One of your databases supports a mixed workload. When monitoring SQL performance, you detect many direct paths reads full table scans. What are the two possible causes?

The correct answer is B. Highly selective filter on indexed columns D. Indexes not built on filter columns. The direct path read Oracle metric occurs during Direct Path operations when the data is asynchronously read from the database files into the PGA instead of into the SGA data buffer. Direct reads occur under these conditions: - When reading from the TEMP tablespace (a sort…

Monitoring and Analyzing SQL Performance

Question

Options

AHistograms statistics not available
BHighly selective filter on indexed columns
CToo many sort operations performed by queries
DIndexes not built on filter columns
EToo many similar type of queries getting executed with cursor sharing disabled

How the community answered

(71 responses)

A
8% (6)
B
70% (50)
C
17% (12)
E
4% (3)

Explanation

The direct path read Oracle metric occurs during Direct Path operations when the data is asynchronously read from the database files into the PGA instead of into the SGA data buffer. Direct reads occur under these conditions: - When reading from the TEMP tablespace (a sort operation) - When reading a parallel full-table scan (parallel query factotum (slave) processes) - Reading a LOB segment * The optimizer uses a full table scan in any of the following cases: - Large Amount of Data - High Degree of Parallelism

Topics

#full table scan#direct path reads#index access#filter selectivity

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