Name
xtree_tridgell32, xtree_sum64 — checksum an XML tree using rolling and 64-bit hashes
Synopsis
integer xtree_tridgell32(
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in entity XML); |
integer xtree_sum64(
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in entity XML); |
Description
xtree_tridgell32 returns the 32-bit Tridgell rolling
checksum of the serialised form of entity. The
result is suitable as a fast pre-filter for change detection: two trees
with different checksums certainly differ; equal checksums require a
follow-up exact comparison.
xtree_sum64 returns a 64-bit sum-style hash computed
by walking the tree structure (element names, attribute name/value pairs
and text content) rather than the serialised bytes. It is therefore
insensitive to whitespace and attribute ordering, making it useful for
de-duplicating semantically-equal XML payloads in a quad-store / WebDAV
setting.