Dimitris Tsirogiannis has posted comments on this change.

Change subject: IMPALA-5538: Use explicit catalog versions for deleted objects
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Patch Set 5:

(2 comments)

Addressing some questions by Dan.

http://gerrit.cloudera.org:8080/#/c/7731/5/common/thrift/CatalogInternalService.thrift
File common/thrift/CatalogInternalService.thrift:

PS5, Line 38: empty list if no objects detected in the Catalog
> s/through/trouble/g
Yes, there is some context that is missing here, hence it's not easy to 
understand what these comments mean. Let me try to explain first here and I 
will expand the comments to clarify some things. 

1. What I think that comment should say is "no deleted objects were detected 
since the last GetAllCatalogObjects request". 

2. Similarly to the previous comment. Deleted and updated/new objects are with 
respect to the previous GetAllCatalogObjects call. The base from which these 
deltas are computed is the "fromVersion" param of the TGetAllCatalogObjects 
struct. 

I'll update the comments.


http://gerrit.cloudera.org:8080/#/c/7731/5/common/thrift/StatestoreService.thrift
File common/thrift/StatestoreService.thrift:

Line 84:   // is not included in the topic key (e.g. catalog version of deleted 
catalog objects).
> Sorry, opaque was the wrong word. I meant to say agnostic.
Let me try to explain. Statestore only uses that flag to avoid sending deleted 
topic entries when the topic update is not a delta one (this is an 
optimization). The statestore subscribers (e.g. impalad) are the ones that 
really need what's in the 'value' field in order to determine how to process a 
deleted topic entry. For the case of catalog update, the value contains among 
other things the catalog version when the deletion occurred and the impalad 
uses that information to determine if the deletion should be applied at the 
local catalog or not. 

We can definitely add the deleted flag inside whatever object we're putting in 
'value' (e.g. TCatalogObject) and I am happy to try this out if you think it's 
better.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I93cb7a033dc8f0d3e0339394b36affe14523274c
Gerrit-PatchSet: 5
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Dimitris Tsirogiannis <dtsirogian...@cloudera.com>
Gerrit-Reviewer: Alex Behm <alex.b...@cloudera.com>
Gerrit-Reviewer: Bharath Vissapragada <bhara...@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dhe...@cloudera.com>
Gerrit-Reviewer: Dimitris Tsirogiannis <dtsirogian...@cloudera.com>
Gerrit-Reviewer: Vuk Ercegovac <vercego...@cloudera.com>
Gerrit-HasComments: Yes

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