Re: Prototype: In-place upgrade v02

Heikki Linnakangas napsal(a):
> The patch seems to be missing the new htup.c file.

I'm sorry. I attached new version which is synchronized with current head. I
would like to say more comments as well.

1) The patch contains also changes which was discussed during July commit
fest.     - PageGetTempPage modification suggested by Tom
- another hash.h backward compatible cleanup

2) I add tuplimits.h header file which contains tuple limits for different
access method. It is not finished yet, but idea is to keep all limits in one
file and easily add limits for different page layout version - for example
replace static computing with dynamic based on relation (maxtuplesize could be
store in pg_class for each relation).

I need this header also because I fallen in a cycle in header dependency.

3) I already sent Page API performance result in
http://archives.postgresql.org/pgsql-hackers/2008-08/msg00398.php

I replaced call sequence PagetGetItemId, PageGetItemId with PageGetIndexTuple
and PageGetHeapTuple function. It is main difference in this patch. PAgeGetHeap
Tuple fills t_ver in HeapTuple to identify correct tupleheader version.

It would be good to mention that PageAPI (and tuple API) implementation is only
prototype without any performance optimization.

4) This patch contains more topics for decision. First is general if this
approach is acceptable. Second is about new Page API if we replace all page
access with new proposed macros/(inline)function. Third is how to name and where
store different data structure version. My idea is use suffix with underscore
and page layout version and keep all version in a same header file.

5) I got another idea about usage of page API. I call it "3 in 1". Because all
page access will be through New API, it could be use for WAL logging and other
WAL recording could be reduced. Replication could be easily added based on page
modification. It is just idea for thinking.

6) it is probably all for Friday evening.

        Zdenek


--
Zdenek Kotala              Sun Microsystems
Prague, Czech Republic     http://sun.com/postgresql