Database Administrator

MySQL master-slave replication asynchronous semi-sync instance MySQL master-slave replication asynchronous semi-sync instance Create mysql ReplicationNode1:Mysql> show master status;+ ------------------ + ---------- + -------------- + -------------

Oracle SQL statement Optimization Although orm ing is used in the project, the optimization of the Oracle system is very valuable. Here we will summarize the commonly used statements from the perspective of SQL statements. 1. Optimization in the

Whether the Oracle database query object is locked and unlocked For details about whether the Oracle database object is locked, see the following SQL statement and the unlock process: -- Query the locked objects of the current userSelect B.

Archive logs (below), archive logs ( 1 SQL> archive log list; # Check whether the archive mode is used2 SQL> alter system set log_archive_start = true scope = spfile; # enable active ArchivingSQL> alter system set log_archive_dest = 'location

Oracle array, oracle Defines an array of 5 strings. Type str_array is varray (5) of varchar2 (30 ); V_str_array str_array: = expr_key_array ('A', 'bb ', 'cc', 'dd', 'ee '); For I in 1 .. v_str_array. count loopDbms_output.put_line (v_expr_key ); End

Oracle memory structure, oracle Structure The memory structure of Oracle is divided into SGA and PGA. SGA is dynamically allocated. It is configured by the sga_max_size parameter and allocated when the oracle database instance is started, share an

MySQL grouping and sorting takes the first N records and generates an automatic number sequence -- group by after limit plus rownumber, -- grouprownumber My colleague asked me to group by column and then extract the first few items from each

ORA-06575: the package or function NO_VM_DROP_PROC is invalid, wndproc FunctionSQL> drop user aaa; Drop user aaa ORA-00604: recursive SQL Level 1 errorORA-06575: the package or function NO_VM_DROP_PROC is invalidORA-06512: In line 21 SQL> alter

Oracle modifies the field type and length, and oracle modifies the field Modify the field name in Oracle Alter table name rename column old field name to new field name Modify the field type and length in Oracle Alter table name modify Field

Oracle transaction processing and instance demonstration jdbc operation batch Delete, oraclejdbc Transactions As the basic unit of logical processing, database operations are composed of one or more SQL statements. Of course, there are also

Understanding of checkpoint not completed, checkpoint Assume that the database has two log groups: log1 and log2. First, --> log1 --> log2 --> log1. At this time (log2 switches to log1), the checkpoint will be flush dirty block to datafile, this

Wait for the event log to wait for the event solution. I insisted on reading three sets of RAC AWR every day and summarized it. Query the SQL statement of the log wait event: 9i: select * from v $ event_name where name like '% log %'; (about 14)10g:

OTL Chinese garbled OTL UTF8, otl Chinese garbled utf8 Character encoding is supported by odbc when unixODBC is used to connect to MySQL. It does not require any compilation conditions when compiling OTL in C ++. If your database uses UTF-8

Mysql optimization and mysql OptimizationMysql Optimization I 've been writing a blog on csdn for a long time. Recently, I 've been learning mysql optimization at Yan 18, and this teacher is still talking about it, today, I just have time to

Basic concepts of data structures Data element: a basic unit that makes up data and has a certain significance. It is usually processed as a whole in a computer, also known as a record. Data items: a data element can contain several data items.

Grant authorization for Oracle cainiao and oraclegrant 1. Authorize the database user (the object is the user table) GRANT privilege [,...] ON object [,...] TO {PUBLIC | GROUP group | username} privilege: select: Query insert: insert update: update

Single-line functions (Chapter Summary), Chapter Summary1. single-row functions can complete many independent small functions.2. The main function of a character function is to process string data, such as converting a string into uppercase,

Common Oracle Database classic queries and oracle database queries This document collects common database queries and requires the database administrator privilege: 1. query temporary tablespace usage SELECT TABLESPACE_NAME, TABLESPACE_SIZE / 10

Oracle histogram, Histogram Histogram when the data distribution of a column is uneven, in order to allow CBO to generate the best execution plan, we may need to collect a histogram for the table. The maximum number of buckets in the histogram is 254

Use bbed (BBED-00200: invalid keyword (file), bbedbbed-00200[Oracle @ ogg1 lib] $ cat filelist.txt