Data Quality Engineer

Window Functions

• RANK, DENSE_RANK, ROW_NUMBER:
  • Assign a rank to each row within a partition.
• LEAD, LAG:
  • Access rows preceding or following the current row within a partition.
• PARTITION BY, ORDER BY:
  • Define partitions and the order within each partition.
• Window frames:
  • Specify the range of rows included in a window function calculation.

Common Table Expressions (CTEs)

• Recursive CTEs:
  • Create recursive queries to process hierarchical data.
• Multiple CTEs:
  • Use multiple CTEs to break down complex queries into smaller, more manageable parts.

Subqueries

• Correlated subqueries:
  • Subqueries that reference columns from the outer query.
• Scalar subqueries:
  • Subqueries that return a single value.
• EXISTS and NOT EXISTS:
  • Test for the existence or non-existence of rows in a subquery.

Analytical Functions

• CUME_DIST:
  • Calculate the cumulative distribution of a value within a group.
• PERCENT_RANK:
  • Calculate the percentile rank of a value within a group.
• NTILE:
  • Divide a result set into a specified number of groups.

Full-Text Search

• Full-text indexes:
  • Create indexes that support full-text search capabilities.
• Ranking functions:
  • Rank search results based on relevance.
• Stop words:
  • Exclude common words from search queries.

Hierarchical Queries

• CONNECT BY PRIOR:
  • Traverse hierarchical relationships in a table.
• START WITH:
  • Specify the starting point for a hierarchical query.

Optimization Techniques

• Indexes:
  • Create appropriate indexes to improve query performance.
• Query tuning:
  • Analyze query execution plans and optimize queries.
• Materialized views:
  • Pre-calculate and store query results for faster access.

Qualifications:

• Exp:- 6+ Years
• Python /Java Coding (any programming language) - Must have
• Advance SQL (Mandatory) - Must have
• Any testing /Knowledge of BDD (Selenium, Cucumber)
• Working knowledge of CI/CD
• Hands on Functional Testing Experience
• Advanced SQL topics delve into more complex database operations and query optimization techniques