[PHOENIX-2702] Show estimate rows and bytes touched in explain plan.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.7.0
• Assignee: Lars Hofhansl
• Reporter: Lars Hofhansl
• Created: 21/Feb/16 19:16
• Updated: 25/Feb/16 19:08
• Resolved: 22/Feb/16 06:34

Description

We can already estimate the size of a table (both rows and uncompressed bytes) with q query like this:

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;

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)