Marko Mäkelä ad6171b91c MDEV-22456 Dropping the adaptive hash index may cause DDL to lock up InnoDB ... If the InnoDB buffer pool contains many pages for a table or index that is being dropped or rebuilt, and if many of such pages are pointed to by the adaptive hash index, dropping the adaptive hash index may consume a lot of time. The time-consuming operation of dropping the adaptive hash index entries is being executed while the InnoDB data dictionary cache dict_sys is exclusively locked. It is not actually necessary to drop all adaptive hash index entries at the time a table or index is being dropped or rebuilt. We can let the LRU replacement policy of the buffer pool take care of this gradually. For this to work, we must detach the dict_table_t and dict_index_t objects from the main dict_sys cache, and once the last adaptive hash index entry for the detached table is removed (when the garbage page is evicted from the buffer pool) we can free the dict_table_t and dict_index_t object. Related to this, in MDEV-16283, we made ALTER TABLE...DISCARD TABLESPACE skip both the buffer pool eviction and the drop of the adaptive hash index. We shifted the burden to ALTER TABLE...IMPORT TABLESPACE or DROP TABLE. We can remove the eviction from DROP TABLE. We must retain the eviction in the ALTER TABLE...IMPORT TABLESPACE code path, so that in case the discarded table is being re-imported with the same tablespace identifier, the fresh data from the imported tablespace will replace any stale pages in the buffer pool. rpl.rpl_failed_drop_tbl_binlog: Remove the test. DROP TABLE can no longer be interrupted inside InnoDB. fseg_free_page(), fseg_free_step(), fseg_free_step_not_header(), fseg_free_page_low(), fseg_free_extent(): Remove the parameter that specifies whether the adaptive hash index should be dropped. btr_search_lazy_free(): Lazily free an index when the last reference to it is dropped from the adaptive hash index. buf_pool_clear_hash_index(): Declare static, and move to the same compilation unit with the bulk of the adaptive hash index code. dict_index_t::clone(), dict_index_t::clone_if_needed(): Clone an index that is being rebuilt while adaptive hash index entries exist. The original index will be inserted into dict_table_t::freed_indexes and dict_index_t::set_freed() will be called. dict_index_t::set_freed(), dict_index_t::freed(): Note that or check whether the index has been freed. We will use the impossible page number 1 to denote this condition. dict_index_t::n_ahi_pages(): Replaces btr_search_info_get_ref_count(). dict_index_t::detach_columns(): Move the assignment n_fields=0 to ha_innobase_inplace_ctx::clear_added_indexes(). We must have access to the columns when freeing the adaptive hash index. Note: dict_table_t::v_cols[] will remain valid. If virtual columns are dropped or added, the table definition will be reloaded in ha_innobase::commit_inplace_alter_table(). buf_page_mtr_lock(): Drop a stale adaptive hash index if needed. We will also reduce the number of btr_get_search_latch() calls and enclose some more code inside #ifdef BTR_CUR_HASH_ADAPT in order to benefit cmake -DWITH_INNODB_AHI=OFF.		2020-05-15 17:23:08 +03:00
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innobase	MDEV-22456 Dropping the adaptive hash index may cause DDL to lock up InnoDB	2020-05-15 17:23:08 +03:00
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