SQL: Querying Data

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This topic provides information about using SQL in WarehousePGs.

You enter SQL statements called queries to view, change, and analyze data in a database using the psql interactive SQL client and other client tools.

• About WarehousePG Query Processing
  This topic provides an overview of how WarehousePG processes queries. Understanding this process can be useful when writing and tuning queries.
• About GPORCA
  In WarehousePG, the default GPORCA optimizer co-exists with the Postgres-based planner.
• Defining Queries
  WarehousePG is based on the PostgreSQL implementation of the SQL standard.
• WITH Queries (Common Table Expressions)
  The WITH clause provides a way to use subqueries or perform a data modifying operation in a larger SELECT query. You can also use the WITH clause in an INSERT, UPDATE, or DELETE command.
• Using Functions and Operators
  Description of user-defined and built-in functions and operators in WarehousePG.
• Working with JSON Data
  WarehousePG supports the json and jsonb data types that store JSON (JavaScript Object Notation) data.
• Working with XML Data
  WarehousePG supports the xml data type that stores XML data.
• Using Full Text Search
  WarehousePG provides data types, functions, operators, index types, and configurations for querying natural language documents.
• Query Performance
  WarehousePG dynamically eliminates irrelevant partitions in a table and optimally allocates memory for different operators in a query.
• Managing Spill Files Generated by Queries
  WarehousePG creates spill files, also known as workfiles, on disk if it does not have sufficient memory to run an SQL query in memory.
• Query Profiling
  Examine the query plans of poorly performing queries to identify possible performance tuning opportunities.
• Just-in-Time Compilation (JIT) WarehousePG supports Just-in-Time compilation for long-running CPU-bound queries.

Parent topic: WarehousePG Administrator Guide