ets

Erlang: ets select and match performance

由 二次信任 提交于 2020-12-31 04:35:02
问题 I find "The functions ets:select/2 and mnesia:select/3 should be preferred over ets:match/2,ets:match_object/2, and mnesia:match_object/3" form ref link : http://www.erlang.org/doc/efficiency_guide/tablesDatabases.html And I'd read some essay about comparing between select and match, I conclude there are some factor effecting the result, such as records' amount in table, select/match a primary key or not, table kind(bag, set...), etc. In my test, I do for all kind of table with 10W records

Erlang: ets select and match performance

由 [亡魂溺海] 提交于 2020-12-31 04:34:13
问题 I find "The functions ets:select/2 and mnesia:select/3 should be preferred over ets:match/2,ets:match_object/2, and mnesia:match_object/3" form ref link : http://www.erlang.org/doc/efficiency_guide/tablesDatabases.html And I'd read some essay about comparing between select and match, I conclude there are some factor effecting the result, such as records' amount in table, select/match a primary key or not, table kind(bag, set...), etc. In my test, I do for all kind of table with 10W records

Erlang: ets select and match performance

由 自闭症网瘾萝莉.ら 提交于 2020-12-31 04:32:37
问题 I find "The functions ets:select/2 and mnesia:select/3 should be preferred over ets:match/2,ets:match_object/2, and mnesia:match_object/3" form ref link : http://www.erlang.org/doc/efficiency_guide/tablesDatabases.html And I'd read some essay about comparing between select and match, I conclude there are some factor effecting the result, such as records' amount in table, select/match a primary key or not, table kind(bag, set...), etc. In my test, I do for all kind of table with 10W records

An error with ets and reading files

由 倾然丶 夕夏残阳落幕 提交于 2020-01-25 08:23:12
问题 Disclaimer: I didn't write this code, I'm just trying to make it work. I'm trying to get the code from here working. The setup is an Ubuntu 14.04 64bit machine with Erlang installed. The sequence of actions is as follows: What I'm doing is as follows: clone the code cd to the folder with the code and erl in terminal make:all([load]). polis:create(). polis:start(). benchmarker:start(slidingwindow50). The errors I get are: 4> benchmarker:start(slidingwindow50). true Dimensions:4, Plasticity

ets:foldl vs deleted elements

由 本小妞迷上赌 提交于 2019-12-23 05:23:04
问题 The documentation for ets:foldl/3 says: If Function inserts objects into the table, or another process inserts objects into the table, those objects may (depending on key ordering) be included in the traversal. But what happens if Function deletes objects from the table? Is there any guarantee that all remaining objects will be included in the traversal in that case? 回答1: According to the source of ets.erl if one process is iterating the table and during that it deletes records those records

Erlang/ets: reset ets table after getting a “bad argument”?

由 随声附和 提交于 2019-12-19 08:11:03
问题 I've been learning how to use ets, but one thing that has bothered me is that, occasionally*, ets:match throws a bad argument … And, from them on, all subsequent calls (even calls which previously worked) also throw a bad argument : > ets:match(Tid, { [$r | '$1'] }, 1). % this match works... % Then, at some point, this comes up: ** exception error: bad argument in function ets:match/3 called as ets:match(24589,{[114|'$1']},1) % And from then on, matches stop working: > ets:match(Tid, { [$r |

ETS creation return value

由 混江龙づ霸主 提交于 2019-12-14 01:27:24
问题 I'm using Elixir 1.6.3. I'm working with the Erlang :ets module in Elixir, and I'm a bit confused by the return value of the :ets.new/2 function. According to the doc's example, when calling :ets.new(:whatever, []) , I should be returned what appears to be an integral value: iex> table = :ets.new(:buckets_registry, [:set, :protected]) 8207 However, when I run the exact same code in iex , I get a reference: iex(1)> table = :ets.new(:buckets_registry, [:set, :protected]) #Reference<0.1885502827

How to identify the exact memory size of an ETS table?

由 五迷三道 提交于 2019-12-09 16:26:38
问题 Give an ETS table with data, the info/1 function returns various properties for the table, including a size value which is specific to the number of rows rather than the physical size. Is there any way to calculate the amount of memory in bytes occupied by an ETS table ? ets:new( mytable, [bag, named_table, compressed]), ets:insert( mytable, { Key, Value } ), .... ets:info ( mytable ). 回答1: TL;DR: ETS table allocated memory size in bytes: ets:info(Table,memory) * erlang:system_info(wordsize).

How to identify the exact memory size of an ETS table?

由 巧了我就是萌 提交于 2019-12-04 04:54:44
Give an ETS table with data, the info/1 function returns various properties for the table, including a size value which is specific to the number of rows rather than the physical size. Is there any way to calculate the amount of memory in bytes occupied by an ETS table ? ets:new( mytable, [bag, named_table, compressed]), ets:insert( mytable, { Key, Value } ), .... ets:info ( mytable ). TL;DR: ETS table allocated memory size in bytes: ets:info(Table,memory) * erlang:system_info(wordsize). To elaborate a bit, ets:info(Table,memory) gives you the words allocated to data in an ETS table (same for

erlang: function called with real 'fun' should be transformed with parse_transform?

由 匿名 (未验证) 提交于 2019-12-03 09:05:37
可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: I'm looking at the O'Reilly Erlang Programming book and there's an example that is run in the erlang shell that looks like this: 17 > MS = ets : fun2ms ( fun ({ Name , Country , Job }) when Job /= cook -> [ Country , Name ] end ). [ .... an erlang match expression is returned .... ] 18 > ets : select ( countries , MS ). [[ ireland , sean ],[ ireland , chris ]] However, when I do something similar in my code (not in the shell): Fun = fun ({ Type , _ , _ , ObjectId , PlayerId }) when Type == player_atom , PlayerId == 2 -> ObjectId
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