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From: Andrew Dunstan on 9 Dec 2009 14:37

I have just noticed while checking the EXPLAIN YAML patch that the
non-text explain formats are output as a single line with embedded line
feeds, while the text format is delivered as a set of text records, one
per line. The practical effect of this is that psql decorates the
non-text format output with continuation characters:

andrew=# explain select count(*) from pg_class where relname ~ 'pg_';
QUERY PLAN
----------------------------------------------------------------
Aggregate (cost=9.67..9.68 rows=1 width=0)
-> Seq Scan on pg_class (cost=0.00..9.16 rows=204 width=0)
Filter: (relname ~ 'pg_'::text)
(3 rows)

Time: 5.813 ms
andrew=# explain (format yaml) select count(*) from pg_class where
relname ~ 'pg_';
QUERY PLAN
-----------------------------------------
- Plan: +
Node Type: Aggregate +
Strategy: Plain +
Startup Cost: 9.67 +
Total Cost: 9.68 +
Plan Rows: 1 +
Plan Width: 0 +
Plans: +
- Node Type: Seq Scan +
Parent Relationship: Outer +
Relation Name: pg_class +
Alias: pg_class +
Startup Cost: 0.00 +
Total Cost: 9.16 +
Plan Rows: 204 +
Plan Width: 0 +
Filter: (relname ~ 'pg_'::text)
(1 row)

Those + chars at the end of the line are ugly, to say the least, and
they make the supposedly machine-readable formats not so machine
readable if anyone wanted to c&p the output into a parser. (I'm mildly
surprised this hasn't been noticed before).

Maybe we need to teach psql not to do this formatting for EXPLAIN output?

cheers

andrew

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Prev: [HACKERS] 答复: questions about concurrency control in Postgresql
Next: explain output infelicity in psql