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Re: Isn't init_irels() dangerous ?

From: Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Isn't init_irels() dangerous ?
Date: 2000-12-21 00:26:58
Message-ID: 3A414E52.23218812@tpf.co.jp (view raw or flat)
Thread:
Lists: pgsql-hackers
Tom Lane wrote:
> 
> "Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp> writes:
> > It seems that init_irels() should be called after
> > InitializeTransactionSystem() was called.
> 
> Can we just swap the order of the RelationCacheInitialize() and
> InitializeTransactionSystem() calls in InitPostgres?  If that
> works, I'd have no objection.
>

It doesn't work. InitializeTransactionSystem() requires
pg_log/pg_variable relations which are already built in 
RelationCacheInitialize(). A few critical relations
including pg_log/pg_variable are built in RelationCache
Initialize() without touching database. It's OK but
init_irels() touches system tables to build a few
critical index relations. IMHO init_irels() should
be separated from RelationCacheInitialize().

In the meantime,I have another anxiety. init_irels()
(RelationCacheInitialize()) seems to be called while 
Locking is disabled. This seems to mean that init_irels()
could access to system tables even when they are in
vacuum. HeapTupleSatisfiesXXXX() doesn't seem to take
such cases into account except HeapTupleSatisfiesDirty().
HeapTupleSatisfiesXXXX() sets HEAP_XMIN_COMMITTED or
HEAP_XMIN_INVALID mask for HEAP_MOVED_IN(OFF) tuples.

Regards.
Hiroshi Inoue

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