update some content

2021-10-28 14:13:06 +08:00
parent 97eb780aa4
commit 4f99455d8f
242 changed files with 1826 additions and 2616 deletions
--- a/public/post/test-pg_prewarm/index.html
+++ b/public/post/test-pg_prewarm/index.html
@@ -13,7 +13,7 @@
        "articleSection" : "post",
        "name" : "[筆記] 測試 postgresql 的pg_prewarm 對效能的影響 \/ test pg_prewarm in postgresql 11",
        "headline" : "[筆記] 測試 postgresql 的pg_prewarm 對效能的影響 \/ test pg_prewarm in postgresql 11",
-        "description" : "\x3cp\x3e老闆提到想要把新系統的 postgresql 資料庫都撈到記憶體裡面\x3c\/p\x3e\n\x3cp\x3e但是否決了我提出的ramdisk 作法(因為當機的話，資料就沒了)\x3c\/p\x3e\n\x3cp\x3e在找資料的時候，發現了這個postgresql 的 pg_prewarm extension\x3c\/p\x3e\n\x3cp\x3e好像有點意思？就來測試看看吧！\x3c\/p\x3e\n\x3cp\x3e只是目前還不知道該怎麼解讀測試的數據就是了\x26hellip;\x3c\/p\x3e\n\x3cp\x3e幹！林北真的不是 DBA 啦 =.=\x3c\/p\x3e",
+        "description" : "\u003cp\u003e老闆提到想要把新系統的 postgresql 資料庫都撈到記憶體裡面\u003c\/p\u003e\n\u003cp\u003e但是否決了我提出的ramdisk 作法(因為當機的話，資料就沒了)\u003c\/p\u003e\n\u003cp\u003e在找資料的時候，發現了這個postgresql 的 pg_prewarm extension\u003c\/p\u003e\n\u003cp\u003e好像有點意思？就來測試看看吧！\u003c\/p\u003e\n\u003cp\u003e只是目前還不知道該怎麼解讀測試的數據就是了\u0026hellip;\u003c\/p\u003e\n\u003cp\u003e幹！林北真的不是 DBA 啦 =.=\u003c\/p\u003e",
        "inLanguage" : "en",
        "author" : "Eric Chang",
        "creator" : "Eric Chang",
@@ -21,8 +21,8 @@
        "accountablePerson" : "Eric Chang",
        "copyrightHolder" : "Eric Chang",
        "copyrightYear" : "2019",
-        "datePublished": "2019-12-20 14:31:42 \x2b0800 CST",
-        "dateModified" : "2019-12-20 14:31:42 \x2b0800 CST",
+        "datePublished": "2019-12-20 14:31:42 \u002b0800 CST",
+        "dateModified" : "2019-12-20 14:31:42 \u002b0800 CST",
        "url" : "https:\/\/h.cowbay.org\/post\/test-pg_prewarm\/",
        "wordCount" : "1314",
        "image" : "https://h.cowbay.orghttps://h.cowbay.org/images/post-default-9.jpg"",
@@ -45,9 +45,9 @@

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-<link href="https://h.cowbay.org/css/style.css?v=1632901489" rel="stylesheet" id="theme-stylesheet" type='text/css' media='all'>
+<link href="https://h.cowbay.org/css/style.css?v=1634607506" rel="stylesheet" id="theme-stylesheet" type='text/css' media='all'>

-<link href="https://h.cowbay.org/css/custom.css?v=1632901489" rel="stylesheet" type='text/css' media='all'>
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@@ -314,7 +314,7 @@ if (!doNotTrack) {
 <h4 id="修改-postgresqlconf">修改 postgresql.conf</h4>
 <p>編輯postgresql.conf，開啟平行處理以及設定可用記憶體容量</p>
 <p>這台測試機的環境是一台三代i7 , 24G RAM , 240G SSD，安裝debian 10(buster)</p>
-<pre><code># load libiriaes
+<pre tabindex="0"><code># load libiriaes
 # 其實這次不會用到pg_stat_statements ，不過出於習慣，還是加入開機自動載入吧
 shared_preload_libraries = 'pg_stat_statements'

