HAWQ-47. Make user able to set statement level resource usage.

[jiny2]

user can use the following statements to set statement level resource quota. When statement level resource quota is active, target hawq resource queue setting is almost all ignored, only the resource queue capacity is considered, i.e. user can not set resource quota more than maximum capacity of the target queue.

the vseg memory can only be chosen from finite value sets : 128mb, 256mb, 512mb, 1024mb/1gb, 2048mb/2gb, 4096mb/4gb, ..., 16384mb/16gb

postgres=# show hawq_rm_stmt_nvseg;

hawq_rm_stmt_nvseg

0
(1 row)

postgres=# show hawq_rm_stmt_vseg_memory;

hawq_rm_stmt_vseg_memory

128mb
(1 row)

postgres=# set hawq_rm_stmt_nvseg=8;
SET
postgres=# set hawq_rm_stmt_vseg_memory='1gb';
SET
postgres=# insert into t values(1);
INSERT 0 1

postgres=# set hawq_rm_stmt_nvseg=10; -- in case setting too much resource!
SET
postgres=# insert into t values(1);
ERROR: failed to acquire resource because of remote error expecting too many virtual segments. (pquery.c:798)

Some error message refinement changes are also included.

[jiny2]

Update error manage to ERROR: failed to acquire resource because of expecting too many virtual segments.

[linwen]

code indent, "}" at the next line should match "{"

[jiny2]

I did not find the mismatch.

[linwen]

Looks good, except some code indent.

[amyrazz44]

Looks good to me