Re: Add YAML option to explain

On Mon, Aug 31, 2009 at 02:15:08PM -0000, Greg Sabino Mullane wrote:
> > Greg, can we see a few examples of the YAML output
> > compared to both json and text?
...
> greg=# explain (format json, analyze on) select * from pg_class where relname ~ 'x' order by 1,2,3;
> QUERY PLAN
> - -----------------------------------------------------------

An interesting property of json, it is almost exactly the same as python
data structure syntax. If I paste the following into python:

plan = [
{
"Plan": {
"Node Type": "Sort",
"Startup Cost": 12.82,
"Total Cost": 13.10,
"Plan Rows": 111,
"Plan Width": 185,
"Actual Startup Time": 1.152,
"Actual Total Time": 1.373,
"Actual Rows": 105,
"Actual Loops": 1,
"Sort Key": ["relname", "relnamespace", "reltype"],
"Sort Method": "quicksort",
"Sort Space Used": 44,
"Sort Space Type": "Memory",
"Plans": [
{
"Node Type": "Seq Scan",
"Parent Relationship": "Outer",
"Relation Name": "pg_class",
"Alias": "pg_class",
"Startup Cost": 0.00,
"Total Cost": 9.05,
"Plan Rows": 111,
"Plan Width": 185,
"Actual Startup Time": 0.067,
"Actual Total Time": 0.817,
"Actual Rows": 105,
"Actual Loops": 1,
"Filter": "(relname ~ 'x'::text)"
}
]
},
"Triggers": [
],
"Total Runtime": 1.649
}
]

I get a python data structure. Which can be manipulated directly, or pretty
printed:

>>> import pprint
>>> pprint.pprint(plan)
[{'Plan': {'Actual Loops': 1,
'Actual Rows': 105,
'Actual Startup Time': 1.1519999999999999,
'Actual Total Time': 1.373,
'Node Type': 'Sort',
'Plan Rows': 111,
'Plan Width': 185,
'Plans': [{'Actual Loops': 1,
'Actual Rows': 105,
'Actual Startup Time': 0.067000000000000004,
'Actual Total Time': 0.81699999999999995,
'Alias': 'pg_class',
'Filter': "(relname ~ 'x'::text)",
'Node Type': 'Seq Scan',
'Parent Relationship': 'Outer',
'Plan Rows': 111,
'Plan Width': 185,
'Relation Name': 'pg_class',
'Startup Cost': 0.0,
'Total Cost': 9.0500000000000007}],
'Sort Key': ['relname', 'relnamespace', 'reltype'],
'Sort Method': 'quicksort',
'Sort Space Type': 'Memory',
'Sort Space Used': 44,
'Startup Cost': 12.82,
'Total Cost': 13.1},
'Total Runtime': 1.649,
'Triggers': []}]

I'm not sure if all json can be read this way, but the python and json
notations are very similar.

-dg

--
David Gould daveg(at)sonic(dot)net 510 536 1443 510 282 0869
If simplicity worked, the world would be overrun with insects.