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找了很久，原來就在 梨子給的範例裡。

假設有兩個 expression: e1, e2

            var combineBody = Expression.AndAlso(e1.Body, Expression.Invoke(e2, e1.Parameters[0]));

            var finalExpression = Expression.Lambda<Func<TestClass, bool>>(combineBody, e1.Parameters).Compile();

同理，把上面的 AndAlso 換成 OrElse 就可以用 Or 合併。

即使只有兩行，還是不太可能背起來，所以當然要來做一下擴充

    public static class ExpressionExtension

    {

        public static Expression<Func<T, bool>> AndAlso<T>(this Expression<Func<T, bool>> e1, Expression<Func<T, bool>> e2)

        {

            var combineE = Expression.AndAlso(e1.Body, Expression.Invoke(e2, e1.Parameters[0]));



            return Expression.Lambda<Func<T, bool>>(combineE, e1.Parameters);

        }



        public static Expression<Func<T, bool>> OrElse<T>(this Expression<Func<T, bool>> e1, Expression<Func<T, bool>> e2)

        {

            var combineE = Expression.OrElse(e1.Body, Expression.Invoke(e2, e1.Parameters[0]));



            return Expression.Lambda<Func<T, bool>>(combineE, e1.Parameters);

        }

    }

使用範例:

            Expression<Func<Market, bool>> e1 = e => e.Is_Deleted == isDelete;



            Expression<Func<Market, bool>> e2 = e => string.IsNullOrEmpty(marketNo) || e.MarketNo.ToUpper().Contains(marketNo.ToUpper());



            return new

            {

                andMarkets = Ds.PageContext.ShopBandContext.Markets.Where(e1.AndAlso(e2)).ToList(),

                orMarkets = Ds.PageContext.ShopBandContext.Markets.Where(e1.OrElse(e2)).ToList(),

            };

 再補兩個擴充, 可以把多個 Expression 用 AndAlso 或 OrElse 串在一起:

        public static Expression<Func<T, bool>> OrElseAll<T>(this IEnumerable<Expression<Func<T, bool>>> exps)

        {

            if (exps.Count() == 1)

            {

                return exps.First();

            }



            var e0 = exps.First();



            var orExp = exps.Skip(1).Aggregate(e0.Body, (x, y) => Expression.OrElse(x, Expression.Invoke(y, e0.Parameters[0])));



            return Expression.Lambda<Func<T, bool>>(orExp, e0.Parameters);

        }



        public static Expression<Func<T, bool>> AndAlsoAll<T>(this IEnumerable<Expression<Func<T, bool>>> exps)

        {

            if (exps.Count() == 1)

            {

                return exps.First();

            }



            var e0 = exps.First();



            var orExp = exps.Skip(1).Aggregate(e0.Body, (x, y) => Expression.AndAlso(x, Expression.Invoke(y, e0.Parameters[0])));



            return Expression.Lambda<Func<T, bool>>(orExp, e0.Parameters);

        }

使用範例:

            Expression<Func<Market, bool>> q = e =>

            e.Is_Deleted == "N"

            && (string.IsNullOrEmpty(marketNo) || e.MarketNo.ToLower().Contains(marketNo.ToLower()))

            && (string.IsNullOrEmpty(isCombination) || isCombination != "Y" || e.TypeEnum == 200);



            if (!string.IsNullOrEmpty(name))

            {

                var nameList = name.Split(',').Select(e => e.Trim())

                    .Where(e => !string.IsNullOrEmpty(e));



                if (nameList.Any())

                {

                    q = q.AndAlso(nameList

                        .Select(s => (Expression<Func<Market, bool>>)(e => e.Name.ToLower().Contains(s.ToLower())))

                        .OrElseAll());

                }

            }

另外在 google，整理了 stackoverflow 幾篇文章之後得到的另一個方法，比較複雜, 不過可以讓人理解一下 Expression 比較底層的東西，也留下來參考一下。

    internal class MergeTool : ExpressionVisitor

    {

        private readonly ParameterExpression _parameter;



        protected override Expression VisitParameter(ParameterExpression node)

        {

            return base.VisitParameter(_parameter);

        }



        internal MergeTool(ParameterExpression parameter)

        {

            _parameter = parameter;

        }



        public static Expression<Func<T, bool>> MergedExpression<T>(Expression<Func<T, bool>> e1, Expression<Func<T, bool>> e2)

        {

            ParameterExpression param = Expression.Parameter(typeof(T));



            BinaryExpression MergeBody = Expression.AndAlso(e1.Body, e2.Body);



            var ReplacedBody = (BinaryExpression)new MergeTool(param).Visit(MergeBody);



            return Expression.Lambda<Func<T, bool>>(ReplacedBody, param);

