Module: PgHero::Methods::Indexes

Included in:
Database
Defined in:
lib/pghero/methods/indexes.rb

Instance Method Summary collapse

Instance Method Details

#duplicate_indexes(indexes: nil) ⇒ Object 



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# File 'lib/pghero/methods/indexes.rb', line 171

def duplicate_indexes(indexes: nil)
  dup_indexes = []

  indexes_by_table = (indexes || self.indexes).group_by { |i| [i[:schema], i[:table]] }
  indexes_by_table.values.flatten.select { |i| i[:valid] && !i[:primary] && !i[:unique] }.each do |index|
    covering_index = indexes_by_table[[index[:schema], index[:table]]].find { |i| i[:valid] && i[:name] != index[:name] && index_covers?(i[:columns], index[:columns]) && i[:using] == index[:using] && i[:indexprs] == index[:indexprs] && i[:indpred] == index[:indpred] }
    if covering_index && (covering_index[:columns] != index[:columns] || index[:name] > covering_index[:name] || covering_index[:primary] || covering_index[:unique])
      dup_indexes << {unneeded_index: index, covering_index: covering_index}
    end
  end

  dup_indexes.sort_by { |i| ui = i[:unneeded_index]; [ui[:table], ui[:columns]] }
end

#index_bloat(min_size: nil) ⇒ Object

gist.github.com/mbanck/9976015/71888a24e464e2f772182a7eb54f15a125edf398 thanks @jberkus and @mbanck



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# File 'lib/pghero/methods/indexes.rb', line 187

def index_bloat(min_size: nil)
  min_size ||= index_bloat_bytes
  select_all "    WITH btree_index_atts AS (\n      SELECT\n        nspname, relname, reltuples, relpages, indrelid, relam,\n        regexp_split_to_table(indkey::text, ' ')::smallint AS attnum,\n        indexrelid as index_oid\n      FROM\n        pg_index\n      JOIN\n        pg_class ON pg_class.oid = pg_index.indexrelid\n      JOIN\n        pg_namespace ON pg_namespace.oid = pg_class.relnamespace\n      JOIN\n        pg_am ON pg_class.relam = pg_am.oid\n      WHERE\n        pg_am.amname = 'btree'\n    ),\n    index_item_sizes AS (\n      SELECT\n        i.nspname,\n        i.relname,\n        i.reltuples,\n        i.relpages,\n        i.relam,\n        (quote_ident(s.schemaname) || '.' || quote_ident(s.tablename))::regclass AS starelid,\n        a.attrelid AS table_oid, index_oid,\n        current_setting('block_size')::numeric AS bs,\n        /* MAXALIGN: 4 on 32bits, 8 on 64bits (and mingw32 ?) */\n        CASE\n          WHEN version() ~ 'mingw32' OR version() ~ '64-bit' THEN 8\n          ELSE 4\n        END AS maxalign,\n        24 AS pagehdr,\n        /* per tuple header: add index_attribute_bm if some cols are null-able */\n        CASE WHEN max(coalesce(s.null_frac,0)) = 0\n          THEN 2\n          ELSE 6\n        END AS index_tuple_hdr,\n        /* data len: we remove null values save space using it fractionnal part from stats */\n        sum( (1-coalesce(s.null_frac, 0)) * coalesce(s.avg_width, 2048) ) AS nulldatawidth\n      FROM\n        pg_attribute AS a\n      JOIN\n        pg_stats AS s ON (quote_ident(s.schemaname) || '.' || quote_ident(s.tablename))::regclass=a.attrelid AND s.attname = a.attname\n      JOIN\n        btree_index_atts AS i ON i.indrelid = a.attrelid AND a.attnum = i.attnum\n      WHERE\n        a.attnum > 0\n      GROUP BY\n        1, 2, 3, 4, 5, 6, 7, 8, 9\n    ),\n    index_aligned AS (\n      SELECT\n        maxalign,\n        bs,\n        nspname,\n        relname AS index_name,\n        reltuples,\n        relpages,\n        relam,\n        table_oid,\n        index_oid,\n        ( 2 +\n          maxalign - CASE /* Add padding to the index tuple header to align on MAXALIGN */\n            WHEN index_tuple_hdr%maxalign = 0 THEN maxalign\n            ELSE index_tuple_hdr%maxalign\n          END\n        + nulldatawidth + maxalign - CASE /* Add padding to the data to align on MAXALIGN */\n            WHEN nulldatawidth::integer%maxalign = 0 THEN maxalign\n            ELSE nulldatawidth::integer%maxalign\n          END\n        )::numeric AS nulldatahdrwidth, pagehdr\n      FROM\n        index_item_sizes AS s1\n    ),\n    otta_calc AS (\n      SELECT\n        bs,\n        nspname,\n        table_oid,\n        index_oid,\n        index_name,\n        relpages,\n        coalesce(\n          ceil((reltuples*(4+nulldatahdrwidth))/(bs-pagehdr::float)) +\n          CASE WHEN am.amname IN ('hash','btree') THEN 1 ELSE 0 END , 0 /* btree and hash have a metadata reserved block */\n        ) AS otta\n      FROM\n        index_aligned AS s2\n      LEFT JOIN\n        pg_am am ON s2.relam = am.oid\n    ),\n    raw_bloat AS (\n      SELECT\n        nspname,\n        c.relname AS table_name,\n        index_name,\n        bs*(sub.relpages)::bigint AS totalbytes,\n        CASE\n          WHEN sub.relpages <= otta THEN 0\n          ELSE bs*(sub.relpages-otta)::bigint END\n          AS wastedbytes,\n        CASE\n          WHEN sub.relpages <= otta\n          THEN 0 ELSE bs*(sub.relpages-otta)::bigint * 100 / (bs*(sub.relpages)::bigint) END\n          AS realbloat,\n        pg_relation_size(sub.table_oid) as table_bytes,\n        stat.idx_scan as index_scans,\n        stat.indexrelid\n      FROM\n        otta_calc AS sub\n      JOIN\n        pg_class AS c ON c.oid=sub.table_oid\n      JOIN\n        pg_stat_user_indexes AS stat ON sub.index_oid = stat.indexrelid\n    )\n    SELECT\n      nspname AS schema,\n      table_name AS table,\n      index_name AS index,\n      wastedbytes AS bloat_bytes,\n      totalbytes AS index_bytes,\n      pg_get_indexdef(rb.indexrelid) AS definition,\n      indisprimary AS primary\n    FROM\n      raw_bloat rb\n    INNER JOIN\n      pg_index i ON i.indexrelid = rb.indexrelid\n    WHERE\n      wastedbytes >= \#{min_size.to_i}\n    ORDER BY\n      wastedbytes DESC,\n      index_name\n  SQL\nend\n"

