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【学习】 2025年阅读清单

MacOS restart ssh Tips

2022-12-19

Linux

Linux ssh Tips

MacOS restart ssh Tips

 % sudo launchctl list | grep ssh
 % sudo launchctl load -w /System/Library/LaunchDaemons/ssh.plist 
 % sudo launchctl list | grep ssh                                
-	0	com.openssh.sshd
 % sudo launchctl unload /System/Library/LaunchDaemons/ssh.plist
 % sudo launchctl list | grep ssh                               
 % sudo launchctl load -w /System/Library/LaunchDaemons/ssh.plist
 % sudo launchctl list | grep ssh                                
-	0	com.openssh.sshd
 % sudo systemsetup -getremotelogin 
Remote Login: On
 % 

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Oracle 23c Store AWR Snapshots In User Defined Tablespace Tips

2022-12-16

Oracle

Oracle 23c awr Tips

Oracle 23c Store AWR Snapshots In User Defined Tablespace Tips

The AWR warehouse is built in the SYS schema, using the SYSAUX tablespace by default. Oracle Database, by default captures snapshots once every hour; the snapshot size varies depending on the database load. These snapshots will be stored in SYSAUX tablespace.

Starting with Oracle Database 19.1c, the user can specify a user defined tablespace for AWR data/snapshots by using the ‘dbms_workload_repository.modify_snapshot_settings’ procedure, using ‘tablespace_name’ parameter.

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Oracle 23c New features - sql_transpiler Tips

2022-12-15

Oracle

Oracle 23c Features Tips

Oracle 23c New features - sql_transpiler Tips

Automatic PL/SQL to SQL Transpiler PL/SQL functions within SQL statements are automatically converted (transpiled) into SQL expressions whenever possible.

Transpiling PL/SQL functions into SQL statements can speed up overall execution time.

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Oracle 23c New features - Parallel DML Tips

2022-12-15

Oracle

Oracle 23c Features Tips

Oracle 23c New features - Parallel DML Tips

Oracle Database allows DML statements (INSERT, UPDATE, DELETE, and MERGE) to be executed in parallel by breaking the DML statements into mutually exclusive smaller tasks. Executing DML statements in parallel can make DSS queries, batched OLTP jobs, or any larger DML operations faster. However, parallel DML operations had a few transactional limitations. This included the touch-once restriction of a parallel DML statement, which meant that once an object is modified by a parallel DML statement, that object cannot be read or modified by subsequent statements within the same transaction.

This feature removes the touch-once restriction, you can now run parallel DMLs and any combination of statements such as queries, serial DML, and parallel DML on the same object, within the same transaction. This enhancement helps provide flexibility in ETL application development using parallel DMLs, and enables data transformation and cleansing tasks before the commit of the transaction.

You can now accelerate critical business processes using parallel DML without previous transactional constraints.

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Oracle 23c New features - Update Using Direct Join Tips

2022-12-14

Oracle

Oracle 23c Features Tips

Oracle 23c New features - Update Using Direct Join Tips

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Oracle 23c New features - IF EXISTS Tips

2022-12-14

Oracle

Oracle 23c Features Tips

Oracle 23c New features - IF EXISTS and IF NOT EXISTS with CREATE, ALTER, and DROP commands Tips

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Oracle 23c New features - Develop role Tips

2022-12-14

Oracle

Oracle 23c Features Tips

Oracle 23c New features - Develop role Tips

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Oracle Developer Tools for VS Code (SQL and PLSQL) Tips

2022-12-13

Oracle

Oracle Developer Tips

Oracle Developer Tools for VS Code (SQL and PLSQL) Tips

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Oracle 23c recover table from rman Tips

2022-12-13

Oracle

Oracle 23c Tips

Oracle 23c recover table from rman Tips

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Oracle 23c PDB parameters Tips

2022-11-28

Oracle

Oracle 23c Tips

Oracle 23c PDB parameters Tips

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Oracle 23c Beta Install Tips

2022-10-28

Oracle

Oracle 23c Tips

Oracle 23c Beta Install Tips

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Oracle SQLcl Tips

2022-06-10

Oracle

Oracle SQLcl Tips
- Generating Table DDL in Oracle Database
Oracle SQLcl Tips

Generating Table DDL in Oracle Database

Table DDL (and a lot of other DDL for that matter) can be generated using DBMS_METADATA. This package has been part of the Oracle database for a long time now and it is documented in the PL/SQL Packages and Types Guide.

DBMS_METADTA is very useful, but it requires a bit of code. And now SQLcl provides a shortcut to using the DBMS_METADATA invoking the PL/SQL API.
```
help
show ddl
ddl <schema>.<object_name>
set ddl storage off
set ddl emit_schema off
set ddl segment_attributes off
```
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Generating Table DDL in Oracle Database