Module: ActiveRecord::ConnectionAdapters::PostgreSQL::SchemaStatements

Defined in:
lib/core_ext/active_record/connection_adapters/postgresql/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+)\(((?:'.+'(?:::\w+)?, *)*)(\w+)\)/
OPERATOR_REGEXP =

Regexp used to find the operator name (or operator string, e.g. “DESC NULLS LAST”):

/(.+?)\s([\w\s]+)$/
INDEX_COLUMN_EXPRESSION =

Regex to find columns used in index statements

/ON [\w\.]+(?: USING \w+ )?\((.+)\)/
INDEX_WHERE_EXPRESSION =

Regex to find where clause in index statements

/WHERE (.+)$/

Instance Method Summary collapse

Instance Method Details

#add_index(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



131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
 
# File 'lib/core_ext/active_record/connection_adapters/postgresql/schema_statements.rb', line 131

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

  # Whether to skip the quoting of columns. Used only for expressions like JSON indexes in which
  # the column is difficult to target for quoting.
  skip_column_quoting = options.delete(:skip_column_quoting) or false

  index, algorithm, if_not_exists = add_index_options(table_name, column_name, **options)
  algorithm = creation_method || algorithm
  create_index = CreateIndexDefinition.new(index, algorithm, if_not_exists)

  # 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 ::PgSaurus::IndexExistsError,
          "Index #{index.name} for `#{table_name}.#{column_name}` " \
          "column can not be created concurrently, because such index already exists."
  end

  execute schema_creation.accept(create_index)
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) 


172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
 
# File 'lib/core_ext/active_record/connection_adapters/postgresql/schema_statements.rb', line 172

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.



212
213
214
215
216
217
218
219
220
221
222
223
224
225
 
# File 'lib/core_ext/active_record/connection_adapters/postgresql/schema_statements.rb', line 212

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

#indexes(table_name) ⇒ Object

Returns an array of indexes for the given table.

Patch 1:

Remove type specification from stored Postgres index definitions.

Patch 2:

Split compound functional indexes to array.



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
66
67
68
69
70
71
72
73
74
75
76
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
 
# File 'lib/core_ext/active_record/connection_adapters/postgresql/schema_statements.rb', line 41

def indexes(table_name)
  scope = quoted_scope(table_name)

  result = query(<<-SQL, "SCHEMA")
    SELECT distinct i.relname, d.indisunique, d.indkey, pg_get_indexdef(d.indexrelid), t.oid,
                    pg_catalog.obj_description(i.oid, 'pg_class') AS comment
    FROM pg_class t
    INNER JOIN pg_index     d  ON t.oid = d.indrelid
    INNER JOIN pg_class     i  ON d.indexrelid = i.oid
    LEFT JOIN  pg_namespace n  ON n.oid = i.relnamespace
    WHERE i.relkind = 'i'
      AND d.indisprimary = 'f'
      AND t.relname = #{scope[:name]}
      AND n.nspname = #{scope[:schema]}
    ORDER BY i.relname
  SQL

  result.map do |row|
    index_name = row[0]
    unique     = row[1]
    indkey     = row[2].split(" ").map(&:to_i)
    inddef     = row[3]
    oid        = row[4]
    comment    = row[5]

    using, expressions, where = inddef.scan(/ USING (\w+?) \((.+?)\)(?: WHERE (.+))?\z/m).flatten

    orders = {}
    opclasses = {}

    if indkey.include?(0)
      definition = inddef.sub(INDEX_WHERE_EXPRESSION, '')

      if column_expression = definition.match(INDEX_COLUMN_EXPRESSION)[1]
        columns = split_expression(expressions).map do |functional_name|
          remove_type(functional_name)
        end

        columns = columns.size > 1 ? columns : columns[0]
      end
    else
      columns = Hash[query(<<-SQL.strip_heredoc, "SCHEMA")].values_at(*indkey).compact
        SELECT a.attnum, a.attname
        FROM pg_attribute a
        WHERE a.attrelid = #{oid}
        AND a.attnum IN (#{indkey.join(",")})
      SQL

      # add info on sort order (only desc order is explicitly specified, asc is the default)
      # and non-default opclasses
      expressions.scan(/(?<column>\w+)"?\s?(?<opclass>\w+_ops)?\s?(?<desc>DESC)?\s?(?<nulls>NULLS (?:FIRST|LAST))?/).each do |column, opclass, desc, nulls|
        opclasses[column] = opclass.to_sym if opclass
        if nulls
          orders[column] = [desc, nulls].compact.join(" ")
        else
          orders[column] = :desc if desc
        end
      end
    end

    IndexDefinition.new(
      table_name,
      index_name,
      unique,
      columns,
      orders:    orders,
      opclasses: opclasses,
      where:     where,
      using:     using.to_sym,
      comment:   comment.presence
    )
  end
end

#quoted_columns_for_index(column_names, options = {}) ⇒ Object

Override super method to provide support for expression column names.



228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
 
# File 'lib/core_ext/active_record/connection_adapters/postgresql/schema_statements.rb', line 228

def quoted_columns_for_index(column_names, options = {})
  return [column_names] if column_names.is_a?(String)

  quoted_columns = Hash[
    column_names.map do |name|
      column_name, operator_name = split_column_name(name)

      result_name = if column_name =~ FUNCTIONAL_INDEX_REGEXP
                      _name = column_name.gsub(/\b#{$3}\b/, quote_column_name($3))
                      _name += " #{operator_name}"
                      _name
                    else
                      quote_column_name(column_name).dup
                    end
      [column_name.to_sym, result_name]
    end
  ]

  add_options_for_index_columns(quoted_columns, **options).values.join(", ")
end

#tables(name = nil) ⇒ Object

Returns the list of all tables in the schema search path or a specified schema.

Patch:

If current user is not ‘postgres` original method return all tables from all schemas without schema prefix. This disables such behavior by querying only default schema. Tables with schemas will be queried later.



25
26
27
28
29
30
31
 
# File 'lib/core_ext/active_record/connection_adapters/postgresql/schema_statements.rb', line 25

def tables(name = nil)
  query(<<-SQL, 'SCHEMA').map { |row| row[0] }
      SELECT tablename
      FROM pg_tables
      WHERE schemaname = ANY (ARRAY['public'])
  SQL
end