@@ -340,17 +340,17 @@ max_parallel_workers = 8
 </code></pre><p>重新啟動postgresql ，準備開始測試囉！</p>
 <p>轉換成 postgres 身份後，進入 psql</p>
 <h4 id="建立測試資料庫">建立測試資料庫</h4>
-<pre><code>postgres=# create database test;
+<pre tabindex="0"><code>postgres=# create database test;
 CREATE DATABASE
 postgres=#
 </code></pre><h4 id="連接測試資料庫建立pg_prewarm-extension">連接測試資料庫、建立pg_prewarm extension</h4>
-<pre><code>postgres=# \c test ;
+<pre tabindex="0"><code>postgres=# \c test ;
 You are now connected to database &quot;test&quot; as user &quot;postgres&quot;.
 test=# CREATE EXTENSION pg_prewarm;
 CREATE EXTENSION
 test=# 
 </code></pre><h4 id="建立測試資料表塞入500萬筆資料">建立測試資料表，塞入500萬筆資料</h4>
-<pre><code>test=# \timing
+<pre tabindex="0"><code>test=# \timing
 Timing is on.
 test=# CREATE TABLE test_tbl AS
 SELECT floor(random() * (9923123) + 1)::int FROM generate_series(1, 5000000) AS id;
@@ -359,10 +359,10 @@ Time: 2940.602 ms (00:02.941)
 test=#
 </code></pre><h4 id="檢查看看剛剛建立的table-用了多少空間">檢查看看剛剛建立的table 用了多少空間</h4>
 <p>哎呀，看起來用得不多啊</p>
-<pre><code>test=# SELECT pg_size_pretty(pg_relation_size('test_tbl'));
+<pre tabindex="0"><code>test=# SELECT pg_size_pretty(pg_relation_size('test_tbl'));
 173 MB
 </code></pre><p><strong>玩大一點，塞個一億筆資料好了</strong></p>
-<pre><code>test=# drop table test_tbl;
+<pre tabindex="0"><code>test=# drop table test_tbl;
 Time: 0.361 ms
 test=# CREATE TABLE test_tbl AS
 SELECT floor(random() * (99343) + 1)::int FROM generate_series(1, 100000000) AS id;
@@ -377,7 +377,7 @@ test=#

 </code></pre><p>好，現在資料庫長到3457MB了</p>
 <p>先來執行一些初步的取得基本數據</p>
-<pre><code>test=# explain (analyze,buffers) select count(*) from test_tbl;
+<pre tabindex="0"><code>test=# explain (analyze,buffers) select count(*) from test_tbl;
                                   QUERY PLAN
 ------------------------------------------------------------------------------------------------------------------------
 Finalize Aggregate  (cost=755978.52..755978.53 rows=1 width=8) (actual time=3331.917..3331.918 rows=1 loops=1)
@@ -398,7 +398,7 @@ test=#

