From: Michael Widenius
Date: June 20 2001 2:46pm
Subject: Re: Testing MySQL 4.0
List-Archive: http://lists.mysql.com/internals/986
Message-Id: <15152.46938.560266.680603@narttu.mysql.fi>
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Hi!

>>>>> "Paul" == Paul Cadach <paul@stripped> writes:

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


>> Hello, MySQL users/hackers:

Paul> [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
Paul> change
>> things.

Paul> Todays I've cloned 4.0 tree and trying to hack sub-select. For now it's can
Paul> be found in attached diff. To continue working under sub-selects I want to
Paul> know an opinions of MySQL team:

Paul> 1) How to store sub-selects in expression? My view is to create
Paul> Item_subselect class and store select's parameters there, then convert it to
Paul> single value/set of values/temptable when running query and this
Paul> optimization is possible (i.e. when sub-query doesn't have cross-references
Paul> to parent's tables/query)

Yes, this should be ok.

Paul> 2) To handle sub-queries mysql_query needs to be splitted into four parts
Paul> (as Monthy said in his message dated March, 7th):

yes.

Paul> a) query preparation (here IMHO we must check all fields, check that all
Paul> result fields of UNIONed tables have same type and size);

Why do you have to check for union ?

Paul> b) optimize (found non-crossreferenced subqueries and execute them before
Paul> main query?, other optimizations);
Paul> c) initialize
Paul> d) execute
Paul> e) free resources
Paul> where initialize/execute/free can be called many times. So, I needs a help
Paul> to make this work.

ok.


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

Good! Can you email Sinisa a patch for this.

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

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

The easy fix is to configure with --without-pstack.

Andrei has sent me a new copy of pstack, but I haven't had time to
upgrade MySQL 4.0 with this yet.

>> So, in short, have fun...

Paul> Yep, I trying... ;-)'

Regards,
Monty