents. With either flag set also XID info is added to the event. When binlog is ON on the server XID::formatID is constrained to 4 bytes. - engines are made aware of the server policy to keep up user prepared XA:s so they (Innodb, rocksdb) don't roll them back anymore at their disconnect methods. - slave applier is refined to cope with two phase logged XA:s including parallel modes of execution. This patch does not address crash-safe logging of the new events which is being addressed by MDEV-21469. CORNER CASES: read-only, pure myisam, binlog-*, @@skip_log_bin, etc Are addressed along the following policies. 1. The read-only at reconnect marks XID to fail for future completion with ER_XA_RBROLLBACK. 2. binlog-* filtered XA when it changes engine data is regarded as loggable even when nothing got cached for binlog. An empty XA-prepare group is recorded. Consequent Commit-or-Rollback succeeds in the Engine(s) as well as recorded into binlog. 3. The same applies to the non-transactional engine XA. 4. @@skip_log_bin=OFF does not record anything at XA-prepare (obviously), but the completion event is recorded into binlog to admit inconsistency with slave. The following actions are taken by the patch. At XA-prepare: when empty binlog cache - don't do anything to binlog if RO, otherwise write empty XA_prepare (assert(binlog-filter case)). At Disconnect: when Prepared && RO (=> no binlogging was done) set Xid_cache_element::error := ER_XA_RBROLLBACK *keep* XID in the cache, and rollback the transaction. At XA-"complete": Discover the error, if any don't binlog the "complete", return the error to the user. Kudos ----- Alexey Botchkov took to drive this work initially. Sergei Golubchik, Sergei Petrunja, Marko Mäkelä provided a number of good recommendations. Sergei Voitovich made a magnificent review and improvements to the code. They all deserve a bunch of thanks for making this work done!	2020-03-14 22:45:48 +02:00