Prevent performance degradation by avoiding unnecessary expensive operations such as premature execution, redundant iterations, and costly data conversions. Use lazy evaluation, short-circuiting, and efficient data handling patterns to optimize execution paths.
Key strategies:
lazy val
for expensive computations that may be accessed multiple times during plan transformations to avoid repeated evaluationExample of lazy evaluation:
// Instead of:
val orderExpressions: Seq[SortOrder] = orderChildExpressions.zipWithIndex.map { ... }
// Use:
private lazy val orderExpressions: Seq[SortOrder] = orderChildExpressions.zipWithIndex.map { ... }
Example of short-circuiting:
// Instead of always computing both:
if (left.maxRows.isDefined && right.maxRows.isDefined) {
val leftMaxRows = left.maxRows.get
val rightMaxRows = right.maxRows.get
// ...
}
// Use short-circuiting:
val leftMaxRowsOption = left.maxRows
val rightMaxRowsOption = if (leftMaxRowsOption.isDefined) right.maxRows else None
This approach reduces computational overhead, improves response times, and prevents unnecessary resource consumption during query planning and execution.
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