        }

    }



使用時要 Compile



            var mergedExpression = MergeTool.MergedExpression(e1, e2);



            var list = testList.Where(mergedExpression.Compile());

--建立 table (要記得改 XXX)
CREATE TABLE IF NOT EXISTS public.table_monitor
(
    table_name text COLLATE pg_catalog."default" NOT NULL,
    update_at timestamp without time zone NOT NULL DEFAULT now(),
    update_count bigint NOT NULL DEFAULT 0,
    CONSTRAINT table_monitor_pkey PRIMARY KEY (table_name)
)

TABLESPACE pg_default;

ALTER TABLE IF EXISTS public.table_monitor
    OWNER to XXX;

-- 這一段只要執行一次
CREATE OR REPLACE FUNCTION public.table_monitor_trigger_fnc()
    RETURNS trigger
    LANGUAGE 'plpgsql'
    COST 100
    VOLATILE NOT LEAKPROOF
AS $BODY$
BEGIN
     Update public.table_monitor Set update_count = update_count + 1, update_at = now()  Where table_name = TG_TABLE_NAME; 
RETURN NEW;
END;
$BODY$;

ALTER FUNCTION public.table_monitor_trigger_fnc()
    OWNER TO XXX;

-- 對於被監控的 table, 要執行以下的指令，記得 monitor_table_name 要改為 table 的名字(要符合大小寫)
INSERT INTO public.table_monitor (table_name, update_at, update_count) VALUES ('monitor_table_name', '2000-01-01', 0) ON CONFLICT DO NOTHING;

CREATE OR REPLACE TRIGGER table_monitor_trigger
    AFTER INSERT OR DELETE OR UPDATE 
    ON monitor_table_name
    FOR EACH STATEMENT
    EXECUTE FUNCTION public.table_monitor_trigger_fnc();

監控用的程式碼:

public static void UpdateTableCache()

{

    //標記自已是正在執行的 Thread. 讓舊的 Thread 在執行完畢之後, 應該會自動結束. 以防舊的 Thread 執行超過 10 秒.

    CurrentThreadId = System.Threading.Thread.CurrentThread.ManagedThreadId;



    try

    {

        //確認自已是正在執行的 Thread, 重覆執行. (另一個 Thread 插入執行)

        while (CurrentThreadId == System.Threading.Thread.CurrentThread.ManagedThreadId)

        {

            LastUpdateDate = DateTime.Now;



            foreach (var dbId in CachedDbs)

            {

                var sql = @"select * from table_monitor";



                var dt = Su.PgSql.DtFromSql(sql, dbId);



                foreach (DataRow row in dt.Rows)

                {

                    string changeId = row["update_count"].DBNullToDefault();

                    string CacheKey = TableCacheKey(dbId, row["table_name"].DBNullToDefault());

                    ObjectCache cache = MemoryCache.Default;



                    string OldValue = (string)cache[CacheKey];



                    if (OldValue == null)

                    {

                        cache.Set(CacheKey, changeId, DateTime.MaxValue);

                    }

                    else

                    {

                        if (changeId != OldValue)

                        {

                            cache.Remove(CacheKey);

                            cache.Set(CacheKey, changeId, DateTime.MaxValue);

                        }

                    }

                }

            }



            //每兩秒檢查一次

            System.Threading.Thread.Sleep(2000);

        }

    }

    catch (Exception)

    {

        //依經驗, 只要 DB 能通, 這裡幾乎不會有問題, 所以這裡暫時不處理, 未來有問題時可以考慮寫入文字檔比較好.

    }

}

比較方式: 對相同的資料表讀取 1000 次，來比較速度。
資料庫為 MS SQL

這裡做了 4 個 Case:

Case 1: 
使用 Entity Framework，DbContext 為每次 new 一個。

Case 2:
使用 Entity Framework，使用同一個 DbContext。

Case 3:
用 DAO，轉為 Data Table 的格式 (使用 DtFromSql)。

Case 4:
使用 Dapper。

專案啟動時的記憶體使用量約為:  123 MB



測試一:
第一次讀取
Case 1, 時間: 3673.0303 ms, 記憶體: 566 MB

Case 2, 時間:  3889.9379 ms, 記憶體: 304 MB  (這個時間有時會測試到 3000 ms)

Case 3, 時間:  1665.7748 ms, 記憶體: 205 MB

Case 4, 時間:  1639.7211 ms, 記憶體: 193 MB

讀取五次
Case 1, 時間: 1984.6395, 記憶體: 544MB (有發生 GC)


