When do we Analyze the tables? How do we do it? - ETL
ETL (extract, transform, and load) Testing Interview Questions
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10. When do we Analyze the tables? How do we do it? - ETL
- The statement ANALYZE allows to validate and computes statistics for an index,table or cluster
- Cost-based optimizer uses these statistics while calculating the most efficient plan for data retrieval.
- ANALYZE statement supports object validation structures and managing space in the system
- The operations include COMPUTER,ESTIMATE and DELETE.
- An example for Oracle 7
sum(decode(nvl(NUM_ROWS,9999), 9999,0,1)) analyzed,
sum(decode(nvl(NUM_ROWS,9999), 9999,1,0)) not_analyzed,
where OWNER not in ('SYS', 'SYSTEM')
group by OWNER
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