数据库日志相关参数：默认设置

log_destination = 'stderr'      # Valid values are combinations of# stderr, csvlog, syslog, and eventlog,# depending on platform.  csvlog# requires logging_collector to be on.logging_collector = on          # Enable capturing of stderr and csvlog
log_directory = 'sys_log'                       # directory where log files are written,
#log_filename = 'kingbase-%Y-%m-%d_%H%M%S.log'  # log file name pattern,
#log_file_mode = 0600                   # creation mode for log files,
#log_rotation_age = 1d                  # Automatic rotation of logfiles will(按时间自动轮换分割日志)
#log_rotation_size = 10MB               # Automatic rotation of logfiles will(按大小自动轮换分割日志)

其中log_destination包括stderr、csvlog和syslog，默认值是stderr格式，csvlog记录内容会比stderr更详细

—stderr时

[kingbase2@localhost sys_log]$ tail -1 kingbase-2023-01-04_000000.log
2023-01-04 14:12:56.979 CST [3037] STATEMENT:  select userid::regrole, dbid, query from sys_stat_statements order by mean_time desc limit 5;

—csvlog 时，会记录数据库、用户信息等

TEST=# alter system set log_destination ='csvlog';
ALTER SYSTEM
TEST=#
TEST=# select sys_reload_conf();sys_reload_conf
-----------------t
(1 row)TEST=# show log_destination ;log_destination
-----------------csvlog
(1 row)[kingbase2@localhost sys_log]$ tail -4 kingbase-2023-01-05_153654.csv
2023-01-05 15:39:13.368 CST,"system","test",4934,"[local]",63b67e91.1346,1,"idle",2023-01-05 15:38:57 CST,4/4681,0,ERROR,42601,"syntax error at or near ""switch""",,,,,,"alter system switch logfile;",14,,"kingbase_*&+_"

KingbaseES数据库日志查看方式只能到默认的sys_log目录下打开数据库日志查看，这种查看方式类似于oracle中的alert log

[kingbase2@localhost sys_log]$ cat  kingbase-2023-01-05_153654.csv |egrep error
2023-01-05 15:39:13.368 CST,"system","test",4934,"[local]",63b67e91.1346,1,"idle",2023-01-05 15:38:57 CST,4/4681,0,ERROR,42601,"syntax error at or near ""switch""",,,,,,"alter system switch logfile;",14,,"kingbase_*&+_"

但是有的时候我们会被这种显示格式困扰，不容易直观的查看。
下面介绍一种日志查看方式：

TEST=# CREATE   TABLE public.sys_log (
TEST(#      logtime timestamp with time zone,
TEST(#      loguser text,
TEST(#      logdatabase text,
TEST(#      logpid text,
TEST(#      loghost text,
TEST(#      logsessionid text,
TEST(#      logcmdcount text,
TEST(#      logcmdtag text,
TEST(#      logsessiontime timestamp with time zone,
TEST(#      logtransaction text,
TEST(#      log_level  text,
TEST(#      logseverity  text,
TEST(#      logstate text,
TEST(#      logmessage text,
TEST(#      logdetail text,
TEST(#      loghint text,
TEST(#      loginternalquery text,
TEST(#      loginternalquerypos text,
TEST(#      logcontext text,
TEST(#      logquery text,
TEST(#      logquerypos text,
TEST(#      loglocation text,
TEST(#      logapplicationname text);
CREATE TABLE
test=# copy public.sys_log from '/opt/Kingbase/ES/V8/data/sys_log/kingbase-2023-01-05_153654.csv' with csv;
COPY 1
test=# select * from public.sys_log limit 1;
TEST=# \x
Expanded display is on.
TEST=# select * from public.sys_log limit 1;
-[ RECORD 1 ]-------+---------------------------------
logtime             | 2023-01-06 05:39:13.368000+08
loguser             | system
logdatabase         | test
logpid              | 4934
loghost             | [local]
logsessionid        | 63b67e91.1346
logcmdcount         | 1
logcmdtag           | idle
logsessiontime      | 2023-01-06 05:38:57+08
logtransaction      | 4/4681
log_level           | 0
logseverity         | ERROR
logstate            | 42601
logmessage          | syntax error at or near "switch"
logdetail           |
loghint             |
loginternalquery    |
loginternalquerypos |
logcontext          |
logquery            | alter system switch logfile;
logquerypos         | 14
loglocation         |
logapplicationname  | kingbase_*&+_

注：
logtransaction 记录事务的一个位置
log_level 日志的级别
logseverity 对应FATAL, ERROR, WARN, INFO, ALL,等等，根据设置的level去记录对应的日志。
这样可以过滤出想要的内容，查看更加直观简洁，但只能每一个日志文件copy进去一张表中。

还有一种方法，可以使用file_fdw插件去直接读取数据库以外的日志文件，如下所示：

test=# create extension file_fdw;
CREATE EXTENSION
test=# \dx file_fdw;List of installed extensionsName   | Version | Schema |                Description
----------+---------+--------+-------------------------------------------file_fdw | 1.0     | public | foreign-data wrapper for flat file access
(1 row)创建外部表接口
test=# create server ser_file_fdw foreign data wrapper file_fdw;
CREATE SERVER查看外部服务接口
test=# \desList of foreign serversName     | Owner  | Foreign-data wrapper
--------------+--------+----------------------ser_file_fdw | system | file_fdwsysaudit_svr | system | sysaudit_fdw
(2 rows)创建外部表查看日志
test=# CREATE foreign TABLE public.sys_log_svt (
test(# logtime timestamp with time zone,
test(# loguser text,
test(# logdatabase text,
test(# logpid text,
test(# loghost text,
test(# logsessionid text,
test(# logcmdcount text,
test(# logcmdtag text,
test(# logsessiontime timestamp with time zone,
test(# logtransaction text,
test(# log_level text,
test(# logseverity text,
test(# logstate text,
test(# logmessage text,
test(# logdetail text,
test(# loghint text,
test(# loginternalquery text,
test(# loginternalquerypos text,
test(# logcontext text,
test(# logquery text,
test(# logquerypos text,
test(# loglocation text,
test(# logapplicationname text
<kingbase-2023-01-05_153654.csv',format 'csv',header 'true',delimiter ',',null ' ');
CREATE FOREIGN TABLEtest=# select * from sys_log_svt limit 1;
logtime | loguser | logdatabase | logpid | loghost | logsessionid | logcmdcount | logcmdtag |
logsessiontime | logtransaction | log_level | logseverity | logstate | logmessa
ge | logdetail | loghint
| loginternalquery | loginternalquerypos | logcontext | logquery
| logquerypos | loglocation | logapplicationname
-------------------------------+---------+-------------+--------+---------+---------------+-------------+-----------+---
---------------------+----------------+-----------+-------------+----------+--------------------------------------------
--------------------------------------+-----------+---------------------------------------------------------------------
------------------------------+------------------+---------------------+------------+-----------------------------------
--+-------------+-------------+--------------------
2023-01-06 08:42:16.201000+08 | system | test | 15396 | [local] | 63b6a982.3c24 | 1 | SELECT | 20
23-01-06 08:42:10+08 | 4/4954 | 0 | ERROR | 42883 | function to_datetime(integer, integer, inte
ger, integer, integer) does not exist | | No function matches the given name and argument types. You might nee
d to add explicit type casts. | | | | select to_datetime(2022,1,1,01,01)
; | 8 | | kingbase_*&+_
(1 row)

以上两种方法可以将数据库日志以数据库表的方式进行查看，可以过滤出想要的内容，查看更加简洁。