Method to safely add index on empty table #93
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| if options[:algorithm] == :concurrently | ||
| # Cannot be run inside a transaction so we are unable to use | ||
| # safely_acquire_lock_for_table to take out ShareUpdateExclusiveLock | ||
| execute_ancestor_statement(:add_index, table, column_names, **options) |
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This is an interesting catch. This is a project philosophy question, but should we insist that the user call safe_add_index_concurrently?
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Not sure I'm following this one
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This seems to be from an earlier version that updated where we did locking. Since that's no longer true in the PR, I think we can wait on this (but I also don't quite remember the context of my question about project policy, and I'm struggling to find the version of the PR at the time I left the comment, so I can't see the full context of this change...)
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I'm also wondering if maybe we want this method to just be called |
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| def _ensure_empty_table!(table) | ||
| table = PgHaMigrations::Table.from_table_name(table) | ||
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| if connection.select_value("SELECT EXISTS (SELECT 1 FROM #{table.fully_qualified_name} LIMIT 1)") |
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Could we also ensure the table size is less than, I don't know, 100 MB? Even that's insanely high for what it should be in this case, but it gives some buffer if it's not entirely clean (a bunch of recent deletes).
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Addressed in 058c4d9
This will raise an error if it detects that the table contains data and/or the total size on disk is greater than 10 megabytes. Otherwise, we safely acquire a
SHARElock and run standardCREATE INDEX ...