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https://issues.apache.org/jira/browse/PHOENIX-2702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15160291#comment-15160291
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Lars Hofhansl commented on PHOENIX-2702:
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I have since realized that we can use the below query to also estimate
size/rows based on the prefix of the key with this:
{noformat}
SELECT SUM(guide_posts_row_count) AS est_rows, SUM(guide_posts_width) AS
est_size from SYSTEM.STATS where physical_name = 'TEST' and guide_post_key >
2200000;
{noformat}
As long as the key-prefix itself is expressible in the shell we can do this. In
my case I had a numeric key, but I also tried with strings, etc.
> Show estimate rows and bytes touched in explain plan.
> -----------------------------------------------------
>
> Key: PHOENIX-2702
> URL: https://issues.apache.org/jira/browse/PHOENIX-2702
> Project: Phoenix
> Issue Type: Bug
> Reporter: Lars Hofhansl
> Assignee: Lars Hofhansl
> Fix For: 4.7.0
>
> Attachments: PHOENIX-2702.txt
>
>
> We can already estimate the size of a table (both rows and uncompressed
> bytes) with q query like this:
> {code}
> SELECT physical_name AS table_name, SUM(guide_posts_row_count) AS est_rows,
> SUM(guide_posts_width) AS est_size from SYSTEM.STATS GROUP BY physical_name;
> {code}
> During the planning phase we have more information, though. So we can report
> the actual numbers for a query during an explain since we have that info
> there anyway (we filtered the guidepost already with the key info provided in
> the query).
> I might whip up a quick patch for this.
> (Could also go further and add a est_count, est_size UDF for this, but that
> would be a bit harder to get hooked up at the right places, I think, and the
> meaning would be ambiguous)
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