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https://issues.jboss.org/browse/TEIID-4768?page=com.atlassian.jira.plugin...
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Ramesh Reddy commented on TEIID-4768:
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There is no 5 minute minimum. When there is error with either source databases or target
materialization database (as in they are down and not available), the retry logic has time
calculation like below to schedule the next run
{code}
MATH.min(ttl/4, 60000)
{code}
So, if TTL was 30 secs, then every 7.5 seconds it will retry. Each time it retries it sets
the {{Status}} table to "LOADING", then when it fails then it flips back to
"FAILED_LOAD". Now depending upon, if view tables's source database is down,
then materialization process fails immediately, that means the {{Status}} could see
"FAILED_LOAD" for 7.5 secs before flipped back to "LOADING". If target
database is down, then process fails when the materialization process starts writing
results to the target database. That means the "LOADING" will appear for amount
of time look to write first row to the target database, which can be long time based on
view, then when it fails, it flips back to "FAILED_LOAD" for 7.5 seconds before
retrying. For user who is monitoring the {{Status}} table manually, this could appear that
the {{Status}} table is struck at "LOADING", but in fact that is not the case.
See more investigation in TEIID-4758.
My suggestion to [~van.halbert] was to use a large enough TTL where he has time to
manually verify.
Clarify Caching guide using external materializaion
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Key: TEIID-4768
URL:
https://issues.jboss.org/browse/TEIID-4768
Project: Teiid
Issue Type: Enhancement
Components: Documentation
Affects Versions: 9.3
Reporter: Van Halbert
Assignee: Ramesh Reddy
Priority: Critical
The caching guide section that relates to external materialization needs to add the
following information for clarity:
- the TTL needs to be set at a minimum of 5 minutes (300000) so in cases where the
status gets hung at "LOADING" (i.e., the target cache goes down during
materialization), the materialization process will recover and restart the loading.
- add a status table "Status" matrix:
LOADED - means the cache was loaded
LOADING - means cache is in the process of loading
FAILED_LOAD - means an error occurred during the load process
...
and these should correlate to the section that describes the process in detail.
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