Class: Postgres

Inherits:
Object
  • Object
show all
Defined in:
lib/pgcp/postgres.rb

Instance Method Summary collapse

Constructor Details

#initialize(dbconfig) ⇒ Postgres

Initialize Postgres instance

Parameters:

  • dbconfig (Hash) —

    Database config



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# File 'lib/pgcp/postgres.rb', line 9

def initialize(dbconfig)
  @dbconfig = dbconfig
end

Instance Method Details

#column_definitions(schema_name, table_name) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 137

def column_definitions(schema_name, table_name)
  with_connection do |conn|
    sql = <<-SQL.strip_heredoc
      SELECT 
        c.relname, a.attname AS column_name,
        pg_catalog.format_type(a.atttypid, a.atttypmod) as type,
        case 
          when a.attnotnull
        then 'NOT NULL' 
        else 'NULL' 
        END as not_null 
      FROM pg_class c,
       pg_attribute a,
       pg_type t,
       pg_namespace n
       WHERE c.relname = '#{table_name}'
       AND n.nspname = '#{schema_name}'
       AND a.attnum > 0
       AND a.attrelid = c.oid
       AND a.atttypid = t.oid
       AND c.relnamespace = n.oid
     ORDER BY a.attnum
    SQL

    rs = conn.exec sql

    rs.values.map do |col|
      {name: col[1], type: col[2], null: col[3]}
    end
  end
end

#copy_from_file(schema_name, table_name, csv_file, options = {}) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 122

def copy_from_file(schema_name, table_name, csv_file, options={})
  with_connection do |conn|
    schema_name = conn.escape_string(schema_name)
    table_name = conn.escape_string(table_name)

    conn.copy_data "COPY #{schema_name}.#{table_name} FROM STDIN CSV #{options[:header]?'HEADER':''}" do
      buf = ''
      while csv_file.read(256, buf)
        conn.put_copy_data(buf)
      end
    end

  end
end

#create_indexes(schema_name, table_name, indexes) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 243

def create_indexes(schema_name, table_name, indexes)
  with_connection do |conn|
    indexes.each do |index|
      if index['primary']
        sql = <<-SQL.strip_heredoc
          ALTER TABLE #{schema_name}.#{table_name} ADD PRIMARY KEY (#{index['columns'][0]})
        SQL
      else
        sql = <<-SQL.strip_heredoc
        CREATE #{index['unique'] ? 'UNIQUE': ''} INDEX #{index['name']}
        ON #{schema_name}.#{table_name} (#{index['columns'].join(', ')})
        #{index['where'] ? 'WHERE ' + index['where'] : ''}
        SQL
      end

      conn.exec(sql)
    end
  end
end

#create_table(schema_name, table_name, columns, options = {}) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 52

def create_table(schema_name, table_name, columns, options={})
  with_connection do |conn|
    if options[:temporary]
      table_name = conn.escape_string(table_name)
      create_sql = create_table_statement(conn, columns,
                                          table_name,
                                          options)
      conn.transaction do
        conn.exec create_sql
        conn.exec "DROP TABLE IF EXISTS #{table_name}"
      end

      true
    else
      unless _table_exists?(conn, schema_name, table_name)
        create_sql = create_table_statement(conn, columns,
                                            "#{schema_name}.#{table_name}",
                                            options)
        conn.exec create_sql

        true
      end

      false
    end
  end
end

#create_table_from_query(query, schema_name, table_name, columns, options = {}) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 80

def create_table_from_query(query, schema_name, table_name, columns, options={})
  with_connection do |conn|
    create_sql = create_table_statement(conn, columns,
                                        "#{schema_name}.#{table_name}",
                                        options)
    conn.transaction do
      conn.exec "DROP TABLE IF EXISTS #{schema_name}.#{table_name}"
      conn.exec create_sql
      conn.exec "INSERT INTO #{schema_name}.#{table_name}\n#{query}"
    end
  end
end

#drop_table(schema_name, table_name) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 38

def drop_table(schema_name, table_name)
  with_connection do |conn|
    if _table_exists?(conn, schema_name, table_name)
      fq_table_name = conn.escape_string("#{schema_name}.#{table_name}")

      sql = <<-SQL.strip_heredoc
        DROP TABLE #{fq_table_name}
      SQL

      conn.exec sql
    end
  end
end

#exec(sql, val = []) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 13

def exec(sql, val=[])
  with_connection do |conn|
    conn.exec sql, val

  end
end

#get_create_table_statement(src_schema_name, src_table_name, dest_schema_name = nil, dest_table_name = nil) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 263

def get_create_table_statement(src_schema_name, src_table_name, dest_schema_name=nil, dest_table_name=nil)
  dest_schema_name ||= src_schema_name
  dest_table_name ||= dest_schema_name

  columns = column_definitions(src_schema_name, src_table_name)

