Re: Explain analyze

On 30/04/16 23:52, Shmagi Kavtaradze wrote:

Thanks for answer. I ran "trace select count(*) from view" and it returned "user | statement" that I really could not understand. In documentation I saw it should return :

What you see is the projection over clk/stmt of the underlying tracelog table. This is sufficient for understanding where the time goes. See updated doc page or further https://www.monetdb.org/Documentation/Manuals/MonetDB/Profiler/TraceFormat

create function sys.tracelog() returns table ( event integer, -- event counter clk varchar(20), -- wallclock, no mtime in kernel pc varchar(50), -- module.function[nr] thread int, -- thread identifier ticks bigint, -- time in microseconds rrsMB bigint, -- resident memory in MB vmMB bigint, -- virtual size in MB reads bigint, -- number of blocks read writes bigint, -- number of blocks written minflt bigint, -- minor page faults majflt bigint, -- major page faults nvcsw bigint, -- non-volantary conext switch stmt string -- actual statement executed )

Any idea how to get user friendly answer for trace?

On Sat, Apr 30, 2016 at 2:18 PM, Martin Kersten mailto:martin.kersten@cwi.nl> wrote:

See the documentation:https://www.monetdb.org/Documentation/Cookbooks/SQLrecipes/QueryTiming

MonetDB does not contain a cost-based optimizer as you find in other systems.

You can use both 'EXPLAIN SELECT....' and 'TRACE SELECT ....' to get insight into the expensive components.

On 30/04/16 12:41, Shmagi Kavtaradze wrote:

In postgres I could use explain analyze to see actions performed by database and their cost. I was not able to run explain analyze. I ran EXPLAIN, but can not see any plan or cost. Any ideas how to get costs and query plan like in Postgres?

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