We want to get current epoch and ahm_epoch value from the vertica.log on each node.

deepvertica

We want to get current epoch and ahm_epoch value from the vertica.log on each node.
Anyone, please advice me how to identify these value from vertica.log

deepvertica

Hello Jim,
Thanks for details clarification...

Jim_Knicely

The CE and AHM should be the same across the cluster unless a node is down.

dbadmin=> SELECT get_current_epoch(), get_ahm_epoch();
 get_current_epoch | get_ahm_epoch
-------------------+---------------
               906 |           904
(1 row)

You can find the AHM in the vertica.log file on each node with Linux commands... something like the following (I have 3 nodes, database name is test_db):

[dbadmin@vertica01 ~]$ ssh vertica01 "grep \"GetClusterAHMCandidate: My local node AHM candidate =\" /home/dbadmin/test_db/v_test_db_node0001_catalog/vertica.log | tail -1" | awk 'NF>1{print $NF}'
0x388

[dbadmin@vertica01 ~]$ ssh vertica02 "grep \"GetClusterAHMCandidate: My local node AHM candidate =\" /home/dbadmin/test_db/v_test_db_node0002_catalog/vertica.log | tail -1" | awk 'NF>1{print $NF}'
0x388

[dbadmin@vertica01 ~]$ ssh vertica03 "grep \"GetClusterAHMCandidate: My local node AHM candidate =\" /home/dbadmin/test_db/v_test_db_node0003_catalog/vertica.log | tail -1" | awk 'NF>1{print $NF}'
0x388

Note that the log file stores epochs in HEX. You can convert them to integer in Linux like this:

[dbadmin@vertica01 ~]$ printf '%d\n' "0x388"
904

Similarly, you can find the Current Epoch in Vertica logs...

[dbadmin@vertica01 v_test_db_node0001_catalog]$ ssh vertica01 "grep \"Commit Complete: Txn:\" /home/dbadmin/test_db/v_test_db_node0001_catalog/vertica.log | tail -1" | awk '{print $12}'
0x38a

[dbadmin@vertica01 v_test_db_node0001_catalog]$ ssh vertica02 "grep \"Commit Complete: Txn:\" /home/dbadmin/test_db/v_test_db_node0002_catalog/vertica.log | tail -1" | awk '{print $12}'
0x38a

[dbadmin@vertica01 v_test_db_node0001_catalog]$ ssh vertica03 "grep \"Commit Complete: Txn:\" /home/dbadmin/test_db/v_test_db_node0003_catalog/vertica.log | tail -1" | awk '{print $12}'
0x38a

[dbadmin@vertica01 v_test_db_node0001_catalog]$ printf '%d\n' "0x38a"
906

RaghavA

Hi,

Best method is to look for Epoch.log file which is located under your catalog directory:

catalog//v___catalog/Epoch.log

Jim_Knicely

Sure!

But the Epoch.log file, which is used during recovery to indicate the latest epoch that contains a complete set of data, is only there when the DB or node was shut down cleanly. It's not there on an up DB or after a crash.

Examples:

DB shut down cleanly (Epoch.log created):

[dbadmin@vertica01 v_test_db_node0001_catalog]$ ls *.log
bootstrap-catalog.log  editor.log  startup.log  vertica.log

[dbadmin@vertica01 v_test_db_node0001_catalog]$ admintools -t stop_db -d test_db
Info: no password specified, using none
        Connecting to database
        Issuing shutdown command to database
Database test_db stopped successfully

[dbadmin@vertica01 v_test_db_node0001_catalog]$ ls *.log
bootstrap-catalog.log  editor.log  Epoch.log  startup.log  vertica.log

Node shut down cleanly, after restarting the DB (Epoch.log created):

[dbadmin@vertica01 v_test_db_node0001_catalog]$ ls *.log
bootstrap-catalog.log  editor.log  startup.log  vertica.log

[dbadmin@vertica01 v_test_db_node0001_catalog]$ admintools -t stop_node -s vertica01
*** Forcing host shutdown ***
        Sending host shutdown command to '192.168.2.200'

[dbadmin@vertica01 v_test_db_node0001_catalog]$ ls *.log
bootstrap-catalog.log  editor.log  Epoch.log  startup.log  vertica.log

DB node killed, after restarting node from previous example (Epoch.log NOT created):

[dbadmin@vertica01 v_test_db_node0001_catalog]$ ls *.log
bootstrap-catalog.log  editor.log  startup.log  vertica.log

[dbadmin@vertica01 v_test_db_node0001_catalog]$ ps -ef | grep [c]atalog
dbadmin   15869      1  0 08:59 pts/0    00:00:00 /opt/vertica/spread/sbin/spread -c /home/dbadmin/test_db/v_test_db_node0001_catalog/spread.conf -D /opt/vertica/spread/tmp
dbadmin   15872      1 12 08:59 ?        00:00:10 /opt/vertica/bin/vertica -D /home/dbadmin/test_db/v_test_db_node0001_catalog -C test_db -n v_test_db_node0001 -h 192.168.2.200 -p 5433 -P 4803 -Y ipv4
dbadmin   15913  15872  0 08:59 ?        00:00:00 /opt/vertica/bin/vertica-udx-zygote 14 3 15872 debug-log-off /home/dbadmin/test_db/v_test_db_node0001_catalog/UDxLogs 60 15 0

[dbadmin@vertica01 v_test_db_node0001_catalog]$ kill -9 15869 15872 15913

[dbadmin@vertica01 v_test_db_node0001_catalog]$ admintools -t view_cluster -d test_db
 DB      | Host          | State
---------+---------------+-------
 test_db | 192.168.2.200 | DOWN
 test_db | 192.168.2.201 | UP
 test_db | 192.168.2.202 | UP

[dbadmin@vertica01 v_test_db_node0001_catalog]$ ls *.log
bootstrap-catalog.log  editor.log  startup.log  vertica.log

RaghavA

Hello Jim,

thanks for the clarification. In our case, most of the time, we find this file in our system so it is easy for us to use it.