Fix c77_dbh_get_mv_details to handle stats_reset outside aggregation
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Tom Rogers
parent
851e79f5c3
commit
b33df12dd8
@ -38,11 +38,39 @@ $$ LANGUAGE plpgsql;
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CREATE OR REPLACE FUNCTION public.c77_dbh_get_mv_details(p_mv_name text)
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RETURNS JSON AS $$
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DECLARE
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v_io_load numeric; -- Estimated I/O rate (blocks/sec)
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v_cpu_wait boolean; -- True if waiting on CPU
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v_mem_pressure numeric; -- Buffer hit ratio (lower = more memory pressure)
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v_io_load numeric; -- Blocks read per second
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v_cpu_time numeric; -- CPU time per call (ms)
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v_mem_hit_ratio numeric; -- Cache hit ratio
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v_has_pg_stat_statements boolean; -- Check if extension is available
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v_stats_reset timestamp; -- Time of last stats reset
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BEGIN
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-- Calculate system stats
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-- Check if pg_stat_statements is installed
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SELECT EXISTS (
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SELECT 1 FROM pg_extension WHERE extname = 'pg_stat_statements'
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) INTO v_has_pg_stat_statements;
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-- Get stats_reset separately for the current database
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SELECT stats_reset
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INTO v_stats_reset
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FROM pg_stat_database
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WHERE datname = current_database();
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-- If pg_stat_statements is available, use it for refined stats
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IF v_has_pg_stat_statements THEN
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SELECT
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COALESCE(SUM(s.shared_blks_read) / EXTRACT(EPOCH FROM (NOW() - v_stats_reset)), 0) AS io_load,
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COALESCE(SUM(s.total_time) / GREATEST(SUM(s.calls), 1), 0) AS cpu_time,
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CASE
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WHEN SUM(s.shared_blks_hit + s.shared_blks_read) = 0 THEN 1.0
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ELSE SUM(s.shared_blks_hit)::numeric / (SUM(s.shared_blks_hit) + SUM(s.shared_blks_read))
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END AS mem_hit_ratio
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INTO v_io_load, v_cpu_time, v_mem_hit_ratio
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FROM pg_stat_statements s
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JOIN pg_stat_database d ON s.dbid = d.datid
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WHERE s.query ILIKE '%REFRESH MATERIALIZED VIEW ' || p_mv_name || '%'
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AND d.datname = current_database();
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ELSE
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-- Fallback to basic stats without pg_stat_statements
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SELECT
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(d.blks_read + d.blks_hit) / EXTRACT(EPOCH FROM (NOW() - d.stats_reset)) AS io_load,
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EXISTS (
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@ -51,15 +79,16 @@ BEGIN
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WHERE query ILIKE '%REFRESH MATERIALIZED VIEW%'
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AND wait_event_type = 'CPU'
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AND state = 'active'
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) AS cpu_wait,
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)::numeric AS cpu_time, -- 1 if waiting, 0 if not (crude proxy)
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CASE
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WHEN b.buffers_clean + b.buffers_backend = 0 THEN 1.0
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ELSE b.buffers_clean::numeric / (b.buffers_clean + b.buffers_backend)
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END AS mem_pressure
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INTO v_io_load, v_cpu_wait, v_mem_pressure
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END AS mem_hit_ratio
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INTO v_io_load, v_cpu_time, v_mem_hit_ratio
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FROM pg_stat_database d
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CROSS JOIN pg_stat_bgwriter b
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WHERE d.datname = current_database();
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END IF;
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RETURN (
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SELECT json_build_object(
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@ -76,15 +105,15 @@ BEGIN
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ELSE 1
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END,
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'insight', CASE
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WHEN v_io_load > 1000 THEN 'Refreshes are slower due to high I/O load.'
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WHEN v_cpu_wait THEN 'Refreshes are slower due to CPU contention.'
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WHEN v_mem_pressure < 0.9 THEN 'Refreshes are slower due to memory pressure.'
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WHEN v_io_load > 100 THEN 'Refreshes are slower due to high I/O load.'
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WHEN v_cpu_time > (CASE WHEN v_has_pg_stat_statements THEN 1000 ELSE 0.5 END) THEN 'Refreshes are slower due to CPU usage.'
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WHEN v_mem_hit_ratio < 0.9 THEN 'Refreshes are slower due to memory pressure.'
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ELSE 'Refreshes are performing normally.'
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END,
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'action', CASE
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WHEN v_io_load > 1000 THEN 'Optimize I/O or schedule during off-peak hours.'
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WHEN v_cpu_wait THEN 'Increase CPU capacity or reduce concurrent load.'
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WHEN v_mem_pressure < 0.9 THEN 'Adjust memory settings (e.g., shared_buffers).'
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WHEN v_io_load > 100 THEN 'Optimize I/O or schedule during off-peak hours.'
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WHEN v_cpu_time > (CASE WHEN v_has_pg_stat_statements THEN 1000 ELSE 0.5 END) THEN 'Increase CPU capacity or optimize queries.'
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WHEN v_mem_hit_ratio < 0.9 THEN 'Adjust memory settings (e.g., work_mem, shared_buffers).'
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ELSE 'No action needed.'
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END,
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'details', json_build_object(
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@ -94,19 +123,25 @@ BEGIN
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'max_refresh_time', refresh_mv_time_max::text,
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'refresh_count', refresh_count,
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'io_load', round(v_io_load)::text || ' blocks/sec',
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'cpu_waiting', v_cpu_wait::text,
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'buffer_hit_ratio', round(v_mem_pressure * 100)::text || '%',
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'cpu_time', (CASE
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WHEN v_has_pg_stat_statements THEN round(v_cpu_time)::text || ' ms/call'
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ELSE (v_cpu_time * 100)::text || '% waiting'
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END),
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'buffer_hit_ratio', round(v_mem_hit_ratio * 100)::text || '%',
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'bottleneck', CASE
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WHEN v_io_load > 1000 THEN 'I/O'
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WHEN v_cpu_wait THEN 'CPU'
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WHEN v_mem_pressure < 0.9 THEN 'RAM'
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WHEN v_io_load > 100 THEN 'I/O'
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WHEN v_cpu_time > (CASE WHEN v_has_pg_stat_statements THEN 1000 ELSE 0.5 END) THEN 'CPU'
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WHEN v_mem_hit_ratio < 0.9 THEN 'RAM'
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ELSE 'None'
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END,
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'explanations', json_build_object(
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'last_refresh_time', 'Last refresh duration compared to historical min/max.',
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'io_load', 'High I/O load (blocks/sec) indicates disk operations are limiting performance.',
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'cpu_waiting', 'True if the refresh is waiting on CPU resources.',
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'buffer_hit_ratio', 'Lower ratio means more disk access due to memory pressure.'
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'io_load', 'Blocks read per second; high values indicate disk I/O bottleneck.',
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'cpu_time', (CASE
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WHEN v_has_pg_stat_statements THEN 'Average CPU time per refresh; high values suggest CPU bottleneck.'
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ELSE 'Percentage of time waiting on CPU (crude estimate).'
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END),
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'buffer_hit_ratio', 'Percentage of blocks from cache; <90% suggests memory pressure.'
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)
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)
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)
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