#index_caching ⇒ Object 



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# File 'lib/pghero/methods/indexes.rb', line 13

def index_caching
  select_all "    SELECT\n      schemaname AS schema,\n      relname AS table,\n      indexrelname AS index,\n      CASE WHEN idx_blks_hit + idx_blks_read = 0 THEN\n        0\n      ELSE\n        ROUND(1.0 * idx_blks_hit / (idx_blks_hit + idx_blks_read), 2)\n      END AS hit_rate\n    FROM\n      pg_statio_user_indexes\n    ORDER BY\n      3 DESC, 1\n  SQL\nend\n"

#index_hit_rate ⇒ Object 



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# File 'lib/pghero/methods/indexes.rb', line 4

def index_hit_rate
  select_one "    SELECT\n      (sum(idx_blks_hit)) / nullif(sum(idx_blks_hit + idx_blks_read), 0) AS rate\n    FROM\n      pg_statio_user_indexes\n  SQL\nend\n"

#index_usage ⇒ Object 



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# File 'lib/pghero/methods/indexes.rb', line 31

def index_usage
  select_all "    SELECT\n      schemaname AS schema,\n      relname AS table,\n      CASE idx_scan\n        WHEN 0 THEN 'Insufficient data'\n        ELSE (100 * idx_scan / (seq_scan + idx_scan))::text\n      END percent_of_times_index_used,\n      n_live_tup AS estimated_rows\n    FROM\n      pg_stat_user_tables\n    ORDER BY\n      n_live_tup DESC,\n      relname ASC\n   SQL\nend\n"

#indexes ⇒ Object

TODO parse array properly stackoverflow.com/questions/2204058/list-columns-with-indexes-in-postgresql



