SPI Interface to Call Procedure with Transaction Control Statements?

[Jack LIU]

Hi All,

I sent an email with the same problem in pgsql-general mailing but no one
has responded, so I try to reach out by asking this question in the hacker
list.

In PG-11, procedures were introduced. In the pg_partman PostgreSQL
extension, a procedure named run_maintenance_proc was developed to replace
run_maintenance function. I was trying to call this procedure in pg_partman
with SPI_execute() interface and this is the command being executed:
CALL "partman".run_maintenance_proc(p_analyze := true, p_jobmon := true)

Detailed code please see: https://github.com/pgpartman/pg_partman/pull/242

 I received the following error:

2019-01-02 20:13:04.951 PST [26446] ERROR:  invalid transaction termination
2019-01-02 20:13:04.951 PST [26446] CONTEXT:  PL/pgSQL function
partman.run_maintenance_proc(integer,boolean,boolean,boolean) line 45
at COMMIT

Apparently, the transaction control command 'COMMIT' is not allowed in a
procedure CALL function. But I can CALL this procedure in psql directly.

According to the documentation of CALL, "If CALL is executed in a
transaction block, then the called procedure cannot execute transaction
control statements. Transaction control statements are only allowed if CALL is
executed in its own transaction."

Therefore, it looks like that SPI_execute() is calling the procedure within
a transaction block. So Is there any SPI interface that can be used in an
extension library to call a procedure with transaction control commands? (I
tried to use SPI_connect_ext(SPI_OPT_NONATOMIC) to establish a nonatomic
connection but it doesn't help.)

Thanks,

Jiayi Liu

Re: SPI Interface to Call Procedure with Transaction Control Statements?

[Jack LIU]

Hi Andrew,

This is my code to call the procedure with
SPI_connect_ext(SPI_OPT_NONATOMIC).

if (run_proc) {
appendStringInfo(&buf, "CALL \"%s\".run_maintenance_proc(p_analyze
:= %s, p_jobmon := %s);", partman_schema, analyze, jobmon);
expected_ret = SPI_OK_UTILITY;
function_run = "run_maintenance_proc() procedure";
SPI_finish();
SPI_connect_ext(SPI_OPT_NONATOMIC);
pgstat_report_activity(STATE_RUNNING, buf.data);

ret = SPI_execute(buf.data, false, 0);
if (ret != expected_ret)
elog(FATAL, "Cannot call pg_partman %s: error code %d",
function_run, ret);
}

It gave the same error:

2019-01-14 22:18:56.898 PST [16048] LOG:  pg_partman dynamic background
worker (dbname=postgres) dynamic background worker initialized with role
ubuntu on database postgres
2019-01-14 22:18:56.918 PST [16048] ERROR:  invalid transaction termination
2019-01-14 22:18:56.918 PST [16048] CONTEXT:  PL/pgSQL function
partman.run_maintenance_proc(integer,boolean,boolean,boolean) line 45 at
COMMIT
SQL statement "CALL "partman".run_maintenance_proc(p_analyze := true,
p_jobmon := true);"
2019-01-14 22:18:56.923 PST [26352] LOG:  background worker "pg_partman
dynamic background worker (dbname=postgres)" (PID 16048) exited with exit
code 1

Thanks,

Jack

On Sun, Jan 13, 2019 at 10:21 PM Andrew Gierth 
wrote:

> >>>>> "Jack" == Jack LIU  writes:
>
>  Jack> (I tried to use SPI_connect_ext(SPI_OPT_NONATOMIC) to establish a
>  Jack> nonatomic connection but it doesn't help.)
>
> You need to be specific here about how it didn't help, because this is
> exactly what you're supposed to do, and it should at least change what
> error you got.
>
> --
> Andrew (irc:RhodiumToad)
>