Day: January 18, 2010

解決用 NFS 當 documentroot 時會當掉的方法

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在 apache 的 core document 中的 EnableMMAP Directive 有提到 ,

With an NFS-mounted DocumentRoot, the httpd may crash due to a segmentation fault if a file is deleted or truncated while the httpd has it memory-mapped.

所以, 

EnableMMAP Off
  • With a network-mounted DocumentRoot (e.g., NFS or SMB), the kernel may be unable to serve the network file through its own cache.

For server configurations that are vulnerable to these problems, you should disable this feature by specifying:

EnableSendfile Off

筆記 DB2 建 table / index syntax

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[2010/1/16 上午 10:25:03] _RUTEN 說 : 

CREATE TABLE DB2INST1.TBL_CODE 
( 
  ID BIGINT  NOT NULL  GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1, NO CACHE ) , 
  XDATE VARCHAR (8)  NOT NULL  WITH DEFAULT ‘000000′ , 
  XHOUR VARCHAR (2)  NOT NULL  WITH DEFAULT ‘00′ , 
  TAG1 VARCHAR (200)  NOT NULL  WITH DEFAULT ” , 
  TAG2 VARCHAR (300)  NOT NULL  WITH DEFAULT ” , 
  VAL BIGINT  NOT NULL  WITH DEFAULT 0  , 
  CONSTRAINT CC1263604830858 
  PRIMARY KEY ( ID)  
) IN USERSPACE1 INDEX IN NDXSPACE1 ;

CREATE  INDEX DB2INST1.NDX_XDATE ON DB2INST1.TBL_CODE (XDATE DESC)  PCTFREE 10 MINPCTUSED 10 ALLOW REVERSE SCANS  PAGE SPLIT SYMMETRIC COLLECT  SAMPLED DETAILED  STATISTICS ;
CREATE  INDEX DB2INST1.NDX_XHOUR ON DB2INST1.TBL_CODE (XHOUR DESC)  PCTFREE 10 MINPCTUSED 10 ALLOW REVERSE SCANS  PAGE SPLIT SYMMETRIC COLLECT  SAMPLED DETAILED  STATISTICS ;
CREATE  INDEX DB2INST1.NDX_TAG1 ON DB2INST1.TBL_CODE (TAG1 ASC)  PCTFREE 10 MINPCTUSED 10 ALLOW REVERSE SCANS  PAGE SPLIT SYMMETRIC COLLECT  SAMPLED DETAILED  STATISTICS ;
CREATE  INDEX DB2INST1.NDX_TAG2 ON DB2INST1.TBL_CODE (TAG2 ASC)  PCTFREE 10 MINPCTUSED 10 ALLOW REVERSE SCANS  PAGE SPLIT SYMMETRIC COLLECT  SAMPLED DETAILED  STATISTICS ;

你的第一個table建完了, 第二個之後可以直接下同樣的指令, 非unique/primary的index要另外建, 如上四行