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Re: How to generate specific WAL records?

From: Koichi Suzuki <koichi(dot)szk(at)gmail(dot)com>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: f(at)alvh(dot)no-ip(dot)org, pgsql-hackers(at)postgresql(dot)org, Oleg Bartunov <oleg(at)sai(dot)msu(dot)su>
Subject: Re: How to generate specific WAL records?
Date: 2010-04-14 02:13:22
Message-ID: p2vef4f49ae1004131913ia8dadf14t9392f8f0e458b10d@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Alvaro-san;

Thank you for a great advice.   I successfully generated all the WAL
records listed below.   By deleteing and VACUUMing a table with
btree_gist based index, I was successful to generate all the GIST WAL
records.

Still have the following WAL record to create:

CLOG_TRUNCATE
XLOG_HEAP_INIT_PAGE
XLOG_BTREE_INSERT_META
XLOG_GIN_CREATE_PTREE
XLOG_GIN_DELETE_PAGE

I have to run good amount of transactions before VACUUM FREEZE to
create CLOG_TRUNCATE.  I'll try.

It's very helpful if anybody knows how to generate XLOG_HEAP_INIT_PAGE
and XLOG_BTREE_INSERT_META.

I'll ask Oleg-san how to generate GIN-related WALs.

Thank you very much;
----------
Koichi Suzuki



2010/4/14 Alvaro Herrera <alvherre(at)commandprompt(dot)com>:
> Koichi Suzuki escribió:
>> Hi,
>>
>> Does anyone know how to generate the following WAL records from psql?
>>
>> I'm now fixing pg_lesslog, which I reported a bug.   Now code is
>> almost okay and I'd like to add test tools to show pg_lesslog can
>> handle all the WAL record correctly.
>>
>> XLOG_MULTIXACT_ZERO_OFF_PAGE
>> XLOG_MULTIXACT_ZERO_MEM_PAGE
>> XLOG_MULTIXACT_CREATE_ID
>
> For these, you need to do SELECT FOR SHARE of a tuple in more than one
> concurrent session.
>
> I think HEAP_LOCK is SELECT FOR UPDATE.
>
>
>> XLOG_BTREE_DELETE_PAGE
>> XLOG_BTREE_DELETE_PAGE_META
>> XLOG_BTREE_DELETE_PAGE_HALF
>
> These are caused during vacuum of a btree.  Create an index, populate
> it, then remove all items.  Then vacuum twice.
>
> --
> Alvaro Herrera                                http://www.CommandPrompt.com/
> PostgreSQL Replication, Consulting, Custom Development, 24x7 support
>

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