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Re: 346c8ab9533: MDEV-11975: SQLCOM_PREPARE of EXPLAIN & ANALYZE statement do not return correct metadata info


Hi, Oleksandr!

On Apr 20, Oleksandr Byelkin wrote:
> Am 19.04.2018 um 11:31 schrieb Sergei Golubchik:
> >> +# cat MYSQL_TMP_DIR/test_explain_meta.out.log
> >> +# ------------------------------------
> > okay, altought I'd rather add prepare metadata output to mysqltest.
> > Like, either print prepare metadata on --enable_metadata or introduce a new
> > command --enable_prepare_metadata
> This two functionality are independent. We have speciall "IFs" in the 
> code to return SQL level prepare in some other place and actually nobody 
> really care what SQL level prepare return (of course I can fix it also, 
> but main request came from JDBC).

No-no. I don't mean sql prepare. I mean this part of mysqltest.cc:

  if (do_stmt_prepare(cn, query, query_len))
    handle_error(command,  mysql_stmt_errno(stmt),
                 mysql_stmt_error(stmt), mysql_stmt_sqlstate(stmt), ds);
    goto end;

+ if (display_metadata)
+   append_metadata(ds, fields, num_fields);

then one will be able to run the test, say

  EXPLAIN SELECT * FROM mysql.user;

and in --ps-protocol it'll show you metadata from prepared EXPLAIN.
May be --enable_metadata cannot be used for that and it'll need a new
command --enable_prepare_metadata (like we have --enable_prepare_warnings)

Chief Architect MariaDB
and security@xxxxxxxxxxx

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