90 lines
3.9 KiB
Ruby
90 lines
3.9 KiB
Ruby
# frozen_string_literal: true
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module Gitlab
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module Database
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module PartitioningMigrationHelpers
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module IndexHelpers
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include Gitlab::Database::MigrationHelpers
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include Gitlab::Database::SchemaHelpers
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# Concurrently creates a new index on a partitioned table. In concept this works similarly to
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# `add_concurrent_index`, and won't block reads or writes on the table while the index is being built.
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#
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# A special helper is required for partitioning because Postgres does not support concurrently building indexes
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# on partitioned tables. This helper concurrently adds the same index to each partition, and creates the final
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# index on the parent table once all of the partitions are indexed. This is the recommended safe way to add
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# indexes to partitioned tables.
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#
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# Example:
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#
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# add_concurrent_partitioned_index :users, :some_column
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#
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# See Rails' `add_index` for more info on the available arguments.
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def add_concurrent_partitioned_index(table_name, column_names, options = {})
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raise ArgumentError, 'A name is required for indexes added to partitioned tables' unless options[:name]
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partitioned_table = find_partitioned_table(table_name)
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if index_name_exists?(table_name, options[:name])
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Gitlab::AppLogger.warn "Index not created because it already exists (this may be due to an aborted" \
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" migration or similar): table_name: #{table_name}, index_name: #{options[:name]}"
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return
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end
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partitioned_table.postgres_partitions.order(:name).each do |partition|
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partition_index_name = generated_index_name(partition.identifier, options[:name])
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partition_options = options.merge(name: partition_index_name)
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add_concurrent_index(partition.identifier, column_names, partition_options)
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end
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with_lock_retries do
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add_index(table_name, column_names, options)
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end
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end
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# Safely removes an existing index from a partitioned table. The method name is a bit inaccurate as it does not
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# drop the index concurrently, but it's named as such to maintain consistency with other similar helpers, and
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# indicate that this should be safe to use in a production environment.
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#
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# In current versions of Postgres it's impossible to drop an index concurrently, or drop an index from an
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# individual partition that exists across the entire partitioned table. As a result this helper drops the index
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# from the parent table, which automatically cascades to all partitions. While this does require an exclusive
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# lock, dropping an index is a fast operation that won't block the table for a significant period of time.
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#
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# Example:
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#
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# remove_concurrent_partitioned_index_by_name :users, 'index_name_goes_here'
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def remove_concurrent_partitioned_index_by_name(table_name, index_name)
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find_partitioned_table(table_name)
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unless index_name_exists?(table_name, index_name)
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Gitlab::AppLogger.warn "Index not removed because it does not exist (this may be due to an aborted " \
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"migration or similar): table_name: #{table_name}, index_name: #{index_name}"
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return
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end
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with_lock_retries do
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remove_index(table_name, name: index_name)
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end
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end
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private
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def find_partitioned_table(table_name)
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partitioned_table = Gitlab::Database::PostgresPartitionedTable.find_by_name_in_current_schema(table_name)
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raise ArgumentError, "#{table_name} is not a partitioned table" unless partitioned_table
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partitioned_table
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end
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def generated_index_name(partition_name, index_name)
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object_name("#{partition_name}_#{index_name}", 'index')
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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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