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https://issues.apache.org/jira/browse/PHOENIX-1594?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14280696#comment-14280696
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Jeffrey Zhong edited comment on PHOENIX-1594 at 1/16/15 7:26 PM:
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I tested the case with multiple CFs. Below are some traces from test case
MultiCfQueryExecIT#testConstantCount
{noformat}
{"timeRange":[0,105],"batch":-1,"startRow":"","stopRow":"","loadColumnFamiliesOnDemand":null,"totalColumns":1,"cacheBlocks":true,"families":{"A":["_0"]},"maxResultSize":-1,"maxVersions":1,"caching":1000}
{noformat}
What's the reason we have this condition "table.getColumnFamilies().size() ==
1"?
was (Author: jeffreyz):
I tested the case with multiple CFs. Below are some traces from test case
MultiCfQueryExecIT#testConstantCount
{noformat}
Getting iterators for ResultIterators
[name=PARALLEL,id=51bdea17-d965-4cf0-b2c1-84044026b465,scans=[[{"timeRange":[0,103],"batch":-1,"startRow":"","stopRow":"","loadColumnFamiliesOnDemand":null,"totalColumns":7,"cacheBlocks":false,"families":{"D":["ALL"],"E":["ALL"],"F":["ALL"],"G":["ALL"],"A":["ALL"],"B":["ALL"],"C":["ALL"]},"maxResultSize":-1,"maxVersions":1,"caching":-1}]]]
{noformat}
What's the reason we have this condition "table.getColumnFamilies().size() ==
1"?
> Using KeyOnlyFilter for simple query "select count(1) from <table>"
> -------------------------------------------------------------------
>
> Key: PHOENIX-1594
> URL: https://issues.apache.org/jira/browse/PHOENIX-1594
> Project: Phoenix
> Issue Type: Improvement
> Reporter: Jeffrey Zhong
>
> I found that underlying scan for query "select count(1) or count(*) from
> <table>" still project all columns.
> It should be fast if we use KeyOnlyFilter for this simple query.
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