Commit 80987dcc authored by Kirill Smelkov's avatar Kirill Smelkov

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parent adf80d7e
......@@ -27,10 +27,10 @@ data is changed, δ(ZODB) is proportional to δ(data).
Being BigFile ZBigFile can be memory-mapped. Created mappings provide lazy
on-read block loading and on-write dirtying. This way ZBigFile larger than RAM
can be accessed transparently as if it was a regular array in RAM. Changes made
to ZBigFile data will be either saved or discarded depending on current
transaction completion - commit or abort. The amount of ZBigFile changes in one
transaction is limited by available RAM.
can be accessed transparently as if it was a regular data in program memory.
Changes made to ZBigFile data will be either saved or discarded depending on
current transaction completion - commit or abort. The amount of ZBigFile
changes in one transaction is limited by available RAM.
ZBigFile does not weaken ZODB ACID properties, in particular:
......@@ -125,6 +125,8 @@ will be our future approach after we teach NEO about object deduplication.
# ZBigFile organization
#
# TODO add top-level overview
#
# As file pages are changed in RAM with changes being managed by virtmem
# subsystem, we need to propagate the changes to ZODB objects back at some time.
#
......@@ -145,7 +147,7 @@ will be our future approach after we teach NEO about object deduplication.
# between virtmem subsystem and ZODB, and virtmem->ZODB propagation happens only
# at commit time.
#
# Since, for performance reasons, virtmem subsystem is going away and BigFiles
# Since, for performance reasons, virtmem subsystem is going away and BigFiles XXX kill
# will be represented by real FUSE-based filesystem with virtual memory being
# done by kernel, where we cannot get callback on a page-dirtying, it is more
# natural to also use "2" here.
......
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