Class | Sequel::Postgres::Dataset |
In: |
lib/sequel/adapters/postgres.rb
|
Parent: | Sequel::Dataset |
Dataset class for PostgreSQL datasets that use the pg, postgres, or postgres-pr driver.
DatasetClass | = | self |
APOS | = | Sequel::Dataset::APOS |
PREPARED_ARG_PLACEHOLDER | = | LiteralString.new('$').freeze |
Execute the given type of statement with the hash of values.
# File lib/sequel/adapters/postgres.rb, line 728 728: def call(type, bind_vars=OPTS, *values, &block) 729: ps = to_prepared_statement(type, values) 730: ps.extend(BindArgumentMethods) 731: ps.call(bind_vars, &block) 732: end
Yield all rows returned by executing the given SQL and converting the types.
# File lib/sequel/adapters/postgres.rb, line 624 624: def fetch_rows(sql) 625: return cursor_fetch_rows(sql){|h| yield h} if @opts[:cursor] 626: execute(sql){|res| yield_hash_rows(res, fetch_rows_set_cols(res)){|h| yield h}} 627: end
Prepare the given type of statement with the given name, and store it in the database to be called later.
# File lib/sequel/adapters/postgres.rb, line 736 736: def prepare(type, name=nil, *values) 737: ps = to_prepared_statement(type, values) 738: ps.extend(PreparedStatementMethods) 739: if name 740: ps.prepared_statement_name = name 741: db.set_prepared_statement(name, ps) 742: end 743: ps 744: end
PostgreSQL uses $N for placeholders instead of ?, so use a $ as the placeholder.
# File lib/sequel/adapters/postgres.rb, line 750 750: def prepared_arg_placeholder 751: PREPARED_ARG_PLACEHOLDER 752: end
Uses a cursor for fetching records, instead of fetching the entire result set at once. Can be used to process large datasets without holding all rows in memory (which is what the underlying drivers do by default). Options:
Usage:
DB[:huge_table].use_cursor.each{|row| p row} DB[:huge_table].use_cursor(:rows_per_fetch=>10000).each{|row| p row}
This is untested with the prepared statement/bound variable support, and unlikely to work with either.
# File lib/sequel/adapters/postgres.rb, line 644 644: def use_cursor(opts=OPTS) 645: clone(:cursor=>{:rows_per_fetch=>1000}.merge(opts)) 646: end