Change temp table name used to IMMV to some less frequent sequence of…

[reshke]

Currently, if user run CREATE TEMP TABLE t(); in their session, IVM will fail. Change its name with generated one, which has a little probability to cause problems.

Also, i added some debug logging and CBDB_IVM_FIXME comment that I feel needed.

[yjhjstz]

think about schema to solve this ?

[reshke]

think about schema to solve this ?

Temporary tables exist in a special schema, so a schema name cannot be given when creating a temporary table.[1]

[1] https://www.postgresql.org/docs/current/sql-createtable.html

reshke=# create temp table ex.t();
ERROR:  cannot create temporary relation in non-temporary schema
LINE 1: create temp table ex.t();
                          ^

[yjhjstz]

think about schema to solve this ?

Temporary tables exist in a special schema, so a schema name cannot be given when creating a temporary table.[1]

[1] https://www.postgresql.org/docs/current/sql-createtable.html

reshke=# create temp table ex.t();
ERROR:  cannot create temporary relation in non-temporary schema
LINE 1: create temp table ex.t();
                          ^

I may found a way out:
refer to refresh_by_match_merge, make_new_heap of RELPERSISTENCE_TEMP tablespace, that will not confilct.

[reshke]

think about schema to solve this ?

Temporary tables exist in a special schema, so a schema name cannot be given when creating a temporary table.[1]
[1] https://www.postgresql.org/docs/current/sql-createtable.html

reshke=# create temp table ex.t();
ERROR:  cannot create temporary relation in non-temporary schema
LINE 1: create temp table ex.t();
                          ^

I may found a way out: refer to refresh_by_match_merge, make_new_heap of RELPERSISTENCE_TEMP tablespace, that will not confilct.

I'm not quite following you suggestion here... First of all, there are no RELPERSISTENCE_TEMP usage inside refresh_by_match_merge? Did you mean ExecRefreshMatView func? If so, it uses RELPERSISTENCE_TEMP, yes. It assigns this value to relpersistence under if-concurrent condition.

https://github.com/cloudberrydb/cloudberrydb/blob/dccc518bea74302c3aebbf446a6fa47f8510c12c/src/backend/commands/matview.c#L502-L506

Then it passes this variable to make_new_heap.

https://github.com/cloudberrydb/cloudberrydb/blob/dccc518bea74302c3aebbf446a6fa47f8510c12c/src/backend/commands/matview.c#L586-L589

In this function we have following:

	if (relpersistence == RELPERSISTENCE_TEMP)
		namespaceid = LookupCreationNamespace("pg_temp");
	else
		namespaceid = RelationGetNamespace(OldHeap);

https://github.com/cloudberrydb/cloudberrydb/blob/dccc518bea74302c3aebbf446a6fa47f8510c12c/src/backend/commands/cluster.c#L756-L759

So, this is the same as CREATE TEMP TABLE $name.

Do I miss something?

[yjhjstz]

yes, in ExecRefreshMatView, or make_new_heap conflict, we may need use tuplestore .

[yjhjstz]

LGTM