Case 2, 時間:  2367.9792 ms, 記憶體: 627 MB (沒有發生 GC)


Case 3, 時間:  1395.1132 ms, 記憶體: 280 MB (有發生 GC)



Case 4, 時間:  1531.3555 ms, 記憶體: 271 MB


結果: Dapper 看來完勝，速度上和直接使用 DAO 轉進 Data Table 的速度相近。但 Dapper 傳回的結果已經轉換為物件 List， 操作上會更為方便。

Entity Framework 一如預期的較慢，且花費較多的記憶體。但和想像中最大的差異是，使用同一個 DbContext 比 new 1000 個 DbContext  的速度還要慢， 花費的記憶體在 GC 之後，差異不大。

所以不一定要用 DI 注入 DbContext, 在各 function 中一直傳遞 DbContext. 在 Static 的 function 中，可以安心的 new 一個 DbContext 出來使用吧，只是要記得用 using 哦，否則可能會有 connection 沒有關閉的問題。


 

感覺上, Oracle 的 table space 和 MS-SQL 的 DB 是一樣的。都是用來指定實體檔案。

google 到的範例居然有小 bug, 記錄一個修正版如下: 

CREATE TABLESPACE TABPE_SPACE_NAME
   DATAFILE 'TABPE_SPACE_NAME.dbf'
   SIZE 1m
   AUTOEXTEND ON;

完成之後，可以列出所有 table space:

SELECT A.TABLESPACE_NAME, A.FILE_NAME,
  ROUND(B.FREE_GB,2) AS FREE_GB , 
  ROUND(A.TOTAL_GB - b.FREE_GB) AS USED_GB ,
  ROUND(A.TOTAL_GB,2) AS TOTAL_GB , 
  ROUND(((A.TOTAL_GB - B.FREE_GB)/ A.TOTAL_GB )*100,2) AS USED_PERCENT,
  ROUND((B.FREE_GB/ A.TOTAL_GB )*100,2) AS FREE_PERCENT
FROM   
  (
    SELECT TABLESPACE_NAME, FILE_NAME,
      SUM(BYTES)/ (1024*1024*1024) AS TOTAL_GB
    FROM DBA_DATA_FILES  
    -- WHERE TABLESPACE_NAME='My_TableSpace_Name'
    GROUP  BY TABLESPACE_NAME, FILE_NAME
  )A,
  (
    SELECT TABLESPACE_NAME,    
      SUM(BYTES) / (1024*1024*1024) AS FREE_GB 
    FROM DBA_FREE_SPACE 
    -- WHERE  TABLESPACE_NAME='My_TableSpace_Name'
    GROUP BY TABLESPACE_NAME
   ) B
WHERE A.TABLESPACE_NAME= B.TABLESPACE_NAME ;

已經有資料的資料庫無法更改。

開啟 sqlplus
用 sys 登入 XPEDB1 指定為SYSDBA 的身份

--sqlplus SYS/password@localhost/XEPDB1 as SYSDBA

sqlplus / as SYSDBA

--修改 NLS_CHARACTERSET to ZHT16MSWIN950
shutdown immediate;
STARTUP MOUNT;
ALTER SESSION SET SQL_TRACE=TRUE;
ALTER SYSTEM ENABLE RESTRICTED SESSION;
ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0;
ALTER SYSTEM SET AQ_TM_PROCESSES=0;
ALTER DATABASE OPEN;
ALTER DATABASE CHARACTER SET INTERNAL_USE ZHT16MSWIN950;
ALTER SESSION SET SQL_TRACE=FALSE;
shutdown immediate;
STARTUP;

查詢 nvarchar 的欄位
select owner, table_name, column_name
from dba_tab_columns
where (data_type = 'NCHAR' or
data_type = 'NVARCHAR2' or
data_type = 'NCLOB') and
owner != 'SYS' and
owner != 'SYSTEM';

要 truncate 兩個 table:
truncate table SYS.RADM_FPTM_LOB$;
truncate table SYS.RADM_FPTM$ ;

執行以下指令

修改 System 的 NLS_NCHAR_CHARACTERSET:
shutdown immediate;
STARTUP MOUNT;
ALTER SYSTEM ENABLE RESTRICTED SESSION;
ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0 SCOPE = MEMORY;
ALTER SYSTEM SET AQ_TM_PROCESSES=0 SCOPE = MEMORY;
ALTER DATABASE OPEN;
ALTER DATABASE NATIONAL CHARACTER SET UTF8;
SHUTDOWN IMMEDIATE;
STARTUP;

