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Sequel::Postgres::DatasetMethods

Instance methods for datasets that connect to a PostgreSQL database.

Public Instance Methods

analyze() click to toggle source

Return the results of an EXPLAIN ANALYZE query as a string

# File lib/sequel/adapters/shared/postgres.rb, line 1131
def analyze
  explain(:analyze=>true)
end
complex_expression_sql_append(sql, op, args) click to toggle source

Handle converting the ruby xor operator (^) into the PostgreSQL xor operator (#), and use the ILIKE and NOT ILIKE operators.

# File lib/sequel/adapters/shared/postgres.rb, line 1138
def complex_expression_sql_append(sql, op, args)
  case op
  when :^
    j = XOR_OP
    c = false
    args.each do |a|
      sql << j if c
      literal_append(sql, a)
      c ||= true
    end
  when :ILIKE, :'NOT ILIKE'
    sql << PAREN_OPEN
    literal_append(sql, args.at(0))
    sql << SPACE << op.to_s << SPACE
    literal_append(sql, args.at(1))
    sql << ESCAPE
    literal_append(sql, BACKSLASH)
    sql << PAREN_CLOSE
  else
    super
  end
end
explain(opts=OPTS) click to toggle source

Return the results of an EXPLAIN query as a string

# File lib/sequel/adapters/shared/postgres.rb, line 1162
def explain(opts=OPTS)
  with_sql((opts[:analyze] ? EXPLAIN_ANALYZE : EXPLAIN) + select_sql).map(QUERY_PLAN).join(CRLF)
end
for_share() click to toggle source

Return a cloned dataset which will use FOR SHARE to lock returned rows.

# File lib/sequel/adapters/shared/postgres.rb, line 1167
def for_share
  lock_style(:share)
end
full_text_search(cols, terms, opts = OPTS) click to toggle source

PostgreSQL specific full text search syntax, using tsearch2 (included in 8.3 by default, and available for earlier versions as an add-on).

# File lib/sequel/adapters/shared/postgres.rb, line 1173
def full_text_search(cols, terms, opts = OPTS)
  lang = opts[:language] || 'simple'
  terms = terms.join(' | ') if terms.is_a?(Array)
  filter("to_tsvector(?::regconfig, ?) @@ to_tsquery(?::regconfig, ?)", lang, full_text_string_join(cols), lang, terms)
end
insert(*values) click to toggle source

Insert given values into the database.

# File lib/sequel/adapters/shared/postgres.rb, line 1180
def insert(*values)
  if @opts[:returning]
    # already know which columns to return, let the standard code
    # handle it
    super
  elsif @opts[:sql]
    # raw SQL used, so don't know which table is being inserted
    # into, and therefore can't determine primary key.  Run the
    # insert statement and return nil.
    super
    nil
  else
    # Force the use of RETURNING with the primary key value.
    returning(insert_pk).insert(*values){|r| return r.values.first}
  end
end
insert_select(*values) click to toggle source

Insert a record returning the record inserted

# File lib/sequel/adapters/shared/postgres.rb, line 1198
def insert_select(*values)
  returning.insert(*values){|r| return r}
end
lock(mode, opts=OPTS) click to toggle source

Locks all tables in the dataset's FROM clause (but not in JOINs) with the specified mode (e.g. 'EXCLUSIVE'). If a block is given, starts a new transaction, locks the table, and yields. If a block is not given just locks the tables. Note that PostgreSQL will probably raise an error if you lock the table outside of an existing transaction. Returns nil.

# File lib/sequel/adapters/shared/postgres.rb, line 1207
def lock(mode, opts=OPTS)
  if block_given? # perform locking inside a transaction and yield to block
    @db.transaction(opts){lock(mode, opts); yield}
  else
    sql = 'LOCK TABLE '
    source_list_append(sql, @opts[:from])
    mode = mode.to_s.upcase.strip
    unless LOCK_MODES.include?(mode)
      raise Error, "Unsupported lock mode: #{mode}"
    end
    sql << " IN #{mode} MODE"
    @db.execute(sql, opts)
  end
  nil
end
multi_insert_sql(columns, values) click to toggle source

PostgreSQL allows inserting multiple rows at once.

# File lib/sequel/adapters/shared/postgres.rb, line 1224
def multi_insert_sql(columns, values)
  sql = LiteralString.new('VALUES ')
  expression_list_append(sql, values.map{|r| Array(r)})
  [insert_sql(columns, sql)]
end
supports_cte_in_subqueries?() click to toggle source

PostgreSQL supports using the WITH clause in subqueries if it supports using WITH at all (i.e. on PostgreSQL 8.4+).

# File lib/sequel/adapters/shared/postgres.rb, line 1232
def supports_cte_in_subqueries?
  supports_cte?
end
supports_distinct_on?() click to toggle source

DISTINCT ON is a PostgreSQL extension

# File lib/sequel/adapters/shared/postgres.rb, line 1237
def supports_distinct_on?
  true
end
supports_modifying_joins?() click to toggle source

PostgreSQL supports modifying joined datasets

# File lib/sequel/adapters/shared/postgres.rb, line 1242
def supports_modifying_joins?
  true
end
supports_regexp?() click to toggle source

PostgreSQL supports pattern matching via regular expressions

# File lib/sequel/adapters/shared/postgres.rb, line 1252
def supports_regexp?
  true
end
supports_returning?(type) click to toggle source

Returning is always supported.

# File lib/sequel/adapters/shared/postgres.rb, line 1247
def supports_returning?(type)
  true
end
supports_timestamp_timezones?() click to toggle source

PostgreSQL supports timezones in literal timestamps

# File lib/sequel/adapters/shared/postgres.rb, line 1257
def supports_timestamp_timezones?
  true
end
supports_window_functions?() click to toggle source

PostgreSQL 8.4+ supports window functions

# File lib/sequel/adapters/shared/postgres.rb, line 1262
def supports_window_functions?
  server_version >= 80400
end
truncate(opts = OPTS) click to toggle source

Truncates the dataset. Returns nil.

Options:

:cascade

whether to use the CASCADE option, useful when truncating

tables with Foreign Keys.

:only

truncate using ONLY, so child tables are unaffected

:restart

use RESTART IDENTITY to restart any related sequences

:only and :restart only work correctly on PostgreSQL 8.4+.

Usage:

DB[:table].truncate # TRUNCATE TABLE "table"
# => nil
DB[:table].truncate(:cascade => true, :only=>true, :restart=>true) # TRUNCATE TABLE ONLY "table" RESTART IDENTITY CASCADE
# => nil
# File lib/sequel/adapters/shared/postgres.rb, line 1281
def truncate(opts = OPTS)
  if opts.empty?
    super()
  else
    clone(:truncate_opts=>opts).truncate
  end
end
window(name, opts) click to toggle source

Return a clone of the dataset with an addition named window that can be referenced in window functions.

# File lib/sequel/adapters/shared/postgres.rb, line 1290
def window(name, opts)
  clone(:window=>(@opts[:window]||[]) + [[name, SQL::Window.new(opts)]])
end

Protected Instance Methods

_import(columns, values, opts=OPTS) click to toggle source

If returned primary keys are requested, use RETURNING unless already set on the dataset. If RETURNING is already set, use existing returning values. If RETURNING is only set to return a single columns, return an array of just that column. Otherwise, return an array of hashes.

# File lib/sequel/adapters/shared/postgres.rb, line 1300
def _import(columns, values, opts=OPTS)
  if @opts[:returning]
    statements = multi_insert_sql(columns, values)
    @db.transaction(opts.merge(:server=>@opts[:server])) do
      statements.map{|st| returning_fetch_rows(st)}
    end.first.map{|v| v.length == 1 ? v.values.first : v}
  elsif opts[:return] == :primary_key
    returning(insert_pk)._import(columns, values, opts)
  else
    super
  end
end

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