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 590 590: def call(type, bind_vars={}, *values, &block) 591: ps = to_prepared_statement(type, values) 592: ps.extend(BindArgumentMethods) 593: ps.call(bind_vars, &block) 594: end
Yield all rows returned by executing the given SQL and converting the types.
# File lib/sequel/adapters/postgres.rb, line 481 481: def fetch_rows(sql) 482: return cursor_fetch_rows(sql){|h| yield h} if @opts[:cursor] 483: execute(sql){|res| yield_hash_rows(res, fetch_rows_set_cols(res)){|h| yield h}} 484: 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 598 598: def prepare(type, name=nil, *values) 599: ps = to_prepared_statement(type, values) 600: ps.extend(PreparedStatementMethods) 601: if name 602: ps.prepared_statement_name = name 603: db.set_prepared_statement(name, ps) 604: end 605: ps 606: end
PostgreSQL uses $N for placeholders instead of ?, so use a $ as the placeholder.
# File lib/sequel/adapters/postgres.rb, line 612 612: def prepared_arg_placeholder 613: PREPARED_ARG_PLACEHOLDER 614: 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 501 501: def use_cursor(opts={}) 502: clone(:cursor=>{:rows_per_fetch=>1000}.merge(opts)) 503: end