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c0eda62aec
btr_search_guess_on_hash() would only acquire an index page latch if it is invoked with ahi_latch=NULL. If it's invoked from row_sel_try_search_shortcut_for_mysql() with ahi_latch!=NULL, a page will not be latched, and row_search_mvcc() will get a pointer to the record, which can be changed by some other transaction before the record was stored in result buffer with row_sel_store_mysql_rec() call. ahi_latch argument of btr_cur_search_to_nth_level_func() and btr_pcur_open_with_no_init_func() is used only for row_sel_try_search_shortcut_for_mysql(). btr_cur_search_to_nth_level_func(..., ahi_latch !=0, ...) is invoked only from btr_pcur_open_with_no_init_func(..., ahi_latch !=0, ...), which, in turns, is invoked only from row_sel_try_search_shortcut_for_mysql(). I suppose that separate case with ahi_latch!=0 was intentionally implemented to protect row_sel_store_mysql_rec() call in row_search_mvcc() just after row_sel_try_search_shortcut_for_mysql() call. After the ahi_latch was moved from row_seach_mvcc() to row_sel_try_search_shortcut_for_mysql(), there is no need in it at all if btr_search_guess_on_hash() latches a page unconditionally. And if btr_search_guess_on_hash() latched the page, any access to the record in row_sel_try_search_shortcut_for_mysql() after btr_pcur_open_with_no_init() call will be protected with the page latch. The fix is to remove ahi_latch argument from btr_pcur_open_with_no_init_func(), btr_cur_search_to_nth_level_func() and btr_search_guess_on_hash(). There will not be test, as to test it we need to freeze some SELECT execution in the point between row_sel_try_search_shortcut_for_mysql() and row_sel_store_mysql_rec() calls in row_search_mvcc(), and to change the record in some other transaction to let row_sel_store_mysql_rec() to store changed record in result buffer. Buf we can't do this with the fix, as the page will be latched in btr_search_guess_on_hash() call. |
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| .. | ||
| fts0ast.cc | ||
| fts0blex.cc | ||
| fts0blex.l | ||
| fts0config.cc | ||
| fts0fts.cc | ||
| fts0opt.cc | ||
| fts0pars.cc | ||
| fts0pars.y | ||
| fts0plugin.cc | ||
| fts0que.cc | ||
| fts0sql.cc | ||
| fts0tlex.cc | ||
| fts0tlex.l | ||
| make_parser.sh | ||
| Makefile.query | ||