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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

:0.00reconn/s:0.00[20s ]thds:30tps:177.80qps:3563.97 (r/w/o:2496.95/711.31/ 355.71) lat (ms,95%): 248.83err/s:0.00reconn/s:0.00[30s] thds:30tps:177.20qps:3542.62 (r/w/o:2479.82/708.30/354.50) lat (ms,95%): NBSP;235.74NBSP;ERR/S:NBSP;0.00NBSP;RECONN/S:NBsp;0.00[40s]thds:30tps:189.60qps:3797.38 (r/w/o: 2658.99/759.20/379.20) lat (ms,95%): 227.40err/s:0.00reconn/s:0.00[ 50s]thds:30tps:190.40qps:3798.09 (r/w/o:2655.29/ 762.20/380.60) lat (ms,95%): 211.60err/s:0.00reconn/s:0.00[60s ]thds:30tps:179.70

[70s] Thds:4 tps:190.40 qps:38 11.24 (r/w/o:2667.73/762.71/380.80) Lat (ms,95%): 45.79 err/s: 0.00 RECONN/S: 0.00 [80s] Thds:4 tps:183.00 qps:3660. (r/w/o:2561.97/732.09/366.00) Lat (ms,95%): 43.39 err/s: 0.00 RECONN/S: 0.00 [90s] Thds:4 tps:211.60 qps:4226.63 (r/w/o:2958.32/845.11/423.20) Lat (ms,95%): 44.17 err/s: 0.00 RECONN/S: 0.00 [100s] thds:4 tps:213.30 qps:4272.92 (r /W/O: 2991.64/854.58/426) Lat (ms,95%): 39.65 err/s: 0.10 reconn/s: 0.00 [11

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

2", Pymongo. Descending)]):Print(u)#another way to sort forUinchDb.users.find ({"name":"User9"}, sort=[['name', 1],['Sex', 1]], fields = ["name"," Age",'Sex']): Print(u)#Combination notationSmall examples of scenarios used in FOF projects:ImportPymongoImportdatetime fromPymongoImportmongoclientconnection= Mongoclient ('localhost') DB=Connection.fofstock_cache=Db.stock_cache#post = {"20160301": "Mike", "text": "My First blog post!", "tags": ["MongoDB", "Python", "Pymongo"], "date": Datetime.d

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