From: Satya Bodapati
Date: July 18 2012 12:19pm
Subject: bzr push into mysql-5.6 branch (satya.bodapati:4047 to 4048) Bug#14212892
List-Archive: http://lists.mysql.com/commits/144461
X-Bug: 14212892
Message-Id: <20120718121937.29456.37199.4048@satya-ThinkPad-T420>
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 4048 Satya Bodapati	2012-07-18
      BUG#14212892 - WHY DOES BUF_PAGE_GET_GEN CONFIRM THE PAGE
                     CHECKSUM FOR COMPRESSED PAGES
      
      For compressed pages, page checksum verification is done
      when reading the page from disk and also while decompressing
      the compressed pages.
      
      Since page checksum verification is already done when
      the page is read from disk, it is not necessary to verify the
      checksums again when decompressing the page. By removing the extra
      page checksum verification, the CPU used will be saved.
      
      No mtr testcase as this change is covered by existing testcases.
      
      Approved by Inaam: rb://1166
     @ storage/innobase/buf/buf0buf.cc
        call buf_zip_decompress() with FALSE in buf_page_get_gen() to
        disable page checksum verification when reading the page from
        disk

    modified:
      storage/innobase/buf/buf0buf.cc
 4047 Bjorn Munch	2012-07-18
      Bug #14336086 DO NOT ERROR OUT IF --DEBUG-SERVER OPTION IS PASSED TO NON...
        Issue only a warning for --debug-server, but still err out for --debug

    modified:
      mysql-test/mysql-test-run.pl
=== modified file 'storage/innobase/buf/buf0buf.cc'
--- a/storage/innobase/buf/buf0buf.cc	revid:bjorn.munch@stripped
+++ b/storage/innobase/buf/buf0buf.cc	revid:satya.bodapati@stripped
@@ -2710,7 +2710,10 @@ wait_until_unfixed:
 		/* Decompress the page and apply buffered operations
 		while not holding buf_pool->mutex or block->mutex. */
 
-		ut_a(buf_zip_decompress(block, TRUE));
+		/* Page checksum verification is already done when
+		the page is read from disk. Hence page checksum
+		verification is not necesary when decompressing the page. */
+		ut_a(buf_zip_decompress(block, FALSE));
 
 		if (UNIV_LIKELY(!recv_no_ibuf_operations)) {
 			ibuf_merge_or_delete_for_page(block, space, offset,

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