[#index_util-CopyHeightIndexToHashIndex]
= xref:index_util.adoc[index_util]::CopyHeightIndexToHashIndex
:relfileprefix: ../
:mrdocs:

Copy an index entry from the height index to the hash index.

== Synopsis

Declared in `<index/db_key.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<typename DBVal>
[[nodiscard]]
static
bool
CopyHeightIndexToHashIndex(
    xref:CDBIterator.adoc[CDBIterator]& db_it,
    xref:CDBBatch.adoc[CDBBatch]& batch,
    std::string const& index_name,
    int height);
----

== Description

Used during a reorg so entries for blocks no longer on the main chain remain queryable by hash.

== Return Value

True on success, false if the expected entry could not be read.

[NOTE]
====
The return value https://en.cppreference.com/cpp/language/attributes/nodiscard[should not be discarded^].
====
== Template Parameters

[cols="1,4"]
|===
| Name| Description
| *DBVal*
| Type of the value stored for the entry.
|===

== Parameters

[cols="1,4"]
|===
| Name| Description
| *db_it*
| Iterator positioned to read the height‐indexed entry.
| *batch*
| Write batch that the hash‐indexed copy is added to.
| *index_name*
| Name of the index, used for error logging.
| *height*
| Block height of the entry to copy.
|===


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