Hi! On Tue, Dec 25, 2018 at 1:27 PM Sergei Golubchik <[email protected]> wrote: > > Hi, Aleksey! > > On Dec 23, Aleksey Midenkov wrote: > > revision-id: 7198e7c71fc (versioning-1.0.6-82-g7198e7c71fc) > > parent(s): 6be155757b7 > > author: Aleksey Midenkov <[email protected]> > > committer: Aleksey Midenkov <[email protected]> > > timestamp: 2018-12-20 13:25:00 +0300 > > message: > > > > MDEV-15458 Segfault in heap_scan() upon UPDATE after ADD SYSTEM VERSIONING > > > > * HA_EXTRA_REMEMBER_POS, HA_EXTRA_RESTORE_POS for HEAP storage engine > > * Versioning tests support > > As far as I can see, there are two approaches to fixing this bug. > And if we go the way of HA_EXTRA_REMEMBER_POS/HA_EXTRA_RESTORE_POS then > your fix is good. > > But I'd still like to understand whether write_row is supposed to > disturb the scan. Why should heap_write() overwrite > info->current_ptr=pos and info->current_hash_ptr? Inserting a row > doesn't happen at the "current position", so I don't quite understand > why it modifies current_ptr at all. There is no functionality like > "continue the scan from the last inserted row", right? It just doesn't > make sense to me.
I don't know why it works like this, maybe to keep consistency at API level: we insert record and then we able to access it without search. HEAP storage was copypasted from MyISAM where `lastpos` analogy also is updated at mi_write(). Without updating `current_ptr` and `lastpos` tests don't fail (main, funcs_1, heap). But I can't say whether the performance is affected and how it will go in production. > > Regards, > Sergei > Chief Architect MariaDB > and [email protected] -- All the best, Aleksey Midenkov @midenok _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