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# File 'lib/pghero/methods/indexes.rb', line 128

def indexes
  indexes = select_all("    SELECT\n      schemaname AS schema,\n      t.relname AS table,\n      ix.relname AS name,\n      regexp_replace(pg_get_indexdef(i.indexrelid), '^[^\\\\(]*\\\\((.*)\\\\)$', '\\\\1') AS columns,\n      regexp_replace(pg_get_indexdef(i.indexrelid), '.* USING ([^ ]*) \\\\(.*', '\\\\1') AS using,\n      indisunique AS unique,\n      indisprimary AS primary,\n      indisvalid AS valid,\n      indexprs::text,\n      indpred::text,\n      pg_get_indexdef(i.indexrelid) AS definition\n    FROM\n      pg_index i\n    INNER JOIN\n      pg_class t ON t.oid = i.indrelid\n    INNER JOIN\n      pg_class ix ON ix.oid = i.indexrelid\n    LEFT JOIN\n      pg_stat_user_indexes ui ON ui.indexrelid = i.indexrelid\n    WHERE\n      schemaname IS NOT NULL\n    ORDER BY\n      1, 2\n  SQL\n  ).map { |v| v[:columns] = v[:columns].sub(\") WHERE (\", \" WHERE \").split(\", \").map { |c| unquote(c) }; v }\n\n  # determine if any invalid indexes being created\n  # hacky, but works for simple cases\n  # can be a race condition, but that's fine\n  invalid_indexes = indexes.select { |i| !i[:valid] }\n  if invalid_indexes.any?\n    create_index_queries = running_queries.select { |q| /\\s*CREATE\\s+INDEX\\s+CONCURRENTLY\\s+/i.match(q[:query]) }\n    invalid_indexes.each do |index|\n      index[:creating] = create_index_queries.any? { |q| q[:query].include?(index[:table]) && index[:columns].all? { |c| q[:query].include?(c) } }\n    end\n  end\n\n  indexes\nend\n"

#invalid_indexes(indexes: nil) ⇒ Object 



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# File 'lib/pghero/methods/indexes.rb', line 117

def invalid_indexes(indexes: nil)
  indexes = (indexes || self.indexes).select { |i| !i[:valid] && !i[:creating] }
  indexes.each do |index|
    # map name -> index for backward compatibility
    index[:index] = index[:name]
  end
  indexes
end

#last_stats_reset_time ⇒ Object 



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# File 'lib/pghero/methods/indexes.rb', line 106

def last_stats_reset_time
  select_one "    SELECT\n      pg_stat_get_db_stat_reset_time(oid) AS reset_time\n    FROM\n      pg_database\n    WHERE\n      datname = current_database()\n  SQL\nend\n"

#missing_indexes ⇒ Object 



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# File 'lib/pghero/methods/indexes.rb', line 49

def missing_indexes
  select_all "    SELECT\n      schemaname AS schema,\n      relname AS table,\n      CASE idx_scan\n        WHEN 0 THEN 'Insufficient data'\n        ELSE (100 * idx_scan / (seq_scan + idx_scan))::text\n      END percent_of_times_index_used,\n      n_live_tup AS estimated_rows\n    FROM\n      pg_stat_user_tables\n    WHERE\n      idx_scan > 0\n      AND (100 * idx_scan / (seq_scan + idx_scan)) < 95\n      AND n_live_tup >= 10000\n    ORDER BY\n      n_live_tup DESC,\n      relname ASC\n   SQL\nend\n"

#reset_stats ⇒ Object 



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# File 'lib/pghero/methods/indexes.rb', line 101

def reset_stats
  execute("SELECT pg_stat_reset()")
  true
end

#unused_indexes(max_scans: 50, across: []) ⇒ Object 



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# File 'lib/pghero/methods/indexes.rb', line 71

def unused_indexes(max_scans: 50, across: [])
  result = select_all_size "    SELECT\n      schemaname AS schema,\n      relname AS table,\n      indexrelname AS index,\n      pg_relation_size(i.indexrelid) AS size_bytes,\n      idx_scan as index_scans\n    FROM\n      pg_stat_user_indexes ui\n    INNER JOIN\n      pg_index i ON ui.indexrelid = i.indexrelid\n    WHERE\n      NOT indisunique\n      AND idx_scan <= \#{max_scans.to_i}\n    ORDER BY\n      pg_relation_size(i.indexrelid) DESC,\n      relname ASC\n  SQL\n\n  across.each do |database_id|\n    database = PgHero.databases.values.find { |d| d.id == database_id }\n    raise PgHero::Error, \"Database not found: \#{database_id}\" unless database\n    across_result = Set.new(database.unused_indexes(max_scans: max_scans).map { |v| [v[:schema], v[:index]] })\n    result.select! { |v| across_result.include?([v[:schema], v[:index]]) }\n  end\n\n  result\nend\n"