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https://issues.apache.org/jira/browse/PHOENIX-7026?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17784660#comment-17784660
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ASF GitHub Bot commented on PHOENIX-7026:
-----------------------------------------
palashc commented on code in PR #1726:
URL: https://github.com/apache/phoenix/pull/1726#discussion_r1388818014
##########
phoenix-core/src/main/java/org/apache/phoenix/monitoring/MetricType.java:
##########
@@ -150,6 +150,7 @@ public enum MetricType {
CLIENT_METADATA_CACHE_MISS_COUNTER("cmcm", "Number of cache misses for the
CQSI cache.", LogLevel.DEBUG, PLong.INSTANCE),
CLIENT_METADATA_CACHE_HIT_COUNTER("cmch", "Number of cache hits for the
CQSI cache.", LogLevel.DEBUG, PLong.INSTANCE),
PAGED_ROWS_COUNTER("prc", "Number of dummy rows returned to client due to
paging.", LogLevel.DEBUG, PLong.INSTANCE),
+ STALE_METADATA_CACHE_EXCEPTION_COUNTER("smcem", "Number of
StaleMetadataCacheException encountered.", LogLevel.DEBUG, PLong.INSTANCE),
Review Comment:
I think I wanted to add a `c` for counter and added `m` instead. I will
remove it.
> Validate LAST_DDL_TIMESTAMP for write requests.
> -----------------------------------------------
>
> Key: PHOENIX-7026
> URL: https://issues.apache.org/jira/browse/PHOENIX-7026
> Project: Phoenix
> Issue Type: Sub-task
> Components: core
> Reporter: Rushabh Shah
> Assignee: Palash Chauhan
> Priority: Major
>
> We need to validate LAST_DDL_TIMESTAMP for write requests.
> We can't create an extra RPC like we do for read requests (PHOENIX-7025)
> since the semantics for executeQuery() and executeMutation() is very
> different.
> The usual semantic for batch write requests (assuming auto commit OFF) is:
> {noformat}
> conn = DriverManager.getConnection(getUrl(), props);
> conn.createStatement().execute("upsert into foo values (1,2)");
> conn.createStatement().execute("upsert into foo values (3,4)");
> conn.createStatement().execute("upsert into foo values (5,6)");
> conn.createStatement().execute("upsert into bar values ('a','b')");
> conn.createStatement().execute("upsert into bar values ('c','d')");
> conn.commit();
> {noformat}
> If we introduce an RPC for every execute() method, then it increases the
> latency of the write request.
> There are 2 options I can think of:
> # Call validateDDLTimestamp rpc for the very first execute() method for
> every table in the batch.
> ** Pros:
> *** An extra RPC is made only once in the whole batch for every table.
> *** Easy to implement.
> *** In case of StaleMetadataCacheException, the retry is very easy to
> implement.
> ** Cons:
> # Call validateDDLTimestamp rpc for all the tables in the batch when we call
> conn.commit()
> ** Pros
> *** We add only 1 extra RPC irrespective of the number of tables in the
> batch.
> ** Cons
> *** In case of StaleMetadataCacheException, the retry becomes very complex.
> We will have to re-create all the mutations that we have created in the
> executeMutation phase.
> *** If autocommit is turned ON, then we introduce an extra RPC for every
> execute() call which will introduce regression in this feature.
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