Horton

Re: SEARCH and CYCLE clauses

Peter Eisentraut <peter.eisentraut@2ndquadrant.com>

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From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
To: pgsql-hackers <pgsql-hackers@postgresql.org>
Cc: Vik Fearing <vik@postgresfriends.org>
Date: 2020-07-03T07:08:26Z
Lists: pgsql-hackers

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While the larger patch is being considered, I think some simpler and 
separable pieces could be addressed.

Here is a patch that adjusts the existing cycle detection example and 
test queries to put the cycle column before the path column.  The CYCLE 
clause puts them in that order, and so if we added that feature that 
would make the sequence of examples more consistent and easier to follow.

(And while the order of columns has no semantic meaning, for a human 
left-to-right reader it also makes a bit more sense because the cycle 
flag is computed against the previous path value, so it happens "before" 
the path column.)

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Enhanced cycle mark values

  2. SEARCH and CYCLE clauses

  3. doc: Expand recursive query documentation

  4. Adjust cycle detection examples and tests