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

On Fri, Oct 17, 2014 at 1:52 PM, Rahila Syed <rahilasyed90@gmail.com> wrote:
> Hello,
>
> Please find the updated patch attached.

Thanks for updating the patch! Here are the comments.

The patch isn't applied to the master cleanly.

I got the following compiler warnings.

xlog.c:930: warning: ISO C90 forbids mixed declarations and code
xlogreader.c:744: warning: ISO C90 forbids mixed declarations and code
xlogreader.c:744: warning: ISO C90 forbids mixed declarations and code

The compilation of the document failed with the following error message.

openjade:config.sgml:2188:12:E: end tag for element "TERM" which is not open
make[3]: *** [HTML.index] Error 1

Only backend calls CompressBackupBlocksPagesAlloc when SIGHUP is sent.
Why does only backend need to do that? What about other processes which
can write FPW, e.g., autovacuum?

Do we release the buffers for compressed data when fpw is changed from
"compress" to "on"?

+    if (uncompressedPages == NULL)
+    {
+        uncompressedPages = (char *)malloc(XLR_TOTAL_BLCKSZ);
+        if (uncompressedPages == NULL)
+            outOfMem = 1;
+    }

The memory is always (i.e., even when fpw=on) allocated to uncompressedPages,
but not to compressedPages. Why? I guess that the test of fpw needs to be there.

Regards,

-- 
Fujii Masao