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

.

parent adf80d7e
...@@ -27,10 +27,10 @@ data is changed, δ(ZODB) is proportional to δ(data). ...@@ -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 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 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 can be accessed transparently as if it was a regular data in program memory.
to ZBigFile data will be either saved or discarded depending on current Changes made to ZBigFile data will be either saved or discarded depending on
transaction completion - commit or abort. The amount of ZBigFile changes in one current transaction completion - commit or abort. The amount of ZBigFile
transaction is limited by available RAM. changes in one transaction is limited by available RAM.
ZBigFile does not weaken ZODB ACID properties, in particular: 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. ...@@ -125,6 +125,8 @@ will be our future approach after we teach NEO about object deduplication.
# ZBigFile organization # ZBigFile organization
# #
# TODO add top-level overview
#
# As file pages are changed in RAM with changes being managed by virtmem # 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. # 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. ...@@ -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 # between virtmem subsystem and ZODB, and virtmem->ZODB propagation happens only
# at commit time. # 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 # 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 # done by kernel, where we cannot get callback on a page-dirtying, it is more
# natural to also use "2" here. # natural to also use "2" here.
......
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