Several sources of index inflation:
1 After a large number of deletions occur, the index pages are sparse, reducing the index usage efficiency.
2 In versions before PostgresQL, vacuum full will also cause sparse index pages.
3 Long-running transactions prohibit the cleanup of tables by vacuum, which causes the sparse page status to remain.
View duplicate indexes
SELECT pg_size_pretty(SUM(pg_relation_size(idx))::BIGINT) AS SIZE, (array_agg(idx))[1] AS idx1, (array_agg(idx))[2] AS idx2, (array_agg(idx))[3] AS idx3, (array_agg(idx))[4] AS idx4 FROM ( SELECT indexrelid::regclass AS idx, (indrelid::text ||E'\n'|| indclass::text ||E'\n'|| indkey::text ||E'\n'|| COALESCE(indexprs::text,'')||E'\n' || COALESCE(indpred::text,'')) AS KEY FROM pg_index) sub GROUP BY KEY HAVING COUNT(*)>1 ORDER BY SUM(pg_relation_size(idx)) DESC;
The size of the table and the number of indexes in the table
SELECT , indexname, AS num_rows, pg_size_pretty(pg_relation_size(quote_ident()::text)) AS table_size, pg_size_pretty(pg_relation_size(quote_ident(indexrelname)::text)) AS index_size, CASE WHEN indisunique THEN 'Y' ELSE 'N' END AS UNIQUE, idx_scan AS number_of_scans, idx_tup_read AS tuples_read, idx_tup_fetch AS tuples_fetched FROM pg_tables t LEFT OUTER JOIN pg_class c ON = LEFT OUTER JOIN ( SELECT AS ctablename, AS indexname, AS number_of_columns, idx_scan, idx_tup_read, idx_tup_fetch, indexrelname, indisunique FROM pg_index x JOIN pg_class c ON = JOIN pg_class ipg ON = JOIN pg_stat_all_indexes psai ON = ) AS foo ON = WHERE ='public' ORDER BY 1,2;
Get the number of rows, indexes and some information about these indexes (more detailed)
SELECT pg_class.relname, pg_size_pretty(pg_class.reltuples::BIGINT) AS rows_in_bytes, pg_class.reltuples AS num_rows, COUNT(indexname) AS number_of_indexes, CASE WHEN x.is_unique = 1 THEN 'Y' ELSE 'N' END AS UNIQUE, SUM(CASE WHEN number_of_columns = 1 THEN 1 ELSE 0 END) AS single_column, SUM(CASE WHEN number_of_columns IS NULL THEN 0 WHEN number_of_columns = 1 THEN 0 ELSE 1 END) AS multi_column FROM pg_namespace LEFT OUTER JOIN pg_class ON pg_namespace.oid = pg_class.relnamespace LEFT OUTER JOIN (SELECT indrelid, MAX(CAST(indisunique AS INTEGER)) AS is_unique FROM pg_index GROUP BY indrelid) x ON pg_class.oid = LEFT OUTER JOIN ( SELECT AS ctablename, AS indexname, AS number_of_columns FROM pg_index x JOIN pg_class c ON = JOIN pg_class ipg ON = ) AS foo ON pg_class.relname = WHERE pg_namespace.nspname='public' AND pg_class.relkind = 'r' GROUP BY pg_class.relname, pg_class.reltuples, x.is_unique ORDER BY 2;
Supplement: postgresql view table inflation
View table inflation (sort the inflation rate of all table products)
The SQL article is as follows:
SELECT schemaname||'.'||relname as table_name, pg_size_pretty(pg_relation_size(schemaname||'.'||relname)) as table_size, n_dead_tup, n_live_tup, round(n_dead_tup * 100 / (n_live_tup + n_dead_tup),2) AS dead_tup_ratio FROM pg_stat_all_tables WHERE n_dead_tup >= 1000 ORDER BY dead_tup_ratio DESC LIMIT 10;
The above is personal experience. I hope you can give you a reference and I hope you can support me more. If there are any mistakes or no complete considerations, I would like to give you advice.