Re: [HACKERS] Solution for LIMIT cost estimation

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От Hannu Krosing
Тема Re: [HACKERS] Solution for LIMIT cost estimation
Дата
Msg-id 38A43BA7.7E172DB3@tm.ee
обсуждение исходный текст
Ответ на Solution for LIMIT cost estimation  (Tom Lane <tgl@sss.pgh.pa.us>)
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"Ross J. Reedstrom" wrote:
> 
> 
> the SQL3 draft that Chris pointed me at (Aug94) only mentions LIMIT as a
> limit clause of a RECURSIVE UNION, whatever that is. (No time to examine
> it right now) This is from the file sql-foundation-aug94.txt.
> 

If I understood it right, RECURSIVE UNION is a way to query a tree
structured 
table, whith parent_id's in each child row.

AFAIK even have it in the TODO list ;)

The LIMIT there probably limits how many levels down the tree are
queried.

---------
Hannu


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