Class PageFilterEvent

java.lang.Object
jdk.jfr.Event
dev.hardwood.jfr.PageFilterEvent
public class PageFilterEvent extends Event

JFR event emitted when pages are filtered by Column Index predicate push-down.

One event per column chunk whose pages the push-down considered, so a row group read with a filter over two projected columns emits two events. pagesSkipped of 0 means every page survived the predicate.

No event at all means no page was a candidate for push-down in that column chunk: the read carries no predicate, the column chunk has no Column Index to evaluate, or the pages were narrowed by something other than a predicate — tail(N) skipping the rows before the tail is not page filtering and is not reported here.

The event covers Column Index push-down only. A column chunk with no Column Index is read through a sequential plan that drops pages from the statistics in each page header as it walks them; those drops are real page filtering and none of them are reported, because that plan has no page total to divide by without first reading every header it set out to avoid.

  • Field Details

    • file

      public String file

    • rowGroupIndex

      public int rowGroupIndex

    • column

      public String column

    • totalPages

      public int totalPages

    • pagesKept

      public int pagesKept

    • pagesSkipped

      public int pagesSkipped

  • Constructor Details

    • PageFilterEvent

      public PageFilterEvent()