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

From Michael Paquier
Subject Re: [REVIEW] Re: Compression of full-page-writes
Date
Msg-id CAB7nPqSXnQ=-h2Rr=OqFc2rhyz6W4rto3Vhk8_gCnFaMLn3Q+g@mail.gmail.com
Whole thread Raw
In response to Re: [REVIEW] Re: Compression of full-page-writes  ("Syed, Rahila" <Rahila.Syed@nttdata.com>)
Responses Re: [REVIEW] Re: Compression of full-page-writes  (Andres Freund <andres@2ndquadrant.com>)
List pgsql-hackers


On Mon, Feb 16, 2015 at 8:30 PM, Syed, Rahila <Rahila.Syed@nttdata.com> wrote:

Regarding the sanity checks that have been added recently. I think that they are useful but I am suspecting as well that only a check on the record CRC is done because that's reliable enough and not doing those checks accelerates a bit replay. So I am thinking that we should simply replace >them by assertions.

Removing the checks makes sense as CRC ensures correctness . Moreover ,as error message for invalid length of record is present in the code , messages for invalid block length can be redundant.

Checks have been replaced by assertions in the attached patch.


After more thinking, we may as well simply remove them, an error with CRC having high chances to complain before reaching this point...



Current

if ((hole_length != 0) &&

+                      (*len >= orig_len - SizeOfXLogRecordBlockImageCompressionInfo))

+          return false;

+return true


This makes sense.

Nitpicking 1:
+                Assert(!(blk->with_hole == 1  && blk->hole_offset <= 0));
Double-space here.

Nitpicking 2:
char * page
This should be rewritten as char *page, the "*" being assigned with the variable name.
--
Michael

pgsql-hackers by date:

Previous
From: "Syed, Rahila"
Date:
Subject: Re: [REVIEW] Re: Compression of full-page-writes
Next
From: Andres Freund
Date:
Subject: Re: [REVIEW] Re: Compression of full-page-writes