>IMO, we should add details about how this new field is used in the comments on 
>top of XLogRecordBlockImageHeader, meaning that when a page hole is present we 
>use the compression info structure and when there is no hole, we are sure that 
>the 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 checks in 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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Attachment: Support-compression-for-full-page-writes-in-WAL_v18.patch
Description: Support-compression-for-full-page-writes-in-WAL_v18.patch

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