Spec-Zone .ru
спецификации, руководства, описания, API
|
|
Spec-Zone .ru
спецификации, руководства, описания, API
|
The PROCESSLIST
table provides information about which threads are running.
INFORMATION_SCHEMA Name |
SHOW Name
|
Remarks |
|---|---|---|
ID |
Id |
MySQL extension |
USER |
User |
MySQL extension |
HOST |
Host |
MySQL extension |
DB |
db |
MySQL extension |
COMMAND |
Command |
MySQL extension |
TIME |
Time |
MySQL extension |
STATE |
State |
MySQL extension |
INFO |
Info |
MySQL extension |
For an extensive description of the table columns, see Section
13.7.5.30, "SHOW PROCESSLIST Syntax".
Notes:
The PROCESSLIST table is a nonstandard table.
Like the output from the corresponding SHOW statement, the PROCESSLIST table will only show information about your own threads,
unless you have the PROCESS privilege, in which case you will see information about other
threads, too. As an anonymous user, you cannot see any rows at all.
If an SQL statement refers to INFORMATION_SCHEMA.PROCESSLIST, then MySQL will populate the entire table
once, when statement execution begins, so there is read consistency during the statement. There is no
read consistency for a multi-statement transaction, though.
Process information is also available from the performance_schema.threads table. However, access to threads does not require a mutex and has minimal impact on server
performance. INFORMATION_SCHEMA.PROCESSLIST
and SHOW PROCESSLIST have
negative performance consequences because they require a mutex. threads also shows information about background threads, which INFORMATION_SCHEMA.PROCESSLIST
and SHOW PROCESSLIST do
not. This means that threads can
be used to monitor activity the other thread information sources cannot.
The following statements are equivalent:
SELECT * FROM INFORMATION_SCHEMA.PROCESSLISTSHOW FULL PROCESSLIST