Slow delete with with cascading foreign keys - Mailing list pgsql-general

From Matthias Karlsson
Subject Slow delete with with cascading foreign keys
Date
Msg-id 83eb635f0810200546ta5798d1n45b3c03322099fd@mail.gmail.com
Whole thread Raw
Responses Re: Slow delete with with cascading foreign keys  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
Hi,

I have a rather complex set of relations, connected with cascading
foreign keys on delete. I'm experiencing very slow performance when
deleting *the* lead node, which everything eventually depends on. The
number of records ultimately to be deleted aren't that many (perhaps
2000-3000) but there are maybe 30 relations involved. I understand
that this is most likely due to missing indices, but I have been
unable to figure out how to get PostgreSQL to tell me where the
performance bottleneck is.

Say my simple query looks like "delete from foo where id = 1". An
"explain" on this won't yield any information for example.

Is there any way to get PostgreSQL to do an analys of a delete
statement like the way I need?

// Matthias

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