From bd0481ffeb6c9317b6493d6237592ad6c55f1f09 Mon Sep 17 00:00:00 2001 From: Jacob Smith Date: Fri, 4 Jan 2019 12:17:44 -0600 Subject: Add dataset header minimization release info. --- release_docs/RELEASE.txt | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt index 228ee43..8ed0a27 100644 --- a/release_docs/RELEASE.txt +++ b/release_docs/RELEASE.txt @@ -144,6 +144,17 @@ New Features (DER - 2018/10/26, HDFFV-10614) + - Add ability to minimze dataset object headers. + + Inform the library to expect no attributes on created datasets, and to + allocate the least space possible for the object headers. + A continuation block is created if attributes are added to a 'minimized' + dataset, which can reduce performance. + + H5Pget/set_dset_no_attrs_hint, H5Fget/set_no_dset_attrs_hint + + (TRILAB-45) + Parallel Library: ----------------- -- cgit v0.12 From 150b73bb1af971dfff45d5f232b979622078d5bd Mon Sep 17 00:00:00 2001 From: Jacob Smith Date: Fri, 4 Jan 2019 14:00:01 -0600 Subject: Tweak minimized datset header release info. --- release_docs/RELEASE.txt | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-) diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt index 8ed0a27..8f24b8c 100644 --- a/release_docs/RELEASE.txt +++ b/release_docs/RELEASE.txt @@ -146,14 +146,28 @@ New Features - Add ability to minimze dataset object headers. + Creation of many, very small datasets resulted in extensive file bloat + due to extra space in the dataset object headers -- this space is + allocated by default to allow for the insertion of a small number of + attributes within the object header and not require a continuation + block, an unnecessary provision in the target use case. + Inform the library to expect no attributes on created datasets, and to allocate the least space possible for the object headers. - A continuation block is created if attributes are added to a 'minimized' - dataset, which can reduce performance. - - H5Pget/set_dset_no_attrs_hint, H5Fget/set_no_dset_attrs_hint - - (TRILAB-45) + NOTE: A continuation block is created if attributes are added to a + 'minimized' dataset, which can reduce performance. + NOTE: Some extra space is allocated for attributes essential to the + correct behavior of the object header (store creation times, e.g.). This + does not violate the design principle, as the space is calculated and + allocated as needed at the time of dataset object header creation -- + unused space is not generated. + New API calls: + H5Fget_dset_no_attrs_hint + H5Fset_dset_no_attrs_hint + H5Pget_dset_no_attrs_hint + H5Pset_dset_no_attrs_hint + + (JOS - 2019/01/04, TRILAB-45) Parallel Library: -- cgit v0.12