Paweł Domański
124 lines
3.9 KiB
SQL
124 lines
3.9 KiB
SQL
WITH btree_index_atts AS (
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SELECT nspname,
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relname,
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reltuples,
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relpages,
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indrelid,
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relam,
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regexp_split_to_table(indkey::text, ' ')::smallint AS attnum,
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indexrelid as index_oid
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FROM pg_index
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JOIN pg_class ON pg_class.oid=pg_index.indexrelid
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JOIN pg_namespace ON pg_namespace.oid = pg_class.relnamespace
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JOIN pg_am ON pg_class.relam = pg_am.oid
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WHERE pg_am.amname = 'btree'
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),
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index_item_sizes AS (
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SELECT i.nspname,
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i.relname,
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i.reltuples,
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i.relpages,
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i.relam,
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s.starelid,
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a.attrelid AS table_oid,
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index_oid,
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current_setting('block_size')::numeric AS bs,
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/* MAXALIGN: 4 on 32bits, 8 on 64bits (and mingw32 ?) */
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CASE WHEN version() ~ 'mingw32' OR version() ~ '64-bit'
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THEN 8
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ELSE 4
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END AS maxalign,
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24 AS pagehdr,
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/* per tuple header: add index_attribute_bm if some cols are null-able */
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CASE WHEN max(coalesce(s.stanullfrac,0)) = 0
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THEN 2
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ELSE 6
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END AS index_tuple_hdr,
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/* data len: we remove null values save space using it fractionnal part from stats */
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sum( (1-coalesce(s.stanullfrac, 0)) * coalesce(s.stawidth, 2048) ) AS nulldatawidth
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FROM pg_attribute AS a
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JOIN pg_statistic AS s ON s.starelid=a.attrelid AND s.staattnum = a.attnum
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JOIN btree_index_atts AS i ON i.indrelid = a.attrelid AND a.attnum = i.attnum
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WHERE a.attnum > 0
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GROUP BY 1, 2, 3, 4, 5, 6, 7, 8, 9
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),
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index_aligned AS (
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SELECT maxalign,
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bs,
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nspname,
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relname AS index_name,
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reltuples,
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relpages,
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relam,
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table_oid,
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index_oid,
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( 2 + maxalign -
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/* Add padding to the index tuple header to align on MAXALIGN */
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CASE WHEN index_tuple_hdr%maxalign = 0
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THEN maxalign
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ELSE index_tuple_hdr%maxalign
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END
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+ nulldatawidth + maxalign -
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/* Add padding to the data to align on MAXALIGN */
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CASE WHEN nulldatawidth::integer%maxalign = 0
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THEN maxalign
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ELSE nulldatawidth::integer%maxalign
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END
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)::numeric AS nulldatahdrwidth,
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pagehdr
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FROM index_item_sizes AS s1
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),
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otta_calc AS
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(
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SELECT bs,
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nspname,
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table_oid,
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index_oid,
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index_name,
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relpages,
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coalesce( ceil((reltuples*(4+nulldatahdrwidth))/(bs-pagehdr::float)) +
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CASE WHEN am.amname IN ('hash','btree')
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THEN 1
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ELSE 0
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END ,
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0 -- btree and hash have a metadata reserved block
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) AS otta
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FROM index_aligned AS s2
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LEFT JOIN pg_am am ON s2.relam = am.oid
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),
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raw_bloat AS
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(
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SELECT current_database() as dbname,
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nspname, c.relname AS table_name,
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index_name,
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bs*(sub.relpages)::bigint AS totalbytes,
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CASE WHEN sub.relpages <= otta
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THEN 0
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ELSE bs*(sub.relpages-otta)::bigint
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END AS wastedbytes,
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CASE WHEN sub.relpages <= otta
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THEN 0
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ELSE bs*(sub.relpages-otta)::bigint * 100 / (bs*(sub.relpages)::bigint)
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END AS realbloat,
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pg_relation_size(sub.table_oid) as table_bytes,
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stat.idx_scan as index_scans
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FROM otta_calc AS sub
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JOIN pg_class AS c ON c.oid=sub.table_oid
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JOIN pg_stat_user_indexes AS stat ON sub.index_oid = stat.indexrelid
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)
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SELECT dbname as database_name,
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nspname as schema_name,
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table_name,
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index_name,
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round(realbloat, 1) as bloat_pct,
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wastedbytes as bloat_bytes,
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pg_size_pretty(wastedbytes::bigint) as bloat_size,
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totalbytes as index_bytes,
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pg_size_pretty(totalbytes::bigint) as index_size,
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table_bytes,
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pg_size_pretty(table_bytes) as table_size,
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index_scans
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FROM raw_bloat
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WHERE ( realbloat > 50 and wastedbytes > 50000000 )
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ORDER BY wastedbytes DESC;
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