如何获得 pg_stat_user_tables n_tup_ins 时间刻度的压缩 table？

Question

我们设置了一个 Prometheus Postgres Exporter，希望我们可以获得插入到 table

中的行的统计信息

pg_stat_user_tables:
      query: |
       SELECT
         current_database() datname,
         schemaname,
         relname,
         seq_scan,
         seq_tup_read,
         idx_scan,
         idx_tup_fetch,
         n_tup_ins,
         n_tup_upd,
         n_tup_del,
         n_tup_hot_upd,
         n_live_tup,
         n_dead_tup,
         n_mod_since_analyze,
         COALESCE(last_vacuum, '1970-01-01Z') as last_vacuum,
         COALESCE(last_autovacuum, '1970-01-01Z') as last_autovacuum,
         COALESCE(last_analyze, '1970-01-01Z') as last_analyze,
         COALESCE(last_autoanalyze, '1970-01-01Z') as last_autoanalyze,
         vacuum_count,
         autovacuum_count,
         analyze_count,
         autoanalyze_count
       FROM
         pg_stat_user_tables
      metrics:
        - datname:
            usage: "LABEL"
            description: "Name of current database"
        - schemaname:
            usage: "LABEL"
            description: "Name of the schema that this table is in"
        - relname:
            usage: "LABEL"
            description: "Name of this table"
        - seq_scan:
            usage: "COUNTER"
            description: "Number of sequential scans initiated on this table"
        - seq_tup_read:
            usage: "COUNTER"
            description: "Number of live rows fetched by sequential scans"
        - idx_scan:
            usage: "COUNTER"
            description: "Number of index scans initiated on this table"
        - idx_tup_fetch:
            usage: "COUNTER"
            description: "Number of live rows fetched by index scans"
        - n_tup_ins:
            usage: "COUNTER"
            description: "Number of rows inserted"
        - n_tup_upd:
            usage: "COUNTER"
            description: "Number of rows updated"
        - n_tup_del:
            usage: "COUNTER"
            description: "Number of rows deleted"
        - n_tup_hot_upd:
            usage: "COUNTER"
            description: "Number of rows HOT updated (i.e., with no separate index update required)"
        - n_live_tup:
            usage: "GAUGE"
            description: "Estimated number of live rows"
        - n_dead_tup:
            usage: "GAUGE"
            description: "Estimated number of dead rows"
        - n_mod_since_analyze:
            usage: "GAUGE"
            description: "Estimated number of rows changed since last analyze"
        - last_vacuum:
            usage: "GAUGE"
            description: "Last time at which this table was manually vacuumed (not counting VACUUM FULL)"
        - last_autovacuum:
            usage: "GAUGE"
            description: "Last time at which this table was vacuumed by the autovacuum daemon"
        - last_analyze:
            usage: "GAUGE"
            description: "Last time at which this table was manually analyzed"
        - last_autoanalyze:
            usage: "GAUGE"
            description: "Last time at which this table was analyzed by the autovacuum daemon"
        - vacuum_count:
            usage: "COUNTER"
            description: "Number of times this table has been manually vacuumed (not counting VACUUM FULL)"
        - autovacuum_count:
            usage: "COUNTER"
            description: "Number of times this table has been vacuumed by the autovacuum daemon"
        - analyze_count:
            usage: "COUNTER"
            description: "Number of times this table has been manually analyzed"
        - autoanalyze_count:
            usage: "COUNTER"
            description: "Number of times this table has been analyzed by the autovacuum daemon"

但是对于压缩的 tables，我们没有得到任何统计数据，就像它不是按时间尺度计算的一样。

Table创建如下：

– Create hypertable
SELECT create_hypertable('our_table', 'timestamp', 'unit_id', 1,
if_not_exists => true, chunk_time_interval => INTERVAL '1 day'
);

-- Add compression policy
SELECT add_compression_policy('our_table', INTERVAL '1 day');

-- Enable compression
ALTER TABLE our_tableSET (
 timescaledb.compress,
 timescaledb.compress_segmentby = 'unit_id'
);

– Compress chunks older then 1 day
SELECT compress_chunk(i)
FROM show_chunks('our_table', older_than => INTERVAL '1 day') i;

什么是 pg_stats 来为这种 table 插入行？有可能吗？

可以清楚地看到，统计数据是针对各个区块计算的，我们看到了区块输入率。有没有一种方法可以查询一些时间尺度的东西，看看是否插入了特定的逻辑 table 数据（看的不是 chinks，而是我们的 table 统计数据）？

pg_stat_user_tables_n_tup_ins{datname="postgres",relname="_hyper_1_489_chunk",schemaname="_timescaledb_internal",server="timescaledb2:5432"} 92106

Answer 1

我不确定我是否理解“所有受影响的表”是什么意思，但是要在单个查询中获取所有超表，您可以使用 ::regclass 转换超表名称。来自一些具有一些随机超表的游乐场数据库的示例：

playground=# select hypertable_name, approximate_row_count(hypertable_name::regclass) from timescaledb_information.hypertables ;
┌──────────────────┬───────────────────────┐
│ hypertable_name  │ approximate_row_count │
├──────────────────┼───────────────────────┤
│ batteries        │                     0 │
│ conditions       │               1000000 │
│ default_forecast │                     0 │
│ forecast         │               1321500 │
│ metrics          │               3162240 │
│ ticks            │                  7202 │
└──────────────────┴───────────────────────┘
(6 rows)

如何获得 pg_stat_user_tables n_tup_ins 时间刻度的压缩 table？

How to get pg_stat_user_tables n_tup_ins for timescale's compressed table?

postgresql

pg-stat-statements

prometheus

timescaledb

prometheus-postgres-exporter