要修特定  PDB 的 NLS_NCHAR_CHARACTERSET:
alter session set container=cdb$root;
show pdbs;
alter pluggable database XEPDB1  close immediate;
alter pluggable database XEPDB1 open read write restricted;
alter session set container=XEPDB1;
truncate table SYS.RADM_FPTM_LOB$;
truncate table SYS.RADM_FPTM$;
ALTER DATABASE NATIONAL CHARACTER SET UTF8;
ALTER PLUGGABLE DATABASE XEPDB1 CLOSE IMMEDIATE;
ALTER PLUGGABLE DATABASE XEPDB1 OPEN;
select * from database_properties where PROPERTY_NAME in ('NLS_CHARACTERSET', 'NLS_NCHAR_CHARACTERSET');

建立 tablespace:
有點類似 SQL 的 Create Database

create tablespace IEDF_D004M datafile 'C:\Oracle\IEDF_D004M.DBF' size 100M autoextend on next 10M maxsize unlimited;

今天小三的網站發生怪異的情況，造成網站莫名其妙跑出天天簽到的彈跳視窗

var oEM = new EverydayMain();

oEM.EndDate__StartOrEqual = DateTime.Now.Date; //只要限結束日期就好. (以日為單位)

oEM.Type = EN.Type.彈出式;



oEM.QuerySql();

// 卻產出SQL Select * from [Everyday_Main] With(NoLock)

// 但應該產出 Select * from [Everyday_Main] With(NoLock)    Where [EndDate] >= Convert(datetime, '2021-07-15T00:00:00') and [EN_Type] = 200

使用 set 條件，但產出的SQL卻是沒有 where 字串，這情況我是第一次遇到
是不是產出SQL時這中間用到 static 物件，可能要查一下
-----------------------------

        private static Hashtable _htTypeDefines;

        public static Hashtable htTypeDefines

        {

            get

            {

                if (_htTypeDefines == null)

                {

                    _htTypeDefines = new Hashtable();

                    _htTypeDefines.Add("Id", "int");

看樣子是網站第一次使用DB物件時，兩個 thread 同時在跑會造成這樣的現象
這裡應該要 lock 
 

因為需要處裡葡萄牙文
例如  Crédito Pré...

在insert 的時候 把內容寫成 N'XXXX'
結果報錯 
 SQLException:java.sql.SQLException: Incorrect string value: '\xE9 XXXX' for column 'OOOOOO' at row 1

理由應該是這篇
https://stackoverflow.com/questions/10957238/incorrect-string-value-when-trying-to-insert-utf-8-into-mysql-via-jdbc
改法
https://dba.stackexchange.com/questions/8239/how-to-easily-convert-utf8-tables-to-utf8mb4-in-mysql-5-5
但解法反而是把 N拿掉就好了

這篇有說 N'XXX' 跟 _utf8'XXX' 不一樣
https://bugs.mysql.com/bug.php?id=17313

用JAVA 寫的不確定C# .NET會不會有類似情況


 

1. 參考這裡設定第一個網站:
https://blog.johnwu.cc/article/centos-asp-net-core-neginx.html
注意, 文章中有一個錯誤:
/etc/nginx/conf.d/my-website.conf 的第 27 行, 應該是 include /etc/nginx/conf.d/default_proxy_settings;

2.  因為要避開 5000 port, 所以修改第二個網站的 appsettings.json, 讓第二個網站開在 5002 port, 如下.

{

"Logging": {

    "LogLevel": {

     "Default": "Information",

     "Microsoft": "Warning",

     "Microsoft.Hosting.Lifetime": "Information"

    }

},

"Kestrel": {

        "EndPoints": {

                "Http": {

                        "Url": "http://localhost:5002"

                }

        }

},

"AllowedHosts": "*"

}

3. 新增 /etc/nginx/conf.d/my-website2.conf, 要注意
    A. portal2
    B. server localhost:5002
    C. server_name coretest2.bike.idv.tw
    當然 SSL 憑証的檔名也要記得改.

upstream portal2 {

    # localhost:5000 改成 ASP.NET Core 所監聽的 Port

    server localhost:5002;

}



server {

    # 只要是透過這些 Domain 連 HTTP 80 Port，都會轉送封包到 ASP.NET Core

    listen 80;

    # 可透過空白區分，綁定多個 Domain

    server_name coretest2.bike.idv.tw;

    location / {

        proxy_pass http://portal2/;

        include /etc/nginx/conf.d/default_proxy_settings;

    }

}



# 用 HTTPS 必須要有 SSL 憑證，如果沒有要綁定 SSL 可以把下面整段移除

server {

    # 只要是透過這些 Domain 連 HTTPS 443 Port，都會轉送封包到 ASP.NET Core

    listen 443 ssl;

    server_name coretest2.bike.idv.tw;

    ssl_certificate /etc/nginx/ssl/coretest2.bike.idv.tw.crt;

    ssl_certificate_key /etc/nginx/ssl/coretest2.bike.idv.tw.key;



    location / {

        proxy_pass http://portal2/;

        include /etc/nginx/conf.d/default_proxy_settings;

    }

}

改完後就可以用了.

