Performance Improvements

This section summarizes performance improvements in Vertica Analytic Database 8.1.x.

Common Subexpression Elimination

Queries with complex expressions are routinely generated by business intelligence tools, and can occasionally be slow to execute. Query execution can be optimized by identifying and reusing common subexpressions (common subexpression elimination, or CSE). With this release, Vertica provides its own CSE implementation, so evaluation results between expressions can be shared within a single query.

All subexpressions in an expression are candidates for substitution. Substitution does not apply to trivial substitutions—for example, variables and constants—and to expressions that occur only once. Substitution can be recursive—that is, substitution can be applied to substituted expressions.

Better Handling of Concurrent Queries

Vertica now handles throughput of concurrent queries much more efficiently, yielding significant improvements in execution time.

Execution of Queries on Tables with Many Projections

With this release, the number of projections anchored to a table has significantly less impact on the execution time of queries on that table.