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.
PREPARED_ARG_PLACEHOLDER | = | LiteralString.new('$').freeze |
Execute the given type of statement with the hash of values.
# File lib/sequel/adapters/postgres.rb, line 412 412: def call(type, bind_vars={}, *values, &block) 413: ps = to_prepared_statement(type, values) 414: ps.extend(BindArgumentMethods) 415: ps.call(bind_vars, &block) 416: end
Yield all rows returned by executing the given SQL and converting the types.
# File lib/sequel/adapters/postgres.rb, line 304 304: def fetch_rows(sql, &block) 305: return cursor_fetch_rows(sql, &block) if @opts[:cursor] 306: execute(sql){|res| yield_hash_rows(res, fetch_rows_set_cols(res), &block)} 307: 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 420 420: def prepare(type, name=nil, *values) 421: ps = to_prepared_statement(type, values) 422: ps.extend(PreparedStatementMethods) 423: if name 424: ps.prepared_statement_name = name 425: db.prepared_statements[name] = ps 426: end 427: ps 428: end
PostgreSQL uses $N for placeholders instead of ?, so use a $ as the placeholder.
# File lib/sequel/adapters/postgres.rb, line 434 434: def prepared_arg_placeholder 435: PREPARED_ARG_PLACEHOLDER 436: 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 324 324: def use_cursor(opts={}) 325: clone(:cursor=>{:rows_per_fetch=>1000}.merge(opts)) 326: end