Am 29.01.2018 um 01:02 schrieb Sergei Golubchik:

Hi, Oleksandr!

On Jan 28, Oleksandr Byelkin wrote:

...

Hi, Sergei!

Flag in SELECT_LEX options dropped at the end of execution (in our case prepare). All commands where EXPLAIN is possible restore the flag in main SELECT_LEX (in mysql_explain_union()) except UPDATE (because it do not use mysql_explain_union() for explain). Without the flag it first try to send OK (as part of update) then EOF as part of EXPLAIN. Ok.

1. Why does it not use mysql_explain_union() ? It is question to them who made explain for non SELECT statements (probably Sergey Petrunia) as I can see it just have a bit different call pathes.

2. Why EXPLAIN flag is need to be removed and restored anyway?

Because it is how our EXPLAIN works (written without taking into account re-execution). If remove the flag cleanup it will change output of prepared explain EXPLAIN.

3. Please append the following to the commit comment: " Without it, mysql_update() didn't know that there will be EXPLAIN result set and was sending OK at the end of the update, which conflicted with the EOF sent later by EXPLAIN.

OK

"

...

On Sun, Jan 28, 2018 at 2:45 PM, Sergei Golubchik wrote:

...

Hi, Oleksandr!

On Dec 22, Oleksandr Byelkin wrote:

...

revision-id: 980a5c318803d6aa7355e019869597976dcf19bf (mariadb-10.0.33-37-g980a5c31880) parent(s): 042f763268c0f209e7c12e0a6a72bb5d204dfe29 author: Oleksandr Byelkin committer: Oleksandr Byelkin timestamp: 2017-12-22 14:00:10 +0100 message:

MDEV-14572: Assertion `! is_set()' failed in Diagnostics_area::set_eof_status upon EXPLAIN UPDATE in PS

Restore EXPAIN flag in SELECT_LEX before execution multi-update by flag in LEX (the same but in other way made before INSERT/DELETE/SELECT) Please explain what was the reason for the bug, why the status was set twice, and how your change fixes it. Regards, Sergei Chief Architect MariaDB and security@mariadb.org

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