Class: ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

Inherits:
Object
  • Object
show all
Defined in:
lib/core_ext/active_record/connection_adapters/postgresql_adapter.rb

Overview

Patched version: 3.1.3

Patched methods

  • indexes

Constant Summary collapse

INDEX_COLUMN_EXPRESSION =

Regex to find columns used in index statements

/ON \w+(?: USING \w+ )?\((.+)\)/
INDEX_WHERE_EXPRESION =

Regex to find where clause in index statements

/WHERE (.+)$/

Instance Method Summary collapse

Instance Method Details

#find_column_names(table_name, index) ⇒ Array

Find column names from index attributes. If the columns are virtual (ie this is an expression index) then it will try to return the functions that represent each column

Parameters:

  • table_name (String) —

    the name of the table

  • index (Hash) —

    index attributes

Returns:

  • (Array) 


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# File 'lib/core_ext/active_record/connection_adapters/postgresql_adapter.rb', line 112

def find_column_names(table_name, index)
  columns = Hash[query(<<-SQL, "Columns for index #{index[:name]} on #{table_name}")]
    SELECT a.attnum, a.attname
    FROM pg_attribute a
    WHERE a.attrelid = #{index[:id]}
    AND a.attnum IN (#{index[:keys].join(",")})
  SQL

  column_names = columns.values_at(*index[:keys]).compact

  if column_names.empty?
    definition = index[:definition].sub(INDEX_WHERE_EXPRESION, '')
    if column_expression = definition.match(INDEX_COLUMN_EXPRESSION)[1]
      column_names = split_expression(column_expression).map do |functional_name|
        remove_type(functional_name)
      end
    end
  end

  column_names
end

#find_lengths(index) ⇒ Array

Find length of index TODO Update lengths once we merge in ActiveRecord code that supports it. -dresselm 20120305

Parameters:

  • index (Hash) —

    index attributes

Returns:

  • (Array) 


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# File 'lib/core_ext/active_record/connection_adapters/postgresql_adapter.rb', line 174

def find_lengths(index)
  []
end

#find_where_statement(index) ⇒ String

Find where statement from index definition

Parameters:

  • index (Hash) —

    index attributes

Returns:

  • (String) —

    where statement



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# File 'lib/core_ext/active_record/connection_adapters/postgresql_adapter.rb', line 165

def find_where_statement(index)
  index[:definition].scan(INDEX_WHERE_EXPRESION).flatten[0]
end

#index_name_exists?(table_name, index_name, default) ⇒ Boolean

Checks if index exists for given table.

Patch:

Search using provided schema if table_name includes schema name.

Returns:

  • (Boolean) 


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# File 'lib/core_ext/active_record/connection_adapters/postgresql_adapter.rb', line 32

def index_name_exists?(table_name, index_name, default)
  schema, table = Utils.extract_schema_and_table(table_name)
  schemas = schema ? "ARRAY['#{schema}']" : 'current_schemas(false)'

  exec_query(<<-SQL, 'SCHEMA').rows.first[0].to_i > 0
    SELECT COUNT(*)
    FROM pg_class t
    INNER JOIN pg_index d ON t.oid = d.indrelid
    INNER JOIN pg_class i ON d.indexrelid = i.oid
    WHERE i.relkind = 'i'
      AND i.relname = '#{index_name}'
      AND t.relname = '#{table}'
      AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname = ANY (#{schemas}) )
  SQL
end

#indexes(table_name, name = nil) ⇒ Object

Returns an array of indexes for the given table.

Patch 1 reason:

Since SchemaDumper#tables is patched to process tables with a schema prefix, the #indexes method receives table_name as “<schema>.<table>”. This patch allows it to handle table names with a schema prefix.

Patch 1:

Search using provided schema if table_name includes schema name.

Patch 2 reason:

#indexes is patched to support partial indexes using :where clause.

Patch 2:

Search the postgres indexdef for the where clause and pass the output to the custom PgSaurus::ConnectionAdapters::IndexDefinition



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# File 'lib/core_ext/active_record/connection_adapters/postgresql_adapter.rb', line 67

def indexes(table_name, name = nil)
  schema, table = Utils.extract_schema_and_table(table_name)
  schemas = schema ? "ARRAY['#{schema}']" : 'current_schemas(false)'

  result = query(<<-SQL, name)
    SELECT distinct i.relname, d.indisunique, d.indkey,  pg_get_indexdef(d.indexrelid), t.oid, am.amname
    FROM pg_class t
    INNER JOIN pg_index d ON t.oid = d.indrelid
    INNER JOIN pg_class i ON d.indexrelid = i.oid
    INNER JOIN pg_am    am ON i.relam = am.oid
    WHERE i.relkind = 'i'
      AND d.indisprimary = 'f'
      AND t.relname = '#{table}'
      AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname = ANY (#{schemas}) )
   ORDER BY i.relname
  SQL

  result.map do |row|
    index = {
      :name          => row[0],
      :unique        => row[1] == 't',
      :keys          => row[2].split(" "),
      :definition    => row[3],
      :id            => row[4],
      :access_method => row[5]
    }

    column_names = find_column_names(table_name, index)

    unless column_names.empty?
      where   = find_where_statement(index)
      lengths = find_lengths(index)

      PgSaurus::ConnectionAdapters::IndexDefinition.new(table_name, index[:name], index[:unique], column_names, lengths, where, index[:access_method])
    end
  end.compact
end

#remove_type(column_with_type) ⇒ String

Remove type specification from stored Postgres index definitions

Examples:

remove_type("((col)::text")
=> "col"

Parameters:

  • column_with_type (String) —

    the name of the column with type

Returns:

  • (String) 


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# File 'lib/core_ext/active_record/connection_adapters/postgresql_adapter.rb', line 186

def remove_type(column_with_type)
  column_with_type.sub(/\((\w+)\)::\w+/, '\1')
end

#split_expression(expression) ⇒ Object

Splits only on commas outside of parens



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# File 'lib/core_ext/active_record/connection_adapters/postgresql_adapter.rb', line 135

def split_expression(expression)
  result = []
  parens = 0
  buffer = ""

  expression.chars do |char|
    case char
    when ','
      if parens == 0
        result.push(buffer)
        buffer = ""
        next
      end
    when '('
      parens += 1
    when ')'
      parens -= 1
    end

    buffer << char
  end

  result << buffer unless buffer.empty?
  result
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.



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# File 'lib/core_ext/active_record/connection_adapters/postgresql_adapter.rb', line 19

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