Hi Sergei! It turned out that only vcol blobs are affected. They are allocated by update_virtual_fields(), so it was enough to just refresh their value by doing update_virtual_fields() again after record is restored from the queue. Please review the fix:
https://github.com/MariaDB/server/pull/1234 On Tue, Mar 12, 2019 at 1:42 PM Sergei Golubchik <s...@mariadb.org> wrote: > Hi, Aleksey! > > On Mar 11, Aleksey Midenkov wrote: > > Hi, Sergei! > > > > ha_partition::handle_ordered_index_scan() stores records in > > m_ordered_rec_buffer. Then TABLE::update_virtual_fields() updates blob > > buffer and frees the old one. Then ha_partition::return_top_record() > > returns record from m_ordered_rec_buffer with stale blob pointer. What > > should we do with this? I propose to duplicate blob buffer when record > > gets into m_ordered_rec_buffer. > > You can make Field_blob to forget that it owns the buffer. > And when reading back from the queue, Field_blob will need to take > over the buffer again. > > It's String::release() and String::reset() methods. > > The tricky part here is that Field_blob doesn't always own the buffer, > sometimes the storage engine does. So, when reading from the queue and > restoring the ownership you'll need to take care to do it only for > values that Field_blob used to own before, not for all blobs. > > Regards, > Sergei > Chief Architect MariaDB > and secur...@mariadb.org > -- All the best, Aleksey Midenkov @midenok
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