A crude form to account for CPUTime would be something like this
Now from monProcessActivity we do get CPUTime + Logical IOs for a given SPID.
We had a number of challenges when we converted our servers to ASE157 with respect to performance. We had extensive data collectors and had minute by minute deltas for monProcessActivity. From this data we started analyzing the LIORatios for different applications (program_name). We noticed that for some of the applications the LIORatio was very low.
On investigation we found the following:
Now this begs the question as of why the parse and compile times are high.
Here are the reasons why statement cache would not effectively
In the above example the statement cache engine does not know the datatype of the columns when it is caching these statements. So based on the literal values passed it will created different sets of statements in the cache. For some of the table with many numeric columns we see that the number of cached statements was higher than 10000. It means the reuse count of the cached statements is very low.
Though 'auto literal parametrization' is turned on if there were to be a literal in a select clause it does not convert such literals into parameters
The literals in derived tables as shown above are not parameterized. So there will 2 different statements in the statement cache
In this case too the literal is not parametrized
In conclusion the parse and compile time for queries in ASE157 can be signficantly higher than the older versions. Statement cache usage is imperative to good performance. However need to be cognizant about the scenarios where statement cache would be not effective.
LIO Ratio is a good way to start investigating some such problems.
We have also used LIO Ratio to solve some of the issues with with spinlock contention and will discuss about this in the next post.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.
User | Count |
---|---|
11 | |
10 | |
7 | |
6 | |
4 | |
4 | |
3 | |
3 | |
3 | |
3 |