Answers:
1. collecting statistics
2. Explain Statements
3. Avoid Product Joins when possible
4. select appropriate primary index to avoid skewness in storage
5. Avoid Redistribution when possible
6. Use sub-selects instead of big "IN" lists
7. Use derived tables
8. Use GROUP BY instead of DISTINCT ( GROUP BY sorts the data locally on the VPROC. DISTINCT sorts the data after it is redistributed)
9. Use Compression on large tables
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