On 2019/03/02 4:15, Robert Haas wrote:
On Thu, Feb 28, 2019 at 11:54 PM Tatsuro Yamada
<yamada.tats...@lab.ntt.co.jp> wrote:
Attached patch is wip patch.
I rewrote the current design of the progress monitor and also
wrote discussion points in the middle of this email. I'd like to
get any feedback from -hackers.
=== Current design ===
CLUSTER command uses Index Scan or Seq Scan when scanning the heap.
Depending on which one is chosen, the command will proceed in the
following sequence of phases:
* Scan method: Seq Scan
0. initializing (*2)
1. seq scanning heap (*1)
3. sorting tuples (*2)
4. writing new heap (*1)
5. swapping relation files (*2)
6. rebuilding index (*2)
7. performing final cleanup (*2)
* Scan method: Index Scan
0. initializing (*2)
2. index scanning heap (*1)
5. swapping relation files (*2)
6. rebuilding index (*2)
7. performing final cleanup (*2)
VACUUM FULL command will proceed in the following sequence of phases:
1. seq scanning heap (*1)
5. swapping relation files (*2)
6. rebuilding index (*2)
7. performing final cleanup (*2)
(*1): increasing the value in heap_tuples_scanned column
(*2): only shows the phase in the phase column
The view provides the information of CLUSTER command progress details as follows
# \d pg_stat_progress_cluster
View "pg_catalog.pg_stat_progress_cluster"
Column | Type | Collation | Nullable | Default
---------------------------+---------+-----------+----------+---------
pid | integer | | |
datid | oid | | |
datname | name | | |
relid | oid | | |
command | text | | |
phase | text | | |
cluster_index_relid | bigint | | |
heap_tuples_scanned | bigint | | |
heap_tuples_vacuumed | bigint | | |
=== Discussion points ===
- Progress counter for "3. sorting tuples" phase
- Should we add pgstat_progress_update_param() in tuplesort.c like a
"trace_sort"?
Thanks to Peter Geoghegan for the useful advice!
- Progress counter for "6. rebuilding index" phase
- Should we add "index_vacuum_count" in the view like a vacuum progress
monitor?
If yes, I'll add pgstat_progress_update_param() to reindex_relation() of
index.c.
However, I'm not sure whether it is okay or not.
- pg_stat_progress_rewrite
- TBA
=== My test case ===
I share my test case of progress monitor.
If someone wants to watch the current progress monitor, you can use
this test case as a example.
[Terminal1]
Run this query on psql:
select * from pg_stat_progress_cluster; \watch 0.05
[Terminal2]
Run these queries on psql:
drop table t1;
create table t1 as select a, random() * 1000 as b from generate_series(0,
999999) a;
create index idx_t1 on t1(a);
create index idx_t1_b on t1(b);
analyze t1;
-- index scan
set enable_seqscan to off;
cluster verbose t1 using idx_t1;
-- seq scan
set enable_seqscan to on;
set enable_indexscan to off;
cluster verbose t1 using idx_t1;
-- only given table name to cluster command
cluster verbose t1;
-- only cluster command
cluster verbose;
-- vacuum full
vacuum full t1;
-- vacuum full
vacuum full;
Thanks,
Tatsuro Yamada
