Karan Mehta created PHOENIX-4328:
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Summary: Support clients having different
"phoenix.schema.mapSystemTablesToNamespace" property
Key: PHOENIX-4328
URL: https://issues.apache.org/jira/browse/PHOENIX-4328
Project: Phoenix
Issue Type: Bug
Reporter: Karan Mehta
Imagine a scenario when we enable namespaces for phoenix on the server side and
set the property {{phoenix.schema.isNamespaceMappingEnabled}} to true. A bunch
of clients are trying to connect to this cluster. All of these clients have
{{phoenix.schema.isNamespaceMappingEnabled}} to true, however
for some of them {{phoenix.schema.isNamespaceMappingEnabled}} is set to false
and it is true for others. (A typical case for rolling upgrade.)
The first client with {{phoenix.schema.mapSystemTablesToNamespace}} true will
acquire lock in SYSMUTEX and migrate the system tables. As soon as this
happens, all the other clients will start failing.
There are two scenarios here.
1. A new client trying to connect to server without this property set
This will fail since the ConnectionQueryServicesImpl checks if SYSCAT is
namespace mapped or not, If there is a mismatch, it throws an exception, thus
the client doesn't get any connection.
2. Clients already connected to cluster but don't have this property set
This will fail because every query calls the endpoint coprocessor on SYSCAT to
determine the PTable of the query table and the physical HBase table name is
resolved based on the properties. Thus, we try to call the method on SYSCAT
instead of SYS:CAT and it results in a TableNotFoundException.
This JIRA is to discuss about the potential ways in which we can handle this
issue.
Some ideas around this after discussing with [[email protected]]:
1. Build retry logic around the code that works with SYSTEM tables (coprocessor
calls etc.) Try with SYSCAT and if it fails, try with SYS:CAT
Cons: Difficult to maintain and code scattered all over.
2. Use SchemaUtil.getPhyscialTableName method to return the table name that
actually exists. (Only for SYSTEM tables)
Call admin.tableExists to determine if SYSCAT or SYS:CAT exists and return that
name. The client properties get ignored on this one.
Cons: Expensive call every time, since this method is always called several
times.
[~jamestaylor] [~elserj] [[email protected]] [~apurtell]
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