read transaction and sync rep

From: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
To: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: read transaction and sync rep
Date: 2012-01-13 11:30:21
Message-ID: CAHGQGwHDQDtaePpgYtfcfhQgXmdy5Km68sPHf5FVxMbkex3i2Q@mail.gmail.com
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Hi,

I found that even read transaction waits for sync rep when it generates
WAL records even if XID is not assigned. For example, imagine the case
where SELECT query does a heap clean operation and generates
XLOG_HEAP2_CLEAN record. ISTM that such a read transaction doesn't
need to wait for sync rep because that's not visible to the client... Can
we skip waiting for sync rep if XID is not assigned?

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center

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