Re: [Maria-developers] c01b3d91690: MDEV-22551 Server crashes in skip_trailing_space upon ANALYZE on table with long unique, or Assertion `marked_for_read()' fails

Hi, Sachin! On Jun 03, Sachin wrote:

revision-id: c01b3d91690 (mariadb-10.4.11-224-gc01b3d91690) parent(s): 0552ed86782 author: Sachin committer: Sachin timestamp: 2020-06-02 08:24:13 +0530 message:

MDEV-22551 Server crashes in skip_trailing_space upon ANALYZE on table with long unique, or Assertion `marked_for_read()' fails

If Blob(or parent) field read_set is not set then Do not calc hash in that case.

No, I think this is wrong. The problem, again, is that read_set bits are set incorrectly, and the fix is, again, to set them correctly, not to perform more read_set checks at run time. Think about what's happening here. The server tries to calculate a generated column value (because gcol is present in read_set) when not all argument columns were read (because they are not in read_set). This is an impossible situation, a gcol can _only_ be in read_set if all its dependencies are also there, you've seen in TABLE::mark_virtual_columns_for_write() that for every marked gcol all dependencies are also recursively marked. So in this case ANALYZE breaks this rule and should be fixed not to do it. There are two possible fixes - either ANALYZE should mark dependencies for all gcols (marking blobs in this bug) or ANALYZE should skip and not mark gcols. Better ask somebody who's more famiiar with EITS about what fix is preferred. Regards, Sergei VP of MariaDB Server Engineering and security@mariadb.org