On Wed, Feb 17, 2010 at 3:27 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Magnus Hagander <magnus(at)hagander(dot)net> writes:
>> On Wed, Feb 17, 2010 at 06:55, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
>>> 2. Straightforwardly observe the alignment rule. Since the received WAL
>>> data might start at the middle of WAL block, walreceiver needs to keep
>>> the last half-written WAL block for alignment. OTOH since the received
>>> data might end at the middle of WAL block, walreceiver needs zero-padding.
>>> As a result, walreceiver writes the set of the last WAL block, received
>>> data and zero-padding.
>> May there be other reasons to d this as well?
> Writing misaligned data is certain to be expensive even when it works...
Yeah, right. After I remove O_DIRECT, I'll change walreceiver so as to
do an alignment correctly, and then I'll test the performance.
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
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