Autovacuum (analyze) on partitioned tables for ATTACH/DETACH/DROP commands

Hello,

While discussing auto analyze on partitioned tables, we recognized that
auto analyze should run on partitioned tables when ATTACH, DETACH
and DROP commands are executed [1]. Partitioned tables are checked
whether they need auto analyze according to their
changes_since_analyze (total number of inserts/updates/deletes on
partitions), but above DDL operations are not counted for now.

To support ATTACH, DETACH and DROP commands, I proposed
the idea as follows:
* I made new configuration parameters,
autovacuum_analyze_attach_partition,
autovacuum_analyze_detach_partition and
autovacuum_analyze_drop_partition to enable/disable this feature.
* When a partition is attached/detached/dropped, pgstat_report_anl_ancestors()
is called and checks the above configurations. If ture, the number of
livetuples of the partition is counted in its ancestor's changed tuples
in pgstat_recv_anl_ancestors.

Attach the v1 patch. What do you think?

[1] https://www.postgresql.org/message-id/ce5c3f04-fc17-7139-fffc-037f2c981bec%40enterprisedb.com
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Best regards,
Yuzuko Hosoya
NTT Open Source Software Center