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Date: Thu, 5 Dec 2019 14:27:52 +0300
From: Nikita Pettik <korablev@tarantool.org>
Message-ID: <20191205112752.GA11015@tarantool.org>
References: <20191202161128.20890-1-bokuno@picodata.io>
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In-Reply-To: <20191202161128.20890-1-bokuno@picodata.io>
Subject: Re: [Tarantool-patches] [PATCH] vinyl: prohibit
 vinyl_level_size_ratio less than two
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To: Maksim Kulis <bokuno@picodata.io>
Cc: tarantool-patches@dev.tarantool.org

On 02 Dec 19:11, Maksim Kulis wrote:
> Change the minimum possible value of the variable vinyl_run_size_ratio to 2.
> 
> Closes #3346
> ---
>  src/box/box.cc            | 4 ++--
>  test/box-tap/cfg.test.lua | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)

Hello. Thanks for the patch.

Firsly, please update check of run_size_ratio during index options
decode (see index_opts_decode()).

I would also update assert() in vy_range_update_compaction_priority():
let's make it check that run_size_ratio always >= 2.

Finally, I would add brief explanation to the commit message why
run_size_ratio less than 2 is meaningless (for those who are not
familiar with vinyl inner organization).
 
> diff --git a/src/box/box.cc b/src/box/box.cc
> index be2390335..e426fdab8 100644
> --- a/src/box/box.cc
> +++ b/src/box/box.cc
> @@ -589,9 +589,9 @@ box_check_vinyl_options(void)
>  		tnt_raise(ClientError, ER_CFG, "vinyl_run_count_per_level",
>  			  "must be greater than 0");
>  	}
> -	if (run_size_ratio <= 1) {
> +	if (run_size_ratio < 2) {
>  		tnt_raise(ClientError, ER_CFG, "vinyl_run_size_ratio",
> -			  "must be greater than 1");
> +			  "must be greater than or uqual to 2");
>  	}
>  	if (bloom_fpr <= 0 || bloom_fpr > 1) {
>  		tnt_raise(ClientError, ER_CFG, "vinyl_bloom_fpr",
> diff --git a/test/box-tap/cfg.test.lua b/test/box-tap/cfg.test.lua
> index d529447bb..b68c6f17b 100755
> --- a/test/box-tap/cfg.test.lua
> +++ b/test/box-tap/cfg.test.lua
> @@ -46,7 +46,7 @@ invalid('vinyl_read_threads', 0)
>  invalid('vinyl_write_threads', 1)
>  invalid('vinyl_page_size', 0)
>  invalid('vinyl_run_count_per_level', 0)
> -invalid('vinyl_run_size_ratio', 1)
> +invalid('vinyl_run_size_ratio', 1.9)
>  invalid('vinyl_bloom_fpr', 0)
>  invalid('vinyl_bloom_fpr', 1.1)
>  
> -- 
> 2.17.1
>