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bford -, 03/22/2007 08:50 AM


these are work in progress reports:

'''Example of IO to locate the busy write tables, in order for this one to be really effective we need to collect information from the pg_statistic table.
'''
select ss.relid , s.relname, ((sum(sn_tup_ins)*1.5) + (sum(sn_tup_upd)*1.73) + sum(sn_tup_del)) AS weighted_io, date_trunc('day',insert_time) as "date", sum(sn_tup_ins) AS "insert",sum(sn_tup_upd) as "update", sum(sn_tup_del) as "delete" FROM (SELECT date_trunc('hour',(insert_time + '3 hours'::interval)) AS insert_time, relid, (max(n_tup_ins) - min(n_tup_ins)) AS sn_tup_ins, (max(n_tup_upd) - min(n_tup_upd)) AS sn_tup_upd, (max(n_tup_del) - min(n_tup_del)) AS sn_tup_del from public.myyearbook_pg_stat_user_tables where datname='myyearbook' and (insert_time + '3 hours'::interval)::date >= '2007-03-03' and (insert_time + '3 hours'::interval)::date < '2007-03-13' and date_part('hour', insert_time + '3 hours'::interval) > 13 GROUP BY 1,2) AS ss, (SELECT distinct relname, relid FROM public.myyearbook_pg_stat_user_tables) AS s WHERE ss.relid = s.relid GROUP BY 4, 1, 2 ORDER by ((sum(sn_tup_ins) + sum(sn_tup_upd)) > sum(sn_tup_del))<>'t', 3 DESC;

'''overview of tuples read:
'''
SELECT insert_time::date, SUM as seq_scan, sum(seq_tup_read) as seq_tup_read, sum(idx_scan) as idx_scan, sum(idx_tup_fetch) as idx_tup_fetch FROM (SELECT insert_time::date, relid,(max(seq_scan) - min(seq_scan)) AS seq_scan , (max(seq_tup_read) - min(seq_tup_read)) AS seq_tup_read, (max(idx_scan) - min(idx_scan)) AS idx_scan, (max(idx_tup_fetch) - min(idx_tup_fetch)) AS idx_tup_fetch from public.myyearbook_pg_stat_user_tables where datname='myyearbook' and insert_time::date >= '2007-03-03' and insert_time::date < '2007-03-13' group by 1,2) AS ss GROUP BY 1 ORDER BY 1 DESC;

'''overview of bytes read:
'''
SELECT insert_time::date, pg_size_pretty((max(blks_read-blks_hit) - min(blks_read-blks_hit))*8192) AS Bytes_read from public.myyearbook_pg_stat_database where datname='myyearbook' and insert_time::date >= '2007-03-03' and insert_time::date < '2007-03-13' group by 1 order by 1 desc;

'''Indexes that are not used, that are not unique and not primary keys:'''

select indexrelname FROM pg_stat_user_indexes JOIN pg_index ON (pg_index.indexrelid = pg_stat_user_indexes.indexrelid) where idx_scan = 0 and indisunique = 'f' and indisprimary = 'f' and idx_tup_read = 0 and idx_tup_fetch = 0;

''before we implement this we may want to rewrite the query to use pg_class instead as this is calling on a couple of views''

Updated by bford - about 17 years ago · 6 revisions