Re: [REVIEW] Re: Compression of full-page-writes - Mailing list pgsql-hackers

From Syed, Rahila
Subject Re: [REVIEW] Re: Compression of full-page-writes
Date
Msg-id C3C878A2070C994B9AE61077D46C3846589AD3DB@MAIL703.KDS.KEANE.COM
Whole thread Raw
In response to Re: [REVIEW] Re: Compression of full-page-writes  (Michael Paquier <michael.paquier@gmail.com>)
Responses Re: [REVIEW] Re: Compression of full-page-writes  (Michael Paquier <michael.paquier@gmail.com>)
List pgsql-hackers
>IMO, we should add details about how this new field is used in the comments on top of XLogRecordBlockImageHeader,
meaningthat when a page hole is present we use the compression info structure and when there is no hole, we are sure
thatthe FPW raw length is BLCKSZ meaning that the two bytes of the CompressionInfo stuff is unnecessary. 
This comment is included in the patch attached.

> For correctness with_hole should be set even for uncompressed pages. I think that we should as well use it for sanity
checksin xlogreader.c when decoding records. 
This change is made in the attached patch. Following sanity checks have been added in xlogreader.c

if (!(blk->with_hole) && blk->hole_offset != 0 || blk->with_hole && blk->hole_offset <= 0))

if (blk->with_hole && blk->bkp_len >= BLCKSZ)

if (!(blk->with_hole) && blk->bkp_len != BLCKSZ)

Thank you,
Rahila Syed



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