not tidy, will cache a lot of items, and collation of time too often, and will cause pressure on the system, this value is to determine the minimum collation cycle interval)
Inet_peer_gc_maxtime:integerThe default value is 120The maximum interval through which the waste collection (GC) passes, which affects the low pressure of memory in the buffer pool. This value is measured in jiffies units. Jiffie: The internal time unit used by the kernel, the size of 1/
previous working directory:
Copy Code code as follows:
CD-
Split a large volume of tar.gz files (each 100MB), and then merge back:
Copy Code code as follows:
Split–b 100m/path/to/large/archive/path/to/output/files
Cat files* > Archive
Use Curl to get HTTP status code:
Copy Code code as follows:
Curl-sl-w "%{http_code}\\n" Www.example.com-o/dev/null
Set root password to enhance MySQL security installation:
Copy Cod
Datagrid
DataGridView is easy to use, but if the amount of data is larger then there will be a performance problem. The general approach provided online is to accelerate through virtual mode. But sometimes, you can speed up DataGridView with simple settings.
(1) Use bound data. is to interact with Datagridview.datasource by loading the DataTable and then through BindingSource.
(2) Do not use Autosizecolumnsmode.allcells. If so, DataGridView will not be displayed until all the cells have been d
Code Download Address
Https://fuchsia.googlesource.com/magenta
Using GitHub's image
Https://github.com/fuchsia-mirror/magenta
Brief introduction
Https://github.com/fuchsia-mirror/magenta/blob/master/docs/index.md
Magenta is the core platform that powers the Fuchsia OS. Magenta iscomposed of a microkernel as well as a small set of userspace services,drivers, and libraries necessary for the System to boot, talk to hardware,load userspace processes and run them, etc. Fuchsia builds a much lar
Tried a bit of quartz, the function is very powerful, unfortunately has already had this aspect the design, wants to replace, the workload is too big.
For a problem that has often been encountered before: the processing mechanism of timeouts (timeout), as if there are no related countermeasures in quartz, so try to write a:
Import Org.apache.log4j.Logger;Import Org.quartz.InterruptableJob;Import Org.quartz.JobExecutionContext;Import org.quartz.UnableToInterruptJobException;
/**** @author Zhouc
Tried a bit of quartz, the function is very powerful, unfortunately before already has this aspect design, want to replace words, the workload is too big.
For a problem often encountered before: timeout (TimeOut) processing mechanism, as if there is no relevant treatment quartz inside countermeasures, so try to write a:
Import Org.apache.log4j.Logger;Import Org.quartz.InterruptableJob;Import Org.quartz.JobExecutionContext;Import org.quartz.UnableToInterruptJobException;
/**** @author Zhoucan*/
The following parameters are used in mysql-5.6.27, and may not be the same as the MySQL version.1. Thread ParametersInnodb_read_io_threads=6--INNODB Storage Engine reads the number of threads for the client to read data, the default value is 4Innodb_read_io_threads=7--innodb The number of write threads for the storage engine for the client to write data to, the default value is 4innodb_purge_threads=2--innodb Storage Engine recycles purge page thread, empties dirty data, default value is 12. Buf
Write in front: indexes have a critical impact on the speed of queries, and understanding indexes is also a starting point for database Performance tuning. Consider the following scenario, assuming that a table in the database has 10^6 records, the DBMS has a page size of 4K, and stores 100 records. If there is no index, the query will scan the entire table, in the worst case, if all the data pages are not in memory, need to read 10^4 pages, if the 10^4 pages on the disk randomly distributed, ne
MySQL 5.6 supports deferred replication and can Specify a deferred value on the Slave server. The default value is 0 seconds. Use the Master_delay option to set the N -second delay for change masterto . 1. following the actual demo , the normal operation from the node execution, set the delay of two secondsSTOP SLAVE; Change MASTER to Master_delay = 100; START SLAVE; Show SLAVE status\g; display sql_delay:100--delay 100S Sql_remaining_delay:null2.
Label:Write in front: indexes have a critical impact on the speed of queries, and understanding indexes is also a starting point for database Performance tuning. Consider the following scenario, assuming that a table in the database has 10^6 records, the DBMS has a page size of 4K, and stores 100 records. If there is no index, the query will scan the entire table, in the worst case, if all the data pages are not in memory, need to read 10^4 pages, if the 10^4 pages on the disk randomly distribut
Tags: remove node uri mit randomly resulting in two fork find tree increment recommended emailI. A table of 200 million records, assuming that a record has 200 bytes, query a record using indexes and performance calculations that do not use indexes
1. Assume that the IOPS of the hard disk is 100
2. Index Length: 10 bytes (4-byte index + 6-byte pointer length)
3. Each page size is 16KB and the number of 16k*1024/(6+4) can be stored on a single page =1638.4
4. A page can store
Tags: reading string comparison ase tuple primary need auto full-text index MySQLReference: http://www.cnblogs.com/hustcat/archive/2009/10/28/1591648.html ———————————— Full: Write in front: indexes have a critical impact on the speed of queries, and understanding indexes is also a starting point for database Performance tuning. Consider the following scenario, assuming that a table in the database has 10^6 records, the DBMS has a page size of 4K, and stores 100 records. If there is no index, the
Write in front: indexes have a critical impact on the speed of queries, and understanding indexes is also a starting point for database Performance tuning. Consider the following scenario, assuming that a table in the database has 10^6 records, the DBMS has a page size of 4K, and stores 100 records. If there is no index, the query will scan the entire table, in the worst case, if all the data pages are not in memory, need to read 10^4 pages, if the 10^4 pages on the disk randomly distributed, ne
Tags: Plpgsql associate an ace off index function preFirst, the problem descriptionWhen the number of records for a table in PostgreSQL recently increased from million to 1 million (design capability is 100 million), the query performance of a multi-table associated view built on top of the table was dramatically slower (from about 10ms to 100s). After analyzing the query plan, it is found that the bottleneck is that the sequencing takes a long time,
Label:Write in front: indexes have a critical impact on the speed of queries, and understanding indexes is also a starting point for database Performance tuning. Consider the following scenario, assuming that a table in the database has 10^6 records, the DBMS has a page size of 4K, and stores 100 records. If there is no index, the query will scan the entire table, in the worst case, if all the data pages are not in memory, need to read 10^4 pages, if the 10^4 pages on the disk randomly distribut
Tags: Oracle data types5. NumberUsed to store 0, positive, fixed-length negative numbers, and floating-point numbers. The number data type can be in number (P,s)form to define the precision and range of the numbers. Here: P represents the precision (1-38), which represents the number stored in the columnThe total length of the word is P-bit: s represents the range, which represents the number of digits after the decimal point. The value can range from 84 to 127. For example:CREATE TABLE Test(Nam
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