以下是 https://blog.johnwu.cc/article/centos-asp-net-core-neginx.html 抄過來的一些檔案, 作為備份:

setup-aspnet-core.sh

#!/bin/bash



main() {

    sudo yum -y install epel-release

    sudo yum -y update



    install_nginx

    install_dotnet



    sudo firewall-cmd --add-service=http --permanent

    sudo firewall-cmd --add-service=https --permanent

    sudo firewall-cmd --reload

}



install_nginx() {

    echo "###################################"

    echo "########## Install Nginx ##########"

    echo "###################################"

    sudo yum -y install httpd-tools nginx

    sudo setsebool -P httpd_can_network_connect on

    sudo sed -i 's/^SELINUX=.*/SELINUX=disabled/' /etc/selinux/config

    sudo setenforce 0

    sudo systemctl enable nginx

    sudo systemctl restart nginx

}



install_dotnet() {

    echo "###########################################"

    echo "########## Install .NET Core 2.2 ##########"

    echo "###########################################"

    sudo rpm -Uvh https://packages.microsoft.com/config/rhel/7/packages-microsoft-prod.rpm

    sudo yum -y install aspnetcore-runtime-2.2

}



main "$@"

用以下指令執行:

sudo sh setup-aspnet-core.sh

/etc/systemd/system/my-website.service, (/bin/dotnet 有可能是 /usr/bin/dotnet)

[Unit]

# Description=<此服務的摘要說明>

Description=MyWebsite



[Service]

# WorkingDirectory=<ASP.NET Core 專案目錄>

WorkingDirectory=/usr/share/my-website



# ExecStart=/bin/dotnet <ASP.NET Core 起始 dll>

ExecStart=/bin/dotnet MyWebsite.dll



# 啟動若失敗，就重啟到成功為止

Restart=always

# 重啟的間隔秒數

RestartSec=10



# 設定環境變數，注入給 ASP.NET Core 用

Environment=ASPNETCORE_ENVIRONMENT=Production

Environment=DOTNET_PRINT_TELEMETRY_MESSAGE=false



[Install]

WantedBy=multi-user.target

服務相關指令：

# 開啟，開機自動啟動服務

systemctl enable my-website.service



# 關閉，開機自動啟動服務

systemctl disable my-website.service



# 啟動服務

systemctl start my-website.service



# 重啟服務

systemctl restart my-website.service



# 停止服務

systemctl stop my-website.service



# 查看服務狀態

systemctl status my-website.service

/etc/nginx/conf.d/default_proxy_settings

proxy_http_version 1.1;

proxy_set_header Upgrade $http_upgrade;

proxy_set_header Connection $http_connection;

proxy_set_header Host $host;

proxy_set_header X-Real-IP $remote_addr;

proxy_set_header X-Forwarded-Host $remote_addr;

proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

proxy_set_header X-Forwarded-Proto $scheme;

proxy_cache_bypass $http_upgrade;

/etc/nginx/conf.d/my-website.conf

upstream portal {

    # localhost:5000 改成 ASP.NET Core 所監聽的 Port

    server localhost:5000;

}



server {

    # 只要是透過這些 Domain 連 HTTP 80 Port，都會轉送封包到 ASP.NET Core

    listen 80;

    # 可透過空白區分，綁定多個 Domain

    server_name demo.johnwu.cc example.johnwu.cc;

    location / {

        proxy_pass http://portal/;

        include /etc/nginx/conf.d/default_proxy_settings;

    }

}



# 用 HTTPS 必須要有 SSL 憑證，如果沒有要綁定 SSL 可以把下面整段移除

server {

    # 只要是透過這些 Domain 連 HTTPS 443 Port，都會轉送封包到 ASP.NET Core

    listen 443 ssl;

    server_name demo.johnwu.cc;

    ssl_certificate /etc/nginx/ssl/demo.johnwu.cc_bundle.crt;

    ssl_certificate_key /etc/nginx/ssl/demo.johnwu.cc.key;



    location / {

        proxy_pass http://portal/;

        include /etc/nginx/conf.d/default_proxy_settings;

    }

}

Nginx 重新啟動:

# 檢查 Nginx 的設定是否有誤

nginx -t



# 若沒有錯誤，即可套用

nginx -s reload