[PATCH v1 4/4] box: introduce hint option for memtx tree index
Vladimir Davydov
vdavydov.dev at gmail.com
Mon Feb 11 19:12:06 MSK 2019
On Tue, Feb 05, 2019 at 02:58:39PM +0300, Kirill Shcherbatov wrote:
> If an index has certain option, a compare hint must be calculated
> and stored within bps_tree along with struct tuple pointer. This
> hint must be used for tuple precomparison in order to avoid memory
> fetching and significantly improve tree performance.
>
> Such a hinted tree will cost twice amount of memory - 20 byte per
> tuple on average.
> Enabled hint option improve performance on average by 15%; Select
> operations are significantly accelerated (there are scenarios in
> which the difference reaches 200-250%).
>
> Test set from original @alyapunov patch.
>
> Needed for #3961
> ---
> src/box/index_def.c | 2 +
> src/box/index_def.h | 6 +
> src/box/lua/schema.lua | 12 ++
> src/box/lua/space.cc | 5 +
> src/box/memtx_tree.c | 192 +++++++++++++++++++++++-
> src/box/memtx_tree_impl.h | 2 +-
> test/box/tree_pk.result | 220 ++++++++++++++++++++++++++++
> test/box/tree_pk.test.lua | 88 +++++++++++
> test/box/tree_pk_multipart.result | 155 ++++++++++++++++++++
> test/box/tree_pk_multipart.test.lua | 65 ++++++++
> 10 files changed, 745 insertions(+), 2 deletions(-)
>
> diff --git a/src/box/index_def.c b/src/box/index_def.c
> index c52aa38d1..4d3fadc6e 100644
> --- a/src/box/index_def.c
> +++ b/src/box/index_def.c
> @@ -49,6 +49,7 @@ const struct index_opts index_opts_default = {
> /* .bloom_fpr = */ 0.05,
> /* .lsn = */ 0,
> /* .stat = */ NULL,
> + /* .hint = */ false,
> };
>
> const struct opt_def index_opts_reg[] = {
> @@ -62,6 +63,7 @@ const struct opt_def index_opts_reg[] = {
> OPT_DEF("run_size_ratio", OPT_FLOAT, struct index_opts, run_size_ratio),
> OPT_DEF("bloom_fpr", OPT_FLOAT, struct index_opts, bloom_fpr),
> OPT_DEF("lsn", OPT_INT64, struct index_opts, lsn),
> + OPT_DEF("hint", OPT_BOOL, struct index_opts, hint),
> OPT_END,
> };
>
> diff --git a/src/box/index_def.h b/src/box/index_def.h
> index 7717ecd64..74814bef5 100644
> --- a/src/box/index_def.h
> +++ b/src/box/index_def.h
> @@ -157,6 +157,10 @@ struct index_opts {
> * LSN from the time of index creation.
> */
> int64_t lsn;
> + /**
> + * Use hint optimization for tree index.
> + */
> + bool hint;
Hints should be enabled unconditionally if possible. Please don't
introduce a new index option.
The tests won't be necessary then, I guess.
> diff --git a/src/box/memtx_tree.c b/src/box/memtx_tree.c
> index 6b22883c2..426a11262 100644
> --- a/src/box/memtx_tree.c
> +++ b/src/box/memtx_tree.c
> @@ -79,8 +79,198 @@ struct memtx_tuple_tree_key_data {
>
> /* }}} */
>
> +/* {{{ Memtx hinted and hint_only tree class. *******************/
Please add a comment somewhere explaining what's the difference.
I also have some concerns about struct/function names, but we'll talk
about them later, when you make patch 2 review-able.
> +
> +/**
> + * Struct that is used as a key in BPS tree definition in
> + * metmx_hint_only_tree and metmx_hinted_tree.
> +*/
> +struct memtx_hinted_tree_key_data {
> + /** Sequence of msgpacked search fields. */
> + const char *key;
> + /** Number of msgpacked search fields. */
> + uint32_t part_count;
> + /**
> + * Compare hint. Is calculated automatically on 'set'
> + * operation with memtx_hinted_tree_key_data_set().
> + */
> + uint64_t hint;
> +};
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