 | | | Subject: table with keep as buffer pool see much more physical reads than the number | Subject: table with keep as buffer pool see much more physical reads than the number 2007-10-31 - By qihua wu
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Hi, everyone, the oracle I use is 10.2.0.2 on HPUX IA64
Our job ran very slow and from AWR report I can see that a table named
ATTRIBUTE_VALUE
consumes most of the physical IO (Physical read was more than 2.5M), as I
know the blocks the table has is only 0.3M(block size is 8K), so I created a
keep buffer and set the buffer pool of ATTRIBUTE_VALUE to "keep buffer". I
was doing this to hope that once ATTRIBUTE_VALUE is read into the keep
buffer, it will never be paged out so there the physical read will not
exceed 0.3M (the blocks the table has). I already set the size of the keep
buffer large enough (4G) to hold all the blocks.
But after that change, ATTRIBUTE_VALUE was still read physically much more
times than 0.3M (about 1.6M). Shouldn't it be only 0.3M if the table was
"kept" in the buffer?
Hi, everyone, the oracle I use is <a href="http://10.2.0.2">10.2.0.2</a> on
HPUX IA64<br><br>Our job ran very slow and from AWR report I can see that a
table named <span style="font-size: 8pt; font-family: Arial; color: black;">
ATTRIBUTE_VALUE </span>consumes most of the physical IO (Physical read was more
than 2.5M), as I know the blocks the table has is only 0.3M(block size is 8K),
so I created a keep buffer and set the buffer pool of <span style="font-size:
8pt; font-family: Arial; color: black;">
ATTRIBUTE_VALUE </span>to "keep buffer". I was doing this to hope
that once <span style="font-size: 8pt; font-family: Arial; color: black;"
>ATTRIBUTE_VALUE </span>is read into<span style="font-size: 8pt; font-family:
Arial; color: black;">
</span>the keep buffer, it will never be paged out so there the physical read
will not exceed 0.3M (the blocks the table has). I already set the size of the
keep buffer large enough (4G) to hold all the blocks.<br><br>But after that
change,
<span style="font-size: 8pt; font-family: Arial; color: black;">ATTRIBUTE_VALUE
</span>was still read physically much more times than 0.3M (about 1.6M).
Shouldn't it be only 0.3M if the table was "kept" in the buffer?
<br><br>
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