Mysql Doc Read notesSelf-turning GitHubSpeed of SELECT statements
Rational use of indexes
Isolate expensive parts of a debug query, such as whether a function call is executed in a row in the result set or a row in a full table
ORA-31693, ORA-02354 and ORA-01555 with Export Datapump (Doc ID 1580798.1), ora-31693datapump
The following error is returned from the development email:
ORA-31693: Table data object "YCDATA ". "T_MESSAGESYNC_HIS" failed to load/unload and is being
Development Mail today back to say backup error:Ora-31693:table data Object "Ycdata". " T_messagesync_his "failed to Load/unload and was being skipped due to error:ora-02354:error in exporting/importing DataORA -01555:snapshot too old:rollback
2015.1.24Today Saturday, Cloudy, 8:17 get up, today is to Nanjing to get up the latest day, because last night sleep a little late, today do not have class, the whole person a little relaxed. Pack up and come to the classroom, the classroom door is
select/distinct operatorApplication Scenario : O (∩_∩) o ... Query for Bai.Description : Unlike the SELECT function in the SQL command, the SELECT and the clauses in the query expression are placed at the end of the expression and the variables in
Select/Distinct Operator
Description: Similar to the select statement in SQL commands, the select statement and the clause in the query expression are placed at the end of the expression, and the variables in the clause, that is, the results are
Issue create Table:specified Key was too long; Max key length is 767 bytes reason database table is UTF8 encoded, where varchar (255) column has a unique key index and MySQL by default the index of a single column cannot exceed 767 bits (different
Analysis we have solved one-dimensional problems (the largest sub-segments and problems in the foundation), and now we are two-dimensional, and we see if we can turn this problem into one-dimensional problem. The last sub-matrix must be between some
1000m free unlimited capacity/single file Max/Picture support external chain network hard disktoofiles.com free network hard disk, capacity unlimited, no need to register to upload files, a single file maximum limit of 100M, a member of the maximum
Encounter a problem, tomcat recently occurred several anomalies, view the log, has been reported too many open files, familiar with the students know that this is the number of users open files caused by too many,Re-use command ls/proc/20861/fd/| Wc-
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