SQL join problem caused by Low cardinality with Histogram(柱状图产生的过低Card.导致表join性能问题)(一)
当CBO产生的Cardinality过低，尤其是在表之间关连时，往往会差之毫厘差之千里，甚至影响表之间的join方式，注意下MERGE JOIN CARTESIAN部分，这里使用了一种NL style的MJ,..
The filter pushed in subquery issue in oracle 11G (filter推进子查询)
注意上面的4# 计划 的fileter 部分， 这就是问题的根源。了解SQL的执行步骤应该清楚在sql parse阶段CBO会帮我们做sql查询转换生成高效的执行计划, 在本案例我们想把TO_NUMBER(“S”.”SCORE”)<60 的条件放到子查询返回的结果集后再过滤, 结果CBO错误把此条件提前和该字段的其它条件一并执行..
ORACLE异机表空间基于时间点恢复 (TSPITR) Method(恢复部分表空间)
RMAN Tablespace Point-In-Time Recovery ( TSPITR) enables you to quickly recover one or more tablespaces in an Oracle database to an earlier time, without affecting the state of the rest of the tablespaces and other objects in the database.
ORACLE异机数据库基于时间点的恢复 (DBPITR) Method
DBPITR enables you to recover a database to some time in the past.I will demonstrate below how to do flashback a database to a point in time.
How to use the MegaCLI Utility with your RAID Controller on your DELL PowerEdge Server in Linux. (在linux监控RAID信息)
The MegaRAID Storage Manager includes both GUI (MSM) and The megacli tool is used for managing the controller via the command-line interface, text based tools (MegaCLI) to monitor and manage the disk array.
What is GridFS?
What is it ?
a way to store files in your database that doesn’s suck.
a way to ensure that metadata is always kept with a file.
a way to get all the scaliing benefits of mongodb for files.
Backup\Restore MongoDB using mongoexport, mongoimport, mongodump, mongorestore(MongoDB备份恢复)
The following examples , I will demonstrate how to restore a backup MongoDB. mongoexport to export mongodb to json,csv format file, mongorestore to backup mongodb to BSON(Binary Serialized dOcumeNt format) File.
How to put username &password in MongoDB(Security&Authentication)?(配置用户认证在MongoDB)
Default do not need username and password authenticate when access mongoDB ,I want to set up the user name & password for my mongoDB. so that any remote access will ask for the user name & password.
How to install MongoDB 2.6 on linux
官网地址:http://www.mongodb.org; 1. Download the binary fil […]
Install Oracle 12c on Windows [INS-30131] Failed to access the temporary location(无法访问临时位置)
A Question in QQ group get ins-30131 error when install oracle database 12c today, following error
[INS-30131] Initial setup required for the execution of installer validations failed
ORACLE data block corrupted ORA-01578&ORA-01110, Rman backup fails with ORA-19566 error.
In the case ,the corrupted block was a index segment
ORA-01578: ORACLE data block corrupted (file # 47, block # 49)
ORA-01110: data file 47: ‘/dev/rdb…’
Rman backup fails with ORA-19566 error
To add datafiles in ASM hit ORA-01119 ORA-17502 ORA-15041 after add new ASMDISKs to ASMDISKGROUP
A friend asked me ,they add new disk to a ASM diskgroup. Disks were added successfully. But when tried alter tablespace add new datafile using the diskgroup one the disks were recently added, they got “ora-01119” and “ORA-17502″,”ORA-15041” errors during add new datafile.
Drop temp tablespace command hang in oracle 11g R2
昨天DB 磁盘空间预警空间不足，发现临时表空间扩展的非常之大，于是规划调整临时表空间换个磁盘路径，本来online switch temp tablespace 并不难，结果还是遇到小问题..
How to duplicate or multiplex control files on ASM ?(复制控制文件)
ON single-instance 1, make sure asm diskgroup is avalia […]
Shell script to backup MySQL database(备份MySQL 脚本)
this is shell script to backup mysql database, using mysqldump to dump all databases into separate files, and encrypt backup file using zip password option, Generate a collective file using tar, ftp to ftp server, to send email to DBA .
RedHat(RHEL)6 support ASMLIB (RHEL6支持asmlib)
With the annoucement of Oracle’s database support on RHEL6 and OEL6, they have decided to stop making ASMLIB for RHEL compatible kernels. ASMLIB is now only available if you are using Oracle Unbreakable Linux Kernel.But Recent events enabled Red Hat and Oracle to work togethe. Oracle ASMLib availability and support on Red Hat Enterprise Linux 6.
PLS-00382: expression is of wrong type When using “execute immediate” dynamic SQL statement
今天测式部门同事遇到的一个问题记录一下，开发库运行正常，同样的复制到测试库执行应用报错,
LINE/COL ERROR
——– —————————————————————–
59/5 PL/SQL: Statement ignored
59/23 PLS-00382: expression is of wrong type
Exp Error exp-56 ORA-24324 and ora-7445 in alert When shared pool is very small
EXP-00056: ORACLE error 24324 encountered
ORA-24324: service handle not initialized
ORA-07445: exception encountered: core dump [kgghstfel()+15] [SIGSEGV] [Address not mapped to object]
Script:List all SQL in the library cache cursor referencing a given table .(列出指定表上所有相关SQL)
PROMPT List all SQL in the library cache cursor referen […]
