Shulou(Shulou.com)06/02 Report--

Yesterday, there was a session running query that kept waiting for the event gc current request.

This wait event represents the time it takes for a resource to read from the remote instance to the local instance. The occurrence of this event does not mean anything. If the waiting time is too long, it may indicate that there is a problem with the intranet or that there is serious block contention.

SQL > select name,parameter1,parameter2,parameter3 from v$event_name where name='gc current request'

NAME PARAMETER1 PARAMETER2 PARAMETER3

--

Gc current request file# block# id#

The wait event p1 represents the file number, p2 represents the block number, and p3 represents the class in v$waitstat

Yesterday's p114009, p214028, p3, 33554433

So make the following query:

SQL > SELECT tablespace_name, file_name FROM dba_data_files WHERE file_id = 20009

TABLESPACE_NAME FILE_NAME

-

The data file could not be queried, so the query criteria were changed:

SQL > SELECT tablespace_name, file_name FROM dba_temp_files f, v$parameter p WHERE p.nameplate databases files' AND f.file_id+p.value = 20009

TABLESPACE_NAME FILE_NAME

-

TEMP + DGDATA01/adw1d/tempfile/temp.596.683026963

P3 We can convert it like this:

SQL > select power (2pm 25) + 1 from dual

POWER (2Cindy 25) + 1

-

33554433

SQL > select rownum,class from v$waitstat

ROWNUM CLASS

--

1 data block

2 sort block

3 save undo block

4 segment header

5 save undo header

6 free list

7 extent map

8 1st level bmb

9 2nd level bmb

10 3rd level bmb

11 bitmap block

12 bitmap index block

13 file header block

14 unused

15 system undo header

16 system undo block

17 undo header

18 undo block

18 rows selected

P3 indicates that you are waiting for data block, because the power function is followed by a 1.

After that, I looked at the p1meme p2jinp3 waiting for the event, and found that p1 became 20011.

SQL > SELECT tablespace_name, file_name FROM dba_temp_files f, v$parameter p WHERE p.nameplate databases files' AND f.file_id+p.value = 20011

TABLESPACE_NAME FILE_NAME

-

TEMP + DGDATA01/adw1d/tempfile/temp.655.715787593

There should be no problem with the intranet, so the problem should be waiting for the temporary files to have serious contention. Due to the heavy work at that time, they did not check carefully.

To write this blog now, I will mainly record the p1 ~ 2 ~ ~ p3 conversion method of gc current request waiting events so that I can check it later.

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