a0af70cfb4
Rails tries to query the system tables to find the primary key and it's controlling sequence, but it doesn't specify that it is looking for objects of class "pg_class" so the pg_depend table has to be sequentially scanned instead of being accessed using the index. Tests on the production database show that the time taken for this query drops from 3.5s to 15ms if the index is used.
34 lines
1.1 KiB
Ruby
34 lines
1.1 KiB
Ruby
module ActiveRecord
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module ConnectionAdapters
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class PostgreSQLAdapter
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alias_method :old_pk_and_sequence_for, :pk_and_sequence_for
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def pk_and_sequence_for(table)
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result = query(<<-end_sql, 'PK and serial sequence')[0]
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SELECT attr.attname, seq.relname
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FROM pg_class seq,
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pg_attribute attr,
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pg_depend dep,
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pg_namespace name,
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pg_constraint cons
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WHERE seq.oid = dep.objid
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AND seq.relkind = 'S'
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AND attr.attrelid = dep.refobjid
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AND attr.attnum = dep.refobjsubid
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AND attr.attrelid = cons.conrelid
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AND attr.attnum = cons.conkey[1]
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AND cons.contype = 'p'
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AND dep.classid = '"pg_class"'::regclass
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AND dep.refclassid = '"pg_class"'::regclass
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AND dep.refobjid = '#{quote_table_name(table)}'::regclass
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end_sql
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if result.nil? or result.empty?
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old_pk_and_sequence_for(table)
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else
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[result.first, result.last]
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end
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end
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end
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end
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end
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