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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 1190
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 1197
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
disable_insert_returning() click to toggle source

Disables automatic use of INSERT … RETURNING. You can still use returning manually to force the use of RETURNING when inserting.

This is designed for cases where INSERT RETURNING cannot be used, such as when you are using partitioning with trigger functions or conditional rules, or when you are using a PostgreSQL version less than 8.2, or a PostgreSQL derivative that does not support returning.

Note that when this method is used, insert will not return the primary key of the inserted row, you will have to get the primary key of the inserted row before inserting via nextval, or after inserting via currval or lastval (making sure to use the same database connection for currval or lastval).

# File lib/sequel/adapters/shared/postgres.rb, line 1234
def disable_insert_returning
  clone(:disable_insert_returning=>true)
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 1239
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 1244
def for_share
  lock_style(:share)
end
full_text_search(cols, terms, opts = OPTS) click to toggle source

Run a full text search on PostgreSQL. By default, searching for the inclusion of any of the terms in any of the cols.

Options:

:language

The language to use for the search (default: ‘simple’)

:plain

Whether a plain search should be used (default: false). In this case, terms should be a single string, and it will do a search where cols contains all of the words in terms. This ignores search operators in terms.

:phrase

Similar to :plain, but also adding an ILIKE filter to ensure that returned rows also include the exact phrase used.

:rank

Set to true to order by the rank, so that closer matches are returned first.

# File lib/sequel/adapters/shared/postgres.rb, line 1259
def full_text_search(cols, terms, opts = OPTS)
  lang = Sequel.cast(opts[:language] || 'simple', :regconfig)
  terms = terms.join(' | ') if terms.is_a?(Array)
  columns = full_text_string_join(cols)
  query_func = (opts[:phrase] || opts[:plain]) ? :plainto_tsquery : :to_tsquery
  vector = Sequel.function(:to_tsvector, lang, columns)
  query = Sequel.function(query_func, lang, terms)

  ds = where(Sequel.lit(["(", " @@ ", ")"], vector, query))

  if opts[:phrase]
    ds = ds.grep(cols, "%#{escape_like(terms)}%", :case_insensitive=>true)
  end

  if opts[:rank]
    ds = ds.order{ts_rank_cd(vector, query)}
  end

  ds
end
insert(*values) click to toggle source

Insert given values into the database.

# File lib/sequel/adapters/shared/postgres.rb, line 1281
def insert(*values)
  if @opts[:returning]
    # Already know which columns to return, let the standard code handle it
    super
  elsif @opts[:sql] || @opts[:disable_insert_returning]
    # Raw SQL used or RETURNING disabled, just use the default behavior
    # and return nil since sequence is not known.
    super
    nil
  else
    # Force the use of RETURNING with the primary key value,
    # unless it has been disabled.
    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. Always returns nil without inserting a query if disable_insert_returning is used.

# File lib/sequel/adapters/shared/postgres.rb, line 1299
def insert_select(*values)
  return unless supports_insert_select?
  with_sql_first(insert_select_sql(*values))
end
insert_select_sql(*values) click to toggle source

The SQL to use for an insert_select, adds a RETURNING clause to the insert unless the RETURNING clause is already present.

# File lib/sequel/adapters/shared/postgres.rb, line 1306
def insert_select_sql(*values)
  ds = opts[:returning] ? self : returning
  ds.insert_sql(*values)
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 1316
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
supports_cte?(type=:select) click to toggle source
# File lib/sequel/adapters/shared/postgres.rb, line 1332
def supports_cte?(type=:select)
  if type == :select
    server_version >= 80400
  else
    server_version >= 90100
  end
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 1342
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 1347
def supports_distinct_on?
  true
end
supports_insert_select?() click to toggle source

True unless insert returning has been disabled for this dataset.

# File lib/sequel/adapters/shared/postgres.rb, line 1352
def supports_insert_select?
  !@opts[:disable_insert_returning]
end
supports_lateral_subqueries?() click to toggle source

PostgreSQL 9.3rc1+ supports lateral subqueries

# File lib/sequel/adapters/shared/postgres.rb, line 1357
def supports_lateral_subqueries?
  server_version >= 90300
end
supports_modifying_joins?() click to toggle source

PostgreSQL supports modifying joined datasets

# File lib/sequel/adapters/shared/postgres.rb, line 1362
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 1372
def supports_regexp?
  true
end
supports_returning?(type) click to toggle source

Returning is always supported.

# File lib/sequel/adapters/shared/postgres.rb, line 1367
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 1377
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 1382
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 1401
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 1410
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 1420
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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