  statement = "CREATE TABLE #{dest_schema_name}.#{dest_table_name} (\n"
  columns.each_with_index do |col, index|
    statement << "  #{col[:name]}  #{col[:type]}  #{col[:null]}"
    statement << ',' if index != columns.size - 1
    statement << "\n"
  end
  statement << ");\n"

  statement
end

#get_indexes(schema_name, table_name) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 192

def get_indexes(schema_name, table_name)
  idx_names = self.index_names(schema_name, table_name)

  with_connection do |conn|
    idx_names.map do |name|
      index_info = index_info(conn, name, schema_name)
      index_info['name'] = name
      index_info['columns'] = index_column_names conn, index_info['oid']

      index_info
    end
  end
end

#hotswap_table(schema_name, src_table_name, dst_table_name) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 93

def hotswap_table(schema_name, src_table_name, dst_table_name)
  with_connection do |conn|
    conn.transaction do
      schema_name = conn.escape_string(schema_name)
      dst_table_name = conn.escape_string(dst_table_name)
      conn.exec "DROP TABLE #{schema_name}.#{dst_table_name}" if _table_exists?(conn, schema_name, dst_table_name)
      conn.exec "ALTER TABLE #{schema_name}.#{src_table_name} RENAME TO #{dst_table_name}"
      #conn.exec "TRUNCATE TABLE #{schema_name}.#{dst_table_name}" if _table_exists?(conn, schema_name, dst_table_name)
      #conn.exec "INSERT INTO #{schema_name}.#{dst_table_name}\n(SELECT * FROM #{schema_name}.#{src_table_name})"
      #conn.exec "DROP TABLE #{schema_name}.#{src_table_name}"
    end

  end
end

#index_column_names(conn, oid) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 230

def index_column_names conn, oid
  sql = <<-SQL.strip_heredoc
  SELECT
       pg_catalog.pg_get_indexdef(A.attrelid, A.attnum, TRUE) AS "column_name"
  FROM pg_catalog.pg_attribute A
  WHERE A.attrelid = $1
    AND A.attnum > 0
    AND NOT A.attisdropped
  ORDER BY A.attnum;
  SQL
  conn.exec(sql, [oid]).map { |row| row['column_name'] }
end

#index_info(conn, index_name, schema_name) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 206

def index_info(conn, index_name, schema_name)
  sql = <<-SQL.strip_heredoc
  SELECT
      C.oid,
      I.indisunique AS "unique",
      I.indisprimary AS "primary",
      pg_get_expr(I.indpred, I.indrelid) AS "where"
  FROM pg_catalog.pg_class C,
       pg_catalog.pg_namespace N,
       pg_catalog.pg_index I
  WHERE C.relname = '#{index_name}'
    AND C.relnamespace = N.oid
    AND I.indexrelid = C.oid
    AND N.nspname = '#{schema_name}';
  SQL

  rs = conn.exec sql
  rs[0].tap do |info|
    info['unique'] = info['unique'] != 'f'
    info['primary'] = info['primary'] != 'f'
    info['where'] = info['where'][1..-2] if info['where'].present?
  end
end

#index_names(schema_name, table_name) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 169

def index_names(schema_name, table_name)
  with_connection do |conn|
    sql = <<-SQL.strip_heredoc
      SELECT
          C.relname AS "index_name"
      FROM pg_catalog.pg_class C,
           pg_catalog.pg_namespace N,
           pg_catalog.pg_index I,
           pg_catalog.pg_class C2
      WHERE C.relkind IN ( 'i', '' )
        AND N.oid = C.relnamespace
        AND N.nspname = '#{schema_name}'
        AND I.indexrelid = C.oid
        AND C2.oid = I.indrelid
        AND C2.relname = '#{table_name}';
    SQL

    rs = conn.exec sql

    rs.values.map(&:first)
  end
end

#list_tables(schema_name) ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 20

def list_tables(schema_name)
  with_connection do |conn|
    sql = <<-SQL.strip_heredoc
      SELECT table_name
      FROM information_schema.tables
      WHERE table_type = 'BASE TABLE'
        AND table_schema NOT IN ('pg_catalog', 'information_schema')
        AND table_schema = '#{schema_name}'
      ORDER BY 1
    SQL

    rs = conn.exec sql

    rs.values.map(&:first)
  end

end

#schema_names ⇒ Object 



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# File 'lib/pgcp/postgres.rb', line 108

def schema_names
  with_connection do |conn|
    sql = <<-SQL.strip_heredoc
    SELECT schema_name
    FROM information_schema.schemata
    WHERE schema_name <> 'information_schema'
    AND schema_name NOT LIKE 'pg_%'
    SQL

    rs = conn.exec sql
    rs.values.map(&:first)
  end
end

#table_exist?(schema_name, table_name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/pgcp/postgres.rb', line 280

def table_exist?(schema_name, table_name)
  with_connection do |conn|
    _table_exists?(conn, schema_name, table_name)
  end
end