[#node-BlockfileCursor-undo_height]
= xref:node.adoc[node]::xref:node/BlockfileCursor.adoc[BlockfileCursor]::undo&lowbar;height
:relfileprefix: ../../
:mrdocs:

Height of the highest block in file&lowbar;num whose undo data has been written&period;

== Synopsis

Declared in `&lt;node&sol;blockstorage&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int undo&lowbar;height = &lcub;0&rcub;;
----

== Description

Block data is written to block files in download order, but undo data is written in validation order (usually by height)&period; Undo files are trimmed once the corresponding block file is finalized and these heights match&period; This is a heuristic and may trim too early or too late in some cases&period;


[.small]#Created with https://www.mrdocs.com[MrDocs]#
