The Heartbeat Table of Oracle GoldenGate (12.2)

This post covers the Heartbeat table of Oracle Goldengate (12.2).

Monitoring lag in GoldenGate has always been an important part of monitoring GoldenGate.  Lags are reported in several ways.  When using the ggsci LAG command only the latest lag is reported with a 1-second resolution providing the last reported lag.  This isn’t trustworthy and nothing significant could be derived out of it!.

In the past, GoldenGate implementer has created heartbeat tables manually.

In Oracle GoldenGate 12.2 a built-in heartbeat table feature has been added.  This heartbeat table allows for more accurate heartbeats and heartbeat history.  It works by creating an artificial transaction every minute that contains timing information that is used for heartbeats.

The heartbeat tables are accessed via views that provide accurate lag data and lag history.

Note: If you would like to set up the older version of the heartbeat, use Oracle Support (MOS Note: 1299679.1) to reference the items needed.

Issue a “help” command from the GGSCI prompt, to notice there are now options to add a heartbeat table (similar to setting up the checkpoint table).

The image below shows the commands that are now available in GGSCI.

GGSCI> help

To create the heartbeat table, you need to run ADD HEARTBEATTABLE from GGSCI after logging into the database as the GoldenGate user.

After logging into the database and issuing the ADD HEARTBEATTABLE command, GoldenGate will create all the items needed for the heartbeat process to work.

ADD HEARTBEATTABE on target

GGSCI > add heartbeattable

Above command creates heartbeat table with the default name GG_HEARTBEAT under GOLDENGATE User. You can change the name of heartbeat table by defining under GLOBALS File of Goldengate.

You should see below output

2017-11-14 12:18:51  INFO    OGG-14001  Successfully created heartbeat seed table [“GG_HEARTBEAT_SEED”].

2017-11-14 12:18:51  INFO    OGG-14032  Successfully added supplemental logging for heartbeat seed table [“GG_HEARTBEAT_SEED”].

2017-11-14 12:18:51  INFO    OGG-14000  Successfully created heartbeat table [“GG_HEARTBEAT”].

2017-11-14 12:18:51  INFO    OGG-14033  Successfully added supplemental logging for heartbeat table [“GG_HEARTBEAT”].

2017-11-14 12:18:51  INFO    OGG-14016  Successfully created heartbeat history table [“GG_HEARTBEAT_HISTORY”].

2017-11-14 12:18:51  INFO    OGG-14023  Successfully created heartbeat lag view [“GG_LAG”].

2017-11-14 12:18:51  INFO    OGG-14024  Successfully created heartbeat lag history view [“GG_LAG_HISTORY”].

2017-11-14 12:18:51  INFO    OGG-14003  Successfully populated heartbeat seed table with [PDB2].

2017-11-14 12:18:51  INFO    OGG-14004  Successfully created procedure [“GG_UPDATE_HB_TAB”] to update the heartbeat tables.

2017-11-14 12:18:51  INFO    OGG-14017  Successfully created procedure [“GG_PURGE_HB_TAB”] to purge the heartbeat history table.

2017-11-14 12:18:51  INFO    OGG-14005  Successfully created scheduler job [“GG_UPDATE_HEARTBEATS”] to update the heartbeat tables.

2017-11-14 12:18:51  INFO    OGG-14018  Successfully created scheduler job [“GG_PURGE_HEARTBEATS”] to purge the heartbeat history table.

You will notice that the ADD HEARTBEAT command creates the following database objects under Goldengate user ggadmin:

Tables:
<heartbeat_table>_SEED (default GG_HEARTBEAT_SEED)
<heartbeat_table> (default GG_HEARTBEAT)
<heartbeat_table>_HISTORY (default GG_HEARTBEAT_HISTORY)

Views:
GG_LAG
GG_LAG_HISTORY

Stored Procedures:
GG_UPDATE_HB_TAB
GG_PURGE_HB_TAB

Scheduler Jobs:
GG_UPDATE_HEARTBEATS
GG_PURGE_HEARTBEATS

ADD HEARTBEATTABLE on Source

GGSCI > add heartbeattable

2017-11-14 01:07:51  INFO    OGG-14001  Successfully created heartbeat seed table [“GG_HEARTBEAT_SEED”].

2017-11-14 01:07:52  INFO    OGG-14032  Successfully added supplemental logging for heartbeat seed table [“GG_HEARTBEAT_SEED”].

2017-11-14 01:07:52  INFO    OGG-14000  Successfully created heartbeat table [“GG_HEARTBEAT”].

2017-11-14 01:07:52  INFO    OGG-14033  Successfully added supplemental logging for heartbeat table [“GG_HEARTBEAT”].

2017-11-14 01:07:52  INFO    OGG-14016  Successfully created heartbeat history table [“GG_HEARTBEAT_HISTORY”].

2017-11-14 01:07:52  INFO    OGG-14023  Successfully created heartbeat lag view [“GG_LAG”].

2017-11-14 01:07:52  INFO    OGG-14024  Successfully created heartbeat lag history view [“GG_LAG_HISTORY”].

2017-11-14 01:07:52  INFO    OGG-14003  Successfully populated heartbeat seed table with [PDB1].

2017-11-14 01:07:52  INFO    OGG-14004  Successfully created procedure [“GG_UPDATE_HB_TAB”] to update the heartbeat tables.

2017-11-14 01:07:52  INFO    OGG-14017  Successfully created procedure [“GG_PURGE_HB_TAB”] to purge the heartbeat history table.

2017-11-14 01:07:52  INFO    OGG-14005  Successfully created scheduler job [“GG_UPDATE_HEARTBEATS”] to update the heartbeat tables.

2017-11-14 01:07:52  INFO    OGG-14018  Successfully created scheduler job [“GG_PURGE_HEARTBEATS”] to purge the heartbeat history table.

Once the heartbeat table was created it should have been an easy matter to go to the target system and query the ggadmin.gg_heartbeat and ggadmin.gg_heartbeat_history tables to see the automated heartbeats.

Managing Heartbeat Data

As seen above the heartbeat table is created via the ADD HEARTBEATTABLE command within GGSCI.  By default a heartbeat is generated every minute, kept for 30 days then purged.

The frequency of the heartbeat, the history retention and how often the purge process runs is configurable.  This is done via the ALTER HEARTBEATTABLE command.

Viewing Heartbeat Data

Viewing the heartbeat table is done via the two heartbeat views; GG_LAG and GG_LAG_history.  These views provide information on lags for each set of ext -> pump -> replicat that is configured.

This information, as well as the history, is valuable for monitoring the performance of the GoldenGate configuration.

The output of the lag history can monitor lags over long periods of time and be used for alerting and monitoring.  The lag history can be imported into a spreadsheet and graphed.

Unlike the old way of creating a heartbeat where GoldenGate used triggers; it is now using stored procedures to populate the tables. Then just like the old way, a scheduler job is used to execute the stored procedures to update or purge the tables. The main difference compared to the old heartbeat way is that there are views used to calculate the lag between processes.

Related/Further Reading: