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13e5c9de80
Starting with MySQL 5.7, temporary tables in InnoDB are handled differently from persistent tables. Because temporary tables are private to a connection, concurrency control and multi-versioning (MVCC) are not applicable. For performance reasons, purge is disabled as well. Rollback is supported for temporary tables; that is why we have the temporary undo logs in the first place. Because MVCC and purge are disabled for temporary tables, we should discard all temporary undo logs already at transaction commit, just like we discard the persistent insert_undo logs. Before this change, update_undo logs were being preserved. trx_temp_undo_t: A wrapper for temporary undo logs, comprising a rollback segment and a single temporary undo log. trx_rsegs_t::m_noredo: Use trx_temp_undo_t. (Instead of insert_undo, update_undo, there will be a single undo.) trx_is_noredo_rseg_updated(), trx_is_rseg_assigned(): Remove. trx_undo_add_page(): Remove the parameter undo_ptr. Acquire and release the rollback segment mutex inside the function. trx_undo_free_last_page(): Remove the parameter trx. trx_undo_truncate_end(): Remove the parameter trx, and add the parameter is_temp. Clean up the code a bit. trx_undo_assign_undo(): Split the parameter undo_ptr into rseg, undo. trx_undo_commit_cleanup(): Renamed from trx_undo_insert_cleanup(). Replace the parameter undo_ptr with undo. This will discard the temporary undo or insert_undo log at commit/rollback. trx_purge_add_update_undo_to_history(), trx_undo_update_cleanup(): Remove 3 parameters. Always operate on the persistent update_undo. trx_serialise(): Renamed from trx_serialisation_number_get(). trx_write_serialisation_history(): Simplify the code flow. If there are no persistent changes, do not update MONITOR_TRX_COMMIT_UNDO. trx_commit_in_memory(): Simplify the logic, and add assertions. trx_undo_page_report_modify(): Keep a direct reference to the persistent update_undo log. trx_undo_report_row_operation(): Simplify some code. Always assign TRX_UNDO_INSERT for temporary undo logs. trx_prepare_low(): Keep only one parameter. Prepare all 3 undo logs. trx_roll_try_truncate(): Remove the parameter undo_ptr. Try to truncate all 3 undo logs of the transaction. trx_roll_pop_top_rec_of_trx_low(): Remove. trx_roll_pop_top_rec_of_trx(): Remove the redundant parameter trx->roll_limit. Clear roll_limit when exhausting the undo logs. Consider all 3 undo logs at once, prioritizing the persistent undo logs. row_undo(): Minor cleanup. Let trx_roll_pop_top_rec_of_trx() reset the trx->roll_limit. |
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