最近维护的一套4节点12c数据库出现会话操作响应缓慢的情况。 查看问题时间段的awr，发现数据库当时负载并不高：
进一步查看问题时间段awr的top等待事件，发现有比较严重的gc index operation等待事件：
观察问题时间段awr的sql部分，发现SQL语句dvr0q1vq2jwx4很怪异，一条简单的insert SQL语句执行效率十分低下：
dvr0q1vq2jwx4：
insert into tsys_p (piljybss, ljhaoshi, jiaoyzht, plzxmosh, plrwzdbz, plrwtjsj, plrwuyxj, jyksshij, kshishjc, jyjsshij, jshishjc, xunijibs, ipdizhii, zhujimic, shujuquu, qslcbzha, qszxxhao, qspljyzu, qsbuzhou, cuowxinx, cuowduiz, fuwbiaoz, zxtongbh, xitongbs, farendma)values (:10, :11, :12, :13, :14, :15, :16, :17, :18, :19, :20, :21, :22, :23, :24, :25, :26, :27, :28, :29, :30, :31, :32, :33)
个人经验而论像是oracle的bug，网上倒是发现了一个类似的问题文章：
https://www.cnblogs.com/cqdba/p/073afa55d272ee9ccb65c2102ba437e3.html 但是，进一步核实又不太一样，
因为本次问题涉及的表并没有blob/clob大字段。针对本次问题，向oracle提起了sr请求进一步确认是否是oracle自身的
bug，得到了印证：
MOS文档28023081.8详细内容：
Bug 28023081 Sessions Hang Due to Waits 'gc current split'/ 'gc index operation'
This note gives a brief overview of bug 28023081.
The content was last updated on: 20-OCT-2020
Click
here for details of each of the sections below.
Affects:
|
Product (
Component) |
Oracle Server (Rdbms) |
|
Range of versions
believed to be affected |
Versions BELOW 19.1 |
|
Versions
confirmed as being affected |
18.4.0
18.3.0
18.1.0
12.2.0.1 (Base Release) |
|
Platforms affected |
Generic (all / most platforms affected) |
Fixed:
|
The fix for 28023081 is first included in |
19.1.0
Database Release Update (DB RU) 18.5.0.0.190115 (Jan 2019)
12.2.0.1.190115 (Jan 2019) Database Jan 2019 Release Update (DB RU)
12.2.0.1.190416 (Apr 2019) Bundle Patch for Windows Platforms |
Interim patches may be available for earlier versions - click
here to check.
Symptoms: |
Related To: |
|
Performance Affected (General)
Waits for "gc current split"
Waits for "gc index operation" |
RAC (Real Application Clusters) / OPS |
Description
This bug is only relevant when using Real Application Clusters (RAC)
In a RAC environment the sessions may hang on 'gc current split'/ 'gc index operation'
Rediscovery Notes
Session hanging on 'gc current split'/ 'gc index operation' cycle, local DLM lock shows repeated message BAST being sent:
GCS SHADOW 0x30661c288,256 resp[0x30e6efa18,0x39b6f.23] pkey 0.11.35289
...
KJBL history 0x84.0x84.0x84.0x84.0x84.0x84.0x84.0x84...
Workaround
_gc_fast_index_split_wait=0
|
Please note: The above is a summary description only. Actual symptoms can vary. Matching to any symptoms here does not confirm that you are encountering this problem. For questions about this bug please consult Oracle Support. |
References
Bug:28023081 (This link will only work for PUBLISHED bugs)
Note:245840.1 Information on the sections in this article