 </code></pre><p>可以看到打中buffer 的部份其實很少，只有 160 ，大部分都是讀進去buffer (442318)</p>
 <p>來看看 buffer 的使用狀況</p>
-<pre><code>test=# CREATE EXTENSION pg_buffercache;
+<pre tabindex="0"><code>test=# CREATE EXTENSION pg_buffercache;
 CREATE EXTENSION
 test=# select c.relname,pg_size_pretty(count(*) * 8192) as buffered, 
 test-#         round(100.0 * count(*) / ( 
@@ -427,7 +427,7 @@ Time: 148.719 ms
 test=# 
 </code></pre><p>可以看到這個 test_tbl 只有0.5% 被撈到shared_buffers 裡面</p>
 <p>接下來就把這個table全部推到shared_buffers 裡面去</p>
-<pre><code>test=# select pg_prewarm('test_tbl','buffer');
+<pre tabindex="0"><code>test=# select pg_prewarm('test_tbl','buffer');
 pg_prewarm 
 ------------
     442478
@@ -436,7 +436,7 @@ test=#
 Time: 1938.043 ms (00:01.938)
 test=#
 </code></pre><p>然後再來看一次shared_buffers的使用狀況</p>
-<pre><code>test=# select c.relname,pg_size_pretty(count(*) * 8192) as buffered, 
+<pre tabindex="0"><code>test=# select c.relname,pg_size_pretty(count(*) * 8192) as buffered, 
        round(100.0 * count(*) / ( 
           select setting from pg_settings 
           where name='shared_buffers')::integer,1)
@@ -466,7 +466,7 @@ test=#
 <p><strong>buffer_percent 表示這個表格佔用多少shared_buffers 的比例</strong></p>
 <p><strong>percent_of_relation 表示這個表格有多少比例被載入 shared_buffers</strong></p>
 <p>再來跑一次explain看看狀況</p>
-<pre><code>test=# explain (analyze,buffers) select count(*) from test_tbl;
+<pre tabindex="0"><code>test=# explain (analyze,buffers) select count(*) from test_tbl;
 Time: 3551.785 ms (00:03.552)
 Finalize Aggregate  (cost=755978.52..755978.53 rows=1 width=8) (actual time=3427.286..3427.287 rows=1 loops=1)
   Buffers: shared hit=442478
@@ -486,7 +486,7 @@ Time: 3551.785 ms (00:03.552)
 <p>看樣子表格還是太小，所以沒有完全發揮？那再來把表格加大！</p>
 <p>先重開一次 postgresql 清除buffer</p>
 <p>然後重新建立表格</p>
-<pre><code>test=# drop table test_tbl;
+<pre tabindex="0"><code>test=# drop table test_tbl;
 DROP TABLE
 Time: 297.493 ms
 test=# CREATE TABLE test_tbl AS
@@ -495,7 +495,7 @@ SELECT 300000000
 Time: 290660.607 ms (04:50.661)
 test=# 
 </code></pre><p>一樣，看看用了多少容量</p>
-<pre><code>test=# SELECT pg_size_pretty(pg_relation_size('test_tbl'));
+<pre tabindex="0"><code>test=# SELECT pg_size_pretty(pg_relation_size('test_tbl'));
 pg_size_pretty 
 ----------------
 10 GB
@@ -505,7 +505,7 @@ Time: 0.474 ms
 test=# 
 </code></pre><p>哇哈哈，用了10G ，這次還不撐爆你！</p>
 <p>跑explain 看看狀況</p>
-<pre><code>test=# explain (analyze,buffers) select count(*) from test_tbl;
+<pre tabindex="0"><code>test=# explain (analyze,buffers) select count(*) from test_tbl;
 Time: 22909.065 ms (00:22.909)

                                              QUERY PLAN
@@ -526,7 +526,7 @@ Time: 22909.065 ms (00:22.909)

 </code></pre><p>看一下現在 shared_buffers 使用狀況</p>
 <p>可以看到這個 test_tbl 幾乎沒被放入 shared_buffers 中</p>
-<pre><code>test=# select c.relname,pg_size_pretty(count(*) * 8192) as buffered, 
+<pre tabindex="0"><code>test=# select c.relname,pg_size_pretty(count(*) * 8192) as buffered, 
        round(100.0 * count(*) / ( 
           select setting from pg_settings 
           where name='shared_buffers')::integer,1)
@@ -552,7 +552,7 @@ group by c.oid,c.relname order by 3 desc limit 10;
 Time: 163.936 ms
 test=# 
 </code></pre><p>強制把test_tbl 全部塞進 shared_buffers</p>
-<pre><code>test=# select pg_prewarm('test_tbl','buffer');
+<pre tabindex="0"><code>test=# select pg_prewarm('test_tbl','buffer');
 pg_prewarm 
 ------------
    1327434
@@ -561,7 +561,7 @@ test=#
 Time: 7472.805 ms (00:07.473)
 test=# 
 </code></pre><p>確認一下test_tbl 有沒有被整個塞進去</p>
-<pre><code>test=# select c.relname,pg_size_pretty(count(*) * 8192) as buffered, 
+<pre tabindex="0"><code>test=# select c.relname,pg_size_pretty(count(*) * 8192) as buffered, 
        round(100.0 * count(*) / ( 
           select setting from pg_settings 
           where name='shared_buffers')::integer,1)
@@ -587,7 +587,7 @@ group by c.oid,c.relname order by 3 desc limit 10;
 Time: 4985.366 ms (00:04.985)
 test=#
 </code></pre><p>GOOD ！ let&rsquo;s do explain again !</p>
-<pre><code>test=# explain (analyze,buffers) select count(*) from test_tbl;
+<pre tabindex="0"><code>test=# explain (analyze,buffers) select count(*) from test_tbl;
 Time: 11451.188 ms (00:11.451)
                             QUERY PLAN
 --------------------------------------------------------------------------------------------------------------------
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