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ESTD_PGA_CACHE_HIT _PERCENTAGE in .NET Maker ean13+2 in .NET ESTD_PGA_CACHE_HIT _PERCENTAGE




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ESTD_PGA_CACHE_HIT _PERCENTAGE use visual studio .net ean13+5 integration tobuild ean13 with .net Microsoft Office Official Website ESTD_OVERALLOC_COUNT Estimated numbe r of overallocations for this PGA target value. Overallocations occur when Oracle has no choice but to expand a work area beyond that which would normally be specified by PGA Aggregate Target. High values might indicate that the estimated PGA Aggregate Target will be too small for the concurrent workload demands.

. Here s an alter visual .net European Article Number 13 native query for V$PGA_AGGREGATE_TARGET that presents the advice in a more visually intuitive fashion. The histogram for each estimated PGA Aggregate Target shows the relative value for ESTD_EXTRA _BYTES_RW.

Estimates where over-allocations exist are indicated as x; otherwise they are shown as *.. SQL> SELECT ROUND(PGA_TARGET_FOR_ESTIMATE / 1048576) size_mb, 2 ROUND(PGA_TARGET_FACTOR * 100, 2) estd_target_pct, 3 RPAD(" ", 4 ROUND(ESTD_EXTRA_BYTES_RW / MAX(ESTD_EXTRA_BYTES_RW) OVER () * 60), 5 DECODE(PGA_TARGET_FACTOR, 6 1, "=", 7 DECODE(SIGN(estd_overalloc_count), 1, "x", "*"))) 8 extra_bytes_histogram 9 FROM v$pga_target_advice 10 ORDER BY 1 DESC;. Optimizing PGA Memory Size MB ------8 ,192 6,144 4,096 3,072 2,048 1,843 1,638 1,434 1,229 1,024 768 512 256 128. Relative Extra EAN-13 Supplement 5 for .NET Bytes RW ---------------------------------------------------------------************** ************** ************** ************** ************** ************** ***************** xxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx ==================== xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx. Looking at this output, it s apparent that performance will degrade fairly significantly if we reduce PGA Aggregate Target. Modest reductions in overhead can be achieved by increasing PGA Aggregate Target from 1GB to 1.8GB, though no further improvements are predicted beyond this point.

However, overallocations are estimated to occur even at the current target of 1GB, and PGA Aggregate Target should be set to at least 1.6GB to avoid these..

Use V$PGA_TARGE visual .net EAN13 T_ADVICE to determine an optimal setting for PGA Aggregate Target. Avoid setting the PGA Aggregate Target to values for which over-allocations are estimated.

. Enterprise Mana ger also displays this data, in the Memory Advisors section of Advisory Central. Figure 19-5 shows Enterprise Manager graphing the PGA hit percent value from V$PGA_TARGET_ADVICE and highlighting estimated overallocations..

OVER-RIDING PGA AGGREGATE TARGET Allowing Oracle to allocate available PGA memory across sessions using the PGA Aggregate Target is generally a Good Thing. Prior to the PGA Aggregate Target mechanism, each Oracle session was free to specify its own memory limit. 19 . FIGURE 19-5. PGA Target Advice in Enterprise Manager. that often led to excessive PGA memory consumption, excessive temporary segment IO, or both. However, from time to time it might make sense for a session to control its own PGA memory allocation. This is particularly true when the number of concurrent sessions is low or where a single session is going to perform a highpriority sort operation.

In these cases, the session can opt out of the PGA Aggregate Target mechanism and set its own PGA size. To opt out of PGA Aggregate Target, you must set the parameter WORKAREA_SIZE_POLICY to MANUAL and then set specific values for the parameters SORT_AREA_SIZE and HASH_AREA_SIZE. For instance, to acquire a 500M area for sorting, we can issue the following commands:1 ALTER SESSION SET workarea_size_policy = manual; ALTER SESSION SET sort_area_size = 524288000; ALTER SESSION SET sort_area_size = 524288000; For instance, let s say that we have a 1GB PGA Aggregate Target and are about to perform a million row ORDER BY.

We know that we are doing the only. Jonathan Lewis EAN 13 for .NET discovered that these settings don t always take effect immediately and recommends setting them twice to ensure that they take effect; see http://jonathanlewis. wordpress.

com/2008/11/25/sas-bug/.. Optimizing PGA Memory significant sor visual .net EAN 13 t within the Oracle instance, so we d like to use a significant amount of the PGA Aggregate Target. However, the sizing policies previously outlined in this chapter result in us only being allocated about 100MB of PGA so that we will, therefore, perform an expensive multipass sort.

If we set WORKAREA_SIZE_POLICY to MANUAL and specify a SORT_AREA_SIZE of 800M 80 percent of the PGA Aggregate Target we only need to perform a one-pass sort. Consequently, our ORDER BY completes more quickly and generates less temporary IO. After the ORDER BY completes, we can revert to automatic work-area sizing: ALTER SESSION SET workarea_size_policy = auto; Figure 19-6 shows the improvement achieved by this technique.

In addition to a reduction in sort IO, we also saw reduced time for table scan IO; this is because the IO required for sorting was competing for the same disk volumes as the IO for the table scan. Of course, our session used more memory than it otherwise would have, so you will want to ensure that the system has sufficient free RAM to accommodate this short-term increase in memory utilization..

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