ANALYZE'ing table hierarchies - Mailing list pgsql-admin

Hello,

I have a question about running ANALYZE on table hierarchies.

The documentation page for partitioning mentions the need to manually issue VACUUM and ANALYZEs for each partition (http://www.postgresql.org/docs/9.4/static/ddl-partitioning.html#DDL-PARTITIONING-CAVEATS), while the page for ANALYZE (http://www.postgresql.org/docs/9.4/static/sql-analyze.html) mentions it does gather statistics for the master table and its children.

When I ANALYZE a master table PostgreSQL says it is working on the entire hierarchy and automatically ANALYZEs the child tables. However, the last_analyze column stays empty for the child tables on pg_stat_user_tables.

I find this somewhat confusing, what is the expected behavior? I figure the child tables have been properly ANALYZEd, but I can't find it registered anywhere. It would be nice to be able to parse pg_stat_user_tables for analyze statistics without having to worry about hierarchies, since each partition seems to have its own statistics for everything else.

      nunks=# analyze verbose tb05;

      INFO:  analyzing "public.tb05"

      INFO:  "tb05": scanned 0 of 0 pages, containing 0 live rows and 0 dead rows; 0 rows in sample, 0 estimated total rows

      INFO:  analyzing "public.tb05" inheritance tree

      INFO:  "tb05_2016": scanned 165 of 165 pages, containing 7465 live rows and 455 dead rows; 7465 rows in sample, 7465 estimated total rows

      INFO:  "tb05_2015": scanned 381 of 381 pages, containing 16281 live rows and 1504 dead rows; 16281 rows in sample, 16281 estimated total rows

      ANALYZE

      nunks=# select relname, last_analyze from pg_stat_user_tables where relname like 'tb05%';

        relname  |         last_analyze

      -----------+-------------------------------

       tb05      | 2016-02-18 22:47:32.770076-02

       tb05_2016 |

       tb05_2015 |

      (3 rows)

      nunks=# \d+ tb05;

                                                           Table "public.tb05"

               Column        |            Type             | Modifiers | Storage  | Stats target | Description

      ---------------------+-----------------------------+-----------+----------+--------------+-------------

        a                  | character varying(8)        | not null  | extended |              |

        b                  | date                        | not null  | plain    |              |

        c                  | timestamp without time zone | not null  | plain    |              |

        d                  | timestamp without time zone | not null  | plain    |              |

        e                  | bigint                      | not null  | plain    |              |

        f                  | bigint                      | not null  | plain    |              |

        g                  | bigint                      | not null  | plain    |              |

        h                  | bigint                      | not null  | plain    |              |

        i                  | bigint                      | not null  | plain    |              |

        j                  | bigint                      | not null  | plain    |              |

        k                  | bigint                      | not null  | plain    |              |

        l                  | bigint                      | not null  | plain    |              |

        m                  | bigint                      | not null  | plain    |              |

        n                  | bigint                      | not null  | plain    |              |

        o                  | bigint                      | not null  | plain    |              |

        p                  | bigint                      | not null  | plain    |              |

        q                  | bigint                      | not null  | plain    |              |

        r                  | bigint                      | not null  | plain    |              |

      Indexes:

            "tb05_pkey" PRIMARY KEY, btree (a, b)

      Triggers:

            tr_partition_tb05 BEFORE INSERT ON tb05 FOR EACH ROW EXECUTE PROCEDURE fn_partition_tb05()

      Child tables: tb05_2015,

                          tb05_2016

Thanks!

 Nunks