Module: ActiveRecord::ConnectionAdapters::SchemaStatements

Defined in:
lib/core_ext/active_record/connection_adapters/abstract/schema_statements.rb

Overview

:nodoc:

Constant Summary collapse

FUNCTIONAL_INDEX_REGEXP =

Regexp used to find the function name and function argument of a function call

/(\w+)\(((?:'.+'(?:::\w+)?, *)*)(\w+)\)/

Instance Method Summary collapse

Instance Method Details

#add_index_with_concurrently(table_name, column_name, options = {}) ⇒ Object

Redefine original add_index method to handle :concurrently option.

Adds a new index to the table. column_name can be a single Symbol, or an Array of Symbols.

Creating a partial index
add_index(:accounts, [:branch_id, :party_id], :using => 'BTree'
 :unique => true, :concurrently => true, :where => 'active')

generates

CREATE UNIQUE INDEX CONCURRENTLY
 index_accounts_on_branch_id_and_party_id
ON
  accounts(branch_id, party_id)
WHERE
  active



25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
 
# File 'lib/core_ext/active_record/connection_adapters/abstract/schema_statements.rb', line 25

def add_index_with_concurrently(table_name, column_name, options = {})
  creation_method = options.delete(:concurrently) ? 'CONCURRENTLY' : nil

  index_name,
  index_type,
  index_columns,
  index_options,
  index_algorithm,
  index_using      = add_index_options(table_name, column_name, options)

  # GOTCHA:
  #   It ensures that there is no existing index only for the case when the index
  #   is created concurrently to avoid changing the error behavior for default
  #   index creation.
  #   -- zekefast 2012-09-25
  # GOTCHA:
  #   This check prevents invalid index creation, so after migration failed
  #   here there is no need to go to database and clean it from invalid
  #   indexes. But note that this handles only one of the cases when index
  #   creation can fail!!! All other case should be procesed manually.
  #   -- zekefast 2012-09-25
  if creation_method.present? && index_exists?(table_name, column_name, options)
    raise ::PgPower::IndexExistsError,
          "Index #{index_name} for `#{table_name}.#{column_name}` " \
          "column can not be created concurrently, because such index already exists."
  end

  statements = []
  statements << "CREATE #{index_type} INDEX"
  statements << creation_method      if creation_method.present?
  statements << index_algorithm      if index_algorithm.present?
  statements << quote_column_name(index_name)
  statements << "ON"
  statements << quote_table_name(table_name)
  statements << index_using          if index_using.present?
  statements << "(#{index_columns})" if index_columns.present?
  statements << index_options        if index_options.present?

  sql = statements.join(' ')
  execute(sql)
end

#index_exists?(table_name, column_name, options = {}) ⇒ Boolean

Check to see if an index exists on a table for a given index definition.

Examples

# Check that a partial index exists
index_exists?(:suppliers, :company_id, :where => 'active')

# GIVEN: 'index_suppliers_on_company_id' UNIQUE, btree (company_id) WHERE active
index_exists?(:suppliers, :company_id, :unique => true, :where => 'active') => true
index_exists?(:suppliers, :company_id, :unique => true) => false

Returns:

  • (Boolean) 


77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
 
# File 'lib/core_ext/active_record/connection_adapters/abstract/schema_statements.rb', line 77

def index_exists?(table_name, column_name, options = {})
  column_names = Array.wrap(column_name)
  index_name = options.key?(:name) ? options[:name].to_s : index_name(table_name, :column => column_names)

  # Always compare the index name
  default_comparator = lambda { |index| index.name == index_name }
  comparators = [default_comparator]

  # Add a comparator for each index option that is part of the query
  index_options = [:unique, :where]
  index_options.each do |index_option|
    comparators << if options.key?(index_option)
      lambda do |index|
        pg_where_clause = index.send(index_option)
        # pg does nothing to boolean clauses, e.g. 'where active' => 'where active'
        if pg_where_clause.is_a?(TrueClass) or pg_where_clause.is_a?(FalseClass)
          pg_where_clause == options[index_option]
        else
          # pg adds parentheses around non-boolean clauses, e.g. 'where color IS NULL' => 'where (color is NULL)'
          pg_where_clause.gsub!(/[()]/,'')
          # pg casts string comparison ::text. e.g. "where color = 'black'" => "where ((color)::text = 'black'::text)"
          pg_where_clause.gsub!(/::text/,'')
          # prevent case from impacting the comparison
          pg_where_clause.downcase == options[index_option].downcase
        end
      end
    else
      # If the given index_option is not an argument to the index_exists? query,
      # select only those pg indexes that do not have the component
      lambda { |index| index.send(index_option).blank? }
    end
  end

  # Search all indexes for any that match all comparators
  indexes(table_name).any? do |index|
    comparators.inject(true) { |ret, comparator| ret && comparator.call(index) }
  end
end

#index_name(table_name, options) ⇒ Object

Derive the name of the index from the given table name and options hash.



117
118
119
120
121
122
123
124
125
126
127
128
129
130
 
# File 'lib/core_ext/active_record/connection_adapters/abstract/schema_statements.rb', line 117

def index_name(table_name, options) #:nodoc:
  if Hash === options # legacy support
    if options[:column]
      column_names = Array.wrap(options[:column]).map {|c| expression_index_name(c)}
      "index_#{table_name}_on_#{column_names * '_and_'}"
    elsif options[:name]
      options[:name]
    else
      raise ArgumentError, "You must specify the index name"
    end
  else
    index_name(table_name, :column => options)
  end
end