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From:Paul Cadach Date:June 20 2001 12:43pm
Subject:Re: Testing MySQL 4.0
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Hi,

----- Original Message -----
From: "Sasha Pachev" <sasha@stripped>
To: <internals@stripped>; <mysql@stripped>
Sent: Wednesday, June 20, 2001 6:44 AM
Subject: Testing MySQL 4.0


> Hello, MySQL users/hackers:

[skipped]

> Also, now is the best time to throw in suggestions, feature requests, etc.
> Once we've stablized the branch, it would be a lot harder to get us to
change
> things.

Todays I've cloned 4.0 tree and trying to hack sub-select. For now it's can
be found in attached diff. To continue working under sub-selects I want to
know an opinions of MySQL team:
1) How to store sub-selects in expression? My view is to create
Item_subselect class and store select's parameters there, then convert it to
single value/set of values/temptable when running query and this
optimization is possible (i.e. when sub-query doesn't have cross-references
to parent's tables/query)
2) To handle sub-queries mysql_query needs to be splitted into four parts
(as Monthy said in his message dated March, 7th):
a) query preparation (here IMHO we must check all fields, check that all
result fields of UNIONed tables have same type and size);
b) optimize (found non-crossreferenced subqueries and execute them before
main query?, other optimizations);
c) initialize
d) execute
e) free resources
where initialize/execute/free can be called many times. So, I needs a help
to make this work.


IMHO I've found and fixed a bug with upcoming UNIONs from Sinisa (check
mysql_init_select(), mysql_new_select() at diff).


Also, I've got a problem with linking mysqld under RedHat-7.0:
../pstack/libpstack.a(linuxthreads.o): In function
`linuxthreads_notify_others':/usr/src/MySQL/mysql-4.0/pstack/linuxthreads.c:
50:
undefined reference to `__pthread_handles_num'
/usr/src/MySQL/mysql-4.0/pstack/linuxthreads.c:58: undefined reference to
`__pthread_offsetof_pid'
/usr/src/MySQL/mysql-4.0/pstack/linuxthreads.c:58: undefined reference to
`__pthread_initial_thread'
/usr/src/MySQL/mysql-4.0/pstack/linuxthreads.c:63: undefined reference to
`__pthread_sizeof_handle'
/usr/src/MySQL/mysql-4.0/pstack/linuxthreads.c:63: undefined reference to
`__pthread_offsetof_descr'
/usr/src/MySQL/mysql-4.0/pstack/linuxthreads.c:63: undefined reference to
`__pthread_handles'
/usr/src/MySQL/mysql-4.0/pstack/linuxthreads.c:65: undefined reference to
`__pthread_offsetof_pid'
/usr/src/MySQL/mysql-4.0/pstack/linuxthreads.c:62: undefined reference to
`__pthread_handles_num'
/usr/src/MySQL/mysql-4.0/pstack/linuxthreads.c:88: undefined reference to
`__pthread_handles_num'

What it could be? At least /lib/libpthread.0.9.so have those symbols...

> So, in short, have fun...

Yep, I trying... ;-)'


WBR,
Paul.

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