update README

diff --git a/src/backend/access/conveyor/README b/src/backend/access/conveyor/README
index 54c0230263d1df804c34c0a3669ff491cb6fbf89..0314abc66477ecd6c0ff90c03d854c867ba5afe9 100644 (file)
--- a/src/backend/access/conveyor/README
+++ b/src/backend/access/conveyor/README
@@ -98,9 +98,13 @@ Removing Old Data
 -----------------
 
 From time to time, we expect to receive a request to discard old data,
-which will come in the form of a statement that all logical pages with
-page numbers less than some threshold value are no longer required. We
-proceed as follows:
+which will come in the form of a call to ConveyorBeltLogicalTruncate stating
+that all logical pages with page numbers less than some threshold value are
+no longer required. Thereafter, a subsequent call to ConveyorBeltVacuum
+may be used to free up any segments that are no longer required as a result
+of the increased logical truncation point. The overall process looks like
+this, with the first step being performed by ConveyorBeltLogicalTruncate
+and the remaining steps by ConveyorBeltVacuum:
 
 1. Update the metapage with the new threshold value. Once this has been
    done, attempts to access logical pages prior